QBManager

GENERAL ORGANIC CHEMISTRY

231284 Assertion : The p-chlorobenzoic acid is stronger than benzoic acid.
Reason : This is due to $+ M$ effect of chlorine.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

Chlorine has donating resonance effect. This is due to inductive effect $(- I)$ which makes it electron withdrawing and increases acidic strength of benzoic acid.

AIIMS 25 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231288 The compound most reactive towards $S_{N} 1$ reaction is:

1

{MeCOCH}_{2} Cl

2

{MeOCH}_{2} Cl

3

C_{6} H_{5} {CH}_{5} {CH}_{2} Cl

4

Explanation:

In $S_{N} 1 {Rx}^{n}$ , carbocation intermediate is formed that carbocation which is stable by any effect such as $+ I + h$ and $+ M$ will favour the $S_{N} 1 {Rx}^{n}$ . All four option explain as follows.
(i) original image In this, reactant attract the electron towards itself. Therefore, it is not favourable condition for $S_{N} 1$ .
(ii) $Me - \ddot{O} - {CH}_{2} Cl \to$ In this, reactant methoxy group show the $+ M$ effect means it donate lone pair electron of oxygen towards carbocation.
(iii) $C_{6} H_{5} - {CH}_{2} - {CH}_{2} - Cl \to$ In shows only $+ I$ effect because the benzene ring is from the carbocation.
(iv) original image It shows only +I effect Therefore (ii) is most reactive towards carbocation because it directly donating electrons.
Therefore, 'b' option is correct.
The decreasing order of $S_{N} 1 {Rx}^{n}$ is-
II $>$ IV $>$ III $>$ I

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231289 $\begin{aligned} (i) C_{6} H_{5} - C O - C_{6} H_{5} \\ (i i) C_{6} H_{5} - C H O \\ (i i i) p - C H_{3} - C_{6} H_{4} - C H O \\ (i v) p - C H_{3} O - C_{6} H_{4} - C H O \end{aligned}$
The correct order for nucleophilic addition reaction is:

1 ii

>

i

>

iii

>

iv

2 iv

>

iii

>

ii

>

i

3 ii

>

iii

>

iv

>

i

4 iv

>

ii

>

iii

>

i

Explanation:

Nucleophile will attack on carbonyl carbon of aldehyde and ketone. Due to the stearic crowding effect. Reactant (i) is least reactive towards nucleophile.
Reactant (ii) is most reactive towards nucleophile due to less crowding effect. But in reactant (iii) and (iv) we see that the $+ I$ and $+ M$ effect and that effect which is least those are reactive towards nucleophile.
Hence, reactant (iii) is second most reactive and reactant (iv) is third most reactive
$∴$ Therefore the order of reactivity towards nucleophile is - (ii) $>$ (iii) $>$ (iv) $>$ (i).
Hence, 'c' option is correct.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231290 Which is most stable conformer of ethan-1,2 diol?

1

2

3

4

Explanation:

The possible conformer of ethane -1,2-diol is
original image
The Gauche conformer is most stable conformer of ethane-1,2-diol due to H-bonding in both the $- OH$ group.

Hence, ' $b$ ' option is correct. The order of stability of all conformer is-
Gauche $>$ Anti $>$ Fully eclipsed $>$ Partially eclipsed.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231284 Assertion : The p-chlorobenzoic acid is stronger than benzoic acid.
Reason : This is due to $+ M$ effect of chlorine.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

Chlorine has donating resonance effect. This is due to inductive effect $(- I)$ which makes it electron withdrawing and increases acidic strength of benzoic acid.

AIIMS 25 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231288 The compound most reactive towards $S_{N} 1$ reaction is:

1

{MeCOCH}_{2} Cl

2

{MeOCH}_{2} Cl

3

C_{6} H_{5} {CH}_{5} {CH}_{2} Cl

4

Explanation:

