TARGET IIT JEE 2014 2 014
CHEM I STR TRY
A LCOHOLS
1
Single correct answers : 1.
The relative rate of acid catalysed dehydration of following alcohols would be,
(A) III > I > IV > II 2.
(B) III >IV > I > II
(D) III > IV > I > II
Which of the following alcohol will show positive iodoform test OH | (A) CH3 CH CH2
OH | (B) CH3 CH CH2 COOH
NO 2
OH | (C) ICH2 CH CH2 3.
(C) I > III > IV > II
(D) none of these
CH3
In the given reaction ,
B2H6 , THF
H2O2 , NaOH
TSCl
t BuO ¯ K
(Y)
The product ‘Y’ is (A) (B) (C) (D) 4.
A positional isomer of X Identical to X Chain isomer of X An oxidation product of X.
Which of the following reaction does not involve formation of an ether.
(A) CH2 = CH2 + C2H5OH
(C)
(CH3COO)2 Hg
(CH3 )2 SO 4, NaOH
NaBH4
(B)
CH2N2
(D) (CH3)3CCl + C2H5 .OH
Alcohol
KOH
5.
The most appropriate major product of the following sequence of reactions would be.
H3O
(A)
()
(C)
6. ,
()
(CH ) CHCHO
NaNH
H3O 2 2 3
CH3 – C CH
(B)
OH | (CH3)2CH – CH – C C – H
NaNH2 CH3 CH3 NaNH2
CH3 – C C – CH – CH2 – CH3 | OH OH | (CH3)2CH – CH – C C – H
CH3Mg CH3
What is the major product of the following sequence of reactions ?
(CH3)2CHCH2OH
9.
(D)
(A)
(D)
8.
()
The best yield of product ‘X’ can be obtained by using which one of the following sequence of reagents and reactants. OH | X = CH3 – C C – CH – CH (CH3)2
(C)
7.
(B)
PBr 3
Mg
?
OH | (A) (CH3)2 CHCHCH2CH3
OH | (B) (CH3 )2 CHCH2 CHCH3
(C) (CH3)2CHCH2CH2OH
(D) (CH3)2CHCH2CH2CH2OH
The reaction of 3-butene-2-ol with aqueous HBr gives (A) 3-bromo-1-butene only (B) 1-bromo-2-butene only (C) a mixture of 3-bromo-1-butene and 1-bromo-2-butene (D) 4-bromo-1-butene
B
CH3OH
CH3O ¯ Na
H2O18
H
A, A & B are
Alcohol
CH3 | (A) CH3 C CH2 | | 18 OH OH
CH3 | (B) CH3 C CH2 | | OH18OH
CH3 | CH3 C CH2 | | OH OCH3
(C) both are correct 10.
CH3 | CH3 C CH2 | | OH OCH3
(D) none is correct
The final major product of the following reaction is ( CH3 CO )2 O
conc . H SO
KMnO 4 OH
2 4 B A BF3
(A)
(B)
+ CH3CH2OH
11.
H dry HCl
(C)
(D)
(dry HCl)
B A
(A) B is
(B) B is
(C) B is
(D) B is
Mg / ether
PCl5
O2,
H O
2 (X),
12.
(A) D-2-Butanol
(B) L-2-Butanol
compound X is
(C) Both A & B
SOCl2 Mg ( C2H5 )2 O pyridine,
13.
C
Product
Product of the reaction is
(A)
(B)
(C)
(D)
Alcohol
(D) Nither A nor B
(Y) product
14.
Compound Y is (A)
(B)
+ X
15.
(C)
(D)
(C)
(D)
H
Write the structure of X
(A)
16.
(B)
CH2
CH CH CH CHMe | OH
MeOH H2SO 4
H | CH CH CH CH C Me (A) 2 | O Me
(C)
CH2 CH CH CH CH CH3 | O Me
CH2
CH CH CH CH Me | OMe
(B) CH2 = CH – CH = CH – CH2 – CH2 – O – Me
(D)
CH2 CH C CH CH2 CH3 | O Me
H
17.
