

image$\xrightarrow{{A{c_2}O}}A\mathop {\xrightarrow{{B{r_2}}}}\limits_{C{H_3}COOH} B\mathop {\xrightarrow{{{H_2}O}}}\limits_{{H^ + }} C$ 
$RCN{\mkern 1mu} \xrightarrow{{reduction}}{\mkern 1mu} (a),$
$RCN{\mkern 1mu} {\mkern 1mu} \mathop {\xrightarrow{{(i){\kern 1pt} C{H_3}MgBr}}}\limits_{(ii){\kern 1pt} {H_2}O} {\mkern 1mu} (b),$
$RNC{\mkern 1mu} {\mkern 1mu} \xrightarrow{{hydrolysis}}{\mkern 1mu} {\mkern 1mu} (c),{\mkern 1mu} $
$RN{H_2}{\mkern 1mu} \xrightarrow{{HN{O_2}}}{\mkern 1mu} {\mkern 1mu} (d)$