Explanation:
Cinnamic acid reacts with bromine in carbon tetrachloride to give dibromocinnamic acid.
\({{C}_{6}}{{H}_{5}}CH=CHCOOH+B{{r}_{2}}\) \(\xrightarrow{CC{{l}_{4}}}\) $\underset{\text{dibromo}\,\,\,\text{cinnamic acid}}{\mathop{\begin{matrix}
\,\,\,\,Br\,\,\,\,\,\,\,\,\,\,\,\,Br\,\,\,\,\,\,\,\, \\
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\, \\
{{C}_{6}}{{H}_{5}}CH-CHCOOH \\
\end{matrix}}}\,$