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Covalently linked ethylmercaptophenyl sulfonic acid and ethylmercaptobenzyl sulfonic acid silica materials—Synthesis and catalytic activity |
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| Authors: | Amanmammet Bugrayev Nazli Al-Haq Rukeme A Okopie Asma Qazi Michael Suggate Alice C Sullivan John RH Wilson |
| Institution: | aDepartment of Chemistry, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK bPhosphonicS Ltd., 114 Milton Park, Oxford, OX14 4SA, UK |
| Abstract: | New covalently linked sulfonic acid modified silicas have been formed and characterised and their catalytic Brönsted activity evaluated. Thus phenylmercaptoethyltrimethoxysilane, (MeO)3SiCH2CH2SC6H5 and benzylmercaptoethyltrimethoxysilane, (MeO)3SiCH2CH2SCH2C6H5, were used to prepare the corresponding T-functional silica derivatives silica  CH2CH2SC6H4-4-SO3H and silica CH2CH2SCH2C6H4-4-SO3H by grafting on commercial silica, followed by sulfonation of the aryl group. Solid-state NMR, DTA and surface area characteristics of the materials are reported. The mercaptophenylsulfonic acid materials are thermally robust highly efficient solid catalysts for a range of transformations including, esterification, etherification and carbonyl group protection. An apparent pore size effect on rate of conversion was observed. The mercaptobenzylsulfonic acid materials were comparatively unstable. |
| Keywords: | Sulfonic acid Silica Solid acid Catalyst Ethylmercaptophenylsulfonic acid Esterification Etherification Carbonyl group protection Condensation |
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