Fatty acid methylesters, preparation

Quaternized esteramines are usually derived from fat or fatty acid that reacts with an alcoholamine to give an intermediate esteramine. The esteramines are then quaternized. A typical reaction scheme for the preparation of a diester quaternary is shown in equation 9 (210), where R is a fatty alkyl group. Reaction occurs at 75—115°C in the presence of sodium methoxide catalyst. Free fatty acids (230) and glycerides (231) can be used in place of the fatty acid methylester. 

The preparation of of-sulfo fatty acid methylesters is a two-stage process taking place at two different rates. At first, an addition compound of 1 mol of methylester with 2 mol of SO3 is formed. Then, in the following reaction, 1 mol, of SO3 is split off, to form the final ester. This sulfur trioxide will slowly react further with another methyl ester. Using the fatty acid methylester and SO3 in a molar ratio results in an undesirably long reaction time. Therefore a surplus of sulfur trioxide is used. The reaction mixture then consists of the main product, the a-sulfo fatty acid methylester and also its anhydride with SO3. By neutralization with a solution of caustic soda, on the one hand the desired sodium salt of the required ester is formed, while on the other hand the anhydride is transformed to the corresponding disodium salt and sodium methyl sulfonate. In order to achieve a complete transformation of the fatty acid methylester, a certain amount of the undesired disodium salt has to be expected. 

Novel catalysts (141) such as Ru-Sn and Re-Sn can be used to hydrogenate fatty acids or methylesters to fatty alcohols. Using these catalysts, the hydrogenation can be carried out at the same temperature (250°C) but lower pressure (50 bars), and the unsaturations present remain unaffected. The presence of tin has been found to be instrumental in the preservation of the unsaturation during hydrogenation. Ru-Sn supported on alumina was found to be most selective when they were prepared via the sol-gel method. 

To prepare 9-decenoic and 13-tetradecenoic acid methylester, we used the transition-metal catalysed olefin metathesis [6, 7], actually applied in petro- and polymerchemistry in seven industrial processes [8], As stated first by C. Boelhouwer et al. [9, 10], this reaction is valid not only for olefins, but for unsaturated fatty acid esters, too. 

Preparation of the Time Index Standard Mixture (FAMEs) Methyl caprylate, methyl pelargo-nate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl eicosanoate, methyl docosanoate, lignoceric acid methyl ester, methyl hexaco-sanoate, methyl octacosanoate, and triaconta-noic acid methylester. Alternatively, alkanes or fatty acids may also be used. The final concentration of each compound in the mixture should be between 0.4 and 0.8 mg/mL of chloroform. 

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