| Summary: | A new method to control pests using sex pheromones are considered to
have high efficiency and effectiveness as well as environmentally friendly.
Commercially, economic value of this method is determined by the effectiveness
of the synthesis of the sex pheromones.
Candidate of sex pheromones have been obtained through the synthesis of
(10E,12E,14E)-10,12,14-octadecatrienal and (10E,12E,14E)-10,12,14-octadecatrienyl acetate using α-linolenic acid (ALA) as the starting material.
Isolation and purification of the ALA were conducted by using the urea
inclusion complex, followed by column chromatography using silica gel as
stationary phase and a mixture of n-hexane-diethyl ether-acetic acid as eluent.
Modification of ALA into sex pheromone molecules was carried out in two
stages. First, an unconjugated of methyl ester of ALA was isomerized into a
conjugated triene. Second, the functional group of carboxylate of conjugated
triene was then converted into alcohol by reduction using LiAlH4/THF. Half
portion of this alcohol then was oxidized into aldehyde by using PCC/CH2Cl2 and
the rest was acetylated by using acetic anhydride in the presense of pyridine.
The results showed that the purity of ALA was approximately 99.5 % and
the conversion was 1.18 % from the basil seed. The modification of methyl ester
of ALA into sex pheromone candidates showed yield and purity of product in
every step of synthesis were 78.06 % and 82.39 % for isomerization, 81.24 % and
91.88 % for reduction, 62.22 % and 100 % for oxidation, 73.33 % and 100 % for
acetylation, respectively. By EAG and olfactometer test and also supported by
Autodock 4.2 analysis, the sex pheromone candidates were known to be able to
interact with receptors on the antenna. Sex pheromone (10E,12E,14E)-10,12,14-octadecatrienal has more power to interact with receptors and to attract the male
imago insects Antheraea jana (Lepidoptera : Saturniidae) than the (10E, 12E,
14E)-10,12,14-octadecatrienyl acetate. The sex pheromone candidates were stable
against oxidation by UV radiation, but the rate of evaporation of (10E, 12E, 14E)-10,12,14-octadecatrienal was higher than that of (10E, 12E, 14E)-10,12,14-octadecatrienyl acetate
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