CHEMISTRY
BIOMOLECULES CARBOHYDRATE Carbohydrate : Molecules of Support and Energy A polyhydroxy compound that has an aldehyde or a ketone functional group present, either free or as hemiacetal or acetal are called carbohydrate. Carbohydrates are substances with the general formula Cx(H2O)y, and were therefore called carbohydrates (hydrates of carbon) because they contained hydrogen and oxygen in the same proportion as in water. However, a number of compounds have been discovered which are carbohydrates by chemical behaviour, but do not conform to the formula Cx(H2O)y, e.g., 2-deoxyribose, C5H10O4. It is also important to note that all compounds conforming to the formula Cx(H2O)y are not necessarily carbohydrates, e.g., formaldehyde, CH2O ; acetic acid, C2H4O2 ; etc. Carbohydrates are often referred to as Saccharides (Latin, Saccharum = sugar) because of the sweet taste of the simpler members of the class, the sugars. The carbohydrates are divided into three major classes depending on the number of simple sugar units present in their molecule. (i) Monosaccharide : A carbohydrate that cannot be hydrolyzed to simpler compounds is called monosaccharide. Monosaccharide which have six carbon are either aldohexoses or ketohexoses (ii) Oligosaccharides : Carbohydrates that yield two to ten monosaccharide units, on hydrolysis, are called oligosaccharides. They are further classified as disaccharides, trisaccharides, tetrasaccharides, etc., depending upon the number of monosaccharides, they provide on hydrolysis. Amongst these the most common are disaccharides. The two monosaccharides units obtained on hydrolysis on a disaccharide may be same or different. For example, sucrose on hydrolysis gives one molecule each of glucose and fructose whereas maltose gives two molecules of glucose only. (iii) Polysaccharide : A carbohydrate that can be hydrolyzed to many monosaccharide molecules is called a polysaccharide. Example : Starch, Cellulose, etc.
Aldohexoses Their structure has been elucidated as follows : (i) Analysis and molecular-weight determinations show that the molecular formula of the aldohexoses is C6H12O6. (ii) When treated with acetic anhydride, aldohexoses form the penta-acetate. This indicates the presence of five hydroxyl groups.
Ac O
2
(iii) Aldohexoses form an oxime when treated with hydroxylamine, or add molecule of HCN to form cyanohydrin and therefore contain a carbonyl group. (iv) when an aldohexose is oxidised with bromine-water or tollens reagent or fehling solution a pentahydroxyacid of formula C6H12O7 is obtained. This indicates that the carbonyl group present is an aldehydic group. (v) When reduced with concentrated hydroiodic acid and red phosphorus at 100°C, aldohexoses give nhexane. This indicates that the six carobn atoms in an aldohexose are in a straight chain.
"manishkumarphysics.in"
1
CHEMISTRY The above reactions show that structure of aldohexoses is
CH2 C(H) C(H) C(H) C(H) CHO | | | | | OH OH OH OH OH Due to four asymmetric carbon atoms, there are sixteen optical isomers. or Eight pairs of enantiomers. (8D-variety & 8L- variety). D-varity of them are as follows
Note # 1. D-aldohexoses shown above have epimeric / diastereomeric relationship with each other # 2. D-aldohexoses can be either dextro (+) or laevo (-)
Glucose : Glucose is the most common monosaccharide. It is known as Dextrose because it occurs in nature principally as the optically active dextrorotatory isomers. Naturally-occurring glucose is dextrorotatory (hence name dextrose). It is a strong reducing agent, reducing both Fehling’s solution and ammonical silver nitrate. When heated with sodium hydroxide, an aqueous solution of glucose turns brown.
+
Ketohexoses The only important ketohexose is D(–)-fructose, the structure of which has been elucidated as follows : (i) Analysis and molecular-weight determinations show that the molecular formula of fructose is C6H12O6.
