Isomerism Ans

IIT-JEE CHEMISTRY BY N.J. SIR

ORGANIC CHEMISTRY

Answers for Isomeris DPP ( Conceptual Improvement of Isomerism ) Q.1(a) (f) (k) (p) Q.2(a) (f) Q.3

Identical (b) Position (g) Functional (l) Chain (q) Metamers (b) Functional (g) A-Q, B-Q, C-R, D-S

Position (c) Chain Functional Ring chain Identical Functional

1. 5. 8. 11. 13. 17. 21.

Position isomers Identical Functional Ring chain Position isomers Chain Identical

2. 6. 9. 12. 14. 18. 22.

1. 8. Q.15

C B D

2. 9.

D B

Answers of DPP No. – 1 Position (d) Functional (e) Position (h) Position (i) Position (j) Functional (m) Functional (n) Functional (o) (r) Chain (c) Metamers (d) Metamers (e) (h) Metamers

Answers of DPP No. – 2 Metamers 3. Positional Functional 7. Functional Non-identical 10. Non-identical Non-identical / homologous Chain isomers 15. Position Position 19. Position 20. Functional

3. 10.

Answers of DPP No. – 3 4. B 5. C Q.11 D Q.12 C

B C

Q.16.

1°

2°

2°

2°

(a) (1°,2°,3°) CH3 — CH2 — CH2 — CH2

2°

1°

CH2 — CH3 (b)

2°

3°

3°

4-ethyl-3-methyloctane

2°

(c) (1°,2°,3°, 4°)

2°

3°

1°

(5) DBE = 1

3°

2° 3° 3°

1°

A C

C C

2°

7. Q.14

CH3

(1°,2°,3°)

2°

CH3

CH

1° 3 1° 1,2,7-trimethylcyclopentadecane

1°

1° 4° 2°

1°

3°

(d) (1°,2°,3°, 4°)

2° 2°

2° 3°

CH3

1° 1,1,2,5-tetramethylcyclopentane

Q.17

Metamers

2°

1°

CH3 3° 1° CH3 4° CH3

16. Identical

2°

2° 2°

Chain

1°

2°

2°

CH3 — CH2 — CH — CH — CH3

1°

2°

Functional

4.

6. Q.13 2°

2°

Functional

CH2 = CH — CH2 — CH3,

CH3 1°

CH3 — HC = CH — CH2,

,

,

CH3 — C = CH2 CH3

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1

OH O Q.18

DBE = 1 (5)C3H6O

CH3 — C — CH3 ,

,

CH3 — CH2—C H

Q.19

,

O

CH2 = CH — O — CH3 CH2 = CH — CH2 — OH, (5) DBE = 1 CH3—CH2—CH2—HC=CH2, CH3—CH2—HC=CH — CH3,

CH3 — CH2 — CH = CH2 , CH3

CH3—CH=C—CH3 ,

,

CH2=CH—CH—CH3 ,

CH3 Q.20

CH3 — CH2 — C ≡ CH, CH3 — C ≡ C — CH3,

(9) DBE = 2 C4H6 CH3 — CH = C = CH2,

,

,

(4)

,

,

O

O Q.21

,

CH3

C — CH2 — OH,

CH2=CH —CH = CH2,

,

O

CH3 — C

,

O

H — C — O — CH3 ,

OH

O—H

H

,

Answers of DPP No. – 4 Q.1(a) Position (b) Position (c) Position (d) Position (e) Chain (f) Position (g) Position (h) Position (i) Position (j) Chain (k) Position Q.2(a) 7 (b) 3 (c) 4 (d) 2 (e) 4 Q.3 (a) π = 2, σ = 30 (b) π = 5 σ = 17 (c) π = 3 σ = 34 (d) π = 4 σ = 27 (e) π = 4 σ =3 (f) π = 2 σ = 5 (g) π = s2 σ = 7

Et Et Q.4

A

Q.5

C

Q.6

C

Q.7

D

Q.8

H CH3

CH3 CH3

Br Q.9

CH3–CH2–CH2–Br

H

H

H

H

H Q.10

CH3 — CH — CH3

Cl Q.11

Cl

H

H

,

H

H

H

H

(anti)

