Kinetic study of the bromine-catalyzed alcoholysis of butoxytriethylsilane: n-Butoxy group–s-butoxy group exchange reaction

✍ Scribed by Katsuko Ito; Takeshi Ibaraki

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 267 KB
• Volume: 22
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550220308

✦ Synopsis

Abstract

In order to compare the catalytic activity of bromine with those of iodine and iodine monohalides, kinetic studies on the reaction, Et~3~SiOBu^n^ + Bu^s^OH ⇌ Et~3~SiOBu^s^ + Bu^n^OH, were undertaken. Pseudo first‐order rate constants were determined at 0°, 10°, 15°, 20°, and 30°C by means of gas chromatography on the reaction mixtures containing both butanols in excess. From the observed rate constants, the catalytic coefficients of bromine were evaluated as follows:

The enthalpies and entropies of activation were estimated to be (42.0 – 42.2) kJ/mol, −(103 – 104) J/K (forward reaction), and (40.4 − 40.7) kJ/mol, − (101 − 102) J/K (reverse reactions). These data suggest that bromine is much more active than iodine and iodine monohalides, and its high activity was interpreted on the basis of the structure of the reaction intermediate.