(A)
(B)
(C)
(D)
(B)
(C)
(D)
(C)
(D)
H H2O
18.
(A)
H
19.
(A)
(B)
Alcohol
CH3CH2OH H2SO 4
20.
(A)
21.
(B)
OH | CH3 CH2 C C CH | CH3
(C)
(D)
H2SO 4
O || (A) CH3 CH C CH2 C H | CH3
H O | || (B) CH2 CH C CH2 CH | CH3
O || (C) CH3 CH C C CH3 | CH3
O || (D) CH3 CH C C CH3 | | CH3 H
(A)
(B)
(C)
(D)
(A)
(B)
(C)
(D)
22.
23.
24.
Compound ‘A’ has following solubilities in different solv ents : Which solvent would you prefer for recrystallization of that compound ? S.No .
(A) 1
So lv en ts
Solubi lit y (g / 100 g) 20°C
80°C
1
Water
0.15
0.27
2
Ethanol
0.70
8.2
3
Benzene
16
38
4
Heptene
36
41
(B) 2
(C) 3
Alcohol
(D) 4
25.
When (A) (given below) reacts with H I product is (B) and not (C). Explain. HI
HI
Br 2 X CH3NO2
26.
(A) X is
(B) X is
(C) X is
(D) X is
27.
CH3 – CH2OH + CH2 = C = O (A) CH3
H
?
O CH2 C CH3
(B) CH3
CH2 C O CH3
(D) CH3
CH2 O C CH3
|| O
(C) CH3
O CH2 CH2 C H
|| O
|| O
|| O
swers EXERCISE - 1 1.
A
2.
C
3.
A
4.
D
5.
C
6.
A
7.
D
8.
C
9.
A
10.
B
11.
C
12.
B
13.
B
14.
A
15.
B
16.
A
17.
C
18.
B
19.
D
20.
A
21.
C
22.
B
23.
C
24.
B
25.
C
26.
A
27.
D
Alcohol
2 Find th e correct answers in t he follow ing reactions : (More than one anwers may be correct) conc . H2SO4
1.
( A ) C9H16
O3
OH¯
(B) (C) (C9H16 O2 ) (C9H14 O)
[(B) gives positive iodoform test.]
(A) A is
(B) B is
PBr 3
2.
(A)
(C) C is
Mg / Et 2O
(B)
(C)
(A) A is
(B) B is
(C) C is
(D) C is
K 2Cr 2O7 , H
3.
O || (A) X is Cl C C CH2Cl || O
X + Y
(D) Y is ClOC C CH3 || O
Conc . H2SO 4
A
(A) A is
SOCl2
(B) X is
(C) Y is
4.
(D) C is
(B) A is
+B
(C) B is
Alcohol
(D) B is
CrO3
(i) CH3MgI
H2SO 4 acetone
(ii) H3O
( ii) BH3 , THF
H2SO 4 ,
D C A B
5.
(A) A is
( ii) H2O 2 , OH ¯
(B) B is
(C) B is
(D) C is
LiAlH
H SO
2 4 4 (B) (A)
6.
(A) A is
(B) B is
(A)
7.
(A) B is CH3
(C) C is CH3
| O CH3
(D) B is
(B)
(C)
(B) B is CH3
CH CH2 C CCH3 | O CH3
CH CH2 CH
(C) A is
CH2 CHC
CCH3
| OCH3
CH CH3
(D) A is
Conc. HI
8.
(A) D is
(B) C is
(C) Bis
(D) A is
9.
(A) E is CH3CH2CH2OH
(B) D is CH3 – CH = CH2
(C) B is CH3CH2 – Cl
(D) F is CH3
Alcohol
CH CH3 | OH
10.
(A)
HCl
(B)
NaHCO3 CrO / Py / CH2Cl2 (D) (C) 3
(A) A is
11.
