Production of Methyl Ester Sulfonates

In the case of methyl ester sulfonation to produce MES, the colour of the final sulfonated product is usually very dark, and the process... 

Foster, N.C. Manufacture of Methyl Ester Sulfonates and Other Derivatives, in SODEOPEC Soaps, Detergents, Oleochemicals, and Personal Care Products, L. Spitz, Editor, AOCS Press, Urbana, IL, 2004. 

Schmid et al. studied in detail the sulfonation reaction of fatty acid methyl esters with sulfur trioxide [37]. They measured the time dependency of the products formed during ester sulfonation. These measurements together with a mass balance confirmed the existence of an intermediate with two S03 groups in the molecule. To decide the way in which the intermediate is formed the measured time dependency of the products was compared with the complex kinetics of different mechanisms. Only the following two-step mechanism allowed a calculation of the measured data with a variation of the velocity constants in the kinetic differential equations. 

For a further separation of the sulfonated surfactants the latter are heated for 4 h with 2 N HC1. The methyl ester sulfonates are split into methanol and a-sulfo fatty acids, which form disodium salts after neutralization with NaOH. The product mixture from acid hydrolysis can be separated by extraction with petroleum ether. For example, the fatty alcohols formed from fatty alcohol sulfo-... 

In addition to their transformation into linear alcohols by hydrogenation, methyl esters obtained in the transesterification of fats and oils can also be used as raw materials for sulfonation, yielding a family of derivatives known as methyl ester sulfonates (MES). These products are only significant in some southeast Asian markets, Japan and to a much lesser extent in other markets such as the US. 

Biodiesel is a mixture of methyl esters of fatty acids and is produced from vegetable oils by transesterification with methanol (Fig. 10.1). For every three moles of methyl esters one mole of glycerol is produced as a by-product, which is roughly 10 wt.% of the total product. Transesterification is usually catalyzed with base catalysts but there are also processes with acid catalysts. The base catalysts are the hydroxides and alkoxides of alkaline and alkaline earth metals. The acid catalysts are hydrochloride, sulfuric or sulfonic acid. Some metal-based catalysts can also be exploited, such as titanium alcoholates or oxides of tin, magnesium and zinc. All these catalyst acts as homogeneous catalysts and need to be removed from the product [16, 17]. The advantages of biodiesel as fuel are transportability, heat content (80% of diesel fuel), ready availability and renewability. The... 

The classic use of methyl esters of vegetable oils has been as intermediates in the production of fatty alcohols from vegetable oils (Peters, 1996 Ahmad et al., 2007) or esterquats and methyl ester sulfonates (Ahmad et al., 2007). Fatty alcohols and the other products are used in surfactants and cleaning supplies. Intermediates were produced from polyisobutylene (PIB) maleic anhydride and rapeseed oil methyl esters which were used to acylate polyethylene polyamines (Hancsok et al., 2006). These additives showed corrosion-inhibiting and lubricity-improving effects. 

The process significantly improves Cie ig methyl ester sulfonates analytical purity and color without raising safety or environmental concerns. It also allows for the purification of products derived from lower grade methyl esters, resolves odor issues, and does not require use of substantial amounts of solvent such as methanol. 

Ester sulfonates. Pyrolysis of a-sulfo fatty acid esters at 400 C in the presence of P20g results in desulfonation, so that the gas chromatogram shows the fatty acid methyl esters. Free fatty acids are also seen as decomposition products of the esters, as well as those originally present as sulfonated impurities (33). 

Thus, the dianion derived from a-amino acid substitutes the /1-chloride to give the ester of 2-(phenylsulfonyl)ethenyl amino acid and subsequent desulfonylation provides N-(benzoyl)vinylalanine methyl ester (62) (equation 61). The conjugate addition of enolates to methyl styryl sulfone (63) and subsequent intramolecular addition to the carbonyl moiety provide a synthetically valuable method for the construction of bicyclic and tricyclic skeletons52. Desulfonylation of the cyclization product 64 with sodium in ethanol-THF gives the diene 65 in good yield (equation 62). 

However, it could be expected that the share of the latter group will rise to the same extent as the rising importance of environmental digestibility. It is very possible that in the future the C16/C18 ester sulfonates will partly replace the alkylbenzenesulfonates produced from petrochemical raw material [6,7]. N. R. Smith [8] expects the a-sulfo methyl esters to be an alternative to ethylene-based surfactants. An increase in the production of surfactants based on ethylene is problematic, because in industrial countries ethylene production is occurring at 95% of capacity and more. 

The analytical methods for a-sulfo fatty acid esters reported in the literature deal with the determination of the surfactants in different matrices like detergents or product mixtures from the fabrication. The methyl esters of a-sulfo fatty acids can be separated from a mixture of different surfactants together with sulfonated surfactants by adsorption on an anionic exchanger resin such as Dowex 1X2 or 1X8. Desorption from the exchanger resin is successful with sodium hydroxide (2%) in a 1 1 mixture of isopropanol and water [105]. 

The chemistry of fatty acid methyl ester (FAME) sulfonation is complicated and not yet fully elucidated, but it may be summarized as depicted in the following reaction scheme. The initial reaction between FAME and S03, although fast, is far from instantaneous. Two intermediate products are formed ... 

Transesterification of fat triglycerides is the predominant method for manufacture of mixed fatty acid methyl esters, and direct esterification of fatty acids (FA) is practiced if very selective cuts of product, in general as an intermediate detergent range alcohol, are desired. Methyl cocoate is a mobile, oily liquid above 25 °C with a yellow tint and a characteristic fatty pungent odor. FAME sulfonation to FAMES is technically possible but been rarely applied up to now (1990) (Table 13). 

Pedersen and coworkers investigated the El mass spectra of several 2-hydroxyphenyl alkyl sulfones (39) and sulfoxides (Section II.B). The methyl derivative seemed to fragment only via sulfinate ester formation giving the primary product ions m/z 157 and 109 (equation 14). Obviously hydrogen bonding between the ortho hydroxyl and the sulfone sulfur makes the loss of CH3SO2 difficult in contrast to the situation in methyl phenyl sulfone. The sulfinate ester rearrangement is not important when R>Et in 39. 

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