Question: 55. What is the IUPAC name of the organic compound formed in the following chemical reaction?
Acetone \xrightarrow[\text{(ii) } \mathrm{H_{2}O},\ \mathrm{H^{+}}]{\text{(i) } \mathrm{C_{2}H_{5}MgBr},\ \text{dry ether}} Product
(1) 2-methyl propan-2-ol
(2) pentan-2-ol
(3) pentan-3-ol
(4) 2-methyl butan-2-ol
Answer: Option (4)
Explanation:
Acetone is a ketone with the structure \mathrm{(CH_3)_2CO}.
In the presence of dry ether, the Grignard reagent \mathrm{C_2H_5MgBr} adds to the carbonyl carbon of acetone.
This forms a tertiary alkoxide intermediate containing an ethyl group and two methyl groups attached to the carbon bearing oxygen.
On hydrolysis with \mathrm{H_2O/H^+}, the alkoxide is converted into a tertiary alcohol.
The carbon skeleton of the product contains four carbon atoms in the longest chain with a methyl substituent at carbon 2 and the hydroxyl group also at carbon 2.
Therefore, the IUPAC name of the product is 2-methyl butan-2-ol.