H2O
(B) A is
(C) B is
(D) C is
Identify of the missing compounds in the following reaction sequences. CH2 = CH – CH2Br
A C 4H8 O
Br 2
B C4H8Br 2O KOH Heat
(A) A is CH2 = CH – CH2CH2OH,
(C) C is 12.
(B) B is CH2 | Br
(D) C is
Identify the products in the following sequence of reactions.
(A)
(B)
(A) A is
(C) C is
(B) B is
(D) E is
Alcohol
CH
| Br
CH2
C C4H7BrO
CH2OH
13.
Study the following road map of reactions. Identify unknown compounds mentioned in various steps.
(A) Z is
(B) J is
(C) C is Hg+2 / H2SO4
(D) K is
NaBr
TsCl Pyridine
A B
14.
(A) A is
(C) A is
(B) B is
(D) B is
15.
(A)
(B) CH3 – O – H
(C)
(D)
swers EXERCISE - 2 1.
A, B, C
2.
A, B, C, D
3.
B, D
4.
B, C
5.
B, C, D
6.
A, B
7.
A, C, D
8.
A, B, C, D
9.
A, B, C, D
10.
B, C, D
11.
A, B, C
12.
B, C, D
13.
A, B, C, D
14.
A, B
15.
A, B
Alcohol
3 One or More than one correct answers : 1.
Alcohol A (C10H18O) is converted to a mixture of alkenes B and C on being heated with KHSO4. Catalytic hydrogenation of B and C yields the same product. Assuming that dehydration of alcohol A proceed s wit hou t rea rrangem ent . Al kene B by ozonoly sis forms cy cl ope ntanone. Identify correct options. (A) A is
2.
(B) B is
(C) C is
An optically inactive organic compound A (C7H11Br) is treated with Mg in ether to give B (C7H11MgBr), which react violently with D2O to give C. Reaction of B with acetone followed by hydrolysis gives D(C10H18O). Heating D with concentrated acid gives
3.
4.
(D) C is
(A) A is
(B) B is
(C) D is
(D) D is
. Identify correct options
A compound ‘A’ C9H10O exist in diastereomeric form, liberates a gas on reaction with CH3MgBr. Treatment of A with aqueous HBr gives B (C 10H13Br), which exist in enantiomeric forms. B on treatment with alcoholic solution of KOH gives a compound C. Ozonolysis of C followed by work up with H2O gives CH3CHO and Ph CO CH3 . Identify correct options (A) A is Ph CO CH2 CH3
(B) A is Ph CH2 CO CH3
(C) B is Ph (CH3 )C CH CH2 Br
(D) C is Ph (CH3 )C CH CH3
A compound X (C14H14O) on mild oxidation yields C14H12O(Y). If X is treated with a dehydrating agent, it loses a molecule of water and resulting product on vigorous oxidation yields two molecules of benzoic acid. Identify structures of X and Y. (A) X is PhCH2CH(OH)Ph (B) X is Ph ( OH)CH CH2 Ph (C) Y is Ph CO CH2 Ph
(D) Y is Ph CH2
CO Ph
5.
Two optically active alcohols A and B have same molecular formula C9H12O and do not decolourise bromine water solution. Both A and B are oxidised by KMnO4 to give benzoic acid and react with Na to give a colourless odourless gas. Compound A gives yellow ppt with I2 / NaOH where as B does not. Also A loses optical activity on oxidation but B does not. Identify structures of A & B. H | (A) A is C 6H5 CH2 CH CH3 (B) A is C 6H5 C CH2CH3 | | H O OH H | (C) B is C 6H5 CH CH2 OH (D) B is C 6H5 C CH2 CH3 | | CH3 CH3
6.