"manishkumarphysics.in"
2
CHEMISTRY (ii) W hen treated with acetic anhydride, fructose forms the penta-acetate. This indicates the presence of five hydroxyl groups. (iii) Fructose forms oxime when treated with hydroxylamine, and therefore contains a carbonyl group. (iv) When oxidised with nitric acid fructose is converted into a mixture of trihydroxyglutaric, tartaric and glycollic acids. Since a mixture of acids each containing fewer carbon atoms than fructose is obtained, the carbonyl group in fructose must be present in a ketonic group. (v) Fructose may be reduced to a hexahydric alcohol, sorbitol, which, on reduction with hydroiodic acid and red phosphorus at 100°C, gives n-hexane. This formation indicates that the six carbon atoms in fructose are in a straight chain.
It is interesting to know that D-fructose is (–) laevo
Sucrose : (Sucrose, cane-sugar C12H22O11) (i) Sucrose is a white crystalline solid, soluble in water. (ii) When heated above its melting point, it forms a brown substance known as caramel. (iii) Concentrated sulphuric acid chars sucrose, the product being almost pure carbon. (iv) Sucrose is dextrorotatory, its specific rotation being + 66.5°. (v) On hydrolysis with dilute acids sucrose yields an equimolecular mixture of D(+)-glucose and D(–)-fructose : HCl
C12H22O11 + H2O C 6H12 O 6 + C 6H12 O 6 glucose
fructose
Since D(–)-fructose has a greater specific rotation than D(+)-glucose, the resulting mixture is laevorotatory. Because of this, hydrolysis of cane-sugar is known as the inversion of cane-sugar this is not to be confused with the Walden inversion, and the mixture is known as invert sugar. The inversion (i.e., hydrolysis) of cane-sugar may also be effected by the enzyme invertase which is found in yeast. (vi) Sucrose is not a reducing sugar, e.g., it will not reduce Fehling’s solution ; it does not form an oxime or an osazone, and does not undergo mutarotation. This indicates that neither the aldehyde group of glucose nor the ketonic group of fructose is free in sucrose.
"manishkumarphysics.in"
3
CHEMISTRY Maltose (malt sugar), C12H22O11, is produced by the action of malt (which contains the enzyme diastase) on starch : (C6H10O6)n +
n n diastase H2O C H O 2 2 12 22 111
When it is hydrolysed with dilute acids or by the enzyme maltase, maltose yields two molecules of D (+)glucose. Maltose is a reducing sugar, e.g., it reduces Fehling’s solution ; it forms an oxime and an osazone, and undergoes mutarotation. This indicates that at least one aldehyde group (of the two glucose molecules) is free in maltose.
Lactose (milk-sugar), C12H22O11, occurs in the milk of all animals and is dextrorotatory. It is hydrolysed by dilute acids or by the enzyme lactase, to an equimolecular mixture of D(+)-glucose and D(+)-galactose. Lactose is a reducing sugar. It should also be noted that lactase is a -glycosidase, i.e., splits -glycosides (it has been shown to be identical with emulsin).
CH2OH HO H
O
O
H OH
OH
OH
OH
H
H
H H
H
H
H
O
H OH
CH2OH
Epimerisation The change of configuration of one asymmetric carbon atom in a compound containing two or more asymmetric carbon atoms is known as epimerisation. Aldoses which produce the same osazones must have identical configuration on all their asymmetric carbon atoms except the alpha (since only the aldehyde group and -carbon atoms are involved in osazone formation). Such sugars are known as epimers e.g. epimerisation of glucose into mannose.
