Fatty Alcohols
1
Fatty Alcohols Klaus Noweck ,
1. 2. 2.1. 2.1. 2.2. 2.2. 2.3. 2.3. 2.3. 2.3.1. 1. 2.3.2.
2.3.3. 2.3.3. 2.3.3.1. 2.3.3.1. 2.3.3.2. 2.3.3.2. 2.4. 2.4.1. 2.4.1. 2.4. 2.4.2. 2.
Condea Chemie GmbH, Brunsb¨ Brunsbuttel, u¨ ttel, Federal Republic of Germany
Introduction . . . . . . . . . . . . . . Saturated Fatty Alcohols . . . . . . Physi ysical Prope opertie ties . . . . . . . . . . Chem Chemiical Prope opertie ties . . . . . . . . . Prod Produc ucti tion on from from Natu Natura rall Sour Source cess Hydr Hydrol olys ysis is of Wax Este Esters rs . . . . . . Reduction of Wax Esters with Sodium . . . . . . . . . . . . . . . . . . Hydrog Hydrogena enatio tion n of Natura Naturall Raw Raw Materials . . . . . . . . . . . . . . . . . . . Raw Material Materialss and Pretreat Pretreatment ment . . Hydrogenat Hydrogenation ion Processes Processes . . . . . . Synthesis from Petrochemical Feedstocks . . . . . . . . . . . . . . . Ziegle Zieglerr Alcoho Alcoholl Proces Processes ses . . . . . . Oxo Oxo Proc rocess . . . . . . . . . . . . . . .
1 2 2 2 2 4 4 5 5 6 9 9 10
1. Introduction Fatty alcohols are aliphatic alcohols with chain lengths between C 6 and C22 : CH3 (CH2 ) CH2 OH ( n = 4 – 2 0 ) n
They are predominantly linear and monohydric, and can be saturated or have one or more double double bonds. bonds. Alcoho Alcohols ls with with a carbon carbon chain chain length length above above C22 are referr referred ed to as wax wax alalcohols. Diols whose chain length exceeds C 8 are regarded as substituted fatty alcohols. The character of the fatty alcohols (primary or secondary, linear or branched-chain, saturated or unsaturated) is determined by the manufacturing process and the raw materials used. Natural products, such as fats, oils, and waxes, and the Ziegler alcohol process provide linear, primary, and even-numbered alcohols; those obtain tained ed from from natu natura rall sour source cess may may be unsa unsatu tu-rated. rated. In contra contrast, st, the oxo process process yields yields 20 – 60 % branch branched ed fatty fatty alcoho alcohols, ls, and also some some odd-numbered ones. Guerbet dimerization results in α-branched, primary alcohols, whereas Bashkirov oxidation yields secondary alcohols. Depending on the raw materials used, fatty alcohols are classified as natural or synthetic. c 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a10 277
2.4. 2.4.3. 3.
2.4. 2.4.4. 4. 2.4. 2.4.5. 5. 2.5. 3. 4. 5. 6. 7. 8. 9. 9.1. 9.1. 9.2. 10.
Hydr Hydrog ogen enat atio ion n of Fatt Fatty y Aci Acids ds ProProduced duced by Oxidat Oxidation ion of Paraf Paraffini finicc Hydrocarbons . . . . . . . . . . . . . . . . Bash Bashki kiro rov v Oxid Oxidat atio ion n . . .. . .. . . Othe Otherr Proc Proces esse sess . . . . . . . . . . . . Uses . . . . . . . . . . . . . . . . . . . Unsa Unsatu tura rate ted d Fatty atty Alco Alcoh hols ols . . . . Guerbet Alcohols . . . . . . . . . . . Bifu Bifun ncti ctional onal Fatty atty Alcoh lcohol olss . . . . Quality Specifications . . . . . . . . Stor Storag agee and and Tran ranspor sporta tati tion on . . . . Economic Aspects . . . . . . . . . . Ecot Ec otox oxiicol cology ogy and and Toxi oxicol cology ogy . . Ecot Ecotox oxic icol olog ogy y and and En Envi virronme onment ntal al Aspects . . . . . . . . . . . . . . . . . Toxicology . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . .
11 12 12 13 14 15 17 19 20 21 22 23 23 24
Natural fatty alcohols are based on renewable resources such as fats, oils, and waxes of plant or animal origin, whereas synthetic fatty alcohols are produced from petrochemicals such as olefins olefins and paraffins paraffins.. Up to 1930, 1930, when when catcatalytic high-pressure hydrogenation was developed Adkins and Folker [7], Norman [8], Schrauth [9], and Schmidt [10], the manufacture of fatty alcohols was based almost most excl exclus usiv ivel ely y on the the spli splitt ttin ing g of sper sperm m oil. oil. By 1962, the world production capacity from natural raw raw material materialss had grown grown to ca. 200 000 t/a. t/a. New processes utilizing petrochemical raw material terials, s, e.g., e.g., the Ziegle Zieglerr alcoho alcoholl proces process, s, the SHOP process, the oxo process, and the construction of additional plants for high-pressure hydrogenation of natural raw materials, allowed a further increase. In 1999, the world nameplate production capacity of fatty alcohols was estimated to be 2 × 106 t/a, being nearly equally based on natural and petrochemical feedstocks. Production and consumption were estimated to amount amount to only 80 – 90 % of the capac capacity ity.. Fatty Fatty alcohols and their derivatives are used in polymers, surfactants, oil additives, and cosmetics and have many specialty uses.
2
Fatty Alcohols
2. Saturated Fatty Alcohols 2.1. Physical Properties Satura Saturated ted fatty fatty alcoho alcohols ls up to dodec dodecano anoll are clear clear,, colorl colorless ess liquid liquids. s. The next next higher higher homologues are soft materials; tetradecanol and higher alcohols have a waxy consistency. The satura saturated ted alcoho alcohols ls crysta crystalli llize ze in a nearly nearly ororthor thorho homb mbic ic latt lattic icee [11] [11] and and all all have have a lowe lowerr spespecific density than water. The lower members of the series have characteristic odors; the higher fatty alcohols are odorless, except for traces of impurities such as carbonyl compounds and hydrocarbons, which are usually present. Physic Physical al proper propertie tiess of linear linear,, primar primary y fatty fatty alcoho cohols ls are are summ summar ariz ized ed in Table able 1 (for (for addi additi tion onal al data on pure alcohols and commercially important blends, see [12–15]). Boiling points and melting points increase uniformly with chain length. Both are significantly higher than those of the hydrocarbons with the same number of carbon atoms. The influence influence of the polarizing polarizing hydroxyl function diminishes with increasing chain length. Thus hexanol and even octanol show some water solubility, but decanol and the higher fatty alcohols can be considered as immiscible with water. ter. Howe Howeve verr, a slight slight hygros hygroscop copici icity ty is observ observed ed even even with with octade octadecan canol ol and higher higher fatty fatty alcoho alcohols, ls, which can absorb water vapor from air during storage. Common organic solvents such as petroleum ether, lower alcohols, and diethyl ether are suitable solvents for fatty alcohols.
2.2. Chemical Properties The industrial importance of the fatty alcohols is due due to the the larg largee numb number er of reac reacti tion onss that that the hydroxyl hydroxyl group may undergo. undergo. Figure 1 lists some typical examples (see also → Alcohols, Alipha Aliphatic tic,, Chap. Chap. 2.2.); 2.2.); many many of the result resulting ing derivatives are intermediates of commercial importance (see Section 2.5). Ethoxylation with ethylene oxide yields fatty alcohol polyglycol ethers ethers,, which which are of high high import importanc ancee for the detergent industry (→ Laundry Laundry Detergents, gents, Chap. 3.1.2.; 3.1.2.; → Surfactants):
Under normal conditions, fatty alcohols are resist resistant ant to oxidat oxidation ion.. Howe Howeve verr, they they can be conconverted into aldehydes or carboxylic acids using stro strong ng oxid oxidan ants ts or by cata cataly lyti ticc oxid oxidat atio ion n with with air air or oxygen oxygen [16–20 [16–20]. ]. This This reacti reaction on is import important ant for the synthesis of C6 – C10 aldehydes if these are not readily available from natural sources [21] and are therefore produced from synthetic alcohols.
2.3. Production from Natural Sources Two grou groups ps of natu natura rall raw raw mate materi rial alss are are used used for for the production of fatty alcohols: (1) fats and oils of plant or animal origin, which contain fatty acids in the form of triglycerides that can be hydrogenated after suitable pretreatment ( → Fats and Fatty Oils, Oils, Chap. 6.) to yield fatty alcohols; alcohols; and (2) wax esters from whale oil ( sperm oil), from which the fatty alcohols are obtained by simple simple hydrol hydrolysi ysiss or reduct reduction ion with with sodium sodium.. The commercial exploitation of sperm oil has led to depletion of whale populations and is banned in some countries. Attention has therefore turned to the jojoba plant whose oil also consists of wax esters. Successful attempts to cultivate this desert shrub and develop it as a source of raw mate materi rial al have have been been made made.. But But this this wax wax is main mainly ly used used in cosm cosmet etic ic appl applic icat atio ions ns in a smal smalll amou amount nt.. Most fatty chemicals obtained from natural sources have chain lengths of C 16 – C18 . The limited limited availab availability ility of compounds compounds with 12 – 14 carbon atoms, which are important in surfactants, was one of the driving forces behind the deve develop lopmen mentt of petroc petrochem hemica icall proces processes ses as well well as the intens intensific ificati ation on of planta plantatio tion n and the breedbreeding ing of new new crop cropss for for the the prod produc ucti tion on of fatt fatty y alco alco-hols (see Section 2.4). Higher alcohols, such as C20 – C22 alcohols, can be produced from rapeseed oils rich in erucic acid and fish oils. Unsaturated fatty alcohols may be manufactured in the presence of selective catalysts. Hydroxyacids for production of diols are available from castor oil. For detailed reviews reviews of large-scale industrial processes for the production of fatty alcohols, see [1], [22], [23]. 2.3.1. Hydrolysis of Wax Esters
The hydrolysis of wax esters is of only limited importance today. It is carried out by heating
Fatty Alcohols
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3
4
Fatty Alcohols
Figure 1. Typical reactions of fatty alcohols
sperm oil with concentrated sodium hydroxide at ca. 300 ◦ C and distilling the alcohol from the sodium soap.
The distillate consists of partially unsaturated C16 – C20 alcohols, which are hardened by catalytic hydrogenation to prevent autoxidation. Since sperm oil contains only ca. 70 % wax esters, the alcohol yield is about 35 %.
2.3.2. Reduction of Wax Esters with Sodium
The reduction of esters with sodium was first described in 1902 by Bouveault and Blanc (for a review, see [24]). Large-scale application of this process was achieved in 1928 (Dehydag).
Molten sodium is dispersed in an inert solvent and the carefully dried ester and alcohol are added. When the reaction is complete, the alkoxides are split by stirring in water, and the alcohols are washed and distilled [25]. The added alcohol R 3 OH, preferably a secondary alcohol, acts as a hydrogen donor. Because of side reactions, the consumption of sodium can be as much as 20 % above the stoichiometric requirement. The reduction proceeds selectively without production of hydrocarbons and isomerization or hydrogenation of double bonds. Extensive safety measures are required due to the large quantity of metallic sodium used. The process was used until the 1950s to produce unsaturated fatty alcohols, especially oleyl alcohol from sperm oil. These alcohols can now be produced by selective catalytic hydrogenation processes using cheap raw materials, and the sodium reduction process is of interest only in special cases. A fully continuous plant with a production capacity of 3600 t/a was built in Japan in 1973 for the reduction of sperm oil [26].