In $S_{N} 1 {Rx}^{n}$ , carbocation intermediate is formed that carbocation which is stable by any effect such as $+ I + h$ and $+ M$ will favour the $S_{N} 1 {Rx}^{n}$ . All four option explain as follows.
(i) original image In this, reactant attract the electron towards itself. Therefore, it is not favourable condition for $S_{N} 1$ .
(ii) $Me - \ddot{O} - {CH}_{2} Cl \to$ In this, reactant methoxy group show the $+ M$ effect means it donate lone pair electron of oxygen towards carbocation.
(iii) $C_{6} H_{5} - {CH}_{2} - {CH}_{2} - Cl \to$ In shows only $+ I$ effect because the benzene ring is from the carbocation.
(iv) original image It shows only +I effect Therefore (ii) is most reactive towards carbocation because it directly donating electrons.
Therefore, 'b' option is correct.
The decreasing order of $S_{N} 1 {Rx}^{n}$ is-
II $>$ IV $>$ III $>$ I

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231289 $\begin{aligned} (i) C_{6} H_{5} - C O - C_{6} H_{5} \\ (i i) C_{6} H_{5} - C H O \\ (i i i) p - C H_{3} - C_{6} H_{4} - C H O \\ (i v) p - C H_{3} O - C_{6} H_{4} - C H O \end{aligned}$
The correct order for nucleophilic addition reaction is:

1 ii

>

i

>

iii

>

iv

2 iv

>

iii

>

ii

>

i

3 ii

>

iii

>

iv

>

i

4 iv

>

ii

>

iii

>

i

Explanation:

Nucleophile will attack on carbonyl carbon of aldehyde and ketone. Due to the stearic crowding effect. Reactant (i) is least reactive towards nucleophile.
Reactant (ii) is most reactive towards nucleophile due to less crowding effect. But in reactant (iii) and (iv) we see that the $+ I$ and $+ M$ effect and that effect which is least those are reactive towards nucleophile.
Hence, reactant (iii) is second most reactive and reactant (iv) is third most reactive
$∴$ Therefore the order of reactivity towards nucleophile is - (ii) $>$ (iii) $>$ (iv) $>$ (i).
Hence, 'c' option is correct.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231290 Which is most stable conformer of ethan-1,2 diol?

1

2

3

4

Explanation:

The possible conformer of ethane -1,2-diol is
original image
The Gauche conformer is most stable conformer of ethane-1,2-diol due to H-bonding in both the $- OH$ group.

Hence, ' $b$ ' option is correct. The order of stability of all conformer is-
Gauche $>$ Anti $>$ Fully eclipsed $>$ Partially eclipsed.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231284 Assertion : The p-chlorobenzoic acid is stronger than benzoic acid.
Reason : This is due to $+ M$ effect of chlorine.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

Chlorine has donating resonance effect. This is due to inductive effect $(- I)$ which makes it electron withdrawing and increases acidic strength of benzoic acid.

AIIMS 25 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231288 The compound most reactive towards $S_{N} 1$ reaction is:

1

{MeCOCH}_{2} Cl

2

{MeOCH}_{2} Cl

3

C_{6} H_{5} {CH}_{5} {CH}_{2} Cl

4

Explanation:

In $S_{N} 1 {Rx}^{n}$ , carbocation intermediate is formed that carbocation which is stable by any effect such as $+ I + h$ and $+ M$ will favour the $S_{N} 1 {Rx}^{n}$ . All four option explain as follows.
(i) original image In this, reactant attract the electron towards itself. Therefore, it is not favourable condition for $S_{N} 1$ .
(ii) $Me - \ddot{O} - {CH}_{2} Cl \to$ In this, reactant methoxy group show the $+ M$ effect means it donate lone pair electron of oxygen towards carbocation.
(iii) $C_{6} H_{5} - {CH}_{2} - {CH}_{2} - Cl \to$ In shows only $+ I$ effect because the benzene ring is from the carbocation.
(iv) original image It shows only +I effect Therefore (ii) is most reactive towards carbocation because it directly donating electrons.
Therefore, 'b' option is correct.
The decreasing order of $S_{N} 1 {Rx}^{n}$ is-
II $>$ IV $>$ III $>$ I

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231289 $\begin{aligned} (i) C_{6} H_{5} - C O - C_{6} H_{5} \\ (i i) C_{6} H_{5} - C H O \\ (i i i) p - C H_{3} - C_{6} H_{4} - C H O \\ (i v) p - C H_{3} O - C_{6} H_{4} - C H O \end{aligned}$
The correct order for nucleophilic addition reaction is:

1 ii

>

i

>

iii

>

iv

2 iv

>

iii

>

ii

>

i

3 ii

>

iii

>

iv

>

i

4 iv

>

ii

>

iii

>

i

Explanation:

