ABSTRACT:Lipases were screened for their ability to transesterify triglycerides with short-chain alcohols to alkyl esters. The lipase from Mucor miehei was most efficient for converting triglycerides to their alkyl esters with primary alcohols, whereas the lipase from Candida antarctica was most efficient for transesterffying triglycerides with secondary alcohols to give branched a|kyl esters. Conditions were established for converting tallow to short-chain alkyl esters at more than 90% conversion. These same conditions also proved effective for transesterifying vegetable oils and high fatty acid-containing feedstocks to their respective alkyl ester derivatives.

The low-temperature properties of mono-alkyl esters derived from tallow and recycled greases were determined for neat esters and 20% ester blends in No. 2 low-sulfur diesel fuel. Properties studied included cloud point, pour point, cold filter plugging point, low-temperature flow test, crystallization onset temperature, and kinematic viscosity. Compositional properties of the alkyl esters determined included water, residual free fatty acids, and free glycerol content. In general, the secondary alkyl esters of tallow showed significantly improved cold-temperature properties over the normal tallow alkyl ester derivatives. The low-temperature flow test did not show a 1:1 correlation with cloud point as previously observed with methyl soyate and methyl tallowate. For the homologous series methyl to n-butyl tallowate, ethyl tallowate had the best broad-spectrum low-temperature properties, both neat and when blended in diesel fuel. For the greases studied, both the normal and branched alkyl ester derivatives showed improved properties over corresponding tallow esters, especially with neat esters. JAOCS 74, 951-955 (1997).

The effects of exogenous phaseic acid (PA) on germination and protein accumulation of cultured immature barley embryos were examined. Chemically synthesized PA was racemic, 87% pure and stable over the course of the experiment. Germination was observable in >90% of the untreated embryos after 3 days of incubation, whereas embryos treated with 10μm abscisic acid (ABA) or PA showed no evidence of germination. Buffer extracts from embryos treated with ABA or PA had similar protein profiles when examined by single and two-dimensional electrophoresis. The profiles differed significantly from those of embryos incubated in the absence of the two compounds. Concentrations of α-amylase inhibitor and barley-germ agglutinin (BGA) increased upon treatment of immature embryos with ABA or PA. This was due to de novo synthesis as there was increased incorporation of radioactivity from 35S-labelled amino acids into the proteins in treated embryos. Endogenous ABA content in PA-treated embryos was not significantly different from that in untreated embryos. An analogue of ABA, 2′, 3′-dihydroabscisic acid, which cannot be metabolized to phaseic acid, inhibited germination and caused increased synthesis of α-amylase inhibitor and germ agglutinin. ABA and PA may both be active in promoting responses associated with ABA in barley embryos, but the embryos are more sensitive to ABA.

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An efficient total synthesis of the marine sesquiterpenoid isoacanthodoral 1 has been achieved using an i n te r m o I ecu I a r Die I s-Al de r approach .Isoacanthodoral 1 is a structurally unique sesquiterpenoid isolated from the dorid nudibranch Acanthodoris nanaimoensis, along with its congeners nanaimoal2 and acanthodoral3, as a mixture.' This mixture, which was found to possess antibacterial, antifungal and antifeedant activities,' gave separable 2,4-dinitrophenylhydrazone (2,4-DNP) derivatives.' The structure of the 2,4-DNP derived from isoacanthodoral was determined by a single-crystal X-ray diffraction