Fatty Alcohols 2.3.3. Hydrogenation of Natural Raw Materials 2.3.3.1. Raw Materials and Pretreatment
For the production of C12 – C14 alcohols, only coconut oil and palm kernel oil can be used. Palm oil, soybean oil, and tallow are the main sources for C16 – C18 alcohols. Rapeseed oil rich in erucic acid yields fatty alcohols with 20 or 22 carbon atoms. Bifunctional fatty alcohols can be obtained from castor oil and other special oils (see Chap. 5). More than 90 % of the vegetable oils are used in food applications. Before hydrogenation, contaminants such as phosphatides, sterols, or oxidation products and impurities such as seed particles, dirt, and water are removed in a cleaning stage, which includes refining with an adsorption agent ( → Fats and Fatty Oils, Chap. 6.). The refined triglycerides are then hydrolyzed to yield fatty acids ( → Fatty Acids) or transesterified with lower alcohols to yield fatty acid esters. Both refined free fatty acids and fatty acid esters (mostly methyl esters and, more rarely, butyl esters) are used for hydrogenation. Direct hydrogenation of triglycerides is also possible; however, under the reaction conditions, glycerol is reduced to propylene glycol and propanol and therefore makes no commercial contribution as a byproduct. More hydrogen is needed and catalyst costs increase. Therefore, triglyceride hydrogenation is not used industrially. Fatty acid esters are produced either by esterification of free fatty acids or by transesterification of triglycerides (see also → Esters, Organic). Esterification of Fatty Acids. Esterification is an equilibrium reaction:
5
acid number (milligrams of KOH needed to neutralize one gram of substance) is used as a quality characteristic and for process control. Batch and continuous processes give esters of similar quality, but the continuous process uses less methanol and the residence time is reduced. The methyl ester is subsequently distilled for purification. Transesterification of Triglycerides. This reaction is carried out continuously with alkaline catalysts. Like esterification, transesterification is an equilibrium reaction and is shifted toward the desired ester by excess methanol or removal of glycerol:
If the reaction is carried out under mild conditions (50 – 70 ◦ C, atmospheric pressure, excess methanol), free fatty acids present in the oils must first be removed or pre-esterified, e.g., with glycerol. Under more severe conditions (i.e., at 9 – 10 MPa and 220 – 250 ◦ C), pre-esterification is unnecessary, and less pure, cheaper raw materials can be used. Disadvantages of this process are the need for high-pressure equipment, a greater excess of methanol, and the energy-intensive further processing of the aqueous methanol. The methyl esters are purified by distillation. Figure 2 demonstrates the production tree of physical and chemical processing of fats and oils. 2.3.3.2. Hydrogenation Processes
Three large-scale hydrogenation processes are used commercially: Excess alcohol or removal of water shifts the equilibrium toward ester formation. Industrial esterification is carried out in a column at 200 – 250 ◦ C under slight pressure and with excess methanol. Distilled fatty acids, which no longer have the composition of the original natural product, are predominantly used. Methanol reacts with the fatty acid in a countercurrent. The
1) Gas-phase hydrogenation 2) Trickle-bed hydrogenation 3) Suspension hydrogenation The first two processes use a fixed-bed catalyst. In contrast to the gas-phase and the tricklebed hydrogenation the suspension process uses a powdered catalyst with a specific particle size distribution. The selection of a process depends
6
Fatty Alcohols
Figure 2. Physical and chemical processing of fats and oils
on the integration into existing plants and the choice of raw materials. In all cases, hydrogenation is carried out with copper-containing, mixed-oxide catalysts at 200 – 300 ◦ C and 20 – 30 MPa. Oleofina/B uses a proprietary fixed bed catalyst which operates at 170 – 250 ◦ C and < 10 MPa [27]. Suspension Hydrogenation. This process is applicable to fatty acid methyl esters as well as to fatty acids. Hydrogen (ca. 50 mol per mole of ester) and the heated methyl ester are fed separately into the bottom of a narrow reactor. The reaction is carried out at ca. 25MPa and 250– 300 ◦ Cinthe presence of a fine powdery copper catalyst; the LHSV (liquid hourly space velocity) is approximately 1. The excess hydrogen serves to circulate the reaction mixture. The product mixture is separated into a gas phase, which is recycled to the reactor, and a liquid phase, from which the methanol is stripped. The crude product, which still has a saponification number of 6 – 10 (milligrams of KOH required to saponify one gram of substance), is distilled off after removal of the catalyst. If a stainless steel reactor is used, this process can be applied to the direct hydrogenation of fatty acids. In this case, an acid-resistant
catalyst is required, and catalyst consumption is increased. A variant that is particularly suitable for the hydrogenation of fatty acids has been developed by Lurgi (Fig. 3) [28], [29] and is used by several manufacturers, including Condea Chemie [30]. This process employs a large excess of fatty alcohol in the hydrogenation reactor. Hydrogen, fatty alcohol – catalyst slurry, and fatty acids are fed separately into the reactor; the ester forms almost instantaneously [31] and is then hydrogenated in the same reactor in a slower, second reaction step. Hydrogenolysis is carried out at ca.30 MPa and 260 – 300 ◦ C. Catalyst consumption is 5 – 7 kg/t fatty acid. The catalyst is separated by centrifugation, and the crude fatty alcohol, which has an acid number of < 0.1 and a saponification number of 2 – 5, is purified by distillation. The selectivity of the process is > 99%. By continuously replacing part of the spent catalyst, the activity of the copper chromite contact can be held constant. Gas-Phase Hydrogenation. This process requires a vaporized substrate and is therefore particularly suitable for methyl esters, preferably with a chain length of 12 – 14 C-atoms. Figure 4 shows a simplified flow diagram of the process. Characteristics of the process are an ex-
Fatty Alcohols
7
Figure 3. Suspension hydrogenation of fatty acids (Lurgi process) a) Reactor; b) Heater; c) Hot separator; d) Cold separator; e) Flash drum; f) Catalyst separation
tremely large excess of recycle gas (ca. 600 mol of H 2 per mole of ester), high gas velocities and the addition of methanol to aid evaporation [32], [33]. Decomposition of methanol creates significant quantities of carbon monoxide, water, and dimethyl ether. Admixture of an inert gas to the hydrogen is claimed to make the addition of methanol superfluous and to reduce the excess of recycle gas [34]. Catalysts like copper-zinc or copper-chrome mixed oxides are used in a fixed bed. The conditions required are < 10 MPa pressure and 230 – 250 ◦ C, with an LHSV of about 0.3. Alcohol yields of > 99 % are achieved. Catalyst consumption is about 0.3 % based on the feed. The product mixture is separated into a gas and a liquid phase; the hydrogen is recycled and the methanol stripped from the fatty alcohol. New developments of, e.g., Davy McKee (DE 439 5501). A 30 000 t/a unit has been constructed by Prime Chem, Philippines. Trickle-Bed Hydrogenation. In this process, the products to be reduced are used in their liquid form. The process is therefore also suitable for non-vaporizable substrates such as wax esters and fatty acids. Corrosive effects of acids can be neutralized by hydrogenation in the presence of amines [35]. If a considerably lower excess of recycle gas (ca. 100 mol of H 2 per mole of ester) is used, a different plant design is necessary. The reaction is carried out at 20 – 30 MPa
and about 250 ◦ C, with an LHSV of ca. 0.2. Normally, catalysts based on copper, chromium- or copper-zinc mixed oxides are employed. More rarely, supported catalysts such as copper chromite on silica are used. Catalyst consumption is about 0.3 % based on the feed. Further treatment of the product is identical to that described for gas-phase hydrogenation (see Fig. 4). Comparison of Hydrogenation Processes. In the case of the fixed-bed processes (gasphase and trickle-bed hydrogenation), the catalyst need not be separated from the crude fatty alcohol. However, a gradual decrease in the hydrogenating activity due to catalyst poisons such as sulfur, phosphorus, or chlorine is observed, whereas continuous replacement of the catalyst in the suspension process ensures constant activity. If methyl esters are employed, separation and further processing of the methanol is necessary. Catalysts that contain noble metals, especially rhenium, may allow hydrogenation at lower pressures, which would reduce capital and operating costs [36–38]. Further modifications of the processes were developed by Metallgesellschaft (DE 93-4343320) and Davy McKee/Kvaerner (DE 4395501) using wax esters as feed.
8
Fatty Alcohols
Figure 4. Flow diagram of the gas-phase and trickle-bed hydrogenation of fatty acid methyl esters a) Heater; b) Reactor; c) Cooler; d) Separator; e) Flash drum
2.4. Synthesis from Petrochemical Feedstocks
2) Ethylation
2.4.1. Ziegler Alcohol Processes
Two processes for the production of synthetic fatty alcohols are based on the work of Ziegler on organic aluminum compounds: the Alfol process, developed by Conoco, and Ethyl Corporation’s Epal process [39], [40]. Fatty alcohols synthesized by these processes are structurally similar to natural fatty alcohols and are thus ideal substitutes for natural products. Conoco started the first Alfol plant in the United States in 1962. This plant is now operated by Condea Vista. In 1964 Condea Chemie installed a similar plant in Brunsbu¨ ttel, Federal Republic of Germany. Ethyl Corporation (today BP/Amoco) developed its own process (Epal process) and began operations in 1964. Additional Alfol alcohol plants were built in Ufa/ Russia in 1981 and in Jilin/ China in 1998. Alfol Process. Figure 5 shows a simplified diagram of the Alfol process [41]. A hydrocarbon is used as solvent. The process involves five steps: hydrogenation, ethylation, growth reaction, oxidation, and hydrolysis.
