ETHER}{\mathop{{{(C{{H}_{3}}C{{H}_{2}})}_{2}}O}}\,+\underset{Acid\,\,ANHYDRIDE}{\mathop{{{(C{{H}_{3}}CO)}_{2}}O}}\,\xrightarrow{anhy.AlC{{l}_{3}}}\underset{Ester}{\mathop{C{{H}_{3}}COOC{{H}_{2}}C{{H}_{3}}}}\,\]