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CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323461 Which statement about the aldol condensation is correct?

1 A Lewis acid is commonly used as a catalyst

2 The initial step is probably the formation of a carbanion.

3 A Lewis base is employed to induce carbocation formation

4 The carbon chain is lengthened throuh the elimination of 1 mole of

H_{2} O

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323462 Which of the following is the incorrect statement?

1

{CCl}_{3} CHO

can give aldol condensation.

2 When mixture of ethanal and propanal is treated with aq. NaOH , structurally four different aldols are formed.

3 Mixture of HCHO and PhCHO cannot give aldol condensation product.

4 Aldol reaction is possible even if one of the carbonyl compounds contains an

α -

hydrogen.

Explanation:

${CCl}_{3} CHO$ can't give aldol condensation as it dosen't have $α$ -Hydrogen. Under the same conditions it gives ${CHCl}_{3}$ and ${HCOO}^{-}$ .

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323463 On treatment of propanone with dilute $Ba (OH)_{2}$ , the product formed is

1 aldol

2 phorone

3 propionaldehyde

4 4-hydroxy-4-methyl-2-pentanone.

Explanation:

In the presence of $Ba (OH)_{2^{'}}$ propanone (acetone) undergoes aldol condensation as :

supporting img

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323464 Assertion :
2 - Butenal lacks enolisable $H$ atom, $α$ to carbonyl group, still it has sufficient acidic character.
Reason :
The conjugate base of 2 - butenal is stabilised by resonance.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Both Assertion and Reason are incorrect.

Explanation:

2 - Butenal contains $γ - H -$ atoms and the conjugate base obtained after the removal of $γ - H -$ atom, is stabilised by resonance. Hence, 2 - Butenal is sufficiently acidic. However, it lacks enolisable $H$ -atom, $α$ to carbonyl group.
supporting img

AIIMS - 2009

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323465 Assertion :
Acetaldehyde undergoes aldol condensation with dilute $NaOH$ .
Reason :
Aldehydes which do not contain $α$ hydrogen undergo aldol condensation.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Acetaldehyde which has $α$ -hydrogen undergoes aldol condensation with dilute $NaOH$ . Aldehydes lacking $α$ - hydrogens undergo Cannizzaro reaction, involving self oxidation and reduction upon heating with concentrated alkali. So the option (3) is correct.

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323461 Which statement about the aldol condensation is correct?

1 A Lewis acid is commonly used as a catalyst

2 The initial step is probably the formation of a carbanion.

3 A Lewis base is employed to induce carbocation formation

4 The carbon chain is lengthened throuh the elimination of 1 mole of

H_{2} O

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323462 Which of the following is the incorrect statement?

1

{CCl}_{3} CHO

can give aldol condensation.

2 When mixture of ethanal and propanal is treated with aq. NaOH , structurally four different aldols are formed.

3 Mixture of HCHO and PhCHO cannot give aldol condensation product.

4 Aldol reaction is possible even if one of the carbonyl compounds contains an

α -

hydrogen.

Explanation:

${CCl}_{3} CHO$ can't give aldol condensation as it dosen't have $α$ -Hydrogen. Under the same conditions it gives ${CHCl}_{3}$ and ${HCOO}^{-}$ .

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323463 On treatment of propanone with dilute $Ba (OH)_{2}$ , the product formed is

1 aldol

2 phorone

3 propionaldehyde

4 4-hydroxy-4-methyl-2-pentanone.

Explanation:

In the presence of $Ba (OH)_{2^{'}}$ propanone (acetone) undergoes aldol condensation as :

supporting img

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323464 Assertion :
2 - Butenal lacks enolisable $H$ atom, $α$ to carbonyl group, still it has sufficient acidic character.
Reason :
The conjugate base of 2 - butenal is stabilised by resonance.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Both Assertion and Reason are incorrect.