1) Hydrogenation
3) Growth Reaction
4) Oxidation
5) Hydrolysis
Two-thirds of the triethylaluminum produced in the ethylation reaction (b) are recycled to the hydrogenation stage (a), and one-third enters the growth reaction (c). Insertion of the ethylene molecule into the aluminum – carbon bonds occurs as a statistical process and leads to a broad distribution (Poisson distribution [42], [43]) of
Fatty Alcohols
9
Figure 5. Alfol alcohol process
chain lengths, ranging from C 2 to beyond C 26 [41]. An optimal yield of the C12 – C14 alcohols, which are important in the surfactant sector, requires addition of about four molecules of ethylene per aluminum – carbon bond (see also Table 2). A small percentage of olefins are formed as byproducts. Table 2. Typical alcohol distributions in Alfol and Epal processes
Distribution, % Alcohol
Alfol process
Epal process
Ethanol Butanol Hexanol Octanol Decanol Dodecanol Tetradecanol Hexadecanol Octadecanol Eicosanol Docosanol
0.5 3.4 9.5 16.1 19.5 18.4 14.1 9.1 5.1 2.5 1.1
traces 0.1 1.5 3.5 8.0 34.0 26.0 16.0 8.8 1.9 0.2
Because of the varying reactivity of partially oxidized trialkylaluminum compounds, oxidation is carried out stepwise by passing through carefully dried air. Cooling is necessary, especially at the start of the reaction. Alkanes and oxygen-containing compounds are formed as byproducts [39]. Prior to hydrolysis, the solvent is removed by distillation. Hydrolysis with water gives highpurity hydrated alumina ( Pural by Condea, Catapal by Condea Vista) as a coproduct, which has many industrial applications, e.g., in catalytic processes (→ Aluminium Oxide, Chap. 6.2.3.) and in ceramics. In the 1960s, hydrolysis was carried out with hot sulfuric acid at Conoco’s and Ethyl Corporation’s plants. Conoco changed to neutral hydrolysis, but the sulfuric acid method is still used in the Epal process and leads to
high-purity aluminum sulfate as a coproduct. The crude alcohols are finally fractionated into marketable blends and single cuts. Epal Process (see Fig. 6). Many attempts have been made to achieve a narrower distribution of chain lengths in the growth reaction [40]. The only process that has been used on an industrial scale is the Epal process developed by the Ethyl Corporation (today BP/Amoco). The reaction steps resemble those of the Alfol process, but the growth reaction is not carried as far. The product of the growth reaction is subjected to transalkylation (290 ◦ C, 3.5 MPa) with C4 – C10 olefins. The chain lengths of the resulting trialkylaluminum compounds are predominantly C4 – C10 . Excess olefins are removed in a stripping column and then fractionated. The trialkylaluminum compound is subjected to a second growth reaction and then transalkylated (200 ◦ C, 35 kPa) with C12 – C18 olefins. Again the olefins are separated in a stripper and fractionated. At this stage, the trialkylaluminum compound consists largely of alkyl chains with 12 – 18 carbon atoms. The alcohol distributions achieved in the Epal and Alfol processes are shown in Table 2 [44]. The Epal process offers greater flexibility than the Alfol process because both the alcohols and the α-olefins that are formed as intermediates can be marketed [45]. Disadvantages of the Epal process are the higher capital and operating costs, a considerably more complicated process control, and an increased proportion of branched-chain olefins and alcohols. 2.4.2. Oxo Process
The oxo process (hydroformylation) consists of the reaction of olefins with an H 2 – CO gas mixture in the presence of suitable catalysts. This
10
Fatty Alcohols
Figure 6. Flow diagram of the Epal process
reaction was discovered in 1938 by O. R oelen at Ruhrchemie during work on the Fisher – Tropsch synthesis. Although the first production plant was constructed before 1945 [46], the oxo process achieved industrial importance only in the 1950s, with the increasing demand for plasticizers and detergents. The process is based on the following reaction (for details on the reaction mechanism, see [47] and → Oxo Synthesis):
α-Olefins yieldapproximately equal amounts
of straight-chain and branched aldehydes (see also Fig. 11). Internal and branched alkenes can also be used in this reaction. Internal olefins give a product containing some primary aldehyde because the catalyst effects double-bond isomerization. For a long time paraffin-based processes were predominant as a source of olefins, especially for detergents [45], [54]. With the development of the SHOP process ( Shell’s Higher Olefin Process), ethylene has become the preferred raw material [55]. The principal steps in the SHOP process are ethylene oligomerization, isomerization, and metathesis ( → Hydrocarbons). The products are C12 – C18 α-olefins and C11 – C14
internal olefins, which are all important in the area of surfactants [56], [57]. Heterogeneous hydrogenation of the oxo aldehydes at 5 – 20 MPa and 150 – 250 ◦ C in the presence of catalysts based on nickel, molybdenum, copper, or cobalt yields the corresponding alcohols. Alternatively, the aldehyde can be sub jected to an aldol reaction as in the production of 2-ethylhexanol (→ 2-Ethylhexanol, Chap. 3.). A flow sheet of the oxo process is depicted in Figure 7. Worldwide there are three variants of the oxo process [49]: (1) the classical process using HCo(CO)4 as catalyst; (2) the Shell process based on a cobalt carbonyl – phosphine complex [48]; and (3) a process using a rhodium catalyst. The key parameters of these processes are compared in Table 3. The classical, cobalt-catalyzed oxo process involves the following steps: oxo reaction, catalyst separation and regeneration, aldehyde hydrogenation, and alcohol distillation. Variants of this process differ mainly in the catalyst separation and regeneration steps [50], [51]. In the Shell process, alcohols are obtained directly because of the greater hydrogenating activity of the catalyst; the aldehyde hydrogenation step is unnecessary. Linearity is improved and the 2-methyl isomer is the main byproduct. A disadvantage is the loss of olefins due to hydrogenation to alkanes.
Fatty Alcohols
11
Table 3. Typical process parameters of the oxo processes
Parameter
Oxo process Classical
Shell
Union Carbide
Catalyst
cobalt carbonyl
Catalyst concentration, % CO : H2 ratio Temperature, C Pressure, MPa LHSV∗ Primary products Linearity, %
0.1 – 1.0 1 : 1 – 1.2 150 – 180 20 – 30 0.5 – 1.0 aldehydes 40 – 50
cobalt carbonyl –phosphine complex ca. 0.5 1 : 2 – 2.5 170 – 210 5 – 10 0.1 – 0.2 alcohols 80 – 85
rhodium carbonyl – phosphine complex 0.01 – 0.1 excess hydrogen 100 – 120 2–4 0.1 – 0.25 aldehydes ca. 90 (n-butanol)
◦
∗ Liquid hourly space velocity
Hydroformylation based on a rhodium catalyst has been used by Union Carbide since the 1970s for the production of n-butanol and 2ethylhexanol [52]. The higher activity of the catalyst enables operation at lower temperature and pressure. For butanol, the linearity is over 90 %. The disadvantage is the high price of rhodium. For a review of the oxo synthesis, see [53].
2.4.3. Hydrogenation of Fatty Acids Produced by Oxidation of Paraffinic Hydrocarbons
The process for the oxidation of paraffinic hydrocarbons, developed in Germany before 1940, is used on an industrial scale in the Comecon countries, particularly in the former Soviet Union, for the manufacture of fatty acids. About 5 – 10 % of these synthetic fatty acids are converted to fatty alcohols. The products are mainly linear, primary alcohols, with 5 – 15 % branched alcohols. An overview is given in [58]. A mixture of paraffins is oxidized above 100 ◦ C in the presence of manganese catalysts. The complex product mixture consists of aldehydes, ketones, esters, carboxylic acids, and other compounds. Since the byproducts cannot be completely removed during further processing and distillation of the carboxylic acids, the uses of fatty alcohol produced by this method are limited. As with the natural fatty acids, hydrogenation is carried out after esterification with methanol or butanol. The suspension hydrogenation process is used (see page 6). The distillation residue contains esters of C10 – C20 alco-
hols, 25 % of which are secondary. These alcohols can be obtained by hydrolysis.
2.4.4. Bashkirov Oxidation
A variant of paraffinic hydrocarbon oxidation was developed in the 1950s in the Soviet Union by Bashkirov [1], [3]. The paraffins are oxidized in the presence of boric acid, which scavenges the hydroperoxides that are formed as intermediates. This results in the formation of boric acid esters of secondary alcohols. These esters are relatively stable to heat and oxidation. Hydrolysis leads to a statistical distribution of secondary alcohols in which the hydroxyl function may occupy any position on the carbon chain. Industrial oxidation is carried out at about 160 ◦ C with a nitrogen – air mixture containing about 3.5 % oxygen [59], [60] (→ Alcohols, Aliphatic, Chap. 2.3.6.). The conversion of paraffins is limited to a maximum of 20 % in order to minimize side reactions. The principle reaction steps are depicted in Figure 8. The process is used in the former Soviet Union and in Japan (Nippon Shokubai). A plant operated by Union Carbide in the United States since 1964 is closed.
2.4.5. Other Processes
Fatty alcohols can also be obtained by reaction of α-olefins with hydroperoxides in the presence of transition-metal catalysts, especially molybdenum [62]:
12
Fatty Alcohols
Figure 7. Flow diagram of the classical oxo process
Figure 8. Bashkirov oxidation
If tert -butyl hydroperoxide is used, the coproduct isobutanol can be readily separated from the epoxide. After separation of the low molecular mass alcohol and purification, the epoxide is hydrogenolyzed in the presence of a nickel catalyst to form the primary alcohol. About 10 – 15 % of the secondary alcohol and 2 % paraffin are obtained as byproducts [63]. Mixtures of linear, primary alcohols with average molecular masses between 400 and 700 (corresponding to a chain length of 30 – 50 carbon atoms) are marketed by Petrolite under the trade name Unilin [64]. The hydrocarbon content of these mixtures is about 20 %. Petrolite
oxidizes ethylene oligomers to produce oxygencontaining products on an industrial scale [65]. 1-Triacontanol, which does not occur in the common natural raw materials and is produced only in minute quantities in petrochemical processes such as the Alfol process, is of interest because of its ability to stimulate plant growth [66]. Several research groups investigated synthetic pathways based on cheap raw materials [67–72].
2.5. Uses Fatty alcohols are mainly employed as intermediates. In Western Europe, only 5 % are used directly and ca. 95 % in the form of derivatives [73].
Fatty Alcohols Surfactants. The amphiphilic character of fatty alcohols, which results from the combination of a nonpolar, lipophilic carbon chain with a polar, hydrophilic hydroxyl group, confers surface activity upon these compounds. Surfactants account for 70 – 75 % of fatty alcohol production [74]. Due to the their amphiphilic properties fatty alcohols orient themselves at phase interfaces and can therefore be used in emulsions and microemulsions. In cosmetic emulsions (creams, lotions) the main function of the fatty alcohols is to provide consistency, in technical emulsions they are used as cosurfactants and solution aids. If the hydroxyl group of the fatty alcohols is replaced by other, larger hydrophilic groups, the polar character is enhanced and surfactants are obtained [4]. The most important surfactants derived from fatty alcohols are described in the following (see also → Laundry Laundry Detergents, → Surfactants). Alkyl polyglycol ethers, fatty alcohol polyglycol ethers, fatty alcohol ethoxylates, RCH2 (OCH2 CH2 )n OH, were the first nonionic surfactants produced on an industrial scale. They are synthesized in a base-catalyzed reaction. In addition, the fatty alcohol-alkylene oxide adducts have to be mentioned, which are also produced in a base-catalyzed reaction of fatty alcohols, ethylene oxide, and propylene oxide. The latter adducts are low-foaming surfactants. Alkyl sulfates, fatty alcohol sulfates, belong to the group of anionic surfactants and are the longest known synthetic surfactants. In order to synthesize this class of compounds, fatty alcohols are reacted with sulfur trioxide, chlorosulfuric acid, oleum, or sulfuric acid. The resulting semiesters are subsequently neutralized with alkali, mostly aqueous NaOH. Alkyl polyglycol ether sulfates, fatty alcohol ether sulfates, also belong to the group of anionic surfactants. They are produced by reaction of fatty alcohols with ethylene oxide and the resulting adducts are then reacted with sulfur trioxide or chlorosulfuric acid. The subsequent neutralization with caustic soda, ammonia, or ethanolamine. Alkyl methylammonium chlorides belong to the group of cationic surfactants and are produced using fatty alcohols especially in the range of C16 − 18 .
