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The increasing order of the rate of HCN addition to compounds A-D is

A.\; \; HCHO

B.\; \; CH_3COCH_3

C.\; \; PhCOCH_3

D.\; \; PhCOPh

  • Option 1)

    A<B<C<D

  • Option 2)

    D<B<C<A

  • Option 3)

    D<C<B<A

  • Option 4)

    C<D<B<A

 

Answers (1)

As we learnt in 

Chemical properties of aldehydes and ketones -

Undergo nucleophilic addition reactions at carbon-oxygen double bond, hybridization of carbon changes from sp2 to  sp2.  Aldehydes are more reactive than ketones due to steric hindrance and  +I effect of an alkyl group.

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 Rate of addition of HCN is determined by steric hindrance.

Thus, D<C<B<A


Option 1)

A<B<C<D

This option is incorrect

Option 2)

D<B<C<A

This option is incorrect

Option 3)

D<C<B<A

This option is correct

Option 4)

C<D<B<A

This option is incorrect

Posted by

Sabhrant Ambastha

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