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Aldehydes Ketones and Carboxylic Acids question

2012 · Shift 2 · Q5
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  5. /2012 · Shift 2 · Q5

Aldehydes Ketones and Carboxylic Acids question

2012 · Shift 2 · Q5

JEE AdvancedChemistryAldehydes Ketones and Carboxylic AcidsMCQ+3 / −1
The major product H of the given reaction sequence is CH3−CH2−CO−CH3→C‾NG⟶Heat95% H2SO4HC{H_3} - C{H_2} - CO - C{H_3}\xrightarrow{\overline C N} G\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Heat}^{95\% \,{H_2}S{O_4}}} HCH3​−CH2​−CO−CH3​CN​GHeat⟶95%H2​SO4​​H
  1. A
    IIT-JEE 2012 Paper 2 Offline Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 29 English Option 1
  2. B
    IIT-JEE 2012 Paper 2 Offline Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 29 English Option 2
  3. C
    IIT-JEE 2012 Paper 2 Offline Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 29 English Option 3
  4. D
    IIT-JEE 2012 Paper 2 Offline Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 29 English Option 4
View written solutionFree

Correct answer: A

  1. Identify the starting compound

The given ketone is: CH3−CH2−CO−CH3CH_3-CH_2-CO-CH_3CH3​−CH2​−CO−CH3​ This is 2-butanone.

  1. Reaction with cyanide ion

A ketone reacts with CN−CN^-CN− to form a cyanohydrin by nucleophilic addition to the carbonyl carbon.

So, compound GGG is: CH3−CH2−C(OH)(CN)−CH3CH_3-CH_2-C(OH)(CN)-CH_3CH3​−CH2​−C(OH)(CN)−CH3​

  1. Action of 95% H2SO495\%\ H_2SO_495% H2​SO4​ and heat

Under strongly acidic conditions and heating, cyanohydrins undergo dehydration to give an alkene nitrile.

From CH3−CH2−C(OH)(CN)−CH3CH_3-CH_2-C(OH)(CN)-CH_3CH3​−CH2​−C(OH)(CN)−CH3​ loss of water occurs from the −OH-OH−OH group and a β\betaβ-hydrogen from an adjacent carbon.

Possible eliminations are:

  • from the left side CH2CH_2CH2​
  • from the right side CH3CH_3CH3​

The more substituted alkene is the major product (Saytzeff product), formed by removing H from the left CH2CH_2CH2​ side.

Thus the major product HHH is: CH3−CH=C(CN)−CH3CH_3-CH=C(CN)-CH_3CH3​−CH=C(CN)−CH3​

  1. Conclusion

So the major product is the more substituted unsaturated nitrile: CH3−CH=C(CN)−CH3\boxed{CH_3-CH=C(CN)-CH_3}CH3​−CH=C(CN)−CH3​​

Since the actual option structures are not visible in the prompt, I infer this corresponds to Option A as per the stored answer.

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