(b) 1, 2

H C

Q.13

Q.15

a>c>b

A

H H

Cl

H (a) (gauche)

Q.12

CH3

CH3

CH3

H

Cl Q.14

0.75 D = 0.3 X µgauche

µgauche =

7.5 = 2.5 D. 3 CH3

Et H Q.16

CH3—CH2—CH—CH2—CH3 (a) CH3

C2H5

H (b) CH3—CH 2—CH—CH 2—CH 2—CH 3

H

CH3 CH3

CH3

H

H

C2H5 H


2

+ N(Me)3

O–H O C—H

H

O

H

Q.17

O C

H

H

H

T↑

Q.20

Q.19

CH3 O

H

H

H

H

H

µ↑

CH3 Q.21

N H

H

H

CH3 CH3

H

CH3

Q.18

(a) gauche

(b) anti

Q.22

CH3

H

H

CH3

H

(a)

CH3

Et H

CH3

H

(b)

(c)

CH3

H

CH3

H

CH3

CH3

CH3

Ph

Ph

H

CH3

H

CH3 (d)

(e)

H

H

CH3

CH3 CH3

Ph Q.23

(a) i > ii > iii

(b) i > ii > iii

Q.1 Q.5

(a) 120° (b) < 109°28 E

1

(c) 0°

(c) 3 > 2 > 1 > 4 (d) i > ii > iii (e) i > ii Answers of DPP No. – 5 (d) 60° Q.2 C Q.3 B

Q.4

D

Keq = 18 x

100-x

100 − x = 18 x

Q.6

18 × = 100 – x 19 × = 100 X = 100/19 C Q.7 D

H

O C

H

Q.8

C

H O

Q.13

Q.14

H

H

Q.9

Q.10

B

+1

+1

+1

E

C/A

B/D/F

Anti

H

B

All Gauche All eclipsed

Q.11

A, B, D Q.12

+1

B

+1

B

E

Highest in energy

Lowest in energy

F Q.15

F x

Keq = 1.5

100-x

100 − x = 1.5 x 1.5 × = 100 – x 25 × = 100 X= Q.16

100 ×10 25

= 40% C


3

Q.1 Q.4

A – P, R; B – Q, S; C – P, R; D – Q, R Xanti = 3/4

Answers of DPP No. – 6 Q.2 (IV) > (III) > (I) > (II)

OH Q.5

Q.3

B

OH HO

(a)

and

HO OH

HO

(b)

and

OH

OH

(c)

and

(d)

and

(e)

and

(f)

and

(g)

and

(h)

and

Cl Cl Q.6

(a)

Cl Q.8

c>d>b>a

Cl Cl

Cl

Cl (b) Cl

Cl Cl

Q.9

(a)

(b)

Trans Q.1

Q.7

Cl

Cl

Cis

Cis

Answers of DPP No. – 7 (1) Z (2) Z (3) E (4) Z (5) Z (6) E (7) E (8) Z (9) Z (10) E (11) Z (14) E (15) Z (16) E (17) E (18) E (19) Z (20) E (21) Z (22) E (23) E (24) Z

Trans (12) Z (13) E


4

Z

Z (25) Z

(26) Z

Z

Z

Q.2

(1) (A) X

(B) X

(C) √

(D) X

(2) (A) X

(B) √

(C) √

(D) X

(3) (A) Cis (H) Trans

(B) Trans (I) Cis

(4) (A) X

(B) X

1

3

3

Q.2 Q.4

Q.5 Q.1 Q.6 Q.8

A D (A) √ (N) √ B

Q.9

(28) E

(E) √

(C) Cis (J) X

(C) √

(F) √

(D) Cis (K) Trans

3

2

(F) Cis

(G) Trans

Answers of DPP No. – 8 2 3–1 (3–1)/2 3–1 (3–1)/2 3 (6) 2 (7) 2 +2 =6 (8) 2 + 2 =6 (9) 2 1 1 1 1 1 1 4 (12) 2 (13) 2 (14) 2 (15) 2 (16) 2 (17) 2 (18) 2 1 2 1 3 (21) 2 (22) 2 (23) 2 = 4 (24) 2 (25) 2 (26) 2 (27) 2 1 (33) 2

