ORGANIC CHEMISTRY
1. Which alkyl halide will react fastest with aqueous ethanol ?
(A) (CH3)3C – Br (B) (CH3)3C – Cl
(C) (CH3)2CH – Br (D) CH3 – CH2 – CH2 – Br
2. When the concentration of alkyl halide is tripled and the concentration of OH¯ ion is reduced to half, the rate of SN2reaction increases by:
(A) 3 times (B) 2 times (C) 1.5 times (D) 6 times
3. AnSN2reaction at an asymmetric carbon of a compound always gives: (A) an enantiomer of the substrate
(B) a product with opposite optical rotation (C) a mixture of diastereomers
(D) a single stereoisomer
4. In the given reaction, CH3CH2 – X + CH3SNa The fastest reaction occurs when ‘X’ is
-(A) – OH (B) – F (C) – OCOCF3 (D) OCOCH3
5. Which of the following involves an “SN2” route of reaction:
(A) CH3Cl ether Na (B) CH 3MgCl + CH3Cl (C) CH3Cl + LiAlH4 (D) All
6. The compound which undergoes fastest reaction with aq. KOH solution is : (SN2) (A) Cl | OCH CH H C6 5 3(B) Cl | CH CH H C6 5 3 (C) C6H5 – CH2 – CH2 – Cl (D) Cl | CH CH CH H C6 5 2 3 7. The rate of 1 N
S reaction is fastest with:
(A) (B)
(C) (D)
8. In the following reaction the most probable product will be:
(A) (B) (C) (D)
9. In the following reaction :
AcetoneNa I
‘X’ [The structure of ‘X’ can be]
(A) (B) (C) (D)
10. The following reaction is described as:
NaOH
(A) SN1with racemisation
(B) intramolecular SN2 with walden inversion
(C) intramolecular SN2 with retention of configuration (D) intermolecular SN1 with recemisation
11. The insecticide chlordane is warmed with dilute NaOH solution for some time. The expected product would be :
(A) (B)
(C) (D)
12. Which configuation will be adopted by the poduct at cabon atoms marked (1) and (2) respectively in the given reaction.
+ Br | CH CH CH CH ) D ( 3 2 3 Ether (A) D, D (B) D, L (C) L, L (D) L, D
13. Which of the following will undergo fastest elimination reaction with alcoholic KOH.
(A) (B) (C) (D)
14. When all-cis isomers of C6H6Cl6 (1, 2, 3, 4, 5, 6 - Hexachlorocyclohexane) is heated with alc. KOH, the most probable product is :
(A) (B) (C) (D)
15. The most probable product in the following reaction is :
Trans
(A) (B) (C) (D)
16. Which product(s) will be formed in the following reaction :
alc.KOH
(A) No reaction (B) Trans alkene (C) cis alkene (D) cis + trans alkene
17. What will be the major product of the following reaction
Br CH H | | | CH CH C C CH | | CH CH 3 3 3 3 3
CH
3OH
,30
C
(A) H H OCH | | | CH C C C CH | | | CH CH CH 3 3 3 3 3 3 (B) 3 3 3 3 3 CH CH C C CH | | | CH CH CH (C) H OCH H | | | CH C C C CH | | | CH CH CH 3 3 3 3 3 3 (D) 3 2 3 3 3 CH H | | CH CH C C CH | | CH CH 18. Which of the following reaction will undergo an elimination reaction and an alkene will be formed in the products.
(A) Zndust, (B)
(C) alc.KOH, (D) concH2SO4,
19. When (1R, 2R)-1, 2-dibromo-1, 2-diphenyl ethane is treated with alcoholic solution of KOH, the most probable product would be :
(A) trans-1, 2-diphenyl ethene (B) A mixture of cis, trans alkenyl bromide
(C) cis-alkenyl bromide (D) trans-alkenyl bromide
20. Which of the following products is formed when m-bromochlorobenzene is treated with magne-sium in the presence of ether ?
(A) (B) (C) (D)
21. The end product Y of the reaction is :
C2H5MgBr + S X
O H3
Y
(A) C2H6 (B) C2H5SMgBr (C) C2H5SH (D) none of these
A
nswers
E X E RC I S E -1
1. A 2. C 3. D 4. C 5. D 6. A 7. A 8. B 9. A 10. B 11. D 12. B 13. A 14. B 15. C 16. C 17. C 18. B 19. D 20. A 21. C1. Predict the compound in each pair that will undergo the SN2 reaction faster.
(a) (i) (ii) (b) (i) (ii)
(c) (i) (ii) (d) (i) (ii)
(e) (i) (ii) (f) (i) (ii)
2. Predict the compound in each pair that will undergo solvolysis (in aqueous ethanol) more rapidly.
(a) (i) (CH3CH2)2CH – Cl (ii) (CH3)3C – Cl (b) (i) (ii)
(c) (i) (ii) (d) (i) (ii)
(e) (i) (ii) (f) (i) (ii)
3. The correct decreasing order of relative reactivity of the following bromides towards hot aqueous KOH solution is:
(I) CH3 – CH2 – Br (II) CH3 – CH2 – CH2 – Br (III) OH – CH2 – CH2 – Br (IV) CH3 – – CH2 – Br
(A) I > III > II > IV (B) I > II > III > IV (C) I > II > IV > III (D) III > I > II > IV
4. For a given alkyl halide, the ease of formation of Grignard reagent is: (A) RI > RBr > RCl (B) RI > RBr < RCl (C) RI < RBr < RCl (D) RI > RCl > RBr
5. The correct order of reactivity of the following halides for bimolecular elimination is : (I) (CH3)2 CH – CHI – CH3 (II) (CH3)2CH – CH2 – CH2 – I (III) CH3 – CH2 – CHI – CH3 (IV) I | CH CH C ) CH ( 3 2 2 3
(A) II > III > I > IV (B) III > II > I > IV (C) I > II > III > IV (D) IV > I > III > I
6. The relative reactivity of following halides towards ethanol follows the order:
(I) CH3 – – Cl (II) CH3CH2Cl (III) CH3 – O – CH2 – Cl (IV) C6H5– CH2 – Cl (A) II > IV > III > I (B) I > IV > III > II (C) IV > III > II > I (D) I > III > IV > II
7. The increasing order of reactivity of the following isomeric halides with alcoholic AgNO3 is : (I) C6H5 – CH = CH – CH2 – CH2 – Cl (II) Cl | CH CH CH CH H C6 5 3 (III) Cl | CH CH CH C H C6 5 2 3 (IV) Cl | CH CH C H C | CH 2 5 6 3
(A) III < IV < II < I (B) I < III < IV < II (C) III < I < II < IV (D) I < II < IV < III
8. Rate of 1
N
S reaction is :
(I) (II) (III) (IV)