13
prepared Alkylpolyglycosides (APG) are from fatty alcohols and sugars following various procedures. They have a good skin compatibility and, if necessary, can be manufactured from renewable raw materials only. However, high production costs are usually a limiting factor for their application. Other Uses. In addition, the polar character of the fatty alcohols allows their use as lubricants. Esters of fatty alcohols with fatty acids, the so-called wax esters, e.g., as lubricants in polymer processing and as raw materials for waxes and creams in technical applications. Esters are used also in cosmetic applications, however, here usually liquid products on the basis of unsaturated fatty alcohols and/or fatty acids are preferred. Acrylic and methacrylic acid esters of fatty alcohols are precursors of polymethacrylates, which are utilized as flow enhancer and viscosity index improvers in oils. Fumaric acid esters have similar applications. Esters of adipic, acelaic, sebacic, trimellitic, citric, and phthalic acid are used as plasticizers for PVC. The various specific applications of specialty plasticizers are based on their chemical structure, their high cold flexibility, compatibility, high thermostability, high aging stability, and low fogging-values in the finished product. Each of the mentioned esters offers special chemical and physical properties for the different application areas. A further high volume application is in the area of fragrances and flavors. Aldehydes, esters, or alkyl groups on the basis of fatty alcohols are sometimes incorporated into more complex molecules like cinnamon aldehyde. Important for this application are high-purity single cuts which can be processed into these products without any loss in quality. Alcohols with a chain length of C 8 − 10 are used as so-called tobacco sucker control agents in the cultivation of tobacco. Especially fatty alcohols with chain lengths ≥ C18 – either in an emulsified form or as derivatives – are suitable for protection of water reservoirs against evaporation during dry seasons. If fatty alcohols are emulsified with interfaceactive substances, the resulting emulsion can be applied to the water surfaces. The layer, which is formed fast and easily on the water surface, prohibits the evaporation and therefore protects
14
Fatty Alcohols
the water reserves. Field tests in Europe and in Africa have proved the effectiveness. The evaporation can be reduced to up to 50 %. The same higher fatty alcohols can also be used as defoamer systems for papers to be produced in modern, fast operating paper machines. Products on the basis of fatty alcohols show the following advantages compared to silicon-based defoamers: high effectiveness, good biodegradability, good drainage and deaeration, water recycling, and high cost effectiveness. Each paper quality and each production facility demands different defoamer qualities, which contain emulsifiers and additives in addition to the alcohol.
3. Unsaturated Fatty Alcohols fatty alcohols are special products and can only be obtained from natural sources; petrochemical processes for their manufacture do not exist. Unsaturated fatty alcohols contain at least one olefinic group in addition to the hydroxyl function. Therefore they can react both as alcohols and as olefins. The physical properties of the most important unsaturated fatty alcohols are listed in Table 4. The melting points are below those of the corresponding saturated alcohols and are influenced by the configuration of the double bond. Production. The first large-scale hydrogenation plant (Henkel) went into operation in the late 1950s. Previously, unsaturated fatty alcohols could be obtained only by hydrolysis of whale oil (Section 2.3.1) or by the Bouveault – Blanc reduction (Section 2.3.2). Today, a broad range of raw materials based on animal or vegetable fats and oils are available. Both market factors and the degree of unsaturation (iodine number) required in the final product influence the selection. For products with iodine numbers around 50, cheap beef tallow or vegetable raw materials are available. Products with iodine numbers of 80 – 100 can be produced from technical oleic acid (animal or vegetable based). Polyunsaturated products are undesirable as they tend to autoxidation. For special applications products with higher iodine numbers ( > 110) based on
sunflower or soybean oils are produced. Unsaturated alcohols with iodine numbers > 150 are produced, e.g., from linseed oil. The hydrogenation processes described in Section 2.3.3.2 are suitable for the large-scale production of unsaturated fatty alcohols. The fixed-bed processes are preferred because of the mild reaction conditions. In suspension hydrogenation, the prolonged contact between fatty alcohol and catalyst results in side reactions such as saturation of the double bond and formation of trans isomers, which leads to a higher solidification point and, hence, loss of quality. With polyunsaturated fatty acids, the formation of conjugated double bonds cannot be completely prevented. Hydrogenation is generally carried out at 250– 280 ◦ Candapressureof20–25MPa.Catalysts include zinc oxide in conjunction with aluminum oxide, chromium oxide, or iron oxide, and possibly other promoters [81–86]; copper chromite whose activity has been reduced by the addition of cadmium compounds; and cadmium oxide on an alumina carrier [87]. Selective hydrogenation can also be carried out in a homogeneous phase with metallic soaps as catalysts. An overview of early catalyst developments is given in [75]; further references can be found in [76–80]. Patent applications of the 1980s indicate great interest in selective catalysts [88–93]. Unsaturated fatty alcohols are produced in the Federal Republic of Germany (Henkel, Salim) and in Japan (New Japan Chemical). Uses. Unsaturated fatty alcohols are used in detergents, in cosmetic ointments and creams, as plasticizers and defoamers and in textile and leather processing [23], [94–96]. Oleyl alcohol is also used as an additive in petroleum and lubricating oils.
4. Guerbet Alcohols Condensation of primary alcohols at 180 – 300 ◦ C in the presence of alkaline condensation agents leads to primary, a-branched dimeric alcohols. The difference in structure between Guerbet and other branched fatty alcohols is shown in Figure 9. The physical and chemical properties of Guerbet alcohols are listed in Table 5.
Fatty Alcohols
e v i t ) c a C r x e f e d , t n ( R i
) ) ) ) ) 0 0 0 0 5 2 ( 2 ( 4 ( 2 ( 2 ( 9 6 2 2 5 0 0 5 8 7 5 6 5 7 7 4 . 4 . 4 . 4 . 4 . 1 1 1 1 1
, y ) t i C s 3 n m c t e / , D g (
) ) ) ) ) ) 5 0 0 0 5 3 1 ( 2 ( 2 ( 2 ( 2 ( 3 ( 5 9 8 2 8 6 9 8 8 1 0 1 4 4 3 6 7 4 8 . 8 . 8 . 8 . 8 . 8 . 0 0 0 0 0 0
) a C P k , , p p b (
) ) ) ) 5 0 4 3 . . . 0 . 2 0 ( 1 ( 1 ( ( ) ) 0 ) 4 7 2 3 1 4 5 2 4 . 1 . 4 2 . 1 0 2 2 2 ( – 2 ( – ( – – 3 8 6 3 3 0 8 3 0 1 5 3 4 3 1 2 2 1 1 2 2
◦
◦
◦
) C e v t , i t c ( a r x e f e d n R i ◦
p m
2 7 – 3 5 o . – t 2 7 6 5 − − 3 –
r e e b n i m d u o n I
9 5 5 1 8 8 8 4 9 9 9 8 7 7 1 1 2
C ,
◦
l y r x e o r b d m y u H n
r
M r a l a u l c u e l o m r o M f
s l o h o c l a y t t a f d e t a r u t a s n u y r a m i r p f o s e i t r e p o r p l a c i m e h c d n a l a c i s y h P . 4 e l b a T
) ) ) ) ) ) ) 0 4 5 5 9 7 7 2 ( 2 ( 2 ( 1 ( 1 ( 1 ( 1 ( 7 0 6 0 5 2 6 5 6 7 5 4 8 0 4 4 4 5 5 5 6 4 . 4 . 4 . 4 . 4 . 4 . 4 . 1 1 1 1 1 1 1
) ) 0 0 2 ( 2 ( 3 8 6 2 2 3 8 . 8 . 0 0
) ) ) ) ) 5 . ) 4 0 5 1 7 7 2 2 1 2 1 ( ( ( ( ( 1 ( 2 0 6 9 6 3 5 8 4 2 7 1 3 3 4 3 4 4 8 . 8 . 8 . 8 . 8 . 8 . 0 0 0 0 0 0
3
m c / g , y ) t i s C n e t , D ( ◦
) ) ) 7 3 7 ) 0 1 0 5 0 ) . . 0 . 0 . 3 1 0 0 0 . ( ( ( ( 1 ) 0 7 ) 8 ) ) ) 7 7 5 1 . 7 7 6 7 ) . 2 . 5 . 0 . 3 a ( 0 1 1 1 1 1 C P 1 2 1 2 9 ( ( ( ( ( – – – – . , k 8 7 6 4 5 8 5 4 3 , 7 p p 4 1 1 2 5 7 9 3 6 7 b ( 1 1 1 1 1 1 1 1 1 1
5 4 3 5 – – 4 3 3 5
◦
C ,
◦
p m
9 9 9 1 2 3 3 2 0 0 1 1 7 7 3 2 2 2 2 1 1
6 7 − <
) 7 0 0 . 0 ( 7 0 2 – 3 0 2
6 2 – o t 0 6 0 3 2 2 – – –
) 0 . 2 ( 0 1 3 – 8 0 3
) 3 1 0 . 0 ( 0 8 2 – 0 7 2
9 3 – 8 3
5 4 – 3 4
l y r x e o b r d m 9 1 4 1 2 1 7 8 2 8 7 7 8 0 3 7 2 8 5 3 y u 4 3 5 0 6 3 0 8 7 5 4 3 2 2 1 0 0 9 9 9 H n 5 4 3 3 2 2 2 1 1 1 1 1 1 1 1 1 1
3 . 4 . 4 . 5 . 5 . 6 . 6 . 0 8 8 6 4 4 4 7 6 6 6 6 2 2 1 2 2 2 2 3 3 O O O O O O O 2 6 6 4 2 4 4 2 3 3 3 3 4 4
H H H H H H H 1 8 8 8 8 2 2 1 1 1 1 1 2 2
C C C C C C C
r
M
] ] ] ] ] ] ] 4 r y e r b t s S i m A g u C e r n
) ) 0 0 2 ( 2 ( 2 8 8 2 1 3 4 . 4 . 1 1
6 - 2 - 3 - 4 - 5 - 1 - 6 3 8 2 3 4 8 2 4 2 4 4 4 9 - - - - - - 4 2 3 6 6 6 9 3 1 4 0 0 0 2 6 1 [ 1 [ 5 [ 5 [ 5 [ 6 [ 5 [
e m a n n o m m o C
l l o o h l l o h l o h o o o l h c c o l o l c a h h o o a c l c o l a l l l c a l y y a l d n y a l i y l e l e l l d y s s y o o c e i u a a i n i n r l r l o e l l e b
e m a n C A P U I
l o 1 l n e o - i r 1 - t a n e c e i d l l d a l l o o a t - - c c o - o 1 e O 1 1 - d - 1 l n n o n a n e t - e e e c c 5 c 1 1 s s , o o - e e n d d O - 2 c c 1 e a a , o o 2 t c t 9 e c c 1 D , ) - D d O - 9 - O 3 3 n 9 ) Z , 9 1 1 U - Z - ) - ) - ) , Z , ) 0 Z E Z 1 ( ( ( Z ( Z ( E (
