Question

Which of the following reagent would you choose for differentiating benzene from cyclohexane?

• A. $B{r}_2$ in $CC{l}_4/C{H}_{2}C{l}_2$
• B. $I_2$ in $CC{l}_4/C{H}_{2}C{l}_2$
• C. $C{l}_2$ in $CC{l}_4/C{H}_{2}C{l}_2$
• D. $F_2$ in $CC{l}_4/C{H}_{2}C{l}_2$

Answer 1

The correct option is A $B{r}_2$ in $CC{l}_4/C{H}_{2}C{l}_2$

$B{r}_2$ in $CC{l}_4/C{H}_{2}C{l}_2$ is preferred for differentiating benzene from cyclohexane.

Cyclohexane will undergo free-radical reaction with bromine in the presence of light which is indicated by the lost of orange color of bromine upon addition of cyclohexane and exposure to light for 10 minutes.

On the other hand, benzene will not react with bromine upon exposure to light since bromination reaction of benzene will require a catalyst. The orange color of the test solution will remain upon addition of benzene and exposure to light for 10 minutes.