Determination Of I-Triacontanol In Kenyan Beeswax (honeybee, Appis Mellifera L.) And Development Of A New Approach To Its Synthesis

Abstract

The thesis consists of two parts of study. The first part describes a chromatographic analysis of a sample of Kenyan beeswax (honeybee, Armis mellifera L.) and, in particular, its I-triacontanol (1) content. The physico-chemical properties of the wax were first determined using standard analytical procedures. The composition of the saponified wax was ascertained by column chromatography, thin-layer chromatography and infrared spectroscopy. By use of gas chromatography, the content of I-triacontanol in the beeswax was determined and found to constitute 21.4% of the whole wax. The second part of the thesis describes a new approach to the synthesis of I-triacontanol starting

from tetracosanoic acid (33). In a model synthesis study, stearic acid (28) was converted to tetracosanoic acid by addition of a six carbon unit through the silyl enol ether synthon, l-cyclohexenyloxytrimethyl- -silane (76). Stearic acid was converted to -' stearoyl chloride (25) which then underwent specific coupling (C-acylation) with the silyl enol ether 76 via both Lewis acid catalysis (zinc(II) bromide in dichloromethane) and base catalysis (triethylamine in tetrahydrofuran) to give 2-stearoylcyclohexanone (31). Re-arrangement of 31 using alcoholic potassium hydroxide followed by hydrazine reduction and subsequent hydrolysis gave tetracosanoic acid. Both coupling reactions gave comnarable yields of the product and were employed for the synthesis of I-triacontanol. Tetracosanoic acid was thus converted to triacontanoic acid (20). Methylation of 20 followed by reduction with lithium aluminium hydride in tetrahydrofuran afforded I-triacontanol in 24% overall yield.