Compounds A, B and C are isomeric alcohols with formula C5H12O. A on oxidation gives ketone, B gives acid while C is not oxidised A gives test with I2 / NaOH. The three isomeric alcohols react with HBr with decreasing relativ e rates C > A > B. Identify A and B. A has 4 diastereomeric form B with Al2O3 / give optically active compound D. (A) A is (CH3 ) 2 CH CH(OH) CH3 (B) A is (CH3 )3 C OH (C) B is (CH3 )2 CHCH2CH2OH
(D) B is (CH3 ) 2 C( OH)CH2CH3
Alcohol
7.
A neutral compound
on acid hydrolysis produces two compounds B
(C4H8O) and C (C 6H10O2). B on treatment with SOCl 2 gives D (C 4H7Cl) which on further treatment with aqueous solution of KCN followed by hydrlysis of product yiel ded ‘t’ (C5H8O2). E on reducing with LiAlH4 gives F (C5H10O). Which on heating with conc. sulphuric acid solution yields G (C5H8). G on treatment with HCl yields.
(A) C is 8.
(B) F is
(C) E is
(D) D is
A 3° optically active alcohol C9H18O ‘A’. On dehydration with conc. H2SO4 produces B (C9H16) which exists in two stereomeric forms. Ozonolysis of B followed by work up with Zn – H2O produces ethanal and C (C7H12O). C on treatment with LiAlH4 produced D (C7H14O). D on dehydration
produced
9.
. Identify correct options.
. Identify the correct options.
(A) A is
(B) A is
(C) D is
(D) D is
An optically active alcohol A (C8H16O) on oxidation gives B. A on heating in acid gives C (C8H14) as O || major product. C on ozonolysis produces D (C 5H8O) and CH3 C CH3 . D on reduction with LiAlH4 gave
10.
(A) D is
(B) C is
(C) B is
(D) A is
Compound A is an optically active alcohol. Treatment with oxidising agent convert it to a ketone B. In a separate reaction A is treated with PBr 3, converting it into C. C on reaction with Mg is added to B to yield (A) A is 2-butanol
11.
. Identify the correct options.
. Identify correct options (B) A is 1-butanol
(C) C is 2-bromobutane (D) C is 1-bromobutane
C7H14 (A) decolourises Br 2 in CCl 4 and reacts with Hg(OAC)2 in THF followed by reduction with NaBH4 to produce a resolvable compound B. A undergoes reductive ozonolysis to give as one of the compounds. Identif y A and B. (A) A is
(B) A is
(C) B is
Alcohol
(D) B is
12.
13.
Compound A (C7H11Br) reacts with Mg in ether to give B. To this solution acetone (propanone) is added slowly. When this solution is added to water a product C (C10H18O) is obtained. C on heating with conc. H2SO4 gives D (C10H16). D on catalytic hydrogenation gives 2-methylpropylcyclohexane (isobutylcyclohexane). If B is treated with water the product is E (C7H12) which on ozonolysis produces 6-oxoheptanal. Identify the correct options.
(A) E is
(B) D is
(C) C is
(D) A is
An optically active compound A (C8H17Br) on heating with alcoholic KOH produces B (C8H16) as the major product. B reacts with NBS (N-Bromo succinimide) and produces C (C 8H15Br), another optically active compound. Further dehydrobromination of C produces D (C8H14). When D is treated with one mole of Bromine at 40° – 50°C, it forms an optically inactive dibromide E (C8H14Br 2) as the major product (80%). When E is added to an ethereal solution containing magnesium F (C8H14Mg2Br 2) is obtained. To this solution 1 mole of Ethyl acetate is added slowly and finally the product is hydrolysed and identified as given bellow :
Identify the correct options. (A) A is 14.
(D) D is CH3
C CH3
|| O
(D) E is
CH CH3
| OH
A compound (A) gives Lucas test in 5 minutes. When 6.0 gm of (A) is treated with Na metal, 1120 ml of hydrogen is evolved at STP. Assuming (A) to contain one atom of oxygen per molecule, write the structural formula of (A). Compound (A) when treated with PBr 3 gives compound (B) which when treated with benzene in presence of anhydrous AlCl3 gives compound (C). Identify the correct options. (A) C is (C) B is CH2 CH CH2 | | Br Br
16.
