Zhang Yan-kun
2011
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Journal
Journal of Natural Science of Heilongjiang University
Abstract
2-Fluorotoluene has been nitrated regioselectively for synthesizing 2-fluoro-5-nitrotoluene under mild conditions using different zeolite catalysts.Under acetic anhydride,the effects of the different zeolite catalysts on 2-fluorotoluene nitration were obtained with fume nitric acid as nitrating agent.The results showed that H-beta zeolite had higher conversion and selectivity in all isomers due to higher acidity.As the 25% amount of H-beta catalyst for 2-Fluorotoluene,1.20∶1.05∶1.0 molar ratio of acetic anhydride∶fume nitric acid∶2-fluorotoluene were used,2-fluorotoluene at-5 ℃ and 2 h aditione time showed 99.5% convertion with 85% selectivity for 2-fluoro-5-nitrotoluene.By simple seperation,higher pure 2-fluoro-5-nitrotoluene was obtained in the yield of 75%.A recycling study of catalyst H-beta for nitration of 2-fluorotoluene showed no significant loss in conversion as well as selectivity even after 5 recycles indicating the high stability of the catalyst.Compared to the conventional process,2-fluorotoluene nitration over H-beta acid catalysts is a highly regioselective,environmentally friendly process with a simpler work up procedure.