ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In order to appreciate the excellent catalytic effect of iodine on the alcoholyses of alkoxysilanes more precisely, the rates of the reaction, Et3SiOBun + BusOH ⇌ Et3SiOBus + BunOH, were determined at various iodine concentrations.Both forward and reverse reactions are first order with respect to butoxysilane and to butanol, and pseudo first-order rate constants were measured at 40°, 30°, and 20°C on reaction mixtures containing both butanols in excess by means of gas-liquid chromatography. The observed rate constants as a function of iodine concentration gave linear relationships, and from these data the catalytic coefficients of iodine were evaluated: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_{2_{{\rm I}_2 } } = 7.4 \times 10^7 \exp (- 55.7 \times 10^3 /RT)} & {({\rm forward\, reaction})} \\ \end{array} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_{{ -2} _{{\rm I} _2 } } = 9.7 \times 10^7 \exp (- 54.3 \times 10^3 /RT)} & {({\rm reverse\, reaction})} \\ \end{array} $$\end{document} The enthalpies and the entropies of activation were estimated to be 53.2 kJ mol-1, -103 J K-1 mol-1 (forward, 30°C) and 51.8 kJ mol-1, minus;100 J K-1 mol-1 (reverse, 30°C).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550190905