"manishkumarphysics.in"
4
CHEMISTRY Starch, (C6H10O5)n (i) Starch is the main contributor of carbohydrates in our diet. It exists exclusively in plants, stored in the seeds, roots, and fibres as food reserve. Example rice, potato. (ii) Starch is actually a mixture of two structurally different polysaccharides, Amylose (20%) and Amylopectin (80%). (iii) When starch is heated with hot water, it can be separated into its components. The part that is soluble in water is amylose and remaining fraction is amylopectin. (iv) Both amylose and amylopectin are composed of D-glucose units. (v) The amylose molecule is made up of D-glucose unit joined by -glycosidic linkages between C-1 of one glucose unit and C-4 of the next glucose unit. The number of D-glucose units in amylose range from 60-300. 6
6
CH2OH 5
H
CH2OH
O
H 4 OH
H
3
H H 1
2
H
O
5
H 4 OH
H
3
O
OH
H 1
2
H
O
OH
n
(1 4) Glucosidic linkage
Amylose (vi) Amylopectin has a branched-chain structure. It is composed of chains of 25 to 30 D-glucose units joined by -glycosidic linkages between C-1 to one glucose unit and C-4 of the next glucose unit. These chains are in turn connected to each other by 1, 6-linkages.
6
CH2OH
Branch
CH2OH
O H
......O
H OH
H
......O
H
H
H H
H
O H OH
OH
H 1
2
O
H
H H 4
1
CH2 5
O
OH
H
3
O H
Amylopectin
(1 6) branch point
OH 6
O H
O
CH2OH
O H OH
3
OH
CH2OH H
5
H 4 OH
O H
Main Chain
HH
OH
H
H 1
2
O.........
OH
(1 4)
Starch, -amylose soluble in water, and the solution gives a blue colour with iodine. Amylopectin is insoluable in water, is stable in contact with water, and gives a violet colour with iodine.
"manishkumarphysics.in"
5
CHEMISTRY Cellulose, (C6H10O5)n
6
CH2OH
(1 4)
H
5
H 4 OH
6
CH2OH 5
H
O
H 4 OH 3
H
H
O
H
1
2
3
O H
O 1
2
H
OH
H
OH
n
Cellulose 1. Cellulose is the main structural material of tree and other plants. Wood is 50% cellulose, while cotton wool is almost pure cellulose. Other sources of cellulose are straw, corncobs, bagasse, and similar agricultural wastes. 2. Artificial silk, rayon, is used collectively to cover all synthetic or manufactured fibres from cellulose. 3. The nitrates are prepared by the reaction of cellulose with a mixture of nitric and sulphuric acids, and the degree of ‘nitration’ depends on the concentrations of the acids and the time of the reaction. Cellulose trinitrate (12.2 – 13.2%N) is known as gun-cotton and is used in the manufacture of blasting explosives and smokeless powders.
"manishkumarphysics.in"
6
CHEMISTRY
AMINO ACID Amino Acid : Building Blocks of Proteins Amino acids are the building blocks of the molecular structure of the important and very complex class of compounds known as proteins. The proteins on hydrolysis yield mixture of the component amino acids. Amino acids are bifunctional compounds containing both an amino and a carboxylic acid group. They are represented by the general formula :
H O | || H2N C C OH | Carboxylic Amine R Acid group
H2N CH COOH | R
or
Where, R = alkyl, aryl, or any other group. Dipolar Nature of Amino acids (Zwitter ion) : .. In a neutral amino acid solution, the –COOH loses a proton and the – NH2 of the same molecule picks up one. H O | || H2N C C OH | R
H H
H O | || H3 N C C O ¯ | R Zwitter ion
The resulting ion is dipolar, charged but overall electrically neutral. This is called Zwitterion (German, “two ions”). Therefore amino acids are amphoteric.
