Weerachai Phutdhawong

Microwave-Assisted Isolation of Essential oil of Cinnamomum iners Reinw. ex Bl.: Comparison with Conventional Hydrodistillation

Microwave-assisted hydrodistillation was used to isolate an essential oil from the leaves of Cinnamomum iners Reinw. ex Bl., and the results compared with those obtained by conventional hydrodistillation. The composition of the oil from both methods was found to be similar, and (-)-linalool was found as the main component (30-50%). The antioxidant activity of the essential oil obtained by both methods was evaluated using DPPH, ABTS, FRAP and lipid peroxidation methods, all of which indicated the same but insignificant activity.

Synthesis of (+/-)epipentenomycin I and III

Abstract A synthesis of (±) epipentenomycin I and III is reported from a regioselective epoxidation of racemic 3-hydroxy- and 3-acetoxy-2-methylene-4-cyclopentenone, respectively, with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide.

Electrocoagulation of Quinone Pigments

Some representative quinones, viz. one naphthoquinone (plumbagin) and five anthraquinones (alizarin, purpurin, chrysazin, emodin, and anthrarufin), were subjected to electrocoagulation. It was found that the rate and extent of coagulation of these compounds appears to correlate with the number and relative position of their phenolic substituent groups, and that all of the coagulated quinones could be recovered. Attempts were then made to electrochemically isolate three quinones, namely plumbagin, morindone and erythrolaccin, from natural sources.

Microwave-assisted facile synthesis and crystal structure of cis-9,10,11,15-tetrahydro-9,10[3'4']-furanoanthracene-12,14-dione

Abstract A facile synthesis and crystal structure of cis‐9,10,11,15‐tetrahydro‐9,10[3′,4′]‐furanoanthracene‐12,14‐dione from the reaction of anthracene and maleic anhydride in xylene in a short time and high yield using a modified commercial domestic microwave oven is reported.

Facile microwave-assisted synthesis of 9,10-dihydro-9,10-ethanoanthracene-11-carboxylic acid methyl ester.

A facile, high yielding synthesis of 9,10-dihydro-9,10-ethano- anthracene-11-carboxylic acid methyl ester using a modified commercial domestic microwave oven is reported.

Dechlorophyllation by Electrocoagulation

Electrocoagulation was used for dechlorophyllation of alcoholic extracts from five plants. The results showed that for every plant extract studied, electrocoagulation was more efficient than the classical solvent extraction method in removing plant pigments, while not affecting the important secondary metabolites in those extracts.

Solvent Effects in Electrocoagulation of Selected Plant Pigments and Tannin

Electrocoagulation of a plant extract and certain substances representative of selected classes of plant pigments, viz. chlorophyll, a carotenoid, a phenolic substance and a tannin, was performed in ethanol containing varying amounts of water (15-75%). The results showed that the extent and efficiency of coagulation of these substances tends to vary in a manner directly related to the water content of the solvent, although the tannin and the phenolic substance were less sensitive to the solvent composition and are equally well coagulated in all solvent systems studied. The findings can be applied to the removal of these substances from aqueous alcoholic plant extracts using the electrocoagulation technique.