Oxidation–Isomerization of an Olefin to Allylic Alcohol Using Titania–Silica and a Base Co-catalyst
作者:C Beck、T Mallat、A Baiker
DOI:10.1006/jcat.2000.2975
日期:2000.10
synthesis of α,β-unsaturated alcohols from olefins is illustrated on the example of 4-hydroxy-isophorone using titania–silica aerogels and basic co-catalysts. Kinetic analysis of the complex reaction network revealed that titania–silica is efficient in the epoxidation of β-isophorone (3,5,5-trimethyl-3-cyclohexen-1-one) with TBHP at 353 K, whereas the acid/base-catalyzed in situ rearrangement to 4-hydroxy-isophorone
使用二氧化钛-二氧化硅气凝胶和碱性助催化剂,以4-羟基-异佛尔酮为例,说明了由烯烃分两步一锅合成α,β-不饱和醇的潜力。复杂反应网络的动力学分析表明,二氧化钛可有效地在353 K下用TBHP对β-异佛尔酮(3,5,5-三甲基-3-环己烯-1-酮)进行环氧化,而酸/碱-原位催化重排成4-羟基-异佛尔酮(4-羟基-3,5,5-三甲基-环己-2-烯酮)的过程很慢。固体碱(例如CaO,Na 2 CO 3和KF / CaF 2)的加入显着加速了重排,并在3小时内在83%的转化率下实现了高达77.5%的选择性。较强的碱(K 2 CO 3,BaO,Mg–Al–O- t Bu,胍碱)可抑制环氧化反应,这是由于孤立的Ti位点失活所致,并且有利于将β-异佛尔酮异构化为α-异佛尔酮。共价键合的表面苯基对二氧化钛-二氧化硅的疏水化作用极大地抑制了β-异佛尔酮的低聚和异构化,但并未提高对4-羟基-异佛尔酮的选择性。