(C) D is
An alcohol (A) when heated with conc. H2SO4 gives an alkene (B). When (B) is bubbled through bromine water and the product obtained is dehydrohalogenated with excess of sodamide, a new compound (C) is obtained. The compound (C) gives (D) when treated with dilute H 2SO4 in presence of HgSO4. (D) can also be obtained either by oxidizing (A) with KMnO 4 or from acetic acid through its calcium salt. Identify the correct options. (A) B is CH3 – CH = CH2 (B) C is CH3 – C C – H (C) A is CH3
15.
(B) B is
(B) C is CH2 OH
(D) A is CH3 – CH = CH – CH2 – OH
An organic compound (A) composed of C, H and O gives characteristic colour with cerric ammonium nitrate. Treatment of (A) with PCl 5 gives (B) which reacts with KCN to form (C). The reduction of (C) with warm Na/C2H5OH produces (D) which on heating gives (E) with evolution of ammonia. Pyridine is obtained on treatment of (E) with nitrobenzene. Identif y the correct options.
Alcohol
(A) A is
(B) C is
(C) D is
(D) E is
17.
Compound A (C6H14O) on reaction with Lucas reagent gives B. B on treatment with alc. KOH gives C. (a) A has 3 more stereoisomers. (b) B does not have any stereoisomer (c) C has 1 more stereoisomer Identify A, B, C and write the possible stereoisomers.What product A will give on treatment with acetone and [(CH3)3C–O] 3 Al. Will it be optically active ? (A) A is tope structure from answer at the back (B) B is draw structure of B (C) C is draw structure of A (D) B is draw structure of B
18.
Treatment of compound (A), C8H10O with chromic acid – pyridine gives (B), C8H8O. Treatment of (B) with two equivalents of bromine yields (C), C8H6OBr, which on treatment with caustic soda followed by acidification gives a compound (D), C8H8O3. The latter liberates CO2 on treatment with NaHCO3 and is resolvable. Identify the correct options. (A) A is PhCH2CH2OH / PhCHOHCH3 /
(B) B is PhCH2COH / PhCHOCH3 / (C) C is PhCBrCHO (D) D is PhCOCOOH 19.
20.
Three isomeric alcohol (A, B, C) (C5H12O) react with HBr with decreasing relative rates of A > B >> C. B and C are oxidized by chromic acid solution, ‘C’ forms an acid in the oxidation process. B is oxidized by NaOI. All three alcohol give the same product on treatment with HBr. Identify A, B, C. CH3 | (A) A is CH3 CH2 C OH | CH3
CH3 | (B) B is HO CH2 CH2 C H | CH3
CH3 | (C) C is CH3 C CH2 OH | CH3
(D) A is CH3CH2CH2CH2CH2OH
An optically active compound (A) reacts with NaBr + H2SO4 Soln & gives an optically inactive compound (B). A on reaction with CrO 3 / aq. acetone gives a chiral compound C (C9H10O2). C on reaction with moist Ag2O followed by treatment with Br 2/CCl4 Soln gives D, a lower homologue of B. A on heating with alkaline KMnO4 produces E (C7H6O2). A, C & E all liberate a Colourless & odourless gas with Na metal. A does not respond to iodoform test . A on controlled oxidation with CrO3 – pyridine produces a chiral compound F. Identify the correct options. (A) A is C 6H5
CH CH2 OH
| CH3
(C) E is C6H5 – CHO
(B) C is C 6H5
CH COOH
| CH3
CH3 | (D) F is C 6H5 CH CHO
Alcohol
21.
22.
