卤代水杨醛的简便合成

Simple way to synthesize halogenated salicyladehydes

以水杨醛(1)为起始原料,乙醇为溶剂,液溴为溴化剂,在10℃的温度下经溴代反应以82.7%的收率得到了5-溴水杨醛(2);以PEG-400为溶剂,NBS(N-溴代丁二酰亚胺)为溴化剂、NCS(N-氯代丁二酰亚胺)为氯化剂,在室温下分别经溴代反应、氯代反应以74.1%、34.8%的收率得到了3,5-二溴水杨醛(3)和3,5-二氯水杨醛(4)。

Salicylaldehyde（1） was brominated using liquid bromine as brominating agent in the presence of ethanol as solvent at 10 ℃ to afford mono-substituted 5-bromosalicylaldehyde（2） in 82.7% yield.When NBS（N-bromosuccinimide） was used as a brominating agent in the presence of PEG-400 as solvent at room temperature,the disubstituted 3,5-dibromosalicylaldehyde（3） was obtained in 74.1% yield.Similarly,when NBS was replaced with NCS（N-chlorosuccinimide） as a chlorination agent under the same reaction conditions,the corresponding 3,5-dichlorosalicylaldehyde（4） was obtained in 34.8% yield.