Disproportionation of oligodimethylsiloxanols in the presence of a protic acid in dioxane
作者:M. Cypryk、S. Rubinsztajn、J. Chojnowski
DOI:10.1016/0022-328x(93)80039-e
日期:1993.3
The kinetics of the acid-catalyzed disproportionation of α,ω-dihydroxyoligodimethylsiloxanes HO[SiMe2O]nH, n = 2, 5, and their analogues having one hydroxyl function replaced by methyl Me[SiMe2O]nH, n = 2, 5, were studied in dioxane in the presence of water. The formation of the primary disproportionation products was monitored by gas-liquid chromatography. The reaction in dioxane solution can compete
α,ω-二羟基低聚二甲基硅氧烷HO [SiMe 2 O] n H,n = 2,5及其具有一个羟基官能团的类似物被甲基Me [SiMe 2 O] n H,n取代的酸催化歧化动力学在水的存在下,在二恶烷中研究= 2、5。通过气-液色谱法监测主要歧化产物的形成。二恶烷溶液中的反应只有在水存在下才能与缩合反应竞争。对于底物,催化剂和水,它是一阶的。根据逐步机理来解释结果,该逐步机理包括速率确定末端硅氧烷单元被水裂解,然后使瞬时形成的二甲基硅烷二醇与底物缩合。建议涉及二甲基硅烷二醇中间体的拉开机理在暴露于水或水蒸气的聚二甲基硅氧烷的水解裂解中起作用。