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Green synthesis of symmetric aryl ether dinitro compounds in deep eutectic solvents
Author : Yan Jin, Yinhao Ding, Xichao Hou, Jingjing Dong, Jianqiang Lu and Baicheng Feng*
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ABSTRACT
A series of symmetric aryl ether dinitro compounds were synthesized by 4Urea/ZnCl2 as green solvent and catalyst, and halogenated aromatic hydrocarbon derivatives and dihydroxy compounds as raw materials. This method has the advantages of easy operation, simple recrystallization, environmental friendliness and biodegradability. The structures of the products were subjected to 1H NMR, and the reaction conditions, reaction mechanism and greening advantages of deep eutectic solvents were discussed at the end of the experiments. We learned from the results of the experiments that both the aliphatic dihydroxy compounds and the aromatic dihydroxy compounds could proceed effectively in Ullmann reaction, and the desired products could be obtained in acceptable yields. When using this methodology, symmetric aryl ether dinitro compounds could be synthesized simply at 80ºC in 2 h with high yields (66%~94%). Meanwhile, the DES, called deep eutectic solvent which is composed of 4Urea/ZnCl2, could be recycled at least five times without an obvious decraese in the catalytic activity.
KEYWORD
Deep eutectic solvent, Ullmann reaction, symmetric aryl ether dinitro compound, fine chemical intermediates