2011年12月
Gas-Phase Alkylation of Pyridine and Phenol with Alcohols Over Halide Clusters of Group 5-7 Transition Metals as Solid Acid Catalysts
JOURNAL OF CLUSTER SCIENCE
- ,
- ,
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- 巻
- 22
- 号
- 4
- 開始ページ
- 647
- 終了ページ
- 660
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1007/s10876-011-0411-5
- 出版者・発行元
- SPRINGER/PLENUM PUBLISHERS
Pyridine is allowed to react with methanol under a hydrogen stream in the presence of (H3O)(2)[(W6Cl8)Cl-6]center dot 6H(2)O supported on silica gel. When the temperature is raised above 200 A degrees C, the catalytic activity of the cluster appears. Methylation of pyridine proceeds yielding 2-methylpyridine in 61% selectivity at 400 A degrees C. The corresponding hexanuclear chloride clusters of niobium, molybdenum, and tantalum also catalyze the reaction. Ethanol affords the corresponding 2-ethylpyridine. When phenol is allowed to react with methanol in the presence of (H3O)(2)[(Mo6Cl8)Cl-6]center dot 6H(2)O supported on silica gel in the same manner, selective O-methylation proceeds yielding anisole in 57% selectivity at 150-200 A degrees C. Above 250 A degrees C, C-methylation predominates and provides o-cresol with 67% selectivity at 300 A degrees C. The corresponding clusters of niobium, tantalum, and tungsten also catalyze the reaction. Ethanol and 1-propanol afford the corresponding 2-alkylphenols. Alkyl cations produced over weak Bronsted acid sites (H (0) a parts per thousand +1.3) developed on the clusters are assumed as intermediates for both reactions.
- リンク情報
- ID情報
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- DOI : 10.1007/s10876-011-0411-5
- ISSN : 1040-7278
- Web of Science ID : WOS:000297250000008