


$C{H_2}CN\xrightarrow{{Na/{C_2}{H_5}OH}}\,A\,\xrightarrow{{HN{O_2}}}\,B\,\xrightarrow{{C{r_2}O_{_7}^{ - 2}}}\,C$


$PhCHO + Ph \cdot CHO \xrightarrow[in\,\,{{D}_{2}}O]{NaOD} A + \begin{matrix} O \\ || \\ Ph-C-{{O}^{-}} \\ \end{matrix}$$\left( Ph\right.$ is $\left.- C _{6} H _{5}\right)$