8 3 9 4 9 5 0 6 1 7 2 7 3 8 4 9 5 1 6 2 1 . 2 . 2 . 3 . 3 . 4 . 5 . 5 . 6 . 6 . 7 . 7 . 8 . 8 . 9 . 9 . 0 . 1 . 1 . 2 . 2 0 8 6 4 2 0 8 6 4 2 0 8 6 4 2 1 9 7 5 0 3 5 8 1 4 7 9 2 5 8 1 3 6 9 2 5 7 0 3 1 1 1 1 2 2 2 2 3 3 3 4 4 4 4 5 5 5 6 6
r O O O O O O O O O O O O O O O O O O a l O 2 6 0 4 8 2 6 0 4 8 2 6 0 4 8 2 6 0 a O u l 4 8 2 2 3 3 3 4 4 5 5 5 6 6 7 7 7 8 8 9 c u 1 1 H H H H H H H H H H H H H H H H H H e l H 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 o m r H 6 8 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 o C C C C C C C C C C C C C C C C C C C C M f s l o h o c l a t e b r e u G f o s e i t r e p o r p l a c i m e h c d n a l a c i s y h P . 5 e l b a T
y r t s i g r e e r b S m A u C n
e m a n C A P U I
] ] ] ] ] 8 ] ] ] ] 0 - ] - 6 - 1 - 2 ] ] 9 8 2 6 8 6 - - - - - 2 9 2 8
6 - 7 - 5 8 7 4 2 5 - 2 - 8 - 0 - 1 0 6 2 0 - 4 - 7 - 4 - 4 - 9 0 4 8 3 7 - - 4 3 3 5 3 3 3 7 6 8 5 4 0 1 3 2 3 3 4 6 8 3 0 0 0 9 3 4 3 3 4 8 9 2 1 [ 1 [ 1 [ 3 [ 5 [ 2 [ 5 [ 5 [ 5 [ 5 [ 7 [ 7 [
]
4 2 3 2 8 5 2 3 [
]
8 3 6 8 5 6 7 1 [
]
6 1 8 1 6 7 3 7 [
l l o o l l l l n l n a l l o o o o a n l n o o c a o s o n n o l a a e n n c n c a l a o c c i e d a e a s n a l o l l e c e d n s s a l e s o o n a d d d t o l l n n o o a n o o c a c a n l o n a e c o c i l o n t a t o a c i c e a a r h o t c a o n n t o a c n x p o n e e c d t a d n r n e e e n a p a n a d e e a 1 - 1 t 1 1 e x e t o c n d d r p h 1 h e 1 i t l t e l p l l r l u o t t e h e 1 y l y 1 n - h 1 1 d y - d - c y y o c y 1 - 1 1 1 - 1 1 l l l c c c e c c - 1 - 1 e l e l y y e y 1 1 e l e d y - c c c d d d d - l - l l - l l y l l y l a d y s y a e e a y e t y n y d d t a n o h y p t a y t y t r t a d t x p t c x p t e t h o c r e n r u n e e e c o e n o i e e e c o i M - E - P - B - P - H - H - O - N - D - U - D - T - T - P - H - H - O - N - E 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
15
16
Fatty Alcohols
The condensation reaction was first observed by M. Guerbet [97]. Its mechanism and selection of catalysts has been thoroughly studied [3], [5]. Figure 10 illustrates the reaction mechanism in simplified terms. Today this reaction is performed on a technical scale with a worldwide production capacity of several thousand tons per year. The alcohol which is to be dimerized is mixed with an alkaline condensation agent and a hydrogenation/dehydrogenation catalyst and then heated to 180 – 300 ◦ C. The water formed in the reaction is distilled off continuously together with the monomeric alcohol. Since the reaction proceeds faster at higher temperatures, especially the reaction of short-chain monomeric alcohols (C6 – C10 alcohols) is performed under pressure to perform it in a suitable temperature range. However, low-molecular, α-branched dimeric alcohols, e.g., 2-ethyl-1-hexanol, can be produced more economically by other methods (→ 2-Ethylhexanol). Physical Properties. The physicochemical properties of Guerbet alcohols can be summarized as follows [98]:
– Melting point or pour point are considerably lower than those of linear alcohols with the same molecular mass. – Volatility and vapor pressure are significantly lower than those of linear alcohols with comparable consistency (but lower molecular mass). – As compared with other liquid unsaturated alcohols the Guerbet alcohols are stable against oxidation and autoxidation. Uses. Based on these properties Guerbet alcohols in the range of C12 − 36 can be used in the following application areas:
– Cosmetic-pharmaceutical oil components with high stability against autoxidation (rancidity) – Plasticizers for synthetic resins, e.g., nitrocellulose lacquers (for the production of permanent templates) – Solvents or solution aids for printing inks and specialty inks – Lubricant components, e.g., for metal processing oils and fiber preparations
– Chemical intermediates, e.g., for production of branched carboxylic acids – Starting materials for textile auxiliaries, e.g., esters, sulfates, phosphates, ethersulfates The Guerbet alcohols C 32 − 36 , which can be manufactured from C16 − 18 -alcohols, are used as: – Esterification components for the manufacture of specialty waxes – Raw materials for cosmetic stick preparations
5. Bifunctional Fatty Alcohols Some natural oils which contain double bonds, hydroxyl groups, or other functional groups can be converted into long-chain diols. These are usually α ,ω -diols or diols whose hydroxyl groups lie far apart. Table 6 lists physical properties of bifunctional fatty alcohols. 1,2-Diols can be produced by epoxidation of internal or α-olefins with subsequent hydrolytic cleavage of the epoxide ring ( → Alcohols, Polyhydric). Dimerization of unsaturated fatty acids such as soybean, linseed, and tallow fatty acid, followed by esterification and catalytic hydrogenation, gives saturated diols [99]. α,ω -unsaturated fatty alcohols can be produced by pyrolysis of castor oil (Atochem) or by metathesis of oleic acid methyl ester (Warwel, PCT/WO96/19287; Noweck PCT/DE/95/01846). Thermal or catalytic dimerization of unsaturated alcohols yields viscous dimers with complex structure and an average of two hydroxyl groups per molecule [100], [101]. 1,12-Octadecanediol, 1,10-decanediol, and 9-octadecene-1,12-diol are obtained from castor oil by transesterification and hydrogenation, or by alkali splitting, esterification, and hydrogenation. α,ω -Diols with high purity can be produced from the corresponding dicarboxylate esters (DE 38 43956, H¨uls AG), e.g., Suberate Sebacate Dodecanedioate
→ 1,8-Octanediol → 1,10-Decanediol → 1,12-Dodecanediol
Sebacic acid is based on castor oil. Nature offers today new plants and new renewable raw
Fatty Alcohols
3
m c / g , y ) t i s C n e t , D ( ◦
) ) ) ) ) 5 5 0 0 5 4 ( 2 ( 6 ( 5 ( 7 ( 0 0 0 0 0 8 7 0 6 6 5 5 2 1 9 9 . 9 . 9 . 9 . 8 . 0 0 0 0 0
) ) ) ) ) ) 5 ) ) 3 7 7 ) ) ) 4 9 2 3 . . . 3 . . 5 . 2 . 2 . 2 . 2 . 2 . 2 1 1 ( ) 1 ( ( 1 ( ( 0 ( 0 ( 0 ( 0 ( 0 ( 0 ( ) ) 8 9 . 6 ) 4 7 ) 7 0 5 1 4 7 4 1 7 6 9 2 0 0 1 1 1 2 ) 3 . 9 . 6 . 8 . 0 a 1 ( 1 1 1 1 1 2 2 2 2 2 2 2 C P 1 1 ( ( 2 ( ( – – – – – – – – – – – . , k 1 7 3 5 8 3 5 0 5 5 4 0 2 5 3 , 4 p p 3 5 6 7 7 7 8 9 0 0 9 0 1 1 1 2 b ( 1 1 1 1 1 1 1 1 2 2 1 2 2 2 2 2
◦
C ,
◦
p m
6 2 . . 6 . 2 5 6 . 1 5 0 5 0 . 1 6 7 8 1 – 6 – 0 7 9 9 1 – – 6 . 4 . – – 4 . – 7 . 2 8 1 5 3 3 1 5 5 0 1 6 7 1 2 5 5 4 1 6 4 7 6 8 7 8 7 9 9 9 0 0 0 0 1 1 1 1
6 0 . 0 / 2 8 1
9 9 0 8 1
l y r x e o r b d m 9 9 7 0 4 6 5 9 7 9 4 2 2 3 7 2 8 4 2 2 4 y u 4 4 6 0 4 9 5 1 8 5 3 1 9 7 5 4 2 1 0 9 9 H n 9 8 7 7 6 5 5 5 4 4 4 4 3 3 3 3 3 3 3 2 3
M
7 0 3 6 9 1 4 7 9 2 5 8 0 3 6 8 1 4 7 9 9 1 . 2 . 2 . 2 . 2 . 3 . 3 . 3 . 3 . 4 . 4 . 4 . 5 . 5 . 5 . 5 . 6 . 6 . 6 . 6 . 4 . 8 2 6 0 4 8 2 6 0 4 8 2 6 0 4 8 2 6 0 4 4 1 3 4 6 7 8 0 1 3 4 5 7 8 0 1 2 4 5 7 8 8 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 3 3 3 3 3 2
a l u m r o f r a l u c e l o M
2 2 2 2 O O O O O O O O O O O O O O O O O O O O O 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 6 4 6 8 0 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 3 1 1 1 2 H H H H H H H H H H H H H H H H H H H H H 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 8 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 1 C C C C C C C C C C C C C C C C C C C C C
r
s l o h o c l a y t t a f l a n o i t c n u f i b f o s e i t r e p o r p l a c i m e h c d n a l a c i s y h P . 6 e l b a T
r e b m u n y r t s i g e r S A C
e m a n C A P U I
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
] ] ] ] ] ] ] ] ] ] ] 1 1 ] ] 2 - 7 - 8 - ] - ] - 1 - 0 - 2 - 0 ] ] ] 2 ] ] 4 4 9 7 5 - 2 4 0 - 9 - - - 0 1 8 2 3 ]
8 4 - 1 - 4 - 6 0 - 8 - 1 5 5 5 3 7 - 6 - 4 - 2 - 3 - 8 - 5 - 8 - 3 - 1 1 0 1 5 7 4 5 4 4 6 4 - 4 0 - 2 2 2 - 7 - - - 8 3 1 3 8 1 1 3 4 - - - 7 - - 5 6 1 2 5 7 5 8 5 0 1 9 1 3 9 9 9 3 2 5 7 3 8 7 3 5 5 6 3 0 5 4 5 2 0 2 2 2 9 1 6 6 3 9 4 7 6 1 2 7 5 2 5 2 2 4 6 [ 6 [ 6 [ 3 [ 1 [ 7 [ 5 [ 1 [ 1 [ 1 [ 7 [ 6 [ 3 [ 7 [ 7 [ 9 [ 2 [ 9 [ 2 [ 9 [ 5 [
l o i d l l l l 2 l 1 l l l o l o , o i o i o 1 o i o i o i o i l l l i l l i d i d d d d l d d o o d o e e e e d e o e i o o e e e i i l i n e n i n d i n n n n l l o d a n a d a e o l l a n e d e d a e i e d a e n a o a i c s o a c e s o i d n n n c c c i d i c n s n e c o e e e n o d a a e a e a d e d e e d d e d a i o c d c s a c c d s e n e n n c d c a d s a a a t a a a t e e e a t e o o n a n a a d a t r n x p t n o r n c d d c t n c i a t a n c t i c e n o e e c o e o p t x i r e e r e e O e e c o D U D T - - - - T - P - H - H - O - N - E - H - D - T - T - P - H H O N - - - - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 9 ) 6 , 7 , 8 , 9 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 2 , 2 , 2 , 2 , 2 , 2 , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Z (
17
18
Fatty Alcohols
Figure 9. Examples of different types of branched fatty alcohols
Figure 10. Mechanism of the Guerbet reaction
materials for different applications by cultivation or genetic engineering. Bifunctional fatty alcohols are mainly used in the production of polyesters and polyamides and as intermediates.
