THE USE OF GRIGNARD REAGENT IN PHEROMONE SYNTHESIS FOR PALM WEEVIL (<i>Rhynchorus, Sp</i>)

Abstract

In an integrated controlling system of palm weevil, using of synthetic feromoid is strickly needed. The research is aimed to synthesize pheromone which secreted by the weevil, e.g. 4-methyl-5-nonanol (R. ferrugineus) and 3-methyl-4-octanol (R. schach) through Grignard reagent which formed in situ. The synthesis was proceded by retrosynthesis to determine the precursor, valeraldehyde. The precursor was reacted with Grignard reagent of sec-amyl magnesium bromide (R. ferrugenieus) and sec-butyl magnesium bromide (R. shach) which made in situ. Characterization of the synthetic molecular pheromone was performed by Gas Chromatography-mass spectroscopy and Fourier Transformed Infra Red. The bioassay of the molecule was carried out by olfactometer. The result showed that the conversion of the reactions were 51.28% (4-methyl-5-nonanol) and 85.90% (3-methyl-4-octanol). The character of physico-chemical and bioactivity of the synthetic pheromone are identic with natural pheromones. Keywords: palm weevil, pheromone, grignard reagent