Vapour phase O-methylation of dihydroxy benzenes with methanol over cesium-loaded silica, a solid base

• Published in: Journal of molecular catalysis. A, Chemical Vol. 181; no. 1; pp. 161 - 171
• Main Authors: Bal, Rajaram, Tope, B.B, Sivasanker, S
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 25.03.2002; Elsevier
• Subjects: Alkali-loaded silica; Basic catalysts; Catalysis; Catalytic reactions; Chemistry; Dihydroxy benzenes; Exact sciences and technology; General and physical chemistry; Methanol; O-methylation; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Alkali-loaded silica; Dihydroxy benzenes; O-methylation; Basic catalysts; Methanol; Heterogeneous catalysis; Benzenic compound; Cesium; Alkali metal; Methylation; Diphenols; Silica; Base; Modified material
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(01)00361-2

Vapour phase O-methylation of the dihydroxy benzenes, catechol, resorcinol and hydroquinone with methanol has been investigated in the temperature range 573–673 K over alkali-loaded fumed silica. Fumed silica (SiO 2) by itself has no O-methylation activity, but on impregnation with alkali metal oxides (Li, Na, K and Cs) becomes active for O-methylation producing mono- and dialkylated products. Activity of the catalysts and selectivity for dialkylates increase with metal loading and basicity of the metal ions (Cs>K>Na>Li). Very high conversion (∼93%), at nearly 100% selectivity for O-methylation was obtained over Cs-loaded fumed silica in the case of resorcinol and hydroquinone.