PREPARATION AND UNUSUAL DECOMPOSITION OF SILICA-SUPPORTED TETRAPHENYLPHOSPHONIUM BROMIDE

被引：16

作者：

CLARK, JH ^{[1
]}

TAVENER, SJ ^{[1
]}

BARLOW, SJ ^{[1
]}

机构：

[1] CONTRACT CATALYSTS LTD,PRESCOT L34 9HY,MERSEYSIDE,ENGLAND

来源：

JOURNAL OF MATERIALS CHEMISTRY | 1995年 / 5卷 / 06期

关键词：

D O I：

10.1039/jm9950500827

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Amorphous silica gel grafted with a directly bound tetraarylphosphonium salt has been prepared and has been characterised by C-13 CP MAS NMR, DRIFTS and elemental microanalysis. Thermal analysis of this material reveals a strikingly different decomposition pattern to its unsupported analogue: free tetraphenylphosphonium bromide obeys pseudo-zeroth-order kinetics, with E(a) = 204 +/- 16 kJ mol(-1), Delta H double dagger = 206 +/- 16 kJ mol(-1) and Delta S double dagger = -87 +/- 25 J K-1 mol(-1), whereas the supported reagent shows a first-order decay, with E(a) = 77 +/- 22 kJ mol(-1), Delta H double dagger = 72 +/- 22 kJ mol(-1) and Delta S double dagger = -197 +/- 34 J K-1 mol(-1). Evolved-gas mass spectrometry shows that the supported tetraarylphosphonium salt shows a greater propensity to eliminate triphenylphosphine than would be expected from purely statistical considerations. This material shows C-13 CP MAS NMR and decomposition characteristics more typical of the solution state than the solid phase.

引用

页码：827 / 830

页数：4

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