(A) IV > I > III > II (B) II > III > I > IV (C) I > III > II > IV (D) IV > II > III > I
9. Rate of reaction with aqueous AgOH solution follows the order.
(I) (II) (III) (IV)
(A) II > IV > I > III (B) IV > II > I > III (C) III > II > IV > I (D) I > IV > II > III
10. In the following compound, arrange the reactivity of different chlorine atoms towards NaSH in decreasing order in non aqueous solvent.
(A) II > IV > I > III (B) I > II > III > IV
(C) II > IV > I > III (D) II > III > I > IV
11. The reactivity order of CH3MgBr with the following reagents is
(I) PhOH (II) CH3CHO (III) R–C CH (IV)
O Cl C CH3 ||
(A) I > III > II > IV (B) I > II > III > IV
Correct decreasing order of reactivity towards SN2reaction : Q. 12 to Q. 18
I II III IV
12. CH3Cl CH3CH2Cl CH3CH2–CH2–Cl CH3CHClCH3
(A) I > II > III > IV (B) III > II > I > IV (C) IV > III > I > II (D) None
13. CH3CH2 CH2Cl CH3 CH2CH2Cl CH3CH2CH2CH2Cl CH3CH2CH2
(A) IV > I > II > III (B) III > II > I > IV (C) IV > I > III > II (D) II > I > IV > III
14. 3 2 3 3 CH | Cl CH C CH | CH CH3 – 3 3 CH | –Cl C | CH H | Cl C CH | CH 3 3 CH3 – CH2 – Cl
(A) II > III > I > IV (B) II > I > IV > III (C) IV > III > I > II (D) I > III > II > I
15. Br – CH2 – CH2 – Br N C – CH2 – Br Br | CH CH CH3 3 CH3 – CH2 – Br
(A) II > I > IV > III (B) II > III > I > IV (C) II > I > III > IV (D) IV > I > II > III
16. CH3CH2Cl CH2 = CH – CH2Cl CH3Cl CH2 = CHCl
(A) II > III > I > IV (B) II > I > IV > III (C) IV > III > II > I (D) none 17. CH3–O–CH2–Cl O Cl CH C H 2 || CH3–CH2–Cl CH3–Cl
(A) IV > III > II > I (B) II > III > I > IV (C) II > I > IV > III (D) none
18. HO–H2C–CH2–Cl CH3–CH2–Cl CH3–CH2–CH2–Cl O Cl C CH3 ||
(A) IV > I > II > III (B) IV > I > III > II (C) II > I > IV > III (D) II > III > I > IV
Arrange the following in decreasing order of reactivity towards SN1 reaction : (19 to 29)
I II III IV
19. CH3Cl CH3CH2Cl CH3CH2–CH2–Cl CH3CHClCH3
(A) IV > I > II > III (B) I > II > III > IV (C) IV > III > II > I (D) III > IV > I > II
20. CH3–CH2–CH2–Cl CH CH CH Cl CH 2 3 3 | 3 2 3 3 CH | Cl CH C CH | CH 3 3 3 CH Cl C CH CH | |
(A) IV > III > II > I (B) I > II > III > IV (C) III > II > I > IV (D) IV > I > II > III
21. CH3CH2 CH2Cl CH3 CH2CH2Cl CH3CH2CH2CH2Cl CH3CH2CH2
(A) IV > III > II > I (B) IV > I > II > III (C) I > II > III > IV (D) IV > II > I > III
22.
I II III IV
23.
(A) IV > III > I > II (B) IV > I > II > III (C) I > II > III > IV (D) II > I > III > IV
24.
(A) III > II > I > IV (B) IV > I > III > II (C) I > II > III > IV (D) IV > III > II > I
25. CH2=CH–CH2–Cl CH CH CH Cl CH 2 3 | CH3–CH=CH–CH2–Cl Cl CH CH C CH3 3 |
(A) IV > III > I > II (B) II > III > I > IV (C) I > II > IV > III (D) III > II > I > IV
26. 3 5 6 3 CH | Br C H C | CH 3 3 CH | Br CH C CH | | O (CH3)2CHBr
(A) II > I > IV > III (B) I > II > IV > III (C) II > IV > I > III (D) III > IV > I > II
27. (C6H5)2CHCl CH2 = CH CH2Cl C6H5 CH2Cl
(A) I > III > II > IV (B) IV > III > II > I (C) II > IV > III > I (D) I > II > III > IV
28.
(A) I > II > III (B) II > III > I (C) II > I > III (D) III > II > I
29.
