单层分散(L)-脯氨酸修饰的Pd/Al2O3催化剂上3,3,5-三甲基环己酮的动力学拆分

Kinetic Resolution of 3,3,5-Trimethylcyclohexaone over Pd/Al2O3 Catalyst Modified by Monolayer (L)-Proline

摘要:

由异佛尔酮不对称加氢产物得到的手性(R-或S-)3,3,5-三甲基环己酮是非常重要的精细化工中间体。该文探究了(L) -脯氨酸修饰Pd/Al2O3催化剂上异佛尔酮的不对称加氢和3,3,5-三甲基环己酮外消旋体的催化加氢动力学拆分。研究发现，异佛尔酮和 (L)-脯氨酸的缩合物会显著抑制异佛尔酮的不对称加氢反应。(L)-脯氨酸在Pd/Al2O3加氢催化剂表面容易发生自发单层分散，有效提高3,3,5-三甲基环己酮外消旋体加氢拆分产物的ee值。在 (L)-脯氨酸单层分散的Pd/Al2O3催化剂上，反应温度为40 ℃、压力为1 MPa、反应时间为10 h时，3,3,5-三甲基环己酮外消旋体加氢拆分产物的ee值达到100 %。

Abstract:

The Product of isophorone(IP) asymmetric hydrogenation, i.e., chiral (R- or S-) 3,3,5-trimethylcyclohexaone (TMCH), is foremost significance fine chemicals intermediates. In the paper， that the asymmetric hydrogenation of isophorone and the catalytic hydrogenation kinetic resolution of TMCH catalyzed by Pd/Al2O3 catalyst in the presence of (L)-proline was investigated. It was shown that the condensation product formed from the pretreatment of the reaction mixture of isophorone with (L)-proline indeed inhibited the asymmetric hydrogenation of isophorone. The spontaneous monolayer dispersion of (L)-proline appeared very easily on the surface of Pd/Al2O3 catalysts, and this phenomenon could effectively increase TMCH enantiomeric excess (ee) from the hydrogenation of TMCH. The ee % of TMCH hydrogenation product was as high as 100 % from the Pd/Al2O3 catalyst modified by the monolayer dispersion of (L)-proline at 40 ℃, and under hydrogen pressure 1 MPa for 10 hrs.