Hexane → 773   K 10 - 20   atm Cr 2 O 3 X → Anhydrous   AlCl 3 CH 3 COCl Y Y in…

$\underset{\mathrm{Hexane}}{{\mathrm{C}}_6{\mathrm{H}}_{14}}$ $\underset{\underset{10-20 \mathrm{atm}}{773 \mathrm{K}}}{\overset{{\mathrm{Cr}}_2{\mathrm{O}}_3}{\to }}$ $\underset{\mathrm{Benzene}}{{\mathrm{C}}_6{\mathrm{H}}_6}$ $\underset{\mathrm{Anhydrous} {\mathrm{AlCl}}_3}{\overset{{\mathrm{CH}}_3\mathrm{COCl}}{\to }}$$\underset{\mathrm{Acetophenone}}{{\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{COCH}}_3}$

When benzene reacts with ${\mathrm{CH}}_3\mathrm{COCl}$ in the presence of ${\mathrm{AlCl}}_3$, Acetophenone will form. This is an electrophilic substitution reaction. It is named as Friedel Craft's acylation reaction.