QBManager

GENERAL ORGANIC CHEMISTRY

231292 The correct order for reaction with alcoholic $KOH$ of the following compounds is
(i)
(ii)
(iii)
(iv)

1 i

>

ii

>

iii

>

iv

2 i

>

iii

>

ii

>

iv

3 iv

>

ii

>

iii

>

i

4 i

>

iv

>

ii

>

iii

Explanation:

When alkyl halide react with alcoholic $KOH$ alkene is formed.
The intermediate of this reaction is carbocation. That carbocation which is more stable give first reaction with alcoholic $KOH$ .

Reactant (i) is stabilized by $3^{\circ} -$ carbocation by rearrangement hence it is fast react with alcoholic $KOH$ . In reactant (ii) and (iii) the reactant (iii) is more reactive because $Br$ is better leaving group than $Cl$ and reactant (iv) least reactive.
Hence, the order of reactivity-
$i > iii > ii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231293 Correct order of electrophilic substitution reaction is:

1 i

>

ii

>

iii

>

iv

2 iv

>

ii

>

i

>

iii

3 ii

>

i

>

iii

>

iv

4 ii

>

i

>

iv

>

iii

Explanation:

Electrophile attack at that position which have higher the electron cloud $+ I$ effect and $+ M$ effect increase the electron cloud at ortho and para position of benzene ring $+ M$ effect dominate over the $+ I$ effect hence (ii) is most reactive and (i) is second most. In reactant (iii)- $Cl$ have $- I$ effect and $+ M$ effect both hence (ii) is third most reactive and benzaldehyd have I effect hence it is least reactive.
Hence the order of reactivity is-
$ii > i > iii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231294 Correct order of basic strength is

1 I

>

II

>

III

>

IV

2 II

>

III

>

I

>

IV

3 III

>

II

>

I

>

IV

4 IV

>

I

>

II

>

III

Explanation:

In structure (i) the lone pair electron of $N$ is delocalized in benzene ring.

Therefore its lone pair electron is not free donation and it $B$ least basic.
In structure (ii) the lone pair electron is not delocalized Therefore its lone pair electron can donate.
Hence it $B$ most basic
In structure (iii) the lone pair electron is delocalized but it have $+ I$ effect therefore it $B$ second basic compound. In compound (iv) the lone pair electron B delocalized and $- {OCH}_{3}$ group is show only weak inductive effect.
Therefore it is least basic. The order basicity B-
$ii > iii > i > iv$
Hence 'b' option is correct.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231295 Assertion: The carbocation ${CF}_{3} - \overset{+}{C} H_{2}$ is less Stable than $\overset{+}{C} F_{3}$ .
Reason: In case of ${CF}_{3} - \overset{+}{C} H_{2}$ , the strongly electron-withdrawing $- {CF}_{3}$ group intensifies the +ve charge but in case of $\overset{+}{C} F_{3}$ , the lone pairs of electrons on each of the three $F$ -atoms overlap with the empty p-orbita of the carbocation carbon thereby dispersing the $+ ve$ charge.

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

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

3 If the Assertion is correct but Reason is incorrect.

4 If the Assertion is incorrect but the Reason is correct.

Explanation:

(A): ${CF}_{3} - \overset{+}{C} H_{2}$ [ carbocation $\to e^{-}$ deficient]
Electron with drawing group $\to$ pulls $e^{-}$ towards itself So, stability decreases.

Stable by resonance.
So, both are correct and reason is a correct explanation of the Assertion.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231292 The correct order for reaction with alcoholic $KOH$ of the following compounds is
(i)
(ii)
(iii)
(iv)

1 i

>

ii

>

iii

>

iv

2 i

>

iii

>

ii

>

iv

3 iv

>

ii

>

iii

>

i

4 i

>

iv

>

ii

>

iii

Explanation:

When alkyl halide react with alcoholic $KOH$ alkene is formed.
The intermediate of this reaction is carbocation. That carbocation which is more stable give first reaction with alcoholic $KOH$ .

