Methyl elaidate

Polar-substituted alkenes where the functionality is not attached to a strained ring are considerably more discriminating in their compatibility with metathesis catalysts and as a rule require relatively high catalyst charges. In the aliphatic series, unsaturated esters have received the most attention. Boelhouwer reported in 1972 the metathesis of the ester methyl oleate and its trans isomer, methyl elaidate, with a homogeneous catalyst based on a 1/1.4 molar combination of WCl6/(CH3)4Sn (23). At 70°C and an ester/W molar ratio of 33, near-thermodynamic equilibrium was attained, and 49 and 52% of the respective esters were converted to equal amounts of 9-octadecene and the dimethyl ester of 9-octadecene-1,18-dioic acid. 

The ability of titanium-grafted silicas in catalyzing the epoxidation with TBHP of fatty compounds was first tested on two pure Qg monounsaturated FAMEs methyl oleate (ds-9-octadecenoate Scheme 12.1) and methyl elaidate (trans-9-octadecenoate) [49]. In both cases, selectivity to 9,10-epoxystearate was very high (>95%) and the reaction was fully stereospecific, confirming that epoxidation with titanium catalysts and TBHP proceeds via a non-radical mechanism with retention of configuration at the C=C bond. Ti-MCM-41 was more active than Ti-SiC>2 (Fig. 12.1). Actually, methyl oleate was almost completely converted after... 

Fig. 12.1 Conversion of fatty acid methyl esters (FAMEs) methyl oleate ( ) and methyl elaidate ( ) vs. reaction time over Ti-MCM-41 (a) and overTi-Si02 (b). (Adapted from [49]).

Conclusive evidence for the participation of 7r-allylic intermediates in double bond migration has been obtained from a study of the nickel-catalysed hydrogenation of the isomeric olefinic esters methyl oleate and methyl elaidate using tritium as a tracer [147]. It was also concluded that in this system cis—trans isomerisation occurred by an addition—abstraction mechanism. 

Methyldodecanoic acid, 874, 975-976 (ran>2-Methyl-2-dodecenoic add, 976 Methyl elaidate, 1007 Methyleneatninoacetonitrile, 368, 400, 412... 

Figure 7. Methyl esters of unsaturated fatty acids as resolved on the 25%-cyanopropyl-25%-phenyl methyl siloxane DB-225. Split Injection to a 30m x 0.25mm column coated with a 0.25 m bonded film, hydrogen carrier at 46cm/sec, isothermal at 200 °C. Components 1, 14 1 methyl myristoleate 2, 16 1 trans methyl palmite-laidate 3, 16 1 cis methyl palmitoleate 4, 18 1 trans methyl elaidate 5, 18 1 cis methyl oleate 6, 18 2 trans methyl linolea-laidate 7, 18 2 cis methyl linoleate 8, 18 3 methyl linoleate ...

Octadec-9-enoic acid methyl ester, (E) irans-9-Octadecenoic acid methyl ester Methyl elaidate... 

The efficiency of gas-liquid chromatography with capillary columns is exemplified by its accomplishing the separation of meta- and- para- xylenes, which had proved to be an extremely difficult separation in earlier attempts made with conventional columns. Various mixtures of acids and esters were resolved chromatographically for the first time making use of capillary columns, a noteworthy example being the resolution of a mixture of methyl elaidate and methyl oleate which are cis- and /ram-isomers. 

Infrared analysis for trans-octadecenoic acid is a standard method (Report of the Spectroscopy Committee, 1959). Good quantitative results for the trans-isomers are possible by infrared analyses, and such analyses are done routinely by many laboratories. Kauffman and Lee (1960) found good agreement between the infrared analysis and the gas-liquid partition chromatographic analysis of methyl elaidate in hydrogenated vegetable oil... 

N.m.r. Studies involving Fluorinated Chemical Shift Reagents.— The determination of the cis-trans composition of methyl elaidate-oleate [Eu(fod)3] assignment of diastereotopic protons in amphetamine [Euffodls] " induced shifts of anils [Euffod)]] conSguration of 4-substituted-2-hydroxy-4-butanolides [Eu(fod)3] structure ofthietan 1,1-dioxide derivatives [Eu(fod)3l ... 

The AOCS method Cd 14-61 (AOCS, 1978) is practically identical to the method described under Section 6.2.6. The method prescribes the use of elaidic acid, methyl elaidate or glycerol trielaidate as primary standard. Also secondary standards calibrated against the primary standards may be used. The AOCS method advises use of methyl esters if the trans content lies below 15%. 

Figure 14. Hydroformylation of pure methyl oleate (3.64 mmol), Pinitiaiiy = 20 bar, CO/H2 = 1 1, T=100 °C, Rh=4.10" mmol, Llgand Rh =25 1, A methyl oleate, methyl elaidate, methyl fomylstearate, 0 methyl formylstearate (Isomers)...

Up until now, mostly pure substrates such as methyl oleate and its -isomer, methyl elaidate, have been tested as model substrates for hydroformylation, but in a few cases, linoleates, linolenates, and esters of ricinoleic acid have also been investigated (Figure 6.10). Oleic acid can be derived from new sunflower, linoleic acid from soybean, linolenic acid from linseed, and ricinoleic acid from castor oil. The long-chain mono-unsaturated fatty acid erucic acid (C22) can be extracted from old rapeseed oil. 

A molecular formula (54) appears in Chemical Abstracts as a product proposed to arise from the treatment of methyl oleate or methyl elaidate with sulphur at 140—160 °C. No details are available to the Reporter. 

In practice then, cis- and frans-isomers of mono-unsaturated fatty acids are not easily separated on the more widely used polyester stationary phases, but some excellent resolutions have been recorded with the newer highly polar cyanoalkylpolysiloxane phases such as Siiar lOC, SP-2340 or OV-275 . For example, near base-line separations of methyl oleate and methyl elaidate have been... 

---