新しい固体酸触媒 : SO<SUB>3</SUB>H基をもつポリオルガノシロキサン

概要

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Solid-acid catalysts having sulfo groups were prepared by two different ways. One way is by surface modification of silica. The other is by the sulfonation of polyorgano-siloxanes. Polysiloxanes containing phenyl, benzyl, 2- (phenyl) ethyl, and 3-mercaptopropyl groups were prepared by co-condensation polymerization of alkoxysilane and alkoxyorganosilane. The ion exchange capacity and the elemental analysis for sulfur and carbon showed that the sulfonated polyorganosiloxanes (SPOS) had much higher acid content (0.8-3.2mmol/g) than the modified silica gel. The thermal stability of SPOS was much higher than Amberlyst 15. Thus, the thermal stability is in a decreasing order; sulfonated polyphenylsiloxane>sulfonated polypropyl-siloxane>Amberlyst 15 under a nitrogen stream, and is in a decreasing order; sulfonated polypropylsiloxane>sulfonated polyphenylsiloxane=Amberlyst 15 under steaming conditions. The catalytic activities for various acid-catalyzed reactions were studied. For vapor phase dehydration of alcohols and the liquid phase esterification, the activities of SPOS were comparable to those of Amberlyst 15. For the vapor-phase nitration of benzene with nitrogen dioxide, the activities of SPOS were much higher than that of the ion-exchange resin.
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