C7H14 (A) decolorize Br 2 in CCl4 and reacts with Hg(OAc)2 in THF – H2O followed by reduction with NaBH4 to produce a resolvable compound B. A undergoes reductiv e ozonolysis to give the same compound obtained by oxidation of 3-hexanol with KMnO4 (C). Identify A, B and C. (A) C is O C CH2CH2 CH3 | C 2H5
(B) A is CH2
(C) B is
(D) B is
(B) D is
(C) C is
. Identify the correct options.
(A)
(B)
(C)
(D)
A (C5H12O) ether, on reaction with PCl5 forms alkyl chloride (B) and (C). (B) and (C) both on reaction with aqueous KOH form alcohol (D) and (E) ; Both (D) and (E) give iodoform test. Identify the correct options. (A) A is
(C) C is CH 3CH2Cl
25.
(D) E is
A cyclic ester on treatment with excess of CH3MgBr followed by treatment with NH4Cl / H2O give a diol which on oxidation gave
24.
C CH2CH2CH3 | C 2H5
A compound ‘C’ on hydroboration oxidation gave . optically active (trans isomers). Compound A which on reaction with TsCl gave compound B, which on treatment with NaI gave D and an optically activ e (trans isomer) D on treatment with aq KOH gave E (C5H10O) ± trans. If ‘C’ contains a four membered cyclic ring having double bond equlvalent 2. Find the correct options. (A) A is
23.
(B) C is CH3
CHCH3
| Cl (D) E is CH3 CH CH3 | OH
Dehydration of 2, 2, 3, 4, 4-pentamethyl-3-pentanol gave two alkenes A and B. Ozonolysis of A gave HCHO and 2, 2, 4, 4-tetramethyl-3-pentanone and that of B gave HCHO and 3, 3, 4, 4-tetramethyl-2-pentanone. Identify A and B and explain reaction. CH3CH2CH3 | || | (A) A is CH3C – C – CCH3 , | | CH3 CH3
CH3CH3 CH2 | | || (B) B is CH3 C – C – C – CH3 | | CH3 CH3
Alcohol
CH3CH3 CH2 | | || (C) A is CH3 C C C CH3 | | CH3 CH3 26.
CH3CH2 CH3 | || | (D) B is CH3 C C C CH3 | | CH3 CH3
Compound A (C11H16O) was found to be an optically active alcohol. Despite its apparent unsaturation, no hydrogen was absorbed on catalytic reduction . On treatment of (A) with H 2SO4, dehydration occured and B, an optically inactiv e alkene (C11H14) was produced as major product. Alkene B on ozonolysis gave two products C & D. The compound C (C 3H6O) does not give iodoform test but gives positive Tollen’s test. The compound D(C8H8O) gives positive iodoform test and on oxidation gives a monobasic acid (E) C7H6O2. Identify A, B, C, D & E and explain reaction sequences.
(A) B is
(B) C is CH3 – CH2 – CHO
(C) D is 27.
(D) E is
An unknown compound ‘A’ with the M.F C9H12O does not decolourize Br 2 in CCl4 and is oxidized by hot KMnO4 to give PhCO2H. The compound reacts with Na to give a colourless odourless gas. Give f ive isomeric structures (A-E) fitting these data and from the f ollowing results deduce the correct structure of (A). (i) the colour of Cr 2O72– changes from orange to blue green when added to A, B, C or D. (ii) the compound can be resolved. (iii) no ppt of CHI3 is observed with I2 / OH – . (iv) oxidation with CrO3 /pyridine gives a chiral compound.
(A) A is
(B) E is
(C) C is
(D) D is
swers EXERCISE - 3 1.
A, B, C
2.
A, B, D
3.
A, D
4.
B, C
5.
A, C
6.
A, C
7.
A, B, C, D
8.
B, D
9.
A, B, C, D
10.
A, D
11.
A, C
12.
B, D
13.
A, C
14.
A, B
15.
A, C
16.
A, B, C, D
17.
A, B, C, D
18.
A, B, C
19.
A, C
20.
A, B, D
21.
