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Environmentally friendly, heterogeneous acid and base catalysis for the methylation of catechol: Chances for the control of chemo-selectivity

Paper ID Volume ID Publish Year Pages File Format Full-Text
48846 46522 2007 9 PDF Available
Title
Environmentally friendly, heterogeneous acid and base catalysis for the methylation of catechol: Chances for the control of chemo-selectivity
Abstract

The properties of catalysts with (i) Brønsted-type acidity (H-mordenite and Al/P mixed oxide), (ii) Lewis-type acidity (Al trifluoride) or (iii) basic characteristics (Mg/Fe mixed oxide) were investigated in the gas-phase methylation of catechol. When methanol was used as the methylating agent, H-mordenite and AlF3 gave high selectivities to guaiacol (the product of O-methylation) under mild reaction conditions, that is at very low catechol conversions. An increase in temperature led to the transformation of guaiacol to phenol and cresols, and to considerable catalyst deactivation. The basic catalyst Mg/Fe/O also favored an extensive degradation of guaiacol to phenol. On the mildly acidic catalyst Al/P mixed oxide a stable catalytic performance and a high selectivity to guaiacol at 40% catechol conversion were obtained. When methylformate, a more reactive methylating agent, was used with AlF3 and Mg/Fe mixed oxide as catalysts, higher catechol conversions and slower deactivation rates could be achieved under mild reaction conditions, with a low extent of guaiacol degradation. However, methylformate rapidly decomposed when temperatures above 350 °C were used. Finally, tests were made by reacting catechol and diethoxymethane with acid catalysts, with the aim of synthesizing methylenedioxybenzene. The latter product was obtained with high selectivity, but with very low yield, due to both catalyst deactivation and decomposition of diethoxymethane.

Keywords
Catechol methylation; Guaiacol; Methylenedioxybenzene; Heterogeneous acid catalysis; Heterogeneous basic catalysis
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Environmentally friendly, heterogeneous acid and base catalysis for the methylation of catechol: Chances for the control of chemo-selectivity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 70, Issues 1–4, 31 January 2007, Pages 597–605
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
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