
image $\xrightarrow{{A{c_2}O}}A\mathop {\xrightarrow{{B{r_2}}}}\limits_{C{H_3}COOH} B\mathop {\xrightarrow{{{H_2}O}}}\limits_{{H^ + }} C$ would be
$R - \mathop {\mathop C\limits^{||} }\limits^O - OH\xleftarrow{{{H_3}{O^ + }}}X\xrightarrow{{[H]}}RC{H_2}N{H_2};$
'$X$' is
