question_answer

What will be the major organic product of the following reaction? \[{{C}_{6}}{{H}_{5}}{{C}_{2}}{{H}_{5}}\xrightarrow[(ii)\,NaCN]{(i)\,B{{r}_{2}},\,hv}\]

Answer:

                When ethyl benzene is treated with  in presence of light, the bromine free radical formed during the reaction, abstracts the \[\alpha \] (but not \[\beta \]-)hydrogen from the ethyl group to form a resonance stabilized benzylic radical \[(I)\] which then reacts with \[B{{r}_{2}}\] to form 1-bromo-1-phenylethane\[(II)\]. This on treatment with \[NaCN\]undergoes nucleophilic substitution to form 2-phenylpropanenitrile \[(III)\].