DISPROPORTIONATION OF OLIGODIMETHYLSILOXANOLS IN THE PRESENCE OF A PROTIC ACID IN DIOXANE

被引：11

作者：

CYPRYK, M ^{[1
]}

RUBINSZTAJN, S ^{[1
]}

CHOJNOWSKI, J ^{[1
]}

机构：

[1] POLISH ACAD SCI,CTR MOLEC & MACROMOLEC STUDIES,SIENKIEWICZA 112,PL-90363 LODZ,POLAND

来源：

JOURNAL OF ORGANOMETALLIC CHEMISTRY | 1993年 / 446卷 / 1-2期

关键词：

D O I：

10.1016/0022-328X(93)80039-E

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The kinetics of the acid-catalyzed disproportionation of alpha,omega-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 with the condensation process only in the presence of water. It is of first order with respect to the substrate, catalyst, and water. The results are interpreted in terms of a stepwise mechanism involving rate determining cleavage of the terminal siloxane unit by water, followed by condensation of transiently-formed dimethylsilanediol with the substrate. The unzipping mechanism involving the dimethylsilanediol intermediate is suggested to operate in hydrolytic cleavage of polydimethylsiloxane exposed to water or water vapour.

引用

页码：91 / 97

页数：7

共 26 条

[11] EFFECT OF STANNOUS 2-ETHYLHEXANOATE ON THE NETWORK FORMATION AND CHAIN EXTENSION REACTIONS OF ALPHA,OMEGA-DIHYDROXY TERMINATED POLY(DIMETHYLSILOXANE) [J].

CLARSON, SJ ;

WANG, ZM ;

MARK, JE .

EUROPEAN POLYMER JOURNAL, 1990, 26 (06) :621-622

[12]

GERARD E, 1990, POLYM COMMUN, V31, P77

[13] COMPETITION BETWEEN POLYCONDENSATION OF ALPHA,OMEGA-DIHYDROXY POLYDIMETHYLSILOXANE AND ITS CONDENSATION WITH ALKOXY SILANE - A KINETIC APPROACH [J].

HE, XW ;

WIDMAIER, JM ;

HERZ, JE ;

MEYER, GC .

EUROPEAN POLYMER JOURNAL, 1988, 24 (12) :1145-1148

[14] CHAIN EXTENSION OF ALPHA, OMEGA-DIHYDROXY POLYDIMETHYLSILOXANE - SIMULATION OF THE LINEAR POLYCONDENSATION REACTION [J].

HE, XW ;

HERZ, JE .

EUROPEAN POLYMER JOURNAL, 1991, 27 (4-5) :449-453

[15]

Kendrick T.C., 1989, CHEM ORGANIC SILICON, P1289

[16] KINETICS OF POLYCONDENSATION OF DIMETHYLSILANEDIOL [J].

LASOCKI, Z ;

CHRZCZONOWICZ, S .

JOURNAL OF POLYMER SCIENCE, 1962, 59 (168) :259-&

[17]

NEMOTO N, 1990, POLYM COMMUN, V31, P65

[18] H-0 AND RELATED INDICATOR ACIDITY FUNCTIONS [J].

PAUL, MA ;

LONG, FA .

CHEMICAL REVIEWS, 1957, 57 (01) :1-45

[19]

PERRIN DD, 1966, PURIFICATION LABORAT

[20] ANOMERIC EFFECTS INVOLVING SILICON CENTERS - SILANOLS [J].

REED, AE ;

SCHADE, C ;

SCHLEYER, PV ;

KAMATH, PV ;

CHANDRASEKHAR, J .

JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1988, (01) :67-69

← 1 2 3 →