question_answer

Compound A reacts with \[PC{{l}_{5}}\]to give B which on treatment with KCN followed by hydrolysis gave propionic acid. What is A and B respectively       [EAMCET 1998]

A)                 \[{{C}_{3}}{{H}_{8}}\] and \[{{C}_{3}}{{H}_{7}}Cl\]

B)                 \[{{C}_{2}}{{H}_{6}}\] and \[{{C}_{2}}{{H}_{5}}Cl\]

C)                 \[{{C}_{2}}{{H}_{5}}Cl\] and \[{{C}_{2}}{{H}_{5}}Cl\]

D)                 \[{{C}_{2}}{{H}_{5}}OH\] and \[{{C}_{2}}{{H}_{5}}Cl\]

Correct Answer: D

Solution :

           \[\underset{\text{(A)}}{\mathop{{{C}_{2}}{{H}_{5}}OH}}\,+PC{{l}_{5}}\to \underset{\text{(B)}}{\mathop{{{C}_{2}}{{H}_{5}}Cl}}\,+POC{{l}_{3}}+HCl\]                    \[\underset{\text{(B)}}{\mathop{{{C}_{2}}{{H}_{5}}Cl}}\,+KCN\to {{C}_{2}}{{H}_{5}}CN+KCl\]