Question

$C{H}_{3}C{H}_{2}C{H}_{2}COOH\stackrel{LiAl{H}_4}{\to }\stackrel{SOC{l}_2}{\to }\stackrel{NaCN}{\to }\stackrel{Dil{H}_{2}S{O}_4}{\to }$.

The product formed by using the above reaction has how many atoms in its parent chain?

Answer 1

$C{H}_{3}C{H}_{2}C{H}_{2}COOH⟶C{H}_{3}C{H}_{2}C{H}_{2}C{H}_{2}COOH$.
The following product can be formed by using $\underrightarrow{LiAl{H}_4}\underrightarrow{SOC{l}_2}\underrightarrow{NaCN}\underrightarrow{Dil{H}_{2}S{O}_4}$.
In the overall reaction, a methylene group is introduced in a carboxylic acid.
The carboxylic acid is first reduced with lithium aluminium hydride to form alcohol, the -OH group is then replaced with chloro group by reaction with thionyl chloride, the Cl atom is displaced with cyano group by treatment with NaCN and finally, cyano group is hydrolyzed to carboxylic group by treatment with dil sulphuric acid.