(A) I > II > III > IV (B) IV > III > II > I (C) II > III > I > IV (D) IV > II > III > I
A
nswers
1. (a) (i) > (ii) (b) (ii) > (i) (c) (ii) > (i) (d) (ii) > (i) (e) (ii) > (i) (f) (i) > (ii) 2. (a) (ii) > (i) (b) (ii) > (i) (c) (i) > (ii) (d) (ii) > (i) (e) (ii) > (i) (f) (ii) > (i)
3. D 4. A 5. D 6. D 7. C 8. D 9. B
10. C 11. D 12. A 13. B 14. C 15. A 16. A
17. C 18. A 19. C 20. A 21. B 22. D 23. C
24. A 25. B 26. A 27. C 28. C 29. D
The major productof the following reactions (Q.1 - Q.4) 1. + (A) (B) (C) (D) 2. ) iodide methyl ( e iodomethan 3 CH I + (A) (B) (C) (D) 3. e tan bromopen 1 Br CH CH CH CH CH3 2 2 2 2 + (A) CH3 – CH2 – CH2 – CH2 – CH3 (B) CH3 – CH2 – CH2 – CH2 – CH2 – SH (C) SH | CH CH CH CH CH3 2 2 3 (D) SH | CH CH CH CH CH3 2 2 3 4. ) chloride butyl n ( e tan chlorobu 1 Cl CH CH CH CH3 2 2 2 + ) excess ( ammonia 3 NH : (A) CH3 – CH2 – CH2 – CH3 (B) 2 3 2 3 NH | CH CH CH CH (C) Cl | CH CH CH CH3 2 3 (D) CH3 – CH2 – CH2 – CH2 – NH2
Predict the products of the following SN2 reactions (Q. 5 - Q. 12) 5. CH3CH2ONa + CH3CH2Cl CH3CH2OH (A) CH3 – CH2 – CH2 – O – CH3 (B) CH3 – CH2 – O – CH2 – CH3 (C) CH3 – CH2 – CH2 – CH2 – OH (D) OH | CH CH CH CH3 2 3
3
6. + NaCN acetone (A) (B) (C) (D) 7. (A) (B) (C) (D) 8. CH3(CH2)8CH2Cl + NaI acetone (A) I | CH CH ) CH ( CH3 2 7 3 (B) CH3(CH2)8CH2I (C) CH3 – (CH2)8 – CH3 (D) CH3 – (CH2)7 – CH = CH2 9. + CH3I (A) (B) (C) (D) 10. excess Br CH CH C ) CH ( 3 3 2 2 + NH3 (A) (B) (CH3)3C – CH2 – CH2 – NH2 (C) (CH3)3C – CH2 – CH2 – CH3 (D) [(CH3)3C – CH2 – CH2]4N 11. + NaOH (A) (B) (C) (D) 12. OH CH NaOH 3 (A) (B) (C) (D)
13. + Mg ether (A) (B) (C) (D) 14. (CH3)2 CHCH2I Li CuI I 3 CH (A) (CH3)2CH – CH3 (B) (CH3)2CH – CH2 – CH3 (C) (CH3)2CH – CH2 – CH2I (D) None of these 15. Br | CH C CH CH CH3 2 3 (C2H5)2CuLi (A) 5 2 3 2 3 H C | CH C CH CH CH (B) 5 2 3 2 3 H C | CH C CH CH CH + C2H5Cl + LiBr (C) CH3 – CH2 – CH = CH – CH3 + 2C2H5Cu (D) 5 2 3 2 3 H C | LiBr CH C CH CH CH 16. + (CH3)2CH Mg Br EtHOO 2 2 ) ii ( ) i ( (A) CH3 – (CH2)4 – CH2 – OH (B) 5 2 3 3 H C | CH CH CH CH CH (C) (D) OH | CH CH CH CH3 2 3 17. C6H5COOH + CH3MgI
(A) C6H5COOMgI (B) CH4 (C) Both A & B (D) none
18. 2-Butanone + Ethyl Magnesium bromide H2O
(A) OH | CH CH C CH | H 3 2 3 (B) OH | CH CH C CH | CH 3 2 3 3 (C) OH | CH CH C CH | H C 3 2 3 5 2 (D) All of these
The major product of the following reactions (Q.19 - Q.23) 19. CH3CH2CH2 – Br + CH3O¯
(A) CH3 – CH2 – CH2 – OH & SN2 (B) CH3 – CH2 – CH2 – O – CH3 & SN2 (C) CH3 – CH2 – CH2 – O – SN1 (D) CH3 – CH2 – O – CH2 – CH3 & E2 20. CH3 – CH2 – CH2 – Br + (CH3)3CO¯ COH ) CH ( C 50 3 3
(A) CH3 – CH2 – CH3 & SN2 (B) CH3 – CH = CH2 & SN1 (C) CH3 – CH = CH2 & E2 (D) None 21. (A) CH3 – CH2 – CH2 – CH2 – SH & SN1 (B) H | SH C CH | CH 3 3 & SN2 (C) & E2 (D) & SN2 22. (CH3CH2)3 C – Br + OH¯ (A) & E2 (B) 3 2 2 3 3 3 2 CH CH | SN & CH C CH | CH CH (C) CH3 – CH = CH – C2H5 (D) None 23. (CH3CH2)3 C – Br
(A) CH3OC (CH2CH3)3 & SN2 (B) CH3OCH (CH2CH3)2 & SN1 (C) CH3OC (CH2CH3)3 & SN1 (D) None
A
nswers
E X E RC I S E -3
1. A 2. C 3. B 4. D 5. B 6. A 7. D 8. B 9. C 10. A 11. C 12. B 13. D 14. B 15. B 16. C 17. C 18. C 19. B 20. C 21. D 22. A 23. CWhich of the following is the correct option of reagents for the given conversion : (Q.1 - Q.6) 1. Propane 2-Iodopropane (A) I2 / h (B) NaI / acetone (C) F2 / h, NaI / acetone (D) Br2 / h, NaI / acetone 2. CH3 – CH2 – CH3 CH3 – C C – H
(A) Br2 / h, alc. / KOH, Br2 / h, NaNH2 (B) Br2 / CCl4, alc. / KOH, Br2 / h, NaNH2 (C) Br2 / h, NaNH2 (D) Br2 / h, aq. KOH, Br2 / h, NaNH2
3. CH3 – CH2 – CH3 H | D C CH | CH 3 3 (A) Br2 / h, NaNH2, D2 / Ni (B) Br2 / h, Mg / Et2O, D2O (C) Br2 / h, Mg / Et2O, CH3 – Br, Br2 / h, D2O (D) Br2 / h, Mg / Et2O, C2H5Br, Br2 / h, D2O 4. CH4 CH CH COOH | CH 3 3 (A) Br2 / h, CH3CH2MgCl, Br2 / h, HCOOH (B) Cl2 / h, CH3CH2MgCl, Br2 / h, KCN, H3O+ (C) Br2 / h, CH3CH2MgCl, Br2 / h, NaNH2, HCN, H3O+ (D) Cl2 / h, CH3MgBr, Br2 / h, CH3 – COOH 5. 3 3 2) C CH CH ( OHC || O
(A) Mg / Et2O, CH3Cl, Br2 / h, alc. KOH, hot KMnO4 (B) OH¯, H2SO4 / , O3 / Zn, H2O
(C) CH3MgBr, Br2 / h, alc. KOH, hot KMnO4 (D) Mg / Et2O, CH3Cl, Br2 / h, alc. KOH, O3
6.
