Stereoselective Hydrogenation of Thymol over Rh/alumina in the Presence of beta-cyclodextrin and its Derivatives

Ravi, Palaniswamy and Divakar, S. (2001) Stereoselective Hydrogenation of Thymol over Rh/alumina in the Presence of beta-cyclodextrin and its Derivatives. Journal of Inclusion Phenomena and Macrocyclic Chemistry, 39. pp. 27-33.

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Abstract

Stereoselective hydrogenation of thymol over Rh/alumina in the presence of various equivalents of -cyclodextrin (-CD) and its derivatives in the solid state was studied. Hydrogenation of thymol in the absence of -CD gave 76.8% epimeric alcohols with a menthol/neomenthol (M/N) ratio of 5.6 and an alcohol/ketone ratio of 4.5, whereas the presence of 0.1 equivalent (to thymol) of -CD gave rise to 94.6% of epimeric alcohols with a M/N ratio of 6.3 and an alcohol/ketone ratio of 45.4. The effect of -cyclodextrin and its derivatives on the modification of the yield and the proportion of epimeric alcohols formed were found to be the salient features of this investigation. Inclusion complexation of thymol by -CD studied by UV-Visible spectroscopy indicated a 2 : 1 stoichiometry of thymol: -CD complex with a binding constant value of 480 40 M−2.

Item Type:	Article
Uncontrolled Keywords:	-cyclodextrin, epimeric menthols, product distribution, reduction, stereoselectivity, thymol
Subjects:	600 Technology > 09 Industrial oils, fats, waxes, gases > 03 Essential oils
Divisions:	Fermentation Technology and Bioengineering
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	04 Jul 2007 05:49
Last Modified:	27 May 2011 05:14
URI:	http://ir.cftri.res.in/id/eprint/1280

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