合成1-环己氧基-4-氧-2,2,6,6-四甲基哌啶酮的新方法

A New Method of Synthesis of 1-Cyclohexyloxy-2,2,6,6-Tetramethylpipirid-4-One

环己氧基-4-氧-2,2,6,6-四甲基哌啶酮是合成具有优异阻燃性能的受阻胺类阻燃剂的关键中间体。研究在前人工作的基础上,探索新的工艺合成路线。先按已有的方法合成2,2,6,6-四甲基哌啶氮氧自由基,再以环己烷和2,2,6,6-四甲基哌啶氮氧自由基为原料,叔丁基过氧化氢和溴化铜为氧化-还原引发体系,四丁基溴化铵为相转移催化剂合成了1-环己氧基-4-氧-2,2,6,6-四甲基哌啶酮。用电子自旋共振谱仪(ESR)和电喷雾质谱仪(ESI-MS)对产物进行了相应表征。实验研究了反应工艺、金属催化剂和相转移催化剂对产率的影响,并对反应机理进行了探讨。研究结果表明,该合成方法的产率可达到82%。

Sterically hindered amine shows great advantages among the various kinds of flame retardants. 1-cyclohexyloxy-2,2,6,6- tetramethylpipirid-4-one is the key intermediate for synthesizing this kind of flame retardant. In this paper, we proposed a novel method for synthesizing 1-cyclohexyloxy-2,2,6,6- tetramethylpipirid-4-one with a higher yield. First, sterically hindered nitroxyl radical was synthesized by using the existing method. Then, cyclohexane and the obtained nitroxyl radical were used to synthesize 1-cyclohexyloxy-2,2,6,6- tetramethylpipirid-4-one. Tert-butyl hydroperoxide and copper bromide were employed as the redox initiator system and tetrabutyl ammonium bromide as the phase transfer catalyst. The target product was characterized by electron-spin resonance（ESR） and electro spray ionization-mass spectroscopy（ESI-MS）. The effects of metal catalyst and phase transfer catalyst on product yield were investigated. The catalytic mechanism of the reaction was also studied. The product yield using this method can reach 82%.