6. Quality Specifications Analytical methods defined by DIN [102] and ASTM [103] standards and by the Deutsche Gesellschaft f ¨ur Fettwissenschaft (DGF) [104] are used for the quality control of fatty alcohols (see Table 7). In addition, analytical methods from the different fatty alcohol suppliers might be used. Composition of fatty alcohol mixtures is determined by gas chromatography, which can be combined with mass spectrometry. Alcohols from different sources can thus be identified; typical examples are given in Figure 11.
Linearity L is defined as the percentage of normal alcohols present in the mixture: L=
n−alcohol n−alcohol + isoalcohol
× 100
Coconut alcohol gives very few impurity peaks. It contains < 0.1% n-tridecanol and varying amounts of n -alkanes, depending on the hydrogenation process. Tallow alcohol contains up to 2 % isomeric pentadecanols (isopentadecanol, anteisopentadecanol, and n-pentadecanol) and nhexadecane, and up to 4 % isomeric heptadecanols (isoheptadecanol, anteisoheptadecanol, and n -heptadecanol) and n -octadecane. Ziegler alcohols (Alfol and Epal alcohols) are primary, straight-chain alcohols with an even carbon number. Gas chromatography shows up to 1 % impurities, consisting of numerous evennumbered, isomeric fatty alcohols.
Fatty Alcohols
19
Figure 11. Typical fatty alcohol compositions obtained by different processes (Blue = n-alcohols; Violet = isoalcohols; Yellow = unsaturated alcohols; L = linearity)
statistical, cracked Oxo alcohols from olefins or from paraffin dehydrogenation by the Pacol process or SHOP olefins contain a large number of isomers that cannot be completely separated, even in the most efficient capillary columns. Both odd- and even-numbered isoalcohols occur. Oxo alcohol mixtures can be identified by spectroscopic determination of the degree of branching, i.e., the ratio of n-alcohols to isoalcohols, which depends on the production process and the raw materials used. Fatty acids obtained by oxidation of paraf finic hydrocarbons yield even- and oddnumbered primary alcohols with a low degree of branching. Branched alkanes present in the original paraffins are lost by oxidative degradation. The boric acid-catalyzed process ( Bashkirov oxidation) yields secondary alcohols with a statistical distribution of isomers.
Guerbet alcohols are primary, α-branched fatty alcohols with two straight-chain alkyl groups of approximately equal length.
7. Storage and Transportation During production, processing, and storage, fatty alcohols are handled as liquids. Fatty alcohols starting from C12 OH solidify at ambient temperatures. Products with a melting point above 40 ◦ C can therefore be transferred to, stored, and handled as flakes or pastilles. Fatty alcohols are sensitive to oxidation and should be stored under an inert gas; the temperature should not be higher than 20 ◦ C above the melting point. Low-pressure steam or warm water are recommended for heating. Water increases stability to autoxidation; as little as 0.1 % has a stabilizing effect. The use of antioxidants
20
Fatty Alcohols
Table 7. Analytical methods for the characterization of fatty alcohols
DGF ∗ Composition Hydrocarbon content Color (Hazen, APHA) Color (Lovibond) Refractive Index Density
DIN
ASTM
by gas chromatography by column chromatography on silica 53409 C-IV 4b C-IV 5 C-IV 2b
53491 51757
Viscosity Solidification point Boiling range
C-IV 7 M-III 4a
53015 51570 51751
Flash point
C-IV 8
51758
Ignition temperature Hydroxyl number Carbonyl number Peroxide number Iodine number (Kaufmann) Iodine number (Wijs) Acid number Saponification number Water content
C-V 17a/b C-V 18 C-VI 6a C-V 1 1b C-V 11d C-V 2 C-V 3 C-III 13a
51794
53402 53401 51777
D 1686-81 D 1209-84 D 1218-82 D 1298-80 D 891-59 (1976) D 445-83 D 87-77 (1982) D 1078-83 E 133-78 (1984) D 56-82 D 93-80 D 2155-66 (1976) D 1957 (1984) E 411 D 1022-76 D 1959 (1984) D 1613-81 D 94-80 D 1744-83
∗ DGF = Deutsche Gesellschaft f u¨ r Fettwissenschaft.
depends on further processing and quality requirements. Stainless steel or an Al– Mg– Mn alloy (DIN 1725/1745) is used as container material; ordinary steel should have a zinc silicate coating, e.g., Dimetcote. Pumps, valves, and pipes exposed to the product should be made of stainless steel. Fatty alcohols are considered as flammable materials and are classified according to properties such as flash point and boiling point. Their transport is governed by national and international regulations dealing with volatile and combustible materials.
8. Economic Aspects The economic significance of fatty alcohols is reflected by the worldwide installed production capacities of ca. 2.0 × 106 t/a in 1998, which will increase to ca. 2.3 × 106 t/a by the year 2000. Table 8 shows these production capacities categorized by volume, location and raw materials. In summary, approx. 50 % of the fatty alcohols are produced from natural raw materials, however, the split per geographical region is different from continent to continent. The world-
wide production and consumption are estimated at 1.5 × 106 t/a for 1998. In Europe only approx. 5 % of this volume is used directly as fatty alcohols. A share of 70 – 75 % is used in surfactants exclusively [73], [74], [105–109]. In theUnitedStates thesynthetic fatty alcohol capacities predominate with ca. 70 % share of the total capacity. The largest producers of synthetic alcohols are Shell (SHOP/oxo process), Amoco (Ziegler/Epal process) and Condea Vista (Ziegler/Alfol process). Natural fatty alcohols are produced by Procter & Gamble and Cognis (formerly Henkel). In Western Europe, approx. 60 % of the production capacity is based on natural raw materials. The largest manufacturer is the Condea Group (today SASOL), exploiting all three technologies, i.e., Ziegler, oxo and natural production processes. Other European manufacturers, such as BASF, ICI, Exxon, and Shell, predominantly use the oxo process. As the second largest Western European manufacturer for fatty alcohols, Cognis, produces exclusively from natural raw materials using high pressure hydrogenation processes. In the Far East the share of production capacities from natural raw materials is ca. 75 %. This share will further increase by planned ad-
Fatty Alcohols
21
Table 8. Estimated production capacities for fatty alcohols in 1998, 103 t
Continent USA Western Europe Eastern Europe Far East Total
Natural alcohols, ≥ C10 170 408 453 1031
ditional capacities of about 50 000 t. The currently largest manufacturers of natural fatty alcohols are the Salim Group and Kao Soap Corp. Synthetic fatty alcohols are manufactured by the oxo process, e.g., by Mitsubishi Chemical, Mitsubishi Petrochemical and Fushun, or by the Ziegler process, used in Jilin. In Eastern Europe fatty alcohols are manufactured predominantly on the basis of the paraffin oxidation process. Considering the existing production capacities and based on the announced capacity increases, assuming an estimated yearly increase of the fatty alcohol demand of 2 % to 3 %, ca. 80 to 90 % of the capacities will be utilized through the year 2005 [73], [74], [112], [114]. The planned new capacities will be based on fats and oils and on petrochemical or FischerTropsch raw materials, respectively. The capacity utilization of each production unit depends on the overall economic development, the product mix and the prices for the used raw materials. Figure 12 shows the differences in price for raw materials based on crude oil, fats, and oils.
Figure 12. Price development of raw materials used for the production of fatty alcohols
While until 1973 crude oil based, synthetic fatty alcohol production units had considerable advantages, this picture changed significantly due to the price increases for crude oil in 1973 –
Synthetic alcohols, ≥ C11 411 289 90 162 952
Total 581 697 90 615 1983
1974 and 1979 – 1980 and subsequently for secondary products such as naphtha, paraffins, and ethylene. On the long run the price increase rate for fats and oils was considered to be lower than for crude oil [73], [74], [111], [112], [115–122], leading to an expansion of the natural production capacities. In the beginning of 1999 the price for crude oil was again nearly as low as the price in 1974. Therefore, fatty alcohols on the basis of petrochemical raw materials had a cost advantage over natural based fatty alcohols. This changed again in the second half of 1999. The long-term estimate was based on an increase in crop yields for fats and oils, new hybrids of oil plants, a wider geographical distribution of their cultivation areas, and the renewable character of these raw materials in contrast to crude oil. All of this guaranteed a reliable supply. Therefore, the ratio of the production capacities of synthetic to natural fatty alcohols changed in favor of natural products to a current ratio (2001) of 1 : 1. In spite of production increases for coconut oils, increased utilization of palm kernel and babassu oils, and the new hybrids of C12 -rich oils like cuphea varieties, natural products are mainly limited to the C 16 – C18 range (90 % of all products) [123]. Synthetic alcohols, however, show their strength especially in the C12 – C15 range, which plays an important role in surfactant applications. Therefore, the C 16 – C18 C-chain range is predominantly based on natural, the C12 – C15 range on petrochemical based raw materials. However, due to logistical, economical and political reasons, overlapping and reversals can occur [73], [111], [112].
9. Ecotoxicology and Toxicology The following toxicological characterization covers alcohols with C-chain lengths from C 6 to C24 . Besides data regarding the acute toxi-
22
Fatty Alcohols
city (after single intake of the substance) and regarding local effects (skin- and mucous membrane irritation, data on sensitization effects), especially data regarding the toxicity after repeated intake of small amounts of a substance need to be taken into account for the toxicological characterization. This is especially valid for substances which have virtually no acute toxicity as e.g. fatty alcohols. Questions regarding a possible carcinogenic effect or regarding a possible reproduction damage or teratogenic effects are the main focus point today when the toxicological properties of chemical substances are assessed. For the assessment of the properties of fatty alcohols Condea data and data from scientific publications were used. Here especially the IUCLID-data [124] were consulted, which were compiled by the manufacturers according to the ECAltstoffverordnung (EEC 793/93).
9.1. Ecotoxicology and Environmental Aspects Linear fatty alcohols are in general easily biodegradable. The biological degradation of secondary fatty alcohols proceeds slightly slower, however, the decomposition rates in standardized lab tests are comparatively high. For the assessment of the data it has to be considered that the solubility of fatty alcohols in water decreases with increasing C-chain length. Therefore, the alcohols are present only in an extremely low concentration in aquatic environments. Effects, which are detected in various test systems, often have to be regarded as secondary effects caused by undissolved, finely dispersed substance particles, and therefore have to be distinguished from “real” substance effects. For aquatic organisms fatty alcohols possess only moderate acute toxicity. In general, in the concentration range of their water solubility no toxic effects are observed. However, a number of studies was performed with concentrations which are considerably above the water solubility. The observed toxic effects can also be attributed to the aforementioned secondary effects. The available data for the chronic toxicity neither indicate a special toxicological potential of fatty alcohols. Dodecanol shows a more distinct toxicity in the studies. However, this toxic-
ity cannot unmistakably be attributed to a direct substance effect, but can possibly be induced by physical effects as well. A complete separation of the aqueous solution from undissolved but finely dispersed dodecanol is virtually impossible. Therefore, a rest of undissolved dodecanol always remains in the water.