H O || | H3 N C C OH | R
H O H O | || HO¯ | || H H2 N C C O ¯ H3N C C O ¯ ( H2O) | | R R
Low pH ( Acid soln. ) Cationic form (II)
Zwitterion Neutral form (I)
High pH (Basic soln.) Anionic form (III)
Isoelectric Point When an ionised amino acid is placed in an electric field, it will actually migrate towards the opposite electrode. Depending upon the pH of the medium, three things can happen. The positive form (II) will migrate to the cathode, the neutral form (Zwitterion) will not migrate, while the negative form (III) will migrate to the anode. The pH at which the amino acid shows no tendency to migrate when placed in an electric field is known as its isoelectric point. This is characteristic of a given amino acid. Thus glycine has its isoelectric point at pH 6.1. Name
Abbreviation
Formula
(+) - Alanine
Ala A
CH3 CHCOO¯ | NH3
(+) - Aspartic acid
Asp D
HOOCCH2 CHCOO ¯ | NH3
(–) - Cysteine
Cys C
HSCH2 CHCOO ¯ | NH3
(+) - Glutamic acid
Glu E
HOOCCH2 CH2 CHCOO ¯ | NH3
(+) - Glutamine
Gin Q
H2NCOCH2CH2 CHCOO ¯ | NH3
"manishkumarphysics.in"
7
CHEMISTRY Glycine
Gly G
CH2COO ¯ | NH3 +
(–) - Hydroxylysine
Hyl
H3NCH2 CH CH2CH2 – CHCOO ¯ | | OH NH2
(–) - Hydroxyproline
Hyp
(–) - Leucine
Leu L
(+) - Lysine
Lys K
(–) - Proline
Pr o P
(–) - Serine
Ser S
(–) - Tyrosine
Tyr Y
(+) - Valine
Val V
(CH3 )2 CH CHCOO ¯ | NH3
(+) - Arginine
Arg R
H2NCNHCH2CH2 CH2 CHCOO ¯ || | NH2 NH2
(CH3 )2 CHCH2 CHCOO ¯ | NH3
H3NCH2 CH2 CH2 CH2 CHCOO ¯ | NH2
HOCH2 CHCOO ¯ | NH3
Peptides Peptides (Proteins) may be defined as condensation polymers of -amino acids and having peculiar overall structure which determines their specific physiological functions in the living organism. Note: A polypeptide with more than 100 amino acid residues (mol. mass > 10,000) is called a protein. Structure of Proteins (Peptides) Amino acids are bifunctional molecules with – NH2 group at one end and – COOH at the other. Therefore, –COOH of one molecule and – NH2 of another molecule interact by elimination of H2O to form an amide-like linkage.
"manishkumarphysics.in"
8
CHEMISTRY
General method of preparation 1.
Aminolysis of -halocarboxylic acid HO
CH3 CHCO 2H 2NH3 2 | excess Br 2 Bromo propanic acid 2.
By strecker synthesis : Aldehyde reacts with a mixture of NH4Cl and NaCN to form -aminonitrile (as an intermediate) which on hydrolysis gives an amino carboxylic acid.
O || 1. H2O / HCl, NH4Cl CH3 CH CH3 CHCN 2. OH¯ NaCN | NH2 2 a min opropaneni trile 3.
From aceto acetic ester :
NaOC H
2 5
RX
C2H5OH
hydrolysis RCHCO 2H | NH2
4.
reduction
By Gabriel Synthesis :
+
O || ClCH2COC 2H5
ethyl chloroacetate
O || H2NCH2COH + glycine
Chemical reaction 1.
Formaldehyde reacts with amino acids to form N-methylene amino acids. In this reaction basic character is lost and thus, free acid can be determined by titration - Sorenson titration method for amino acids. O || CH2O H2NCH2COH
O || CH2 NCH2COH H2O N methylene glycine
"manishkumarphysics.in"
9
CHEMISTRY 2.
DNFB (2, 4-dinitrofluorobenzene) also called Sanger’s reagent reacts with the free amino group of terminal amino acid in a peptide or protein to form yellow coloured dinitro phenyl amino acid. This is thus, used to determine N-terminal amino acid.
H | R C NH2 + | COOH 3.
Na CO
2 3
Cu2+ salts form blue coloured complex with amino acids which is a bidentate legand.
O O || 2CH2COH + Cu2+ | NH2
4.
Effect of Heat : -amino acids undergo intermolecular dehydration on heating at about 200°C to give diketopiperazines.
+ 2H2O
-amino acids undergo intramolecular deamination on heating to form -unsaturated acids.
-amino acids and -amino acid undergo intramolecular dehyderation to form cyclic amides called.
Lactams.