Nucleophile will attack on carbonyl carbon of aldehyde and ketone. Due to the stearic crowding effect. Reactant (i) is least reactive towards nucleophile.
Reactant (ii) is most reactive towards nucleophile due to less crowding effect. But in reactant (iii) and (iv) we see that the $+ I$ and $+ M$ effect and that effect which is least those are reactive towards nucleophile.
Hence, reactant (iii) is second most reactive and reactant (iv) is third most reactive
$∴$ Therefore the order of reactivity towards nucleophile is - (ii) $>$ (iii) $>$ (iv) $>$ (i).
Hence, 'c' option is correct.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231290 Which is most stable conformer of ethan-1,2 diol?

1

2

3

4

Explanation:

The possible conformer of ethane -1,2-diol is
original image
The Gauche conformer is most stable conformer of ethane-1,2-diol due to H-bonding in both the $- OH$ group.

Hence, ' $b$ ' option is correct. The order of stability of all conformer is-
Gauche $>$ Anti $>$ Fully eclipsed $>$ Partially eclipsed.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231284 Assertion : The p-chlorobenzoic acid is stronger than benzoic acid.
Reason : This is due to $+ M$ effect of chlorine.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

Chlorine has donating resonance effect. This is due to inductive effect $(- I)$ which makes it electron withdrawing and increases acidic strength of benzoic acid.

AIIMS 25 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231288 The compound most reactive towards $S_{N} 1$ reaction is:

1

{MeCOCH}_{2} Cl

2

{MeOCH}_{2} Cl

3

C_{6} H_{5} {CH}_{5} {CH}_{2} Cl

4

Explanation:

In $S_{N} 1 {Rx}^{n}$ , carbocation intermediate is formed that carbocation which is stable by any effect such as $+ I + h$ and $+ M$ will favour the $S_{N} 1 {Rx}^{n}$ . All four option explain as follows.
(i) original image In this, reactant attract the electron towards itself. Therefore, it is not favourable condition for $S_{N} 1$ .
(ii) $Me - \ddot{O} - {CH}_{2} Cl \to$ In this, reactant methoxy group show the $+ M$ effect means it donate lone pair electron of oxygen towards carbocation.
(iii) $C_{6} H_{5} - {CH}_{2} - {CH}_{2} - Cl \to$ In shows only $+ I$ effect because the benzene ring is from the carbocation.
(iv) original image It shows only +I effect Therefore (ii) is most reactive towards carbocation because it directly donating electrons.
Therefore, 'b' option is correct.
The decreasing order of $S_{N} 1 {Rx}^{n}$ is-
II $>$ IV $>$ III $>$ I

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231289 $\begin{aligned} (i) C_{6} H_{5} - C O - C_{6} H_{5} \\ (i i) C_{6} H_{5} - C H O \\ (i i i) p - C H_{3} - C_{6} H_{4} - C H O \\ (i v) p - C H_{3} O - C_{6} H_{4} - C H O \end{aligned}$
The correct order for nucleophilic addition reaction is:

1 ii

>

i

>

iii

>

iv

2 iv

>

iii

>

ii

>

i

3 ii

>

iii

>

iv

>

i

4 iv

>

ii

>

iii

>

i

Explanation:

Nucleophile will attack on carbonyl carbon of aldehyde and ketone. Due to the stearic crowding effect. Reactant (i) is least reactive towards nucleophile.
Reactant (ii) is most reactive towards nucleophile due to less crowding effect. But in reactant (iii) and (iv) we see that the $+ I$ and $+ M$ effect and that effect which is least those are reactive towards nucleophile.
Hence, reactant (iii) is second most reactive and reactant (iv) is third most reactive
$∴$ Therefore the order of reactivity towards nucleophile is - (ii) $>$ (iii) $>$ (iv) $>$ (i).
Hence, 'c' option is correct.

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231290 Which is most stable conformer of ethan-1,2 diol?

1

2

3

4

Explanation:

The possible conformer of ethane -1,2-diol is
original image
The Gauche conformer is most stable conformer of ethane-1,2-diol due to H-bonding in both the $- OH$ group.

Hence, ' $b$ ' option is correct. The order of stability of all conformer is-
Gauche $>$ Anti $>$ Fully eclipsed $>$ Partially eclipsed.

AIIMS 26 May 2019 (Morning)