固体碱碱性位对碳酸二甲酯与环己酮合成反应的影响

Effect of Basic Site Type of Solid Base Catalyst on Reaction of Dimethyl Carbonate with Cyclohexanone

考察了固体碱不同的碱性位对碳酸二甲酯(DMC)与环己酮反应的影响,并对在不同碱性位上的反应机理进行了推测。实验结果表明,由表面羟基引起的弱碱性位有利于环己酮缩合反应(主产物为2-环己烯基环己酮)的进行,Lewis-Br(o|")nsted酸碱离子对有利于DMC甲基化反应(主产物为2-甲基庚二酸二甲酯,还含有2-甲基环己酮、2,6-二甲基环己酮和环己烯基甲醚)的进行,而由固体碱表面配位不饱和的O^(2-)所形成的强碱性位有利于DMC甲氧基羰基化反应(主产物为庚二酸二甲酯和2-羰基甲氧基环己酮)的进行;同时由实验结果还发现,焙烧温度不同的MgO催化剂中各碱性位的碱量不同,且各碱性位的碱量与对应产物的收率之间具有较好的线性关系。

Effect of basic site types of the solid base catalysts on the reaction of dimethyl carbonate （DMC） with cyclohexanone was researched. The results showed that the weak basic sites caused by hydroxyl groups on the catalysts, namely Al2O3, ZrO2 and NH2/SBA-15, were favorable for cyclohexanone condensation and 2-（1-cyclohexenyl） cyclohexanone was obtained as the main product. Over the solid base catalysts with Lewis （Mn＋ ）-Br6nsted （An-） ion pairs （namely KI and KzCO3 ） , the methylation product 2-methyl dimethyl pimelate with the byproducts （2-methyl cyclohexanone, 2,6- dimethyl cyclohexanone and 2-methoxy cyclohexene） was obtained through the reaction. The strong basic sites on ZnO, La2O3 and CaO formed by unsaturated O2 ions could promote the methoxycarbonylation which produced dimethyl pimelate and 2-carbomethoxycyclohexanone. For MgO-based catalysts calcined at different temperatures good linear relationships were observed between the product yields and the basicities of corresponding basic sites. Furthermore, the reaction mechanisms over the different basic sites were proposed.