Answer:
(a) (i)
In cyclohexanone, cyanohydrin is formed easily as there is
no steric hindrance. But in 2, 2, 6- tri methyl cyclohexanone, adjacent
positions are occupied. This produces steric hindrance and thus approach of
HCN, in nucleophilic addition is prevented. [1]
(ii)
Lone pair on this N is delocalized due to presence of
CO group. Thus, it is less basic as compared to attached
to NH.
[1]
(iii) (alkoxide)
is a better leaving group. If or ester
is not removed, above reaction becomes reversible and yield of the ester
(product) is decreased. [1]
(b)
When and both take
part in one reaction.
acts
as nucleophile then product is
acts
as nucleophile then product is
Or
(a) (i) Benzaldehyde to 3-phenyl propan -1-ol
[1]
(ii) Benzoic acid (X) to m-nitro benzyl alcohol (Y)
[1]
(iii) Propanone (X) to propene (Y)
[1]
(b) (i) Cross aldol condensation When two different
aldehydes having at least one a - H are treated with NaOH, there is formation
of aldol.
One of the aldehyde acts as nucleophile and condensation
product can be converted into enal. This type of reaction involving different aldehydes
is called cross aldol condensation.
Ketones can also undergo this reaction.
From
+
From
+
From A and B
+
[1]
(ii) Decarboxylation Sodium salt of carboxylic acids
on heating with sodalime changes to hydrocarbon with one carbon less.
This is called decarboxylation of the acid.
Decarboxylation is used for descending a chain.
[1]
You need to login to perform this action.
You will be redirected in
3 sec