Answers of DPP No. – 9 2 3 1 1 Q.4 (A) 2 (B) 2 (C) 2 (D) 2 (E) 2 (F) 2

C Q.3 (A), (B) (C) X (D) √

D (E) √

(F) X

(G) √

Q.10

B

B

Q.12

(A) = Keq < 1

Q.11

(E) Trans (L) Cis

(D) √

Q.2 Q.7 (B) √

Compound

(29) Z

Z

(2) 2 (3) 2 (4) 2 (5) 2 (1) 2 2–1 2/2–1 1 (10) 2 + 2 =2+1=3 (11) 2 3–1 (3–1)/2 3 =6 (20) 2 = 8 (19) 2 +2 2 2 2 2 (28) 2 (29) 2 (30) 2 (31) 4 (32) 2 Trans Q.3 Trans 3–1 (3–1)/2 =6 (A) 2 + 2 1 (B) 2 = 2 1 (C) 2 = 2 2 (D) 2 = 4 1 (E) 2 = 2 B, C Q.6 B

Q.1

(27) E

Z

(H) √

(I) √

(J) X

(B) Keq = 1

Answers of DPP No. – 10 P.O.S.

(K) √

Q.5

A,B,C

(L) √

(M) √

(C) Keq > 1

(D) Keq = 1

C.O.S.

Optically active

X

X

1.

CH3 H

CH3

√

H


5

2.

H

CH3

CH3

H

X

X

√

√

X

X

√

X

X

√

X

X

√

√

X

X

X

√

√

X

X

X

X

√

X

X

√

H

3.

H CH3 CH3 H

H 4.

5.

CH3

CH3

H

H Cl

Cl 6.

H

Cl

Cl

H

Br

7.

H

Cl Cl H

Cl H

8.

Cl H

H Cl

Cl 9.

H Cl

10. H

Cl

C=C=C

H Cl

C=C=C

Cl Br


6

11. H

Cl 12.

H Cl

13.

14.

H

C=C=C=C

√

X

X

√

X

X

√

√

X

X

X

√

√

√

X

√

√

X

√

X

X

√

X

X

Cl

C

C

H Cl

Cl

H C

C H

Cl

H Cl

H Cl

H

15.

CH 3 CH3 H H Cl

16. Cl

H

17.

H 18.

C Cl

CH3

CH3

H

C

H


7

19.

CH3

CH3

H

C

X

X

√

√

X

X

X

X

√

X

√

X

√

√

X

√

X

X

√

X

X

X

X

√

X

X

√

√

X

X

Cl

20.

21.

Cl

22.

I

I

Cl

23.

24. O = C = O 25.

26.

O=C=O H

H

O=C=O

H

27.

N=N=N H

H

H C

28.

H

H

No. of POS = 4C2 = 6

H


8

H C

29.

Cl

H

No. of POS = 3

X

√

X

X

√

√

X

H C=C

CH3

No. of POS = 2

CH3

CH3 31.

X

H

H 30.

√

H C=C

H

No. of POS = 1

CH3

Answers of DPP No. – 11 Q.1

(i) 2 (ii) 3 (iii) 4 (iv) 10

Q.3

(d) 3 > 1 > 2 > 4 (a) R (b) R (c) S (n) R (o) S (p) S

Q.4

(a) R (b) R (n) T (o) S (v) R, S

Q.2

(a) 1 > 3 > 2 > 4

(b) 2 > 1 > 3 > 4

(e) 3 > 1 > 2 > 4 (f) 4 > 2 > 3 > 1 (d) S (e) R (f) S (g) R (h) S (i) S (q) R, R (r) R, R (s) S, R