Explanation:

2 - Butenal contains $γ - H -$ atoms and the conjugate base obtained after the removal of $γ - H -$ atom, is stabilised by resonance. Hence, 2 - Butenal is sufficiently acidic. However, it lacks enolisable $H$ -atom, $α$ to carbonyl group.
supporting img

AIIMS - 2009

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323465 Assertion :
Acetaldehyde undergoes aldol condensation with dilute $NaOH$ .
Reason :
Aldehydes which do not contain $α$ hydrogen undergo aldol condensation.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Acetaldehyde which has $α$ -hydrogen undergoes aldol condensation with dilute $NaOH$ . Aldehydes lacking $α$ - hydrogens undergo Cannizzaro reaction, involving self oxidation and reduction upon heating with concentrated alkali. So the option (3) is correct.

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323461 Which statement about the aldol condensation is correct?

1 A Lewis acid is commonly used as a catalyst

2 The initial step is probably the formation of a carbanion.

3 A Lewis base is employed to induce carbocation formation

4 The carbon chain is lengthened throuh the elimination of 1 mole of

H_{2} O

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323462 Which of the following is the incorrect statement?

1

{CCl}_{3} CHO

can give aldol condensation.

2 When mixture of ethanal and propanal is treated with aq. NaOH , structurally four different aldols are formed.

3 Mixture of HCHO and PhCHO cannot give aldol condensation product.

4 Aldol reaction is possible even if one of the carbonyl compounds contains an

α -

hydrogen.

Explanation:

${CCl}_{3} CHO$ can't give aldol condensation as it dosen't have $α$ -Hydrogen. Under the same conditions it gives ${CHCl}_{3}$ and ${HCOO}^{-}$ .

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323463 On treatment of propanone with dilute $Ba (OH)_{2}$ , the product formed is

1 aldol

2 phorone

3 propionaldehyde

4 4-hydroxy-4-methyl-2-pentanone.

Explanation:

In the presence of $Ba (OH)_{2^{'}}$ propanone (acetone) undergoes aldol condensation as :

supporting img

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323464 Assertion :
2 - Butenal lacks enolisable $H$ atom, $α$ to carbonyl group, still it has sufficient acidic character.
Reason :
The conjugate base of 2 - butenal is stabilised by resonance.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Both Assertion and Reason are incorrect.

Explanation:

2 - Butenal contains $γ - H -$ atoms and the conjugate base obtained after the removal of $γ - H -$ atom, is stabilised by resonance. Hence, 2 - Butenal is sufficiently acidic. However, it lacks enolisable $H$ -atom, $α$ to carbonyl group.
supporting img

AIIMS - 2009

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323465 Assertion :
Acetaldehyde undergoes aldol condensation with dilute $NaOH$ .
Reason :
Aldehydes which do not contain $α$ hydrogen undergo aldol condensation.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Acetaldehyde which has $α$ -hydrogen undergoes aldol condensation with dilute $NaOH$ . Aldehydes lacking $α$ - hydrogens undergo Cannizzaro reaction, involving self oxidation and reduction upon heating with concentrated alkali. So the option (3) is correct.

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323461 Which statement about the aldol condensation is correct?

1 A Lewis acid is commonly used as a catalyst

2 The initial step is probably the formation of a carbanion.

3 A Lewis base is employed to induce carbocation formation

4 The carbon chain is lengthened throuh the elimination of 1 mole of

H_{2} O

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323462 Which of the following is the incorrect statement?

1

{CCl}_{3} CHO

can give aldol condensation.

2 When mixture of ethanal and propanal is treated with aq. NaOH , structurally four different aldols are formed.

3 Mixture of HCHO and PhCHO cannot give aldol condensation product.

4 Aldol reaction is possible even if one of the carbonyl compounds contains an

α -

hydrogen.

Explanation:

${CCl}_{3} CHO$ can't give aldol condensation as it dosen't have $α$ -Hydrogen. Under the same conditions it gives ${CHCl}_{3}$ and ${HCOO}^{-}$ .