9.2. Toxicology Linear fatty alcohols are predominantly metabolized by oxidation. The resulting fatty acids can be subsequently integrated into the fatty acid metabolism. A further metabolic reaction is con jugation of the fatty alcohols with glucuronic acid and subsequent excretion. Fatty alcohols possess virtually no acute toxicity after oral intake or after exposure to the skin. Especially fatty alcohols with a shorter C-chain length irritate the skin in higher concentrations, in animal tests eye irritations were observed as well. The irritating effect decreases with increasing C-chain length. In studies with volunteers some fatty alcohols show a considerably lower skin irritating effect. This has, at least in part, to be attributed to the different test conditions of studies with volunteers as compared with animal experiments. The available data and the chemical structure of fatty alcohols do not indicate a sensitizing potential of fatty alcohols. From today’s point of view even after long-term intake of the typical linear fatty alcohols, substance induced damage is not to be expected. The available data show that fatty alcohols do not possess genotoxicity, which is not to be expected anyway on grounds of their chemical structure. Valid data regarding a carcinogenic effect are not available. But, based on structure-effect considerations, it can be assumed that fatty alcohols do not have a carcinogenic potential. For some of the fatty alcohols at least guidance data on reproduction toxicity are available. These data show that under the study conditions fatty alcohols neither reduced the fertility nor had an embryo or fetotoxic effect. In Table 9 data on the toxicity of fatty acids after short-term exposure are listed. Table 10 summarizes data on the acute toxicity to aquatic organisms and degradability data [124–129].
Fatty Alcohols
23
10. References
n o i t a z i t i s n e S
) s t n e m i r e p x e l a m i n a m o r f a t a d ( s l o h o c l a y t t a f f o n o i t a z i t i s n e s d n a , n o i t a t i r r I e y e , n o i t a t i r r I n i k s , ) l a m r e d d n a l a r o ( y t i c i x o t e t u c A . 9 e l b a T
n n n o o o i i t i t t a a a z z i z i i t t t i i i s s s n n n e e e s s s o o o n n - - - n
) ) ) a t a , , a t g i g t a a i a d d p p d n n a a n a a e e a n i n m m i m u u u u u h h g g h ( ( ( ( ( n n n n n o o i o o o i t i t t ) i t ) i t a a a a a a a z i z i z z t z t i i i a t a t t t t i i i d i d i s s s n s n s n n n a n a n e s e s e s m e s m e s o o o u o u o - - - n n n h n h n
) g i p a e n i t t u n n g a t a ( t i i t t t r r r r n n i i a a n a t t y y t i i i l r r r t l t i r r r i h h t i t t g g i i o o o - - l s l s n n n
) g i p a e n i u g ( t n a t i r r i y l t h g i l s
t n a t i r r i t o n
t t t ) t n n n i a t a a b t t i i i t t b r r r n n a n i r r r r i i a a o ( t t i y y i i t y t t t t r r l l l a e e r r n n n n t e i i a t a t a i t a t t t r t a a a y y i i i i t r r r r l l r r r r r t r I e e n e t r r i i i h i a d h n d d t i t t t t i g g o o o i r k o o o i o r m l S m m i s - - n n n l s n
) g i p a e n i u g ( t n a t i r r i y l t h g i l s
t n a t i r r i t o n
) t i ) b g b i a r ) ) p ( a ) ) t t i e t i t i g i b b n b b k b b i / b b u a a a g a r ( r ( g ( r ( r ( m ) l 0 g g g g g a 0 k k k k k / / / / / m g g g g g r 0 e 5 m m m m m d > ( 0 0 0 0 – 0 0 0 0 0 0 0 0 0 5 3 0 0 5 5 3 8 5 5 D 0 5 L 1 > > > > > - - - - - -
-
-
t n a t i t r r n n i a t o i y i r t l r a e i t t i a y r t t t l r n n n r I e t a a a h d t i t i t e i g o l y r r r r i r i r m i E i s
) ) t ) t t a a a r ( r r ) ( ( t ) g g a g t k r k a ( / k / r / ) ) t t ) t ( g ) g g g ) t a a a k a m m g m t r r ( r / r a ( ( k ( 0 0 g ) r / 0 ) t t ( 0 0 g g g g 0 a g k a m 5 0 k k / k r / r g 0 ( m 0 ( 7 8 / / 5 k ) 0 g g g g g l 0 g / g 0 > > m m k > m m a k r 0 / 0 0 – g m 2 – – 0 0 / 0 g 0 o 5 0 0 0 ( 0 – 0 0 0 0 3 0 0 0 – m 0 0 0 0 0 3 0 0 2 0 0 0 0 0 0 0 – 3 9 5 3 0 5 0 5 5 1 1 3 3 D 0 1 0 0 7 L 3 > 5 > 5 > > > > 2 > > s l o h o c l A d e l h o c n n l a a r o c e B l l l n d o o a o l l t l n n n l o c 1 0 e o l a a a c n o l o o o l 2 n c c c n n l n o a e e e a a C a n a y y a c s d n x t d s o t – e d a a s x e t c a e u a o r x t c c B H 6 d t b H O c e o e c o i u - e - - 1 S 1 1 D D T H O E D 2 2 C
) t a r ( g k / g m 0 0 0 2 4 – 0 0 0 5
) t a r ( g k / g m 0 0 0 9 3
>
>
l o n a c e d o d l y t c O 2
l o n a c e d a r t e t l y c e D 2
>
General References 1. Ullmann, 4th ed., 11, 427 – 445. 2. ACS Symp. Ser. 159 (1981) . 3. F. Korte (ed.): Methodicum Chimicum, vol. 5, Stuttgart 1975. 4. H. Stache, Tensid Taschenbuch, Carl Hanser Verlag, M¨unchen 1981. 5. Houben-Weyl, VI/1a/b, 1ff. 6. Fettalkohole, 2nd ed., Henkel, D¨usseldorf 1982. Specific References 7. H. Adkins, K. Folkers, J. Am. Chem. Soc. 53 (1931) 1095 – 1097. 8. W. Normann, Angew. Chem. 44 (1931) 714 – 717. DE 617 542, 1930 (W. Normann, H. Pr¨uckner); B¨ohme Fettchemie GmbH, DE 639 527 , 1930 (W. Normann). 9. W. Schrauth, O. Schenk, K. Stickdorn, Ber. Dtsch. Chem. Ges. 64 (1931) 1314 – 1318. 10. O. Schmidt, Ber. Dtsch. Chem. Ges. 64 (1931) 2051 – 2053. 11. D. Precht, Fette, Seifen, Anstrichm. 78 (1976) no. 4, 145. 12. Alfol-Alkohole, Typische Analysendaten, Condea Chemie, Brunsb¨uttel. 13. VDI-W ¨ armeatlas, D¨usseldorf 1984. ¨ Chemiker und 14. D’Ans Lax – Taschenbuch f ur Physiker, vol. II, Springer Verlag, Berlin 1964. CRC Handbook, 55th ed., Cleveland 1974 /75. 15. 16. Houben-Weyl, E3, 265–300. 17. Houben-Weyl, E5/1, 202–212. 18. K. Heyns, L. Blasejewicz, Tetrahedron 9 (1960) 67. 19. E. S. Gore, Platinum Met. Rev. 27 (1983) no. 3, 111. 20. Atlantic Richfield Co., US 3 997 578, 1976 (Ming Nan Sheng). 21. Kirk-Othmer, 9, 795 ff. 22. U. R. Kreutzer, J. Am. Oil Chem. Soc. 61 (1984) no. 2, 343. 23. H.-D. Komp, M. P. Kubersky in: Fettalkohole, 2nd ed., Henkel, D¨usseldorf 1982, p. 51 ff. 24. E. F. Hill, G. R. Wilson, E. C. Steinle, Jr., Ind. Eng. Chem. 46 (1954) 1917. 25. M. L. Karstens, H. Peddicord, Ind. Eng. Chem. 41 (1949) 438. 26. H. Igo, CEER Chem. Econ. Eng. Rev. 8 (1976) no. 3, 31. 27. Oleofina, DE 3425758 C2, 1984/94. 28. H. Buchold, Chem. Eng. (N.Y.) 90 (1983) no. 4, 42. 29. Th. Voeste, H. Buchold, J. Am. Oil Chem. Soc. 61 (1984) no. 2, 350.
24
Fatty Alcohols
Table 10. Ecotoxicity of fatty alcohols
Substance
Bio-Degradability
Acute Fish Toxicity
Acute Daphnia Toxicity
Algae Toxicity
Bacteria Toxicity
1-Hexanol 1-Octanol Decanol Dodecanol Tetradecanol Hexadecanol Octadecanol Eicosanol Docosanol 2-Butyloctanol 2-Hexyl-1-decanol C16 – C20 -Branched Alcohols 2-Octyldodecanol 2-Decyltetradecanol
biodegradable biodegradable easily biodegradable easily biodegradable biodegradable biodegradable biodegradable biodegradable easily biodegradable -
> 100 mg/L
> 100 mg/L
10 – 100 mg/L 1 – 10 mg/L < 1 mg/L > 100 mg/L > 100 mg/L -
10 – 100 mg/L 1 – 10 mg/L < 1 mg/L > 100 mg/L -
10 – 100 mg/L 10 – 100 mg/L < 1 mg/L > 100 mg/L > 100 mg/L -
3000 – 10 000 mg/L 350 –> 10 000mg/L > 10 000mg/L > 10 000mg/L > 10 000mg/L -
> 100 mg/L
-
100 mg/L -
> 10 000mg/L
biodegradable biodegradable
-
30. Chem. Ind. (D¨ usseldorf) 32 (1980) 739. 31. Metallgesellschaft AG, DE 2 853 990, 1978 (Th. Voeste, H.-J. Schmidt, F. Marschner). 32. Dehydag GmbH, DE 1 005 497, 1954 (W. Rittmeister). 33. Dehydag GmbH, US 3 193 586, 1965 (W. Rittmeister). 34. Henkel KGaA, DE-AS 2 613 226, 1976 (G. Demmering) 35. VEB Deutsches Hydrierwerk Rodleben, DD 213 430, 1983 (H. Aring, K. Busch, P. Franke, G. Konetzke et al.) 36. Institut Franc¸ais du P´etrole, DE-OS 3 217 429, 1982 (R. Snappe, J.-P. Bournonville). 37. B. C. Triverdi, D. Grote, Th. O. Mason, J. Am. Oil Chem. Soc. 58 (1981) no. 1, 17. 38. Ashland Oil, Inc. US 4 104 478, 1978 (B. C. Triverdi). 39. Houben-Weyl, 13/4, 1ff. 40. T. Mole, E. A. Jeffery: Organoaluminium Compounds, Elsevier, Amsterdam 1972. 41. A. Lundeen, R. Poe: “Alpha-Alcohols,” in J. J. Mc Ketta, W. A. Cunningham (eds.): Encyclopedia of Chemical Processing and Design, vol. 2, Marcel Dekker, New York 1977, p. 465. 42. K. Ziegler, H.-G. Gellert, K. Zosel, E. Holzkamp et al., Justus Liebigs Ann. Chem. 629 (1960) 121. 43. H. Wesslau, Justus Liebigs Ann. Chem. 629 (1960) 198. 44. P. H. Washecheck, ACS Symp. Ser. 159 (1981) 87. 45. K. L. Lindsay: “Alpha-Olefins,” in J. J. Mc Ketta, W. A. Cunningham (eds.): Encyclopedia of Chemical Processing and Design, vol. 2, Marcel Dekker, New York 1977, p. 482.
