Sugar fatty acid esters ethoxylated sugars

This category includes polyoxyethylene glycol esters, sorbitan esters, fatty acid esters of glycols and glycerol, including ethoxylated derivatives, and sugar esters. 

One area of rapidly expanding interest is the use of reverse micellar systems of sugar-based surfactants in the extraction of proteins and other sensitive materials. The use of hydrophilic, nonionic, sugar-based surfactants for membrane protein extraction is well known to be effective due to the mild, nondenaturing properties of these surfactants when compared with ionic surfactants or polyoxyethylene derivatives. For the same reasons, protein extraction into reverse micellar systems is now becoming a popular medium for such applications. Alkyl sorbitan esters and ethoxylated sorbitan esters, such as Tween 85 [107] and Span 60 [108], have been used successfully to form reverse micellar systems for protein extraction. Blends of Tween and Span have also been found to be effective for this purpose [109]. More recently, commercially available sucrose fatty acid esters have been shown to form biocompatible reverse micellar systems into which cytochrome c is effectively extracted [110]. 

There are over 150 different producers and some 2 million tonnes of commercial nonionic surfactants manufactured worldwide of which at least 50% are alkoxylated alcohols. Ethoxylated nonylphenol production is falling and accounts for 20% of the market while alkoxylated fatty acids account for some 15%. Fatty acid amides and sugar esters account for another 10% and there are a large number of specialities making up the balance. In general, non-ionic surfactants are easy to make, relatively inexpensive and derived from a variety of feedstocks. 

Polyhydric alcohol esters. Reactