Partially saponified triglyceride ethoxylates

Abstract

Various triglycerides (coconut oil, palm kernel oil, tallow) were ethoxylated with a proprietary catalyst (calcium/aluminum alkoxide complex partially neutralized in an alcohol ethoxylate base) to obtain triglyceride ethoxylates. Triglyceride ethoxylates were then partially saponified with sodium hydroxide to form mixtures of mono-, di-, and triglyceride ethoxylates, fatty acid soap, and glycerol ethoxylate. These mixtures were characterized in terms of physical properties, surface activity, and mildness. Partially saponified triglyceride ethoxylates were found to be unexpectedly mild and capable of imparting mildness to other surfactants.Paper no. S1157 in JSD 3, 213-220 (April 2000).Ethoxylation is the most common method for adding a nonionic hydrophile to an organic hydrophobe. Prior to 1989, substrates suitable for ethoxylation were thought to require a labile hydrogen, most commonly a hydroxyl hydrogen, in order for ethoxylation to occur. In the late 1980s, the concept of ethoxylating esters was introduced by Hoechst and Henkel (1,2). Hoechst demonstrated that ethoxylation of esters was feasible using catalysts based on alkali and alkali earth metals (e.g., sodium hydroxide, sodium methoxide, barium hydroxide, etc.), while Henkel showed that calcined hydrotalcite (aluminum/magnesium oxide complexes) had potential as well. Relatively poor reactivities and conversions, however, prevented these catalysts from being utilized commercially. In the early 1990s, Vista Chemical Company (now CON-DEA Vista Company, Houston, TX) developed a commercially viable process for ethoxylating esters (3). Their process utilized a more complex alkoxylation catalyst (activated calcium and aluminum alkoxides) that efficiently and effectively inserted ethylene oxide between the carbonyl carbon and the ester oxygen. Immediately thereafter, Lion Corporation (Tokyo, Japan) demonstrated that a magnesium/aluminum oxide-based catalyst also worked well (4). Since then, the development and use of ester alkoxylates have become an active area of research (5-22). This paper deals with an extension of ester alkoxylation technology. Previous studies have demonstrated that the CONDEA Vista catalyst (a calcium and aluminum alkoxide complex partially neutralized in an alcohol ethoxylate base) can be used to ethoxylate esters, including triglycerides (5,13-16). It is also known that mono-and diglyceride ethoxylates are mild surfactants (23). The object of this research was first to prepare triglyceride ethoxylates and then partially saponify them to obtain a mild surfactant blend of mono-, di-, and triglyceride ethoxylates and fatty acid soap. It was thought that such a blend would make a lower-cost surfactant for mild personal-wash bars, pastes, and gels. This paper details our initial studies on partially saponified triglyceride ethoxylates (PSTE). It describes the preparation and cursory assessment of PSTE made from three different triglycerides. The impacts of surfactant structure (carbon chain length, unsaturation, degree of ethoxylation, degre...

Synthesis and performance of surfactants based on epoxidized methyl oleate and glycerol

“…Both the heptaglyceride ester and hexaglyceride ester material show significant surface tension reduction and both reduce the surface tension to ~34 mN m -1 -with no obvious critical micelle concentration observed below 0.01%. This is similar behavior to commercial surfactants of the formula C 11-12 H 23-25 (OC 2 H 4 ) 7-14 Cl or C 12 H 25 (OC 2 H 4 ) [9][10][11][12]. This data shows that the hydrophilic polyglyceride moiety behaves as a reasonably large hydrophilic head group.…”

Surfactants Based on Natural Fatty Acids

“…Based on experiences of narrow-range ethoxylation catalysis, new catalysts have been developed that enable a direct ethoxylation of short-chain alkyl esters of fatty acids. Cox and Weerasooriya extensively described this alkoxylation technology and the properties of ethoxylated methyl esters of various fatty acids in a series of papers [60][61][62]. The difference in distribution of ethyleneoxide units between a fatty acid methyl ester ethoxylated with a conventional hydroxide catalyst or a more active Ca/Al catalyst was shown to be drastic (see Figure 1.3, from Reference [61]).…”

“…Thratnig [63] later described how a similar effect in the distribution of ethylene oxide (EO)units can be obtained with ethoxylation of fatty acids rather than the methyl ester. Furthermore, the technique has also been shown to be applicable to ethoxylation of several types of fatty acid esters like triglycerides or branched alkyl esters [62,64], as well as for propoxylation of fatty acid esters [65]. Alejski et al [66,67] and Bialowas and Szymanowski [68] have contributed to the understanding of how the oxyethylation reaction of fatty acid methyl esters proceeds in stepwise incorporation of the ethylene oxide units.…”

“…Various tests have showed that methyl ester ethoxylates have an improved mildness to human skin compared to ordinary alcohol ethoxylates [62,64]. From the standpoint of environmental properties, fatty acid methyl ester ethoxylates are readily biodegradable and an order of magnitude less toxic than alcohol ethoxylates [70,75].…”

Chemical reactions of fatty acids with special reference to the carboxyl group

“…Even without any separation this mixture has good surfactant properties [27]. Interesting products result from triacylglycerols including natural mixtures such as the lauric oils (coconut and palmkernel) and tallow.…”