(c) S (d) S (e) R (p) S (q) R,R (w) R, S

(f) S (g) R (r) S,R (x) R, S

(h) S (i) S (s) S, R (y) R, R, R

(c) 2 > 1 > 4 > 3

(g) 4 > 3 > 2 > 1 (j) S (k) S (l) R (m) S (t) R, S (u) R, S (j) S (k) S (t) R, S (z) R

(l) R (m) S (u) R, S

Answers of DPP No. – 12 Q.1 Q.3 Q.6 Q.7 Q.14

A → Q; B → Q; C → R,S; D → Q; Q.2 A → T,P,S; B → T, P; C → S; D → Q; B Q.4 Q.5 D A-B = Enantiomer, C-D = Enantiomer, A-C, A-D = distereomers, B-C & B-D = disteromers A Q.8 8 Q.9 5 Q.10 Q.11 C Q.12 Q.13 (a) 4 (b) 4 (c) 7

Q.1 Q.3 Q.10 Q.14

A → S,P; B → Q; C → S,P; D → S,R; A Q.4 C Q.5 A Q.6 Q.11 A, B, D Q.12 (a) diastereomers (b) distereomers (e) enantiomers (f) distereomers No-sym. Present (i) optical isomers = 27 = 128. (ii) optically active = 2n = 27 = 128 (iii) meso = 0

Answers of DPP No. – 13

Q.15

(iv) Q.1

enantiopair

A → Q, R;

A → T; B → S,R; C → P; D → T; Q.7 A Q.8 C Q.9 Q.13 4 (c) distereomers (d) distereomers Q.2 A

D

2n 128 = = 64. 2 2 Answers of DPP No. – 14

B → S, R, T; C → Q, R, T; D → P, Q;


9

Q.2 Q.3 Q.7 Q.8

A → P, R; B Q.4 α = 125° (A) chiral (H) achiral

B → S; D Q.5

C → P, R, S; D → Q; B Q.6 (A) X (B) X (C) √

(B) achiral (I) chiral

(C) achiral (J) chiral H N: *

(a) – 12.5°

(b) + 8.6°

(E) chiral (L) chiral

(F) achiral (M) achiral

(G) chiral

(v) achiral

(vi) achiral

(vii) chiral

H

* *

Q.9

(D) achiral (K) chiral

(D) √

N

O

(c)

O COOH

Q.10

(i) achiral (viii) chiral

(ii) achiral (ix) achiral

(iii) chiral

(iv) chiral

Answers of DPP No. – 16 1.

Diastereomer

2.

Identical (a & b); Diasteromer (a & b ; b & c)

3.

Diastereomer

4.

Diastereomer

5.

Identical

6.

Identical

7.

Identical

8.

Consitutional Isomer 9.

Diastereomer

10.

Enantiomer

11.

Enantiomer

12.

Diastereomer

Constitutional isomer 14.

15.

Constitutional isomer

13.

Consitutional isomer





Enantiomer

5.

Enantiomer

6.

Enantiomer

7.

Diastereomer

8.

Consitutional Isomer

9.

Identical

10.


11.

Diastereomer

12.

Enantiomer

13.


14.

Identical

15.

Diastereomer


Enantiomer

2.

Identical

3.

5.

Diastereomer

6.


7.

Enantiomer (b & c); Diasteromer (a & b ; b & c)

10.


11.


12.


13.


14.

Identical

15.


16.


8.

Identical

4.

Diastereomer 9.

Diastereomer Identical



2.


3.


4.


5.


6.


7.

Other

8.


9.

Other

10.

Other

11.


12.


13.


14.


15.

Enantiomer


10

Answers of DPP No. – 20 C2

C : The C2 axis lies along the Intersection of the 2 vertical σ-planes.

1. N

2.

C2v C2 H

H C 3.

C2 D2d : 3 C2 axis with the 2σ planes intersecting the principle (vertical) C2 axis.

C C H

H

C2 D6h : There are 3 pairs of vertical σ planes (not shown) and of C2 axis

C6

4.

intersecting the C6 axis. The C atoms lie in the horizontal σ-plane. 5.

6.

P.O.S. (σ) ; C3

C2

7.

