Ethylbenzene is generally prepared by acetylation of benzene followed by reduction and not by direct alkylation. Explain why.

(N/A) Direct alkylation of benzene (Friedel-Crafts alkylation) with ethyl chloride $(CH_3CH_2Cl)$ in the presence of anhydrous $AlCl_3$ leads to polyalkylation because the alkyl group is electron-donating,which activates the benzene ring towards further electrophilic substitution.
Additionally,primary alkyl halides can undergo rearrangement.
To avoid these issues,ethylbenzene is prepared by Friedel-Crafts acylation of benzene with acetyl chloride $(CH_3COCl)$ to form acetophenone,followed by Clemmensen reduction $(Zn-Hg/HCl)$ to yield ethylbenzene.
The reaction sequence is:
$C_6H_6 + CH_3COCl$ $\xrightarrow{Anhydrous \ AlCl_3} C_6H_5COCH_3$ $\xrightarrow{Zn-Hg/HCl} C_6H_5CH_2CH_3$.