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Regioselectivity in the preparation of 2-hydroxy-4-methoxy benzaldehyde from resorcinol

Pattekhan, H. H. and Divakar, S. (2001) Regioselectivity in the preparation of 2-hydroxy-4-methoxy benzaldehyde from resorcinol. Journal of Molecular Catalysis A: Chemical, 160. pp. 185-191.

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Abstract

Three reactions, namely, Reimer–Tiemann reaction of resorcinol, one pot Reimer–Tiemann reaction of resorcinol and its methylation and finally Reimer–Tiemann reaction of resorcinol monomethyl ether were studied. Better selectivities were observed in the first two reactions when b-cyclodextrin (b-CD) and its derivatives were employed. The formation of 2,4-dihydroxybenzaldehyde and 2-hydroxy-4-methoxybenzaldehyde from the first two reactions showed better conversion than the control reaction. In the process, 70.0% 2,4-dihydroxybenzaldehyde was detected in the presence of 1 equivalent of b-CD and 48.2% 2-hydroxy-4-methoxybenzaldehyde was detected in the presence of 0.2 equivalent of HPb-CD. However,Reimer–Tiemann reaction of resorcinol monomethyl ether resulted in only amarginal increase (43.9%) of 2-hydroxy-4-methoxybenzaldehyde (I) in the presence of 0.2 equivalent of b-CD as compared to the control (35.2%). The observed results were explained in terms of specific orientation of resorcinol inside the b-CD cavity which facilitates the attack of dichlorocbenzene from the narrower end on the electron rich ortho position to the –OH of resorcinol leading to the formation of 2,4-dihydroxybenzaldehyde or 2-hydroxy-4-methoxybenzaldehyde(I).

Item Type: Article
Uncontrolled Keywords: b-Cyclodextrin; Regioselectivity; Resorcinol; 2-Hydroxy-4-methoxybenzaldehyde
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 12 Aromatic Chemistry
Divisions: Fermentation Technology and Bioengineering
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 22 Jun 2007 03:47
Last Modified: 05 Oct 2018 06:17
URI: http://ir.cftri.com/id/eprint/1221

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