(A) alc. KOH, Br2 / CCl4, NaNH2, Na / liq NH3 , Br2 / CCl4 (B) alc. KOH, Br2 / CCl4, NaNH2, H2 / Pd-CaCO3, Br2 / CCl4 (C) alc. KOH, Br2 / CCl4
(D) NaNH2, cold KMnO4, excess HBr
A
nswers
E X E RC I S E -4
1. D 2. A 3. B 4. B 5. D 6. A
Read the following questions and choose :
(A) If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
(B) If both Assertion and Reason are true, but Reason is not correct explanation of the Assertion.
(C) If Assertion is true, but Reason is false. (D) If Assertion is false, but the Reason is true.
1. Assertion : The SN2 reaction of neopentyl bromide, (CH3)3CCH2Br, with sodium ethoxide, Na+(OCH
2CH3)¯, proceeds about 0.00001 times as fast as the reaction of bromoethane.
Reason : The bulky groups present at -position in neopentyl bromide exert a strong steric hinderance to the approaching nucleophile.
(A) A (B) B (C) C (D) D
2. Assertion : The major product of the reaction of methylenecyclohexane with N-bromosuccinimide is 1-(bromomethyl)cyclohexene.
Reason : In the reaction of methylenecyclohexane with N-bromosuccinimide a more stable secondary as well as allylic radical intermediate is formed which giv es 2-Bromo-1-methylenecyclohexne
(A) A (B) B (C) C (D) D
3. Assertion : Aryl halides are less reactive than alkyl halides towards nucleophilic reagents. Reason : In aryl halides halogens create negative charge centres to the ortho & para position of benzene ring which favours electrophilic substitution reactio but not the nucleophilic substitution reaction.
(A) A (B) B (C) C (D) D
4. Assertion : The trans isomer of 2-chlorocyclohexanol is hydrolysed with many times faster rate than the cis isomer on heating with NaOH solution.
NaOH
Reason : The trans isomer causes less steric crowding in the SN2 reaction to the nucleophile.
(A) A (B) B (C) C (D) D
5. Assertion : CH3CH2CH2CH2Cl reacts with 0.01 M NaCN in ethanol to yield primarily CH3 CH2CH2CH2CN whereas under the same conditions (CH3)3CCl reacts to give primarily (CH3)3 COCH2CH3.
Reason : The first reaction is a SN2 reaction in which CN¯ is a strong nucleophile, in the second reaction the reactant forms a carbocation intermediate which is solvent stabilised by C2H5OH & SN1 reaction takes place.
(A) A (B) B (C) C (D) D
6. Assertion : Rate of hydrolysis of (CH3)3C – F increases under strongly acidic conditions. Reason : It is an example of electrophilic catalysis. F¯ is a poor leaving group H-bonding with strong acid encourages its departure.
(A) A (B) B (C) C (D) D
7. Assertion : Hydrolysis of n-Butylchloride in aqueous ethanol is accelerated in presence of NaI. Reason : In all SN1 reactions the reactivity increases in a polar medium in which the carbocation is solvent stabilised.
(A) A (B) B (C) C (D) D
8. Assertion : When the alkyl bromides were subjected to hydrolysis in a mixture of ethanol & water (80% C2H5OH, 20% H2O) at 55ºC, the rates of reaction showed the following order : (CH3)3C – Br > CH3 – Br > CH3CH2 – Br > (CH3)2 CH – Br
Reason : In SN1 reaction the reactivity order of different alkanes is R3CH > R2CH2 > RCH3 > CH4 since the carbocation produced in the rate determining step has the stability order as
R3C+ > R 2CH + > RCH 2 + > CH 3 +. (A) A (B) B (C) C (D) D
9. Assertion: In contrast to SN2 reactions,SN1 reactions show relatively little nucleophile selectivity.
Reason : The reactivity of nucleophile is less in SN1 as compared to SN2.
(A) A (B) B (C) C (D) D
10. Assertion: CH3CH2 – CH2 – CH2 – Cl reacts with 0.01 M NaCN in ethanol to yield primarily CH3 – CH2 – CH2 – CH2 – CN whereas under the same conditions (CH3)3 C – Cl reacts to give primarily (CH3)3 COCH2–CH3.
Reason : With different alkyl halide the nucleophilicity of nucleophiles changes.
A
nswers
EXERCISE - 5
1. A
2. B
Explanation :
The intermediate allylic radical reacts at the more accesible site and gives the more highly substituted double bond.
NBS 3. B Explanation :
due to : Halogen atoms has double bond character and p-orbital of benzene ring repels the nucleophile therefore SN2 reactivity is also very low.
4. C Explanation : NaOH NGP
does not have NGP..
(NGP = Neighboring group participation or anchimeric assistance)
5. A Explanation : CH3CH2CH2CH2Cl 2 5 2 SN OH H C NaCN CH3CH2CH2CH2CN 1 5 2 SN OH H C NaCN
ionises in C2H5OH and solvolysis (ethanolysis) takes place. while in
CH3CH2CH2CH2Cl, CN¯ (being strong anionic nucleophile) attacks and bimolecular substitution takes place.
6. A Explanation : 3 3 3 CH | F C C H | CH + H | H O H H CH | | H O H ... F ... C C H | CH 3 3 3 1 3 3 3 CH | OH C C H | CH + HF + H+ 7. B Explanation : CH3 – CH2 – CH2 – CH2 – Cl NaI CH3 – CH2 – CH2 – CH2 – I + NaCl CH3 – CH2 – CH2 – CH2 – OH
is a good nucleophile as well as a good leaving group.
8. B
Explanation :
(CH3)3 C – Br hydrolyses by SN1 route, so due to ionisation reaction it is fastest.
CH3 – Br will hydrolyse by SN2, and rate of SN2 will be faster in CH
3 Br than CH3 – CH2 – Br. (CH3)2 CH – Br will be hydrolysed by mixed mechanism (SN1 + SN2) and both routes will have
moderate speed.
9. B
Explanation :
In SN1 reactions the first step is slow ionisation of alkyl halide. This is the rate determining step so the rate of overall reaction depends upon nature and concentration of alkyl halide only. There is no direct dependence of rate on nature or concentration of nucleophile.