A, B, C
22.
A, B, D
23.
A, B
24.
A, B, D
25.
A, B
26.
A, B, C, D
27.
A, C, D
Alcohol
4 Ass ertion Reason ty pe Question
(A) If both assertion and Reason is correct explanation of A (B) If both assertion and Reason are correct but Reason is not correct explanation of A (C) If assertion is correct, reason is wrong (D) If assertion is wrong, reason is correct 1.
Assertion : Esters are hydrolysed by acids or alkalis. Reason : Alkaline hydrolysis is far more rapid than acid hydrolysis.
2.
Assertion : Alkaline hydrolysis of esters is a second order reaction in B AC 2 mechanism. Reason : Mechanism of the reaction is
+
3.
Assertion : Acid catalysed hydrolysis and acid catalysed esterification are the reverse of each
other. Reason : This is because of the principle of microscopic reversibility. 4.
Assertion : Lucas reagent gives white turbidy immediately with tertiary alcohol. Reason : With tertiary alcohol the reaction proceds by SN2 mechanism.
5.
Assertion : The ease of dehydration of alcohol being 1° > 2° > 3°. Reason : The acid catalysed dehydration of alcohol may be accompanied by rearrangement.
6.
Assertion : Rearrangement often occurs in acid-catalysed dehydration. Reason : Carbocation intermediate formed during dehydration may rearrange to get more stable
product. 7.
Assertion : The oxidation of primary and secondary alcohols by dichromate and permangnate
ions involves an ester intermediate. Reason : The rate determining step is the removal of hydrogen from the intermediate formed. 8.
Assertion : (CH3)3C – Br and CH3CH2ONa will react and form only (CH3)3C – O – CH2CH3 Reason : Ethers are prepared by the reaction of alkoxides with alkyl halides.
9.
Assertion : The boiling point of ethanol is much higher than that of diethyl ether. Reason : In ethanol, the molecules are associated by the formation of intermolecular hydrogen
bonding whereas in diethyl ether it is not possible. 10.
Assertion : Addition of C2H5OH to 3, 3-dimethyl-1-butene gives 2-ethoxy-2, 3-dimethylbutane in-
stead of 3-ethoxy-2, 2-dimethylbutane. Reason : The reaction occurs by SN2 mechanism.
Alcohol
11.
Assertion : On treatment with concentrated H2SO4, tert butyl alcohol does not give ditertiary butyl
ether ; instead it gives 2-methyl propene. Reason : On reaction with concentrated H2SO4, tertiary alcohols do not giv e ethers due to the instability of ethers formed in H2SO4 and also due to steric crowding.
12.
Assertion : Some alcohols are poured in small quantity in the fuel tanks of automobiles, particu-
larly in cold countries. Reason : The moisture present in gasoline gets dissolved in the alcohol, and therefore, does not freeze. 13.
Assertion : One being heated with n-butanol in the presence of sodium butoxide (n-C 4H9ONa),
ethylacetate gives n-butylacetate. Reason : In trans esterification the alkyl group of one ester is preplaced by the alkyl group of another alcohol.
swers EXERCISE - 4 1.
B Hint : R1CO2H + R2OH
H3O
1
R
CO2R2
2.
A
3.
A Hint : The mechanism of acid catalysed hydrolysis is the reverse of acid catalysed esterification.
4.
C Hint : Tertiary alcohol forms carbocation easily resulting in immediate reaction with Lucas reagent.
5.
D Hint : The ease of dehydration of alcohol is 3° > 2° > 1° which due to the stability of intermediate carbocation which is formed.
6.
A
7.
B Hint : The mechanism is Cr 2O7 –2 + H2O 2HCrO4¯ Me2CHOH + HCrO 4¯ + 2H+
Me2CH – O – CrO 3H2+ + H2O Me2CO + H3O+ + H2CrO3
8.
D
9.
A
10.
C
11.
A
12.
A
13.
A
Alcohol