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323463 On treatment of propanone with dilute $Ba (OH)_{2}$ , the product formed is

1 aldol

2 phorone

3 propionaldehyde

4 4-hydroxy-4-methyl-2-pentanone.

Explanation:

In the presence of $Ba (OH)_{2^{'}}$ propanone (acetone) undergoes aldol condensation as :

supporting img

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323464 Assertion :
2 - Butenal lacks enolisable $H$ atom, $α$ to carbonyl group, still it has sufficient acidic character.
Reason :
The conjugate base of 2 - butenal is stabilised by resonance.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Both Assertion and Reason are incorrect.

Explanation:

2 - Butenal contains $γ - H -$ atoms and the conjugate base obtained after the removal of $γ - H -$ atom, is stabilised by resonance. Hence, 2 - Butenal is sufficiently acidic. However, it lacks enolisable $H$ -atom, $α$ to carbonyl group.
supporting img

AIIMS - 2009

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323465 Assertion :
Acetaldehyde undergoes aldol condensation with dilute $NaOH$ .
Reason :
Aldehydes which do not contain $α$ hydrogen undergo aldol condensation.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Acetaldehyde which has $α$ -hydrogen undergoes aldol condensation with dilute $NaOH$ . Aldehydes lacking $α$ - hydrogens undergo Cannizzaro reaction, involving self oxidation and reduction upon heating with concentrated alkali. So the option (3) is correct.

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323461 Which statement about the aldol condensation is correct?

1 A Lewis acid is commonly used as a catalyst

2 The initial step is probably the formation of a carbanion.

3 A Lewis base is employed to induce carbocation formation

4 The carbon chain is lengthened throuh the elimination of 1 mole of

H_{2} O

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323462 Which of the following is the incorrect statement?

1

{CCl}_{3} CHO

can give aldol condensation.

2 When mixture of ethanal and propanal is treated with aq. NaOH , structurally four different aldols are formed.

3 Mixture of HCHO and PhCHO cannot give aldol condensation product.

4 Aldol reaction is possible even if one of the carbonyl compounds contains an

α -

hydrogen.

Explanation:

${CCl}_{3} CHO$ can't give aldol condensation as it dosen't have $α$ -Hydrogen. Under the same conditions it gives ${CHCl}_{3}$ and ${HCOO}^{-}$ .

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323463 On treatment of propanone with dilute $Ba (OH)_{2}$ , the product formed is

1 aldol

2 phorone

3 propionaldehyde

4 4-hydroxy-4-methyl-2-pentanone.

Explanation:

In the presence of $Ba (OH)_{2^{'}}$ propanone (acetone) undergoes aldol condensation as :

supporting img

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323464 Assertion :
2 - Butenal lacks enolisable $H$ atom, $α$ to carbonyl group, still it has sufficient acidic character.
Reason :
The conjugate base of 2 - butenal is stabilised by resonance.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Both Assertion and Reason are incorrect.

Explanation:

2 - Butenal contains $γ - H -$ atoms and the conjugate base obtained after the removal of $γ - H -$ atom, is stabilised by resonance. Hence, 2 - Butenal is sufficiently acidic. However, it lacks enolisable $H$ -atom, $α$ to carbonyl group.
supporting img

AIIMS - 2009

CHXII12:ALDEHYDES KETONES AND CARBOXYLIC ACIDS

323465 Assertion :
Acetaldehyde undergoes aldol condensation with dilute $NaOH$ .
Reason :
Aldehydes which do not contain $α$ hydrogen undergo aldol condensation.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Acetaldehyde which has $α$ -hydrogen undergoes aldol condensation with dilute $NaOH$ . Aldehydes lacking $α$ - hydrogens undergo Cannizzaro reaction, involving self oxidation and reduction upon heating with concentrated alkali. So the option (3) is correct.

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