Methyl malvalate

Methods of determining cyclopropene acids continue to be developed (Fisher and Schuller, 1981 Vickery, 1980). Methyl malvalate and methyl sterculate have been separated by spinning band distillation (Pawlowski a/., 1981). 

Methyl sterculate and methyl malvalate were prepared from trans-esterified Sterculia foetida oil by a combination of urea clathration and reverse phase HPLC [8]. The methyl esters were added to cultures of Ustilago maydis (DC) Cda. and Fusarium oxysporum Schlecht in small quantities of methanol. Control cultures received methanol alone. 

The synthesis of labelled and unlabelled methyl malvalate (20) and methyl sterculate (21) has attracted attention. In the best known route an acetylenic... 

A popular method is to analyse the total fatty acid methyl esters by CjC after reaction with silver nitrate/anhydrous methanol for 2 h at 30°C (Bianchini, Ralaimanarivo and Gaydou, 1981 Eisele et aL, 1974 Gaydou, Bianchini and Ralaimanarivo, 1983 Ralaimanarivo, Gaydou and Bianchini, 1982). Most fatty esters remain unchanged, but cyclopropene esters are converted to later-eluting methoxy ether derivatives and small amounts of ketone derivatives. Two partially resolved peaks, those from sterculic acid eluting later, are observed for each type of derivative from each cyclopropene acid and can be quantified and used to determine the proportion of sterculic and malvalic acids in the untreated oil. Verification of the identities of the acids can be determined from GC-MS of the methyl esters of the products (Ahmad et al., 1979 Eisele et ai, 1974) but prominent allylic ions in the mass spectra of the DMOX derivatives of the methoxy ethers are more readily interpretable to reveal the positions of the cyclopropene rings (Spitzer, 1995). 

Figure 5.14. Analysis of kapok seed oil methyl esters after reaction with silver nitrate in anhydrous methanol, on a glass WCOT column coated with Carbowax 20M, maintained at 190°C with hydrogen as carrier gas [99]. Abbreviations 18 CA, dihydromalvalic acid 19 CA, dihydrosterculic acid 18 CM, methoxy derivatives of malvalic acid 19 CM, methoxy derivatives of sterculic acid 18 CC, enone derivatives of malvalic acid 19 CC, enone derivatives of sterculic acid. (Reproduced by kind permission of the authors and of Analytical Chemistry, and redrawn from the original paper).

Cyclopropane and Cyclopropene Adds.— The undesirable physiological properties of cyclopropene acids such as malvalic acid (20 R = H) and sterculic acid (21 R = H) and their presence, albeit in small amount, in cottonseed oil has aroused interest in these compounds. The content of cyclopropene acids is reduced by heating with palladium catalysts, though not with nickel or platinum catalysts. Palladium treatment cleaves the cyclopropene ring and produces methyl- and methylene-substituted acids. Hydrogenolysis of cyclopropane acids is reported to give methyl-substituted fatty acids which can be identified by their g.l.c. behaviour on capillary columns. The chemical reactions of cyclopropene acids (malvalic and sterculic) shown in Scheme 5 have been reported. ... 

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