A Levels Chemistry

Cyanohydrins can be made from carbonyl compounds by generating CN ions from HCN in the
presence of a weak base.
R
R
OH
CN-
C=0
HCN
R'
R'
CN
In a similar reaction, CH2CO,CH3 ions are generated from CH;CO,CH3 by strong bases.
Which compound can be made from an aldehyde and CH3CO2CH3 in the presence of a strong
base?
A CH;CH(OH)CO,CH3
B CH;CO,CHCH(OH)CH3
C CH;CH,CH(OH)CH,CO,CH3
D (CH3),C(OH)CH;CO,CH3


Choice C is correct because:

In the presence of a strong base, -CH2CO2CH3 ions are generated from CH3CO2CH3. These ions act as nucleophiles and can react with an aldehyde to form a new compound via a nucleophilic addition reaction. 

The reaction between an aldehyde and CH3CO2CH3 in the presence of a strong base results in the formation of a compound with a secondary alcohol group (OH) and an ester group (CO2CH3) on adjacent carbons.

The correct product of this reaction is represented by the formula CH3CH2CH(OH)CH2CO2CH3, which corresponds to Choice C. The product contains a secondary alcohol group (OH) on the third carbon and an ester group (CO2CH3) on the fourth carbon.

Choice A is incorrect because:

The compound CH3CH(OH)CO2CH3 does not have an alcohol and an ester group on adjacent carbons, as required in the reaction between an aldehyde and CH3CO2CH3 in the presence of a strong base.

Choice B is incorrect because:

The compound CH3CO2CH2CH(OH)CH3 has the ester group and the alcohol group in the wrong positions. The ester group should be on a carbon adjacent to the alcohol group, but in this compound, they are separated by a CH2 group.

Choice D is incorrect because:

The compound (CH3)2C(OH)CH2CO2CH3 has a tertiary alcohol group, which would not be formed in the reaction between an aldehyde and CH3CO2CH3 in the presence of a strong base. The reaction should result in a secondary alcohol group.

Aldehydes and Ketones | 2009 - O/N - 9701/11 | Q28