$\mathop {Br - {{\mathop {CH}\limits^3 }_2} - \mathop {CH}\limits^2 = {{\mathop {CH}\limits^1 }_2}}\limits_{3\, - \,bromoprop\, - \,1\, - \,ene} $ is
$\begin{array}{*{20}{c}}
{C{H_3} - C = CH - C{H_2} - COOH} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}
\end{array}$