CH2– CH 2 | | O CH2 C
butyrolactam
NH–H OH amino acid
In case of -amino acid, intramolecular cyclisation would given a seven-membered ring, which is formed with difficulty. Hence, there is intermolecular polymerisation forming nylon-6.
nH2N(CH2)5COOH
"manishkumarphysics.in"
10
CHEMISTRY 5.
Zwitter ion formation in amino acids Aspartic acid :
The pI of aspartic acid is the average of pKa1 (1.88) and the pKa of the side chain (3.65) or 2.77. Lysine :
The pI of lysine is the average of pKa2 (8.95) and the pKa of the side chain (10.53) or 9.74. Peptides The amide bond between the amino group of one amino acid and the carboxyl of another is called a peptide bond. Alanylglycine is a representative dipeptide.
N-terminal amino acid
C-terminal amino acid
By agreement, peptide structures are written so that the amino group is at the left and the carboxyl group (as CO2¯ or CO2H) is at the right. The left and right ends of the peptide are referred to as the N terminus (or amino terminus) and the C terminus (or carboxyl terminus), respectively. Alanine is the Nterminal amino acid in alanylglycine ; glycine is the C-terminal amino acid.
Chemical Nature
Deficiency Diseases
Vitamin A (Carotenoids or Axerophytol or Tetinol) Soluble in oils and fats, but insoluble in water.
Night blindness, Xerophthalmia (cornea becomes opaque), drying of skin.
Vitamin B1 (Thiamine). Soluble in water, destroyed by heat
Beriberi, loss of appetite
Vitamin B2 (Ribofavin), Soluble in water. Stable to heat, destroyed by light
Cracked lips, sore tongue and skin disorders.
Vitamin B6 (Pyridoxine)
Nervous disturbances and convulsions (pernicous anaemia).
Vitamin B12 (Cyano cobalamin). Soluble in water and contains cobalt, red crystalline.
A serious type of anaemia.
Vitamin C (Ascorbic Acid, C6H8O6). Soluble in water, destroyed by cooking and exposure to air
Scurvy, dental caries, pyorrhea, anaemia
Vitamin D (Calciferol), mixture of 4 complex compound containing C, H and O. Soluble in fats and oils but insoluble in water. Stable towards heat and oxidation. This vitamin regulates the absorption of calcium and phosphate in intestine.
In fantile rickets ; deformation of bones and teeth.
Vitamin E (Tocopherrol). Mixture of 3 complex substances containing C, H and O. Soluble in fats and oils but insoluble in water. Stable to heat and oxidation.
Loss of sexual power and degeneration of muscle fibres in animals
Vitamin K, mixture of two complex substances containing C, H and O. Soluble in fats but insoluble in water. Stable to heat and oxidation.
Tendency to haemorrhage and imparied clotting of blood.
"manishkumarphysics.in"
11
CHEMISTRY
POLYMER Classification of Polymers : (i) Homopolymers. Polymers whose repeating structural units are derived from only one type of monomer units are called homopolymers.
Other examples of homopolymers are polypropylene, polyvinyl chloride (PVC), polyisoprene, neopreene (polychloroprene, polyacrylonitrile (PAN), nylon-6, polybutadiene, teflon (polytetrafluoroethylene), cellulose, starch etc. (ii) Copolymers. Polymers whose repeating structural units are derived from two or more types of monomer unit are called copolymers.
Depending upon these two modes of synthesis, polymers have been broadly classified into two types : 1. Addition polymers and 2. Condensation polymers 1. Addition polymers. In this type of polymerization, the molecules of the same or different monomers simply add on one another the molecular formula of the repeating structural units is the same as that of the starting monomer. These are also called chain-growth polymers since they are formed by successive addtion of monomer molecules to the growing chain.
