二丁基氧化锡催化碳酸二甲酯与苯酚酯交换反应机理研究

研究了二丁基氧化锡催化碳酸二甲酯与苯酚酯交换合成碳酸二苯酯的反应机理, 发现原料苯酚和产物DPC都能与二丁基氧化锡生成同一种中间体, 并测定了其晶体结构. 该晶体属于单斜晶系, P2₁/n空间群; 晶胞参数: a＝1.3336(2) nm, b＝1.7208(2) nm, c＝1.3759(3) nm, β＝101.00(2)°; V＝3.0993(9) nm³; D_c＝1.432 g/cm³; Z＝4; F(000)＝1352; μ＝1.635 mm^－1. 分析结果显示该中间体是一种新型的二聚四烃基二锡氧烷化合物Bu₂Sn(OPh)OSnBu₂O(Ph)]₂ (I), 该化合物具有中心对称的层状结构. MS和XPS结果证实I在酯交换反应条件下能稳定存在. 基于实验结果, 本文提出了一个合理的酯交换反应机理.

Mechanism Study of Di-n-butyltin Oxide Catalyzed Transesterification of Dimethyl Carbonate with Phenol

The transesterification mechanism of dimethyl carbonate with phenol to diphenyl carbonate (DPC) over di-n-butyltin oxide was studied. It has been found that both phenol and DPC could react with di-n-butyltin oxide to form an intermediate. Its crystal structure was determined by X-ray single crystal diffraction analysis. The crystal belongs to monoclinic system with space group P2₁/n. Its unit cell parameters are as follows: a＝1.3336(2) nm, b＝1.7208(2) nm, c＝1.3759(3) nm, β＝101.00(2)°, V＝3.0993(9) nm³, D_c＝1.432 g/cm³, Z＝4, F(000)＝1352, μ＝1.635 mm^－1. The identification results show that the intermediate is a novel dimeric tetraorganodistannoxane Bu₂Sn(OPh)OSnBu₂O(Ph)]₂ (I), which has a layer structure with centric symmetry. The MS and XPS results demonstrate that I exists steadily in the reaction condition. A reasonable transesterification mechanism based on the experimental consequence was then offered in this paper.