柠檬酸对钨酸及磷钨酸的催化活性的改进

Phosphotungstic Acid or Tungstic Acid-Catalyzed Oxidation of Cyclohexanone to Adipic Acid in the Presence of Citric Acid

以磷钨酸/钨酸-柠檬酸为催化体系,在无有机溶剂和相转移剂的情况下,催化30%过氧化氢氧化环己酮合成己二酸。当磷钨酸∶柠檬酸∶环己酮∶过氧化氢=1∶20∶400∶200(0物质的量比,磷钨酸用量为0.25mmol)时,使用柠檬酸来调节钨酸催化活性,反应8h时,己二酸分离产率达81.2%、产品熔点为150￣153℃;以钨酸为催化剂,当钨酸∶柠檬酸∶环己酮∶过氧化氢=1∶2∶40∶200(物质的量比,钨酸用量为2.5mmol)时,反应8h,己二酸分离产率只有82.5%、产品熔点为150￣153℃。反应时间在2￣8h内,随反应时间的延长,己二酸分离产率增大,而8h后略有下降。

Without organic solvent and phase-transfer reagent, the catalytic oxidation of cyclohexanone to adipic acid with aqueous 30% hydrogen peroxide can be achieved in the presence of phosphotungstic acid or tungstic acid-citric acid. When the molar ratio of phosphotungstic acid ： citric acid ： cyclohexanone ： hydrogen peroxide is 1：20：400：2000 （phosphotungstic acid, 0.25 mmol）, the isolated yield of adipic acid is up to 81.2% for 8 hs. If the tungstic acid is used as catalyst when the molar ratio of tungstic acid ： citric acid ： cyclohexanone ： hydrogen peroxide is 1：2：40：200 （phosphotungstic acid, 2.5 mmol）, the isolated yield of adipic acid is 82.5% and the purity of product is high. During the reaction time of 2-8 hs, the yield of adipic acid increased with reaction time prolonged. After 8 hours, the yield of adipic acid decreased with time increased little by little.