Some other examples of addition or chain growth polymers are : Monomer (i) Butadiene (ii) Tetrafluoroethylene (iii) Vinyl chloride (iv) Isoprene
Polymer Polybutadiene Polytetrafluoroethylene Polyvinyl chloride (PVC) cis-Polyisoprene (natural rubber)
2. Condensation polymers. In this type of polymerization, a large number of monomer molecules combine together usually with the loss of simple molecules like water, alcohol, ammonia, carbon dioxide, hydrogen chloride etc. to form a macromolecule in which the molecular formula of the repeating structural unit is generally not the some as that of the monomer. The polymers thus formed are called condensation polymers. These are also called step-growth polymers since they are formed as result of stepwise reactions. Some other example of condensation or step-growth polymers are :
"manishkumarphysics.in"
12
CHEMISTRY Polymer
Monomers
(i) Terylene or Dacron
Ethylene glycol and terephthalic acid or its methylester
(ii) Alkyl resin
Ethylene glycol and phthalic acid
(iii) Bakelite
Phenol and formaldehyde
(iv) Melamine formaldehyde resin
Melamine and formaldehyde
(v) Polyurethane
Ethylene glycol and toluene m-diisocyanate
(i) Elastomers Polymers in which the intermolecular forces of attraction between the polymer chains are the weakest are called elastomers. (ii) Fibres Polymers in which the intermolecular forces of attraction are the strongest are called fibers. These forces are either due to H-bonding or dipole-dipole interactions. In case of nylons (polyamides), the intermolecular forces are due to H-bonding while in polyesters (terylene, dacron etc.) and polyacrylonitrile (orlon, acrylin etc.) They are due to powerful dipole-dipole interactions between the polar carbonyl (C = O) groups and, between carbonyl and cyano (– C N) groups respectively. (iii) Thermoplastics Polymers in which the intermolecular forces of attraction are in between those of elastomers and fibres are called thermoplastics. The process of heat softening and cooling can be repeated as many times as desired without any change in chemical composition and mechanical properties of the plastic. (iv) Thermosetting polymers. These are semifluid substances with low molecular weights which when heated in a mould, undergo change in chemical composition to give a hard, infusible and insoluble mass. This hardening on heating is due to extensive cross-linking between different polymer chains to give a threedimensional network solid. Some example of thermosetting polymers are : phenol-formaldehyde (bakelite), urea-formaldehyde, melamineformaldehyde etc. Polyvinyl Chloride (PVC) It is obtained by polymerising vinyl chloride. PVC is used in the manufacture of imitation leather, floor covering, corrugated roofing material, and gramophone records. Cl | n CH2 CH
Polymerisation
Cl | CH2 CH n
Vinyl chloride PVC Vinyl chloride is obtained from acetylene by treatment with HCl in the presence of HgCl2. HgCl
2 CH2 = CH – Cl HC CH + HCl Acetylene Vinyl chloride
Teflon (PTFE) It is obtained by polymerising tetrafluoroethylene. Teflon is familiar because of its use as non-stick coating particularly for cooking utensils. Nirlep non-stick frying pans have teflon coating. Because of its low chemical reactivity, excellent toughness, electrical and heat resistance, teflon is used as insulation for electrical items and in the manufacture of gaskets and valves.
Polymerisation n CF2 CF2 Tetrafluoroethylene
F F | | C C | | F F n Teflon
Tetrafluoroethylene is obtained from chloroform as follows : CHCl3 + 2HF CHClF2 + 2HCl Chlorodifluoromethane 900C CF2 = CF2 + 2HCl CHClF2 Tetrafluoroethylene
"manishkumarphysics.in"
13
CHEMISTRY Nylon-6, 6 Nylon-6,6 is the most important polyamide. It is obtained by heating adipic acid with hexamethylene diamine under nitrogen at 200°C. Nylon-6, 6 derives its name from its starting materials, adipic acid and hexamethylene diamine, both of which have six carbons. Heat
HOOC(CH2)4CONH(CH2)6NH2 + H2O HOOC(CH2)4COOH + NH2(CH2)6 NH 2
[ CO(CH2 ) 4 CONH (CH2 )6 NH]n Natural rubbers Natural rubber is hydrocarbon polymer built up from the monomer isoprene. CH3 | n H2C C CH CH2 Isoprene
Polymerisation
(1, 4 Addition)
CH3 | CH2 C CH CH2
(Nylon 6, 6 )
n
Natural rubber
Vulcanisation : Raw rubber obtained from milky sap (latex) of the rubber tree does not possess the characteristics of the rubber with which we are familiar. In order to give it strength and elasticity it is vulcanised. In the vulcanisation process, raw rubber is mixed with small amount of sulphur and heated. The sulphur reacts with polymer molecules forming a cross-linked net work.
