학술논문

Tetramethylguanidine covalently bonded onto silica gel as catalyst for the addition of nitromethane to cyclopentenone
Document Type
article
Source
Journal of the Brazilian Chemical Society. October 2006 17(5)
Subject
silica
tetramethylguanidine
Michael addition
nitroalkane
Language
English
ISSN
0103-5053
Abstract
A catalyst based on silica chemically modified with tetramethylguanidine (TMG) was synthesized by the co-condensation of tetraethylorthosilicate (TEOS) with a new silylant agent derived from the reaction between the TMG molecule and (3-chloropropyl)trimethoxysilane. A neutral n-dodecylamine template was used to organize the polymerization of the inorganic-organic catalyst. Thermogravimetry showed that the number of active pendant groups in the catalyst was 1.35 mmol g-1, with a surface area of 811 ± 75 m² g-1. Infrared spectroscopy and 13C and 29Si nuclear magnetic resonance data are in agreement with the proposed structure. This material has been used to catalyse the addition of nitromethane to cyclopentenone. The catalytic efficiency was followed and the nitromethylcyclopentanone conversion presented a yield of 98% at 3 h of reaction. The catalyst was recovered and reused 14 times, maintaining about 98% of its catalytic efficiency.