Reactant (i) is stabilized by $3^{\circ} -$ carbocation by rearrangement hence it is fast react with alcoholic $KOH$ . In reactant (ii) and (iii) the reactant (iii) is more reactive because $Br$ is better leaving group than $Cl$ and reactant (iv) least reactive.
Hence, the order of reactivity-
$i > iii > ii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231293 Correct order of electrophilic substitution reaction is:

1 i

>

ii

>

iii

>

iv

2 iv

>

ii

>

i

>

iii

3 ii

>

i

>

iii

>

iv

4 ii

>

i

>

iv

>

iii

Explanation:

Electrophile attack at that position which have higher the electron cloud $+ I$ effect and $+ M$ effect increase the electron cloud at ortho and para position of benzene ring $+ M$ effect dominate over the $+ I$ effect hence (ii) is most reactive and (i) is second most. In reactant (iii)- $Cl$ have $- I$ effect and $+ M$ effect both hence (ii) is third most reactive and benzaldehyd have I effect hence it is least reactive.
Hence the order of reactivity is-
$ii > i > iii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231294 Correct order of basic strength is

1 I

>

II

>

III

>

IV

2 II

>

III

>

I

>

IV

3 III

>

II

>

I

>

IV

4 IV

>

I

>

II

>

III

Explanation:

In structure (i) the lone pair electron of $N$ is delocalized in benzene ring.

Therefore its lone pair electron is not free donation and it $B$ least basic.
In structure (ii) the lone pair electron is not delocalized Therefore its lone pair electron can donate.
Hence it $B$ most basic
In structure (iii) the lone pair electron is delocalized but it have $+ I$ effect therefore it $B$ second basic compound. In compound (iv) the lone pair electron B delocalized and $- {OCH}_{3}$ group is show only weak inductive effect.
Therefore it is least basic. The order basicity B-
$ii > iii > i > iv$
Hence 'b' option is correct.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231295 Assertion: The carbocation ${CF}_{3} - \overset{+}{C} H_{2}$ is less Stable than $\overset{+}{C} F_{3}$ .
Reason: In case of ${CF}_{3} - \overset{+}{C} H_{2}$ , the strongly electron-withdrawing $- {CF}_{3}$ group intensifies the +ve charge but in case of $\overset{+}{C} F_{3}$ , the lone pairs of electrons on each of the three $F$ -atoms overlap with the empty p-orbita of the carbocation carbon thereby dispersing the $+ ve$ charge.

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

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

3 If the Assertion is correct but Reason is incorrect.

4 If the Assertion is incorrect but the Reason is correct.

Explanation:

(A): ${CF}_{3} - \overset{+}{C} H_{2}$ [ carbocation $\to e^{-}$ deficient]
Electron with drawing group $\to$ pulls $e^{-}$ towards itself So, stability decreases.

Stable by resonance.
So, both are correct and reason is a correct explanation of the Assertion.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231292 The correct order for reaction with alcoholic $KOH$ of the following compounds is
(i)
(ii)
(iii)
(iv)

1 i

>

ii

>

iii

>

iv

2 i

>

iii

>

ii

>

iv

3 iv

>

ii

>

iii

>

i

4 i

>

iv

>

ii

>

iii

Explanation:

When alkyl halide react with alcoholic $KOH$ alkene is formed.
The intermediate of this reaction is carbocation. That carbocation which is more stable give first reaction with alcoholic $KOH$ .

Reactant (i) is stabilized by $3^{\circ} -$ carbocation by rearrangement hence it is fast react with alcoholic $KOH$ . In reactant (ii) and (iii) the reactant (iii) is more reactive because $Br$ is better leaving group than $Cl$ and reactant (iv) least reactive.
Hence, the order of reactivity-
$i > iii > ii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231293 Correct order of electrophilic substitution reaction is:

1 i

>

ii

>

iii

>

iv

2 iv

>

ii

>

i

>

iii

3 ii

>

i

>

iii

>

iv

4 ii

>

i

>

iv

>

iii

Explanation:

Electrophile attack at that position which have higher the electron cloud $+ I$ effect and $+ M$ effect increase the electron cloud at ortho and para position of benzene ring $+ M$ effect dominate over the $+ I$ effect hence (ii) is most reactive and (i) is second most. In reactant (iii)- $Cl$ have $- I$ effect and $+ M$ effect both hence (ii) is third most reactive and benzaldehyd have I effect hence it is least reactive.
Hence the order of reactivity is-
$ii > i > iii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231294 Correct order of basic strength is

1 I

>

II

>

III

>

IV

2 II

>

III

>

I

>

IV

3 III

>

II

>

I

>

IV

4 IV

>

I

>

II

>

III

Explanation:

In structure (i) the lone pair electron of $N$ is delocalized in benzene ring.

