Ultrasound-Assisted Regioselective Nitration of Phenols Using Dilute Nitric Acid in a Biphasic Medium

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• 作者：Nitin S. Nandurkar ; Malhari D. Bhor ; Shriniwas D. Samant ; Bhalchandra M. Bhanage
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2007
• 出版时间：December 5, 2007
• 年：2007
• 卷：46
• 期：25
• 页码：8590 - 8596
• 全文大小：140K
• 年卷期：v.46,no.25(December 5, 2007)
• ISSN：1520-5045

文摘

A simple and convenient methodology for the regioselective nitration of phenols using dilute nitric acid asa nitrating agent under sonication is described. The protocol eliminates the use of any additive and requireslower concentration of nitric acid (9 wt %). The effect of various reaction parameters such as agitation speed,solvent, phase hold-up ratio, substrate concentration, nitric acid concentration, and temperature on the reactionsystem has been studied. The present methodology shows a considerable enhancement in the reaction ratealong with improved para-selectivity compared with the reactions performed under silent conditions. Thekinetic analysis of nitration of phenol both with and without sonication has been investigated by studyingreaction parameters such as substrate and nitric acid concentration. The increased rate of reaction and selectivityare explained on the basis of ultrasonically generated cavitational effects. The work presented hereby clearlyindicates the methodology to be followed for investigating the optimum extent of intensification achievedusing ultrasound as compared to conventional methods. It will be useful for the design engineers to investigatea particular application in question.