Y. Isaev et Jj. Fripiat, A Lewis acid site-activated reaction in zeolites: Thiophene acylation by butyryl chloride, J CATALYSIS, 182(1), 1999, pp. 257-263
The acylation of thiophene by butyryl chloride has been studied in the liqu
id phase in the presence of 12 catalysts: HZSM-5, H-mordenite, and HY (ultr
astable Y) with various framework Si/Al ratios, various numbers of Bronsted
and Lewis sites, and various amounts of nonframework aluminum. The numbers
of Bronsted and Lewis acid sites were obtained by FT-LR using chemisorbed
ammonia, as described elsewhere. There is a correlation between the initial
rates of reaction and the number of Lewis acid sites, whereas there is no
correlation between the initial rates and the number of Bronsted sites. The
correlation with the number of Lewis sites may be considered significant,
since it expands on more than one order of magnitude. Poisoning of the cata
lyst probably results from the oligomerization on butyryl chloride. No carb
oxylic acid has been detected in the course of the reaction. Na attempt has
been made to determine the nature of the poisoning reaction. (C) 1999 Acad
emic Press.