Which will produce highest yield in Friedel-Crafts reaction?

Step 1: Reactivity in Friedel-Crafts Reactions Friedel-Crafts reactions require an activated ring. Deactivated rings (especially strongly deactivated) give poor or no yield.

• (d) Aniline: lone pair on $-\ce{NH2}$ reacts with the catalyst $\ce{AlCl3}$ to form a strongly deactivating $-\ce{NH2^+-AlCl3^-}$ complex. (Poor yield).
• (a) Benzamide: $-\ce{CONH2}$ is deactivating.
• (b) Phenol: lone pair on Oxygen also complexes with $\ce{AlCl3}$.
• (c) Chlorobenzene: Chlorine is weakly deactivating, but it does not complex as strongly with $\ce{AlCl3}$ compared to $N$ or $O$ lone pairs. Thus, it often gives better yields than aniline or phenol in direct FC alkylation/acylation.

From Jerry March - P709: It is important to note that the OH, OR, NH2, and so on groups do not facilitate the reaction, since most Lewis acid catalysts coordinate with these basic groups. Although phenols give the usual Friedel–Crafts reactions, orienting ortho and para, the reaction is very poor for aniline derivatives.

$\boxed{\text{Answer: (c) Option C}}$