Acid catalyzed alkylation of phenols with cyclohexene: Comparison between homogeneous and heterogeneous catalysis, influence of cyclohexyl phenyl ether equilibrium and of the substituent on reaction rate and selectivity
作者:L. Ronchin、A. Vavasori、L. Toniolo
DOI:10.1016/j.molcata.2011.12.007
日期:2012.3
CH3SO3H ortho/para is variable from 3 to 5, suggesting an involvement of the cyclohexyl phenyl ether rearrangement. This is proved also by a direct relationship between the ortho/para ratio and the concentration of the cyclohexyl phenyl ether when CH3SO3H is used as a catalyst. The formation of cyclohexyl aryl ethers is reversible; on the contrary, ring alkylation appears irreversible. The reactivity of the
研究了在均相和均相酸催化剂存在下,在358 K下几种酚对环己烯液相烷基化反应的反应性。作为非均相和均相体系的实例,Amberlyst 15和CH 3 SO 3 H的比较表明,前者具有较高的活性,并且两个系统之间的选择性行为不同,无论如何,在两个系统中都会发生O-烷基化和环烷基化。观察到异构和均相体系之间环烷基化选择性的显着差异:Amberlyst 15的邻位/对位比恒定,接近2,而在存在CH 3 SO 3 H邻位/对是3至5之间的变量,表明参与了环己基苯基醚的重排。当使用CH 3 SO 3 H作为催化剂时,邻/对比率与环己基苯基醚浓度之间的直接关系也证明了这一点。环己基芳基醚的形成是可逆的;相反,环烷基化是不可逆的。二甲基苯酚的反应性显示出取代基的空间位阻对环己基阳离子的亲电子进攻的强烈影响,而甲基丙烯酸的感应作用对此影响很小。