10. C Explanation : CH3 – CH2 – CH2 – CH2 – Cl 2 5 2 SN OH H C NaCN CH3 – CH2 – CH2 – CH2 – CN 1 5 2 SN OH H C NaCN
ionises in C2H5OH and solvolysis (ethanolysis) takes place. while in
CH3 – CH2 – CH2 – CH2 – Cl, CN¯ (being strong anionic nucleophile) attacks and bimolecular substitution takes place.
Identify the unknown compound/s or reagent/s in the following reactions : (Q.1 - Q.16) 1. Br | CH CH C CH | CH 2 3 3 NaI,Acetone (X) (Allylic SN2) (a) 2 2 3 CH CH C CH | CH (b) I | CH CH C CH | CH 2 3 3 (c) 3 2I 3 CH CH C CH | CH (d) I | CH CH C CH | CH 3 2 3 2. NaOH CH2CHCH2Br (X) (a) (b) (c) (d) 3. NaOH, (X) (a) (b) (c) (d) 4. X (major) (a) (b) (c) (d)
5. Ag , O H2 W (major product) (a) (b) (c) (d) 6. ‘X’ (a) (b) (c) (d) 7. CH22 + 2Na+ CH¯
(a) HOOC – CH2 – CH2 – CH2 – COOH (b)
(c) (d) 8. V (C6H14) Sunlight Cl2 W + X + Y (Monochlorides) W or X COH ) CH ( K ¯ CO ) CH ( 3 3 3 3 Z (C6H12) Y C2H5OH KOH No reaction.
(a) V : CH3 – CH2 – CH2 – CH2 – CH2 – CH3 (b) V : 3 3 2 3 3 CH | CH CH C CH | CH (c) Y : 3 3 2 2 3 CH | CH CH C CH Cl | CH (d) Y : Cl – CH2 – CH2 – CH2 – CH2 – CH3 9. Br2/h alc.KOH (X) (a) (b) (c) (d) 10. OH 5 H 2 C K ¯ O 5 H 2 C X (a) (b) (c) (d) 11
.
O || OH CH CH C CH | H COOC CH 2 2 2 5 2 2 CH3MgBr X CH3MgBr Y CH3MgBr Z (a) Z : OMgBr | OMgBr CH CH ) CH ( C CH | COCH CH 2 2 3 2 3 2 (b) Y : OMgBr | OMgBr CH CH ) CH ( C CH | H COOC CH 2 2 3 2 5 2 2 (c) Y : O | | OMgBr CH CH C CH | COCH CH 2 2 2 3 2 (d) X : O | | OH CH CH C CH | COCH CH 2 2 2 3 2 12. CH3 – CH2 – CH2 – CH2 – MgBr + (X) O H ) ii ( O ) H C ( ) i ( 3 2 5 2 n – C7H15OH (a) Br – CH2 – CH2 – CH2 – OH (b) (c) H2O+ – CH 2 – CH2 – CH2 – OH (d) TsO – CH2 – CH2 – CH2 – OH 13. 3 2 3 CH | Br CH CH CH (2(1))CuLiI X Y 2, 7-Dimethyloctane (a) X : 3 2 3 CH | CuLi CH CH CH (b) X : 2 3 2 3 CH | CH CH CH CuLi (c) Y : 3 3 2 2 2 CH | CH CH CH CH CH Br (d) Y : 3 2 2 2 3 CH | Br CH CH CH CH CH 14. W + CH3–CH2–CH2–Br (a) (b) (c) (d) 15. W + (CH3)2CuLi (a) (b) (c) (d) 16. (CH3CH2)2CuLi + W (a) (b) (c) (d)
17. A monoprotic acid ‘A’ on reduction with red P + HI gives an alkane ‘B’ which on reaction with Cl2 / h gives a mixture of two isomeric monochloro alkanes. ‘B’ can be prepared by catalytic hydrogenation of a hydrocarbon ‘C’ whose one mole on reaction with excess C2H5MgI gives 4 moles of ethane. Identify the incorrect option / options.
(a) A is an acid (b) B is an alkane (c) C is an alkene (d) C is an alkyne 18. Optically active compound (A) C4H8Br2 is treated with CH3ONa / CH3OH to obtain compound (B).
C4H7Br. ‘B’ reacts with Gilman reagent of n-butyl iodide and gives ‘C’ (C8H16). ‘C’ on reductive ozonolysis gives D and E. D gives red precipitate with fehling solution but E does not. Both respond positively towards I2 / NaOH solution. Identify A.
(a) Br Br | | H C CH CH | CH 2 2 3 (b) Br | Br C CH CH | CH 2 3 3
(c) H Br | | H C C CH | | CH Br 3 3 (d) Br Br | | H C CH CH | CH 3 3
19. One mole of compound A (C3H8O3) is treated with excess of CH3MgBr in ether. The liberated gas measured 67.2 litres at S.T.P. Identify the structure of A.
(a) OH CH | OH CH | OH CH 2 2 (b) 3 2 3 CH | O | CH | O | CH (c) 3 3 CH | O | H O C H | O | CH (d) CHO | CHOH | CHO
20. A primary alkyl halide (A), C4H9Br, reacted with alcoholic KOH to give compound (B).Compound (B) reacted with hydrogen bromide to give (C), an isomer of (A). When (A) was treated with sodium, it gave a compound (D), C8H18, which was different from the compound produced when n-butyl bromide was reacted with sodium. The structural formula of A is.
(a) Br | CH C CH | CH 3 3 3 (b) H | Br CH C CH | CH 2 3 3 (c) CH3 – CH2 – CH2 – CH2 – Br (d) Br | CH CH CH CH3 2 3
21. When 1-chloromethyl-4-methyl-1, 3-cyclopentadiene (A) is treated with H2O / Ag+, three isomeric alcohols are obtained. Then which is not among these isomeric alcohols.