Properties and uses of few polymers
"manishkumarphysics.in"
14
CHEMISTRY Some commercially Important Polymers
"manishkumarphysics.in"
15
CHEMISTRY
MISCELLANEOUS SOLVED PROBLEMS (MSPS) 1.
For HOOC – (CH2)2 – CH – COOH Glutamic acid value of pKa1, pKa2, pKa3 are 2.00, 4.65 and 9.98 | + NH3
Ans.
respectively. At which pH Glutamic acid will not be obtained during electrophoresis at any one of the electrodes. (A) 3.325 (B) 7.325 (C) 6.012 (D) 4.65 (A)
Sol.
pi =
2.
Identify the anomers
pKa1 pKa 2 2
(A)
(C)
and
(B)
and
(D)
and
and
Ans. Sol.
(D) The compounds of this pair are the diastereomers which have different configuration only at C-1 and are thus anomers.
3.
Which of the following is a C-4 epimer of D-glucose.
(A)
Ans.
(B)
(C)
(D)
(A)
Sol.
"manishkumarphysics.in"
16
CHEMISTRY 4.
Which of the following will form same product (osazone) on reaction with PhNHNH2 (excess).
Ans. Sol.
(A) X, Y (B) X, Z (D) Osazone formation involves following reaction :
CH2 OH | CO | R
5.
(D) X, Z, W
CH N NHPh | C N.NHPh | R
CHO | CHOH | R
When D-Glucose is placed in basic aqueous solution an equilibrium mixture of three compounds is obtained. Which of the following will not be present in equilibrium mixture.
(A)
Ans.
or
(C) Z, W
(B)
(C)
(D)
(D)
Sol.
"manishkumarphysics.in"
17
CHEMISTRY 6.
Ans.
The smallest repetitive unit of following polymer is
(A) CH3 – CH2 – CH = CH – CH2 – CH3
(B) CH2 = CH – CH = CH2
CH3 | (C) CH2 C CH CH2
(D) CH3 – CH = CH – CH = CH2
(D)
Sol.
7.
+
Which of the following polymerisation reaction can have branched polymers also. R | (A) H2N CH COOH
(B)
(C)
(D) Me CH COOH | OH
Ans. Sol.
(B) It can have branching by (1, 6) condensation.
"manishkumarphysics.in"
18
CHEMISTRY 8.
What monomer would you use to prepare the following polymer.
(A) CH3 CH CH2 CH3 | COOCH3 (C) CH2 C CH2 CH3 | COOCH3 Ans.
(B) CH3 CH CH CH2 | COOCH3 (D) CH3 CH C CH2 CH3 | COOCH3
(D)
Sol.
9.
Ans. Sol.
Column-I Column-II (A) Bakelite (p) Butadiene and styrene (B) Dacron (q) Phenol and methanal (C) Nylon-66 (r) 1,2-dihydroxyethane and dimethyl terepthalate (D) Buna-S (s) 1,6-hexanedioic acid and 1,6-diamine hexane (A – q) ; (B – r) ; (C – s) ; (D – p) (A) Bakelite is made from phenol and methanal. (B) Dacron is obtained by the condensation of ester of terephthalic acid and ethylene glycol. (C) Nylon-66 is obtained by the condensation of 1,6-hexanedioic acid and 1,6-diamino hexane. (D) Buna-S is an addition polymer of butadiene, styerene.
"manishkumarphysics.in"
19