-
46. Produkte aus der Oxosynthese, Ruhrchemie AG, Frankfurt 1969. 47. J. Falbe: Synthesen mit Kohlenmonoxid, Berlin 1967. 48. R. E. Vincent, ACS Symp. Ser. 159 (1981) 159. 49. B. Cornils, Compend. Dtsch. Ges. Mineral¨ olwiss. Kohlechem. 78/79 (1978) no. 1, 463. 50. B. Cornils, “New Syntheses with Carbon Monoxide,” React. Struct. Concepts Org. Chem. 11 (1980) . 51. H. Lemke, Hydrocarbon Process. 45 (1966) no. 2, 148. 52. C. E. O’Rourke, P. R. Kavasmaneck, R. E. Uhl, ACS Symp. Ser. 159 (1981) 71. 53. B. A. Murrer, J. H. Russel, Catalysis 6 (1983) 169. 54. A. H. Turner, J. Am. Oil Chem. Soc. 60 (1983) no. 3, 623. 55. R. L. Banks, Appl. Ind. Catal. 1984, no. 3, 215. 56. E. R. Freitas, C. R. Gum, Chem. Eng. Prog. 75 (1979) 73. 57. E. L. T. M. Spitzer, Seifen, Oele, Fette, Wachse 107 (1981) no. 6, 141. 58. H. Stage, Seifen, Oele, Fette, Wachse 99 (1973) no. 6/7, 143; no. 8, 185; no. 9, 217; no. 11, 299. 59. N. Kurata, K. Koshida, Hydrocarbon Process. 57 (1978) 145. 60. N. J. Stevens, J. R. Livingstone, Jr., Chem. Eng. Prog. 64 (1968) no. 7, 61. 61. N. Kurata, K. Koshida, H. Yokoyama, T. Goto, ACS Symp. Ser. 159 (1981) 113. 62. L. Marko, J. Organomet. Chem. 283 (1985) 221.
Fatty Alcohols 63. B. N. Bobylev, M. J. Farberov, S. A. Kesarev, Khim. Promst. (Moscow) 1979 no. 3, 138. 64. Unilin Alcohols, Petrolite Corp., St. Louis 1985. 65. Petrolite Corp., US 4 426 329, 1984 (J. H. Woods, C. E. Laughlin, T. R. Graves). 66. S. K. Ries, V. Wert, C. S. Sweely, R. A. Leavitt, Science 195 (1977) 1339. 67. J. Penninger, M. Biermann, H.-J. Krause, Fette, Seifen, Anstrichm. 85 (1983) no. 6, 239. 68. T. Gibson, L. Tulich, J. Org. Chem. 46 (1981) no. 9, 1821. 69. A. V. Rama Rao, J. S. Yadav, G. S. Annapurna, Synth. Commun. 13 (1983) no. 4, 331. 70. S. M. Kulkarni, V. R. Mamdapur, M. S. Chadha, Indian J. Chem., Sect. B 22 (1983) no. 7, 683. 71. U. T. Bhalerao, S. J. Rao, B. D. Tilak, Tetrahedron Lett. 25 (1984) no. 47, 5439. 72. G. Kirchner, H. Weidmann, Liebigs Ann. Chem. 1985, no. 1, 214. 73. H. J. Richtler, J. Knaut, J. Am. Oil Chem. Soc. 61 (1984) no. 2, 160 – 175. 74. J. Knaut, H. J. Richtler, J. Am. Oil Chem. Soc. 62 (1985) no. 2, 317. 75. H. Bertsch, H. Reinheckel, K. Haage, Fette, Seifen, Anstrichm. 66 (1964) 763. 76. H. Bertsch, H. Reinheckel, K. Haage, Fette, Seifen, Anstrichm. 71 (1969) 357, 785. 77. H. Bertsch, K. Haage, H. Reinheckel, Fette, Seifen, Anstrichm. 71 (1969) 851. 78. K. Lindner: Tenside, Textilhilfsmittel, Waschrohstoffe, vol. I, 2nd ed., Wissenschaftl. Verlags GmbH, Stuttgart 1964, p. 144. 79. J. Richter: Dissertation, TH Delft, 1968. 80. J. W. E. Coenen, Fette, Seifen, Anstrichm. 77 (1975) 431. 81. Dehydag, US 3 193 586, 1965 (W. Rittmeister). 82. Henkel, US 3 729 520, 1973 (H. Rutzen, W. Rittmeister). 83. Henkel, DE-AS 2 513 377, 1975 (G. Demmering, H. Sch¨utt, H. Rutzen). 84. J. Cieslar, W. Bulanda, Przem. Chem. 63 (1984) 375; Chem. Abstr. 101 (1984) 153810t. 85. Institute Blachownia and Nitrogen Works Kedzierzyn, PL 118 880, 1978 (E. Fabisz, K. Chmielewski, A. Jakubowicz, A. Mankowski et al.). 86. Institute Blachownia and Nitrogen Works Kedzierzyn, PL 118 979, 1978 (E. Fabisz, K. Chmielewski, A. Jakubowicz, A. Mankowski et al.). 87. New Japan Chemical Ltd., GB 1 335 173, 1972.
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88. VEB Deutsches Hydrierwerk Rodleben, DD 213 429, 1983 (H. Aring, K. Busch, P. Franke, G. Konetzke et al.). 89. UOP Inc., US 4 340 546, 1982 (G. Qualeatti, D. Germanas). 90. UOP Inc., US 4 446 073, 1984 (G. Qualeatti, D. Germanas). 91. Kao Soap, JP 58 210 035, 1983 (K. Kokubo, K. Tsukada, Y. Miyabata, Y. Kazama). 92. Kao Soap, JP 5 995 227, 1984 (K. Tsukada, Y. Miyabata). 93. Kao Soap, JP 59 106 431, 1984 (K. Tsukada, Y. Miyabata, K. Fukuoka). 94. H. Sch¨utt in W. Foerst, H. Buchholz-Meisenheimer (eds.): Neue Verfahren, Neue Produkte, Wirtschaftliche Entwicklung, Urban und Schwarzenberg, M¨unchen 1970. 95. U. Ploog, Seifen, Oele, Fette, Wachse 109 (1983) no. 8, 225. 96. R. R. Egan, G. W. Earl, J. Ackermann, J. Am. Oil Chem. Soc 61 (1984) no. 2, 324. ´ Acad. Sci. 97. M. Guerbet, C. R. Hebd. S eances 128 (1898) 511; M. Guerbet, Bull. Soc. Chim. Fr. 21 (1899) no. 3, 487. 98. J. Glasl in: Fettalkohole, 2nd ed., Henkel, D¨usseldorf 1982, p. 169. 99. Henkel & Cie GmbH, DE-OS 1 768 313, 1971 (H. Rutzen). 100. Henkel & Cie GmbH, DE 1 198 348, 1961 (W. Stein, M. Walther). 101. Henkel & Cie GmbH, DE 1 207 371, 1963 (H. Hennig, W. Stein, M. Walther). 102. “Mineral- und Brennstoffnormen,” DIN-Taschenbuch, Beuth-Vertrieb, Berlin-K¨oln-Frankfurt 1984. 103. Annual Book of ASTM Standards, Sections 5, 6, 15, 1985. 104. Deutsche Einheitsmethoden zur Untersuchung von Fetten, Fettprodukten und verwandten Stoffen, Wissenschaftl. Verlags GmbH, Stuttgart 1950 – 1984. 105. H. J. Richtler, J. Knaut, Chem. Ind. (D¨ usseldorf) 36 (1984) 131 – 134. 106. H. J. Richtler, J. Knaut, Chem. Ind. (D¨ usseldorf) 36 (1984) 199 – 201. 107. L. Marcou, Rev. Fr. Corps. Gras. 30 (1983) no. 1, 3 – 6. 108. J. Am. Oil Chem. Soc. 58 (1981) no. 11, 873 – 874A. 109. A. L. de Jong, J. Am. Oil Chem. Soc. 60 (1983) no. 3, 634 – 639. 110. Kirk-Othmer, 1, 740–754. 111. E. C. Leonard, J. Am. Oil Chem. Soc. 60 (1983) no. 6, 1160 – 1161.
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Fatty Alcohols
112. C. A. Houston, J. Am. Oil Chem. Soc. 61 (1984) no. 2, 179 – 184. 113. J. Am. Oil Chem. Soc. 62 (1985) no. 4, 668. 114. J. C. Dean, Chem. Week 1985, May 15, 3 – 34. 115. J. W. E. Coenen, J. Am. Oil Chem. Soc. 53 (1976) no. 6, 382 – 389. usseldorf) 33 116. H. Klimmek, Chem. Ind. (D¨ (1981) 136 – 141. 117. H. Fochem, Fette, Seifen, Anstrichm. 87 (1985) no. 2, 47 – 52. 118. Chem. Week 1982, April 28, 40 – 44. 119. Chem. Ind. (D¨ usseldorf) 35 (1983) 251 – 255. 120. J. Am. Oil Chem. Soc. 61 (1984) no. 8, 1298 – 1314. ¨ 34 121. H. Lindemann, Chem. Ind. (Dusseldorf) (1982) 713 – 716. 122. S. Field, Hydrocarbon Process. 1984, Oct., 34G–N. 123. W. Stein, Fette, Seifen, Anstrichm. 84 (1982) no. 2, 45 – 54.
Fatty Amines → Amines, Aliphatic Feeds → Foods, 1. Survey
124. Public data on high volume chemicals: IUCLID CD-ROM, Year 2000 edition: European Commission, Joint Research Centre, Institute for Health and Consumer Protection, European Chemicals Bureau. 125. D. L. J. Opdyke, Fd. Cosmet. Toxicol. 11 (1973) 95 – 115. 126. Food Cosmet. Toxicol. 13 (1975) 699 – 700. 127. “Final Report on the Safety Assessment of Cetearyl alcohol, Cetyl Alcohol, Isostearyl Alcohol, Myrsityl Alcohol, and Behenyl Alcohol”; J. Am. Coll. Toxicol. 7 (1988) no. 3, 359–411. 128. D. L. J. Opdyke, Fragrance Raw Materials Monographs “Cetyl alcohol”; Food Cosmet. Toxicol. 16 (1978) 683 – 686. 129. “Final Report on the Safety Assessment of Stearyl Alcohol, Oleyl Alcohol, and Octyl Dodecanol”, J. Am. Coll. Toxicol. 4 (1985) no. 5, 1–29.