(a) (b) (c) (d)
22. An organic compound (A), C7H15Cl on treatment with alcoholic caustic potash gives a hydrocarbon (B) C7H14.(B) on treatment with ozone and subsequent hydrolysis giv es acetone and butyraldehyde. What (B) ? (a) H H CH | | | CH C C C C H | H 3 3 3 (b) 3 3 2 2 3 CH | CH CH CHCH C C H (c) 3 2 2 3 CH | CH CH CH C C H | H (d) 3 3 2 2 3 CH | CH CH CH C C H
23. Treatment of 2-bromobutane with hot alcoholic KOH gives a mixture of three isomeric butenes (A), (B) and (C). Ozonolysis of the minor product (A), gives formaldehyde and another aldehyde in equimolar amounts. Both (B) and (C) gave the same single product (D) on ozonolysis. What is the structural formula of (D) ? (a) H | O C CH CH3 2 (b) H | O C H (c) H | O C CH3 (d) CH3 C CH3 || O
24. The reaction of 2-chloro-2-methyl-1-phenylpropane with methanol yields a mixture composed of a substitution product A (54%) and two elimination products, B (27%) and C (19%). which structure is written with incorrect percentage.
(a) (b) Ph CH C CH (27%) | CH 2 2 3 (c) 3 3 CH | CH C CH Ph (27%) (d) PhCH C CH (19%) | CH 2 2 3
25. Compound X is optically inactive and has the formula C16H16Br2. On treatment with strong base, X gives hydrocarbon Y, C16H14. Compound Y absorbs 2 equivalents of hydrogen when reduced over a palladium catalyst and reacts with ozone to give two fragments. One fragment, Z, is an aldehyde with formula C7H6O. The other fragment is glyoxal, (CHO)2. suggest structure for X.
(a) Br Br | | Ph CH CH CH CH Ph 2 2 (b) Ph Ph | | Br CH CH CH CH Br 2 2 (c) Br Br | | Ph CH CH CH CH Ph 2 2 (d) Br H | | Br CH CH CH C Ph | Ph 2 2
26. Organic compound (A) C5H11Cl on treatment with sodamide form compound (B). Compound (B) reacts with dilute acid to form (C), C5H12O. When compound (C) is heated with Al2O3 ,it forms (D) which is isomeric to (B). Combined ozonolysis of (B) and (D) forms four compounds two of which reduces Tollen’s reagent and three of which show haloform reaction. What will be the nature of (C).
(a) A primary alcohol (b) A secondary alcohol
(c) A tertiary alcohol (d) An ether
27. The alkyl halide C4H9Cl (A) reacts with alcoholic KOH and gives alkene (B) which reacts with bromine to form a dibromide (C). (C) is transformed with sodamide to a gas (D) which forms a precipitate with ammonical silver nitrate solution. Give the structures (C).
(a) CH3 – CH2 – CH(Br)CH – Br (b) Br Br | | CH CH CH CH3 2 2 (c) Br Br | | CH CH CH CH2 2 2 2 (d) CH3 – CH2 – CH2 – CHBr2
28. Five isomeric alkyl halides (C6H13Cl) produce the same alkane (A) (C6H14) on reduction with Zn/Cu couple. Identify (A).
(a) H | CH C CH CH | CH 3 2 3 3 (b) 3 2 2 3 3 CH CH CH CH C H | CH (c) 3 2 2 3 3 CH CH CH CH C H | CH (d) 3 3 2 3 3 CH | CH C CH CH | CH
29. A chloroderivative (X) on treatment with Zn-Cu couple in ethanol gives a hydrocarbon (Y). When (X) is dissolved in ether and treated with sodium, 2, 2, 5, 5 - tetramethylhexane is obtained. Identify how many different types of hydrogen atoms are present in Y.
(a) 1 (b) 2
(c) 3 (d) 4
30. An alkane C6H14 (A) on chlorination at 300° gives a mixture of 4 monochlorinated derivative B, C, D and E. Two of these (C, D) derivatives give the same stable alkene (F) on dehydrohalogenation. The other two alkyl halides (B, E) give alkenes (G) and (H) respectively. Which on ozonolysis give methanal as the common product. (H) gives a ketone while (G) gives an aldehyde. Give structure of (H). (a) H | CH CH C CH CH | CH 3 2 2 3 (b) 3 2 3 3 CH CH C CH CH | CH (c) 3 2 2 3 2 CH CH C CH CH || CH (d) 3 2 2 3 2 CH CH CH C CH || CH
31. A compound A has molecular formula C6H13Br. When it is treated with magnesium metal in ether, dilute acid produces the compound n–hexane as a product.When compound A is reacted with sodium metal in ether, the product is 4, 5 –diethyloctane .From the above information deduce the structural formula of (A).
(a) CH3 – CH2 – CH2 – CH2 – CH2 – CH2 – Br (b) CH3– CH2 – CH2 – CH2 – CHBr – CH3 (c) CH3 – CH2 – CH2 – CH(Br)CH2 – CH3 (d) Br | CH CH C CH CH | CH 3 2 2 3 3
32. The D-isomer of an optically active organic compound A (C8H17Br) on reaction with NaI in acetone produced another optically pure compound B (C8H17I). A on hydrolysis with NaOH solution in H2O (20%) + Acetone (80%) mainly produced optically active compound C (C8H18O). B also on hydrolysis under similar conditions produced another compound (D). Both A and B on reaction with CH3MgBr in ether produced 2-methyloctane. Indicate how C and D are related ?
(a) Identical (b) Enantionmers
33. A mixture of isobutane and iso butene is catalytically hydrogenated and the entire alkane is monobrominated in the presence of light at 1270C, which exclusive product would be formed?
(a) 3 3 2 CH Br | | CH C CH | H (b) 3 3 3 CH | CH C CH | Br (c) 2 2 2 3 CH CH Br | CH CH (d) CH3 – CH2 – CHBr – CH3
34. (W) and (X) are optically active isomers of C5H9Cl.(W) on treatment with one mol of H2 is converted to an optically inactive compounds (Y), but (X) gives an optically active compounds (Z) under the same conditions. Give configurations of (W), in fischer projections.
(a) (b)
(c) (d)
35. An alkyl halide (A) C4H9Cl on reaction with CH3MgCl gives on alkene (B) (C4H8) as major product with CH4. Only one dichloro derivative can be obtained by C4H9Cl. Give structure of B.
(a) CH2 = CH – CH2 – CH3 (b) (c) (d) 3 2 3 CH | CH C CH
36. An alkyl halide (A) on reaction with Mg in ether gives a Grignard reagnet (B). B on reaction with C2H5Cl gives C5H12 (C). Monochlorination of (C) gives 4 structures. Out of which how many structures contain one chiral carbon ?
