ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Zinc catalyst recycling in the preparation of (all-rac)-α-tocopherol from trimethylhydroquinone and isophytol

Juraj Gömöry, Milan Králik, and Alexander Kaszonyi

Zentiva, a.s., Nitrianska 100, 920 27 Hlohovec, Slovakia
Department of Organic Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia

E-mail: alexander.kaszonyi@stuba.sk

Abstract: Recycling of ZnCl₂ as a catalyst in the cyclocondensation of trimethylhydroquinone and isophytol to all-rac-α-tocopherol was studied. ZnCl₂ was recycled at over 98 % efficiency in required purity by repeated extraction of the reaction streams with water, followed by switching of solvent to butyl acetate and then back to water. Recycled ZnCl₂ had no negative effect on the yield of all-rac-α-tocopherol (maintaining over 90 %) at nearly total conversion of isophytol and only a 3 % molar excess of trimethylhydroquinone.

Keywords: all-rac-α-tocopherol – trimethylhydroquinone – isophytol – ZnCl2 – catalyst recycling – mechanism

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-011-0027-0

Chemical Papers 65 (4) 427–436 (2011)