Therefore its lone pair electron is not free donation and it $B$ least basic.
In structure (ii) the lone pair electron is not delocalized Therefore its lone pair electron can donate.
Hence it $B$ most basic
In structure (iii) the lone pair electron is delocalized but it have $+ I$ effect therefore it $B$ second basic compound. In compound (iv) the lone pair electron B delocalized and $- {OCH}_{3}$ group is show only weak inductive effect.
Therefore it is least basic. The order basicity B-
$ii > iii > i > iv$
Hence 'b' option is correct.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231295 Assertion: The carbocation ${CF}_{3} - \overset{+}{C} H_{2}$ is less Stable than $\overset{+}{C} F_{3}$ .
Reason: In case of ${CF}_{3} - \overset{+}{C} H_{2}$ , the strongly electron-withdrawing $- {CF}_{3}$ group intensifies the +ve charge but in case of $\overset{+}{C} F_{3}$ , the lone pairs of electrons on each of the three $F$ -atoms overlap with the empty p-orbita of the carbocation carbon thereby dispersing the $+ ve$ charge.

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

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

3 If the Assertion is correct but Reason is incorrect.

4 If the Assertion is incorrect but the Reason is correct.

Explanation:

(A): ${CF}_{3} - \overset{+}{C} H_{2}$ [ carbocation $\to e^{-}$ deficient]
Electron with drawing group $\to$ pulls $e^{-}$ towards itself So, stability decreases.

Stable by resonance.
So, both are correct and reason is a correct explanation of the Assertion.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231292 The correct order for reaction with alcoholic $KOH$ of the following compounds is
(i)
(ii)
(iii)
(iv)

1 i

>

ii

>

iii

>

iv

2 i

>

iii

>

ii

>

iv

3 iv

>

ii

>

iii

>

i

4 i

>

iv

>

ii

>

iii

Explanation:

When alkyl halide react with alcoholic $KOH$ alkene is formed.
The intermediate of this reaction is carbocation. That carbocation which is more stable give first reaction with alcoholic $KOH$ .

Reactant (i) is stabilized by $3^{\circ} -$ carbocation by rearrangement hence it is fast react with alcoholic $KOH$ . In reactant (ii) and (iii) the reactant (iii) is more reactive because $Br$ is better leaving group than $Cl$ and reactant (iv) least reactive.
Hence, the order of reactivity-
$i > iii > ii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231293 Correct order of electrophilic substitution reaction is:

1 i

>

ii

>

iii

>

iv

2 iv

>

ii

>

i

>

iii

3 ii

>

i

>

iii

>

iv

4 ii

>

i

>

iv

>

iii

Explanation:

Electrophile attack at that position which have higher the electron cloud $+ I$ effect and $+ M$ effect increase the electron cloud at ortho and para position of benzene ring $+ M$ effect dominate over the $+ I$ effect hence (ii) is most reactive and (i) is second most. In reactant (iii)- $Cl$ have $- I$ effect and $+ M$ effect both hence (ii) is third most reactive and benzaldehyd have I effect hence it is least reactive.
Hence the order of reactivity is-
$ii > i > iii > iv$

AIIMS 26 May 2019 (Morning)

GENERAL ORGANIC CHEMISTRY

231294 Correct order of basic strength is

1 I

>

II

>

III

>

IV

2 II

>

III

>

I

>

IV

3 III

>

II

>

I

>

IV

4 IV

>

I

>

II

>

III

Explanation:

In structure (i) the lone pair electron of $N$ is delocalized in benzene ring.

Therefore its lone pair electron is not free donation and it $B$ least basic.
In structure (ii) the lone pair electron is not delocalized Therefore its lone pair electron can donate.
Hence it $B$ most basic
In structure (iii) the lone pair electron is delocalized but it have $+ I$ effect therefore it $B$ second basic compound. In compound (iv) the lone pair electron B delocalized and $- {OCH}_{3}$ group is show only weak inductive effect.
Therefore it is least basic. The order basicity B-
$ii > iii > i > iv$
Hence 'b' option is correct.

2018 (M)]**

GENERAL ORGANIC CHEMISTRY

231295 Assertion: The carbocation ${CF}_{3} - \overset{+}{C} H_{2}$ is less Stable than $\overset{+}{C} F_{3}$ .
Reason: In case of ${CF}_{3} - \overset{+}{C} H_{2}$ , the strongly electron-withdrawing $- {CF}_{3}$ group intensifies the +ve charge but in case of $\overset{+}{C} F_{3}$ , the lone pairs of electrons on each of the three $F$ -atoms overlap with the empty p-orbita of the carbocation carbon thereby dispersing the $+ ve$ charge.

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

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

3 If the Assertion is correct but Reason is incorrect.

4 If the Assertion is incorrect but the Reason is correct.

Explanation:

(A): ${CF}_{3} - \overset{+}{C} H_{2}$ [ carbocation $\to e^{-}$ deficient]
Electron with drawing group $\to$ pulls $e^{-}$ towards itself So, stability decreases.

Stable by resonance.
So, both are correct and reason is a correct explanation of the Assertion.

2018 (M)]**

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