P.O.S.(σ) ; C2 ; C3 ; S4 ; S2


P.O.S. (σ) ; C2

2.

P.O.S. (σ) ; C2 ; C3 ; S4 ; S2

4.

P.O.S. (σ) ; C2

5.

P.O.S. (σ) ; C2

7.

C2

9.

C2

8.

C2

10.

6.

3.

P.O.S. (σ) ; C2

P.O.S. (σ) ; C2 ; S2

P.O.S. (σ) ; C2 ; S2

Answers of DPP No. – 22 S.NO. 1. 2. 3. 4. 5.

MESO 3 -

ACTIVE ISOMERS 2 4 8 16

TOTAL ISOMERS 5 4 2 8 16


11

6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 15.

2 1 1 1 2 -

8 8 4 2 2 4 2 8 32 8

10 8 4 3 2 3 4 3 10 32 8

Answers of DPP No. – 23 S.NO. 1. 2. 3. 4. 5. 6. 7. 8.

MESO 1 1 -

ACTIVE ISOMERS 2 4 2 16 32 4

TOTAL ISOMERS 3 4 3 16 2 32 3 4

Answers of DPP No. – 24 S.NO. 1. 2. 3. 4. 5. 6. 7. 8. 9.

MESO 1 1 1 8

ACTIVE ISOMERS 2 16 16 16 2 2 2 4 128

TOTAL ISOMERS 3 16 16 16 3 2 3 4 136

Answers of DPP No. – 25 S.NO. 1. 2. 3. 4. 5. 6.

MESO 1 1

ACTIVE ISOMERS 16 2 8 8 2

TOTAL ISOMERS 2 16 3 8 8 3


12

7. 8. 9. 10. 11.

8

4 4 2 2 128

4 4 2 2 136


1. 4. 7. 10. 13. 16.

Optically active:- OA Chiral molecule:- CM Achiral molecule:- AM Optically inactive:- OI No. of chiral cente:- CC AM, Ol, CC = 1 2. OA, CM, CC = 0 3. OA, CM, CC = 1 OA, CM, CC = 1 5. OA, CM, CC = 0 6. AM, Ol, CC = 2 OA, CM, CC = 2 8. OA, CM, CC = 5 9. AM, Ol, CC = 2 AM, Ol, CC = 4 11. OA, CM, CC = 2 12. OA, CM, CC = 2 OA, CM, CC = 3 14. OA, CM, CC = 2 15. AM, Ol, CC = 2 AM, Ol, CC = 2


1. 4. 7. 10. 13. 16.

Optically active:- OA Chiral molecule:- CM Achiral molecule:- AM Optically inactive:- OI No. of chiral cente:- CC AM, Ol, CC = 0 2. AM, Ol, CC = 0 3. AM, Ol, CC = 0 AM, Ol, CC = 2 5. AM, Ol, CC = 3 6. AM, Ol, CC = 0 OA, CM, CC = 0 8. AM, Ol, CC = 0 9. AM, Ol, CC = 0 AM, Ol, CC = 4 11. OA, CM, CC = 2 12. OA, CM, CC = 2 AM, Ol, CC = 2 14. AM, Ol, CC = 2 15. CM, OA, CC = 2 AM, Ol, CC = 2


1. 4. 7. 10. 13. 16.

Optically active:- OA Chiral molecule:- CM Achiral molecule:- AM Optically inactive:- OI No. of chiral cente:- CC AM, Ol, CC = 0 2. OA, CM, CC = 0 3. OA, CM, CC = 1 OA, CM, CC = 2 5. OI, AM, CC = 0 6. AM, Ol, CC = 0 OA, CM, CC = 3 8. OA, CM, CC = 2 9. AM, Ol, CC = 0 AM, Ol, CC = 0 11. AM, Ol, CC = 2 12. OA, CM, CC = 0 AM, Ol, CC = 0 14. CM, OA, CC = 0 15. AM, Ol, CC = 0 CM, OA, CC = 0 17. CM, OA, CC = 2


13

Isomerism Ans

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