(a) 1 (b) 2
(c) 3 (d) 4
37. One mole of hydrocarbon C9H12 (A) on reaction with CH3MgX gives 2 moles of CH4. On complete hydrogenation A gives C9H20 (B). B is optically inactive & on monohalogenation it gives only 2 structurally different monohalo derivatives. Give structures of these derivatives.
(a) 3 2 3 2 3 3 2 CH CH X | | CH CH C CH CH | CH CH (b) 3 2 3 2 2 3 2 CH CH X | | CH CH C CH CH | CH CH (c) 3 2 2 2 2 3 3 2 CH CH | X CH CH CH C CH | CH CH (d) 3 2 3 2 2 3 3 2 CH CH | CH CH CH C CH | X CH CH
38. An organic compound P (C5H8O) decolourises Br2 water & Baeyer’s reagent. P does not responds to 2, 4-DNP but on reaction with PhMgBr, (P) gives 2 moles of benzene. On complete hydrogenation ‘P’ gives (Q) which on reaction with Luca’s reagent gives immediately white turbidity. Give possible structure of P.
(a) 3 3 2 3 CH | CH C CH C H | OH (b) 3 3 2 CH | CH C CH C H | OH (c) 3 3 CH | CH C C C H | OH (d) H | CH CH C C C H | OH 3 2
A
nswers
EXERCISE - 6
1. c 2. b 3. c 4. c 5. b 6. d 7. a 8. b, c 9. a 10. c 11.
a, b 12. b 13. b, c 14. d 15. a 16. d 17. b 18. c 19. a 20. b 21. a,b 22. b 23. c 24. b 25. c 26. c 27. a 28. b 29. a 30. c 31. c 32. b 33. b 34. c 35. d 36. b 37. a, b 38. c1.
CH CH Br2 2 CHO
CH3
? The final product of the reaction is
(A) (B) (C) (D)
2. Which one is correct for the products of the given reaction
(A) only X and Z are formed (B) Z > Y
(C) X > Y (D) Y > X
3. The most polar as well as stable conformation of 1-chloropropane is
(A) (B) (C) (D)
4. Dehydrohalogenation by a strong base is slowest in.
5. In which case an alkene is formed on reaction with a strong anionic base.
(A) (B) (C) (D)
6. Which statement is correct for the following reaction, regarding rate, and stereorientation at C1 and C2 respectively (for the major product)
(A) Very slow, inversion and retention (B) Very fast, inversion and retention (C) Very fast, retention and retention (D) Very fast inversion and inverstion 7. The correct reactivity order for the following reaction is
RBr NaI/Acetone R – I + NaBr R : I 3 CH II 2 3CH CH III 2 .. .. 3 O CH CH IV CH CH2
(A) I > II > III > IV (B) III > I > II > IV (C) IV > III > I > II (A) III > IV > I > II
8. The major product of the following reaction is
(A) (B)
(C) (D)
9. The rate of reaction of CH3CH2Br is fastest with
(A) (CH3)3CLi (B) NaNH2 (C) CH3ONa (D) NaOH
10. In which of the following reactions an optically active single product is formed
(A) CH3ONa + (B)
11. Which one is correct for the products of the given reaction
(A) only X and Z are formed (B) Z > Y
(C) X > Y (D) Y > X
12. Read the following question and choose the correct answer :
(A) If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
(B) If both Assertion and Reason are true, but Reason is not correct explanation of the Assertion. (C) If Assertion is true, but Reason is false.
(D) If Assertion is false, but the Reason is true.
Assertion : In the above reaction a mixture of two stereoisomeric products can be formed Reason : The OO
group of the molecule provides anchimeric assistance (neighbouring group participation) in substitution of so there is retention of configuration at both the asymmetric carbon atoms.
13. Which one of the following hexachlorocyclohexane is least reactive and which one is most reactive in E2 reactions with a strong base for dehydrohalogenation.
(A) I least & II most (B) II least & I most (C) III least & I most (D) III least & II most
14. Which of the following reaction is not feasible. (A) CH3OH + CH3 CH3 OCH3 (B) + (C) C2H5OH + + (D) 3 3 3 CH | Cl C CH | CH + HC + O
Section - B (Reading comprehension Q. 15 - 19)
Observe the following reactions and give answers of questions. (Q.13 – Q.17)
+ 3 2 2 3 CH C CH CH | CH +
15. In Ist reaction the structure of reaction intermediate should be
(A) (B) (C) (D)
16. Which statement seems to be most appropriate for reaction II. (A) It is an E1 reaction
(B) The product is a mixture of stereoisomers
(C) is a good nucleophile but a poor base which can cause dehalogenation in vicinal dihalides (D) It is SN1 reaction at 3° C – Cl bond while SN2 reaction at 1° C – Cl bond.
17. Which of the following structure represents the transition state of slow step of reaction III.
(A) (B)
(C) (D)
18. Which of the reaction (I – VI) involves rearrangement of reaction intermediate.
(A) III only (B) III, V (C) II, III, V (D) I, III, V
19. Planar reactive intermediates are formed in reactions
(A) III, V (B) I, III, V (C) V, VI (D) I, III, V, VI
1. D 2. D 3. C
4. (C)
All ‘Cl’ are having trans orientation with respect to each other. So the required anti orientation of – H and ‘Cl’ is not available.
5. (B) H and Cl are in anti position to each other only in case B.
6. C 7. B
8. (B) Na(First/AcetoneSN2)
I
9. (A) The nucleophilicity order is > > >
10. D 11. D 12. D 13. B 14. D
15. B 16. C 17. D 18. B 19. D
EXERCISE - 7
A
1. (i) C6H5 – CH2CO2CH3 H . 2 ) excess ( MgBr CH . 1 3 ? (ii) C6H5C2H5 NaCN . 2 Light , Heat , Br . 1 2 ? [JEE - 94] 2. 2 N S NaOH ? [JEE - 94]
3. Which statement is incorrect about the following reaction: [JEE - 1995]
(A) only one product is formed
(B) the product will have walden inversion
(C) the reaction mixture will have optical rotation zero (D) the product is a mixture of D + L isomers
4. Optically active 2-iodobutane on treatment with NaI in acetone gives a product which does not
show optical activity. Explain briefly. [JEE - 95]
5. Acetone Na I C [JEE - 96]
6. An alkyl halide (X) of formula C6H13Cl on treatment with potassium tertiary butoxide gives two isomeric alkenes (Y) and (Z) of formula C6H12. Both alkenes on hydrogenation giv e
2,3-dimethylbutane. Predict (X), (Y) and (Z). [JEE - 96]
7. (i) A hydrocarbon A, of the formula C8H10, on ozonolysis gives compound B(C4H6O2) only. The compound B can also be obtained from the alkyl bromide, C (C3H5Br) upon treatement with magnesium in dry ether, followed by carbon dioxide and acidification. Identify A, B and C and also give equations for the reactions.
(ii) A compound D(C8H10O) upon treatment with alkaline solution of iodine gives a yellow precipitate. The filtrate on acidification gives a white solid E (C7H6O2). Write the structures of D, E and explain
the formation of E. [JEE - 1996]
8. Cl – CH2 – CH2 – CH2 – COPh + KOH + MeOH ? [JEE - 97]
9. + KNH2 AA [JEE - 97]
10. Which of the following is an organometallic compound
(A) Lithium methoxide (B) Lithium acetate
(C) Lithium dimethylamide (D) Methyl lithium [JEE-1997]
11. (CH3)3CMgCl on reaction with D2O produces : [JEE-1997]
(A) (CH3)3CD (B) (CH3)3OD (C) (CD3)CD (D) (CD3)3OD
12. Which of the following is the correct method for synthesizing methyl–t–butylether and why ? (i) (CH3)3C Br + NaOMe (ii) CH3Br + NaO–t–Bu [JEE - 97] 13. Complete the following giving the structure of the principal organic products.
14. The reaction with HBr gives : [JEE-1998]
(A) (B)
(C) (D)
15. Which of the following will react with water : [JEE-98]
(A) CHCl3 (B) Cl3CCHO (C) CCl4 (D) ClCH2CH2Cl
16. C6H5CH2CHClC6H5 alcoholicKOH,heat [JEE - 98] 17. Benzyl chloride (C6H5CH2Cl) can be prepared from toluene by chlorination with :
(A) SO2Cl2 (B) SOCl2 (C) Cl2 / h (D) NaOCl
[JEE - 1998] 18. (b) Show the steps to carry out the following transformations.
(ii) Ethylbenzene 2-phenylpropionic acid [JEE - 1998]
19. 3 2 3 3 CH | Br CH C CH | CH C2H5OH [JEE - 2000]
20. An SN2 reaction at an asymmetric carbon of a compound always gives
(A) an enantiomer of the substrate (B) a product with opposite optical rotation
(C) a mixture of diastereomers (D) a single stereoisomer [JEE-2001] 21. An alkene (A) C16H16 on ozonolysis gives only one product (B) C8H8O. Compound (B) reacts with
NaOH / I2 yields sodium benzoate. Compound (B) reacts with KOH / NH2NH2 forming (C) C8H10. Write the structures of compound (A), (B) & (C). [JEE - 2001] 22. Identify the set of reagent / reaction conditions ‘X’ and ‘Y’ in the following set of transformations
CH3 – CH2 – CH2Br X Product Y Br | CH CH CH3 3 [JEE-2002]
(A) X = dilute aqueous NaOH, 20°C Y = HBr / Acetic acid, 20°C
(B) X = Concentrated alcoholic NaOH, 80°C Y = HBr / acetic Acid, 20°C
(C) X = dilute aqueous NaOH, 20°C Y = Br2 / CHCl3, 0°C
(D) X = Conc. alcoholic NaOH, 80°C Y = Br2 / CHCl3, 0°C
23. Consider the following reaction : [JEE-2002]
3 3 3 CH D | | Br H X Br CH CH CH CH
Identify the structure of the major product ‘X’ :-(A) 3 2 3 CH D | | H C CH CH CH (B) 3 3 3 CH D | | CH C CH CH (C) 3 3 3 CH D | | CH CH C CH (D) 3 3 3 CH | CH CH H C CH
24. Ethylester excess MgBr CH 3
P. The product P will be [JEE-2003]
(A) (B) (C) (D)
25. The order of reactivity of compound I - III towards phenyl magnesium bromide is
[JEE-(scr.)2004] I PhCOPh II CHO CH3 III 3 3COCH CH
(A) I > II > III (B) II > I > III (C) II > III > I (D) III > II > I 26. The number of chiral compounds produced upon monochlorination of 2-methylbutane is
[JEE-(scr.)2004]
(A) 2 (B) 4 (C) 6 (D) 8
27. 1-Bromo-3-chlorocyclobutane will react with two moles of Na in ether producing [JEE-(scr.)2005]
(A) (B) (D) (D)
28. Phenyl magnesium bromide reacting with t-Butyl alcohol gives [JEE-(scr.)2005]
(A) Ph – OH (B) Ph – H (C) (D)
29. Compound (X) is reacted with aqueous acetone it gives
following products.
[JEE-(scr.)2005]
(A) K, L (B) K, M (C) 'L' only (D) 'M' only
30. Explain the following observations [JEE(M)-05]
Acidic solution
A
nswers
LEVEL - JEE
1. (i) (ii) 2. 3. D
5.
6. (X) (2-chloro -2, 3-dimethyl butane)
(Y) (2, 3, 4-trimethyl but-1-ene)
(Z) (2, 3-dimethyl but-2-ene) 7. (i) (A) (B) (C) (ii) (D) (E) 8. 9. (A) Ph – C C – Ph ( = Elimination) 10. D 11. A
12. equation (ii) is better method. In equation (1) Isobutene will be the major product due to elimination. 13. It is Ullmann’s reaction ) Cu ( Heat 2 I 14. B 15. B 16. + 17. (A, C)
18. (ii) Br2/h Mg/THF H / O H ) ii ( CO ) i ( 2 2 19. 5 2 3 2 3 3 H OC | CH CH C CH | CH 20. D 21. (A) or (B) C6H5 C CH3 || O (C) C6H5 – CH2 – CH3 22. B 23. B 24. A 25. C 26. B 27. A 28. B 29. A 30. + HBr (strong acid) + (SN1 reaction) No reaction
