a Gabriel Synthesis KOH NH R一X Etoh NK O h or oh COH RNHo t HO CO,H N-R ①D H2NNH2 NH RNH, NH ⑨D Etoh OOrganic Chemistry Organic Chemistry Xiamen Xiamen University University Gabriel Synthesis NH O O KOH EtOH N K O O R X N O O R H + or O H H 2 O H 2NNH 2 EtOH CO 2 H CO 2 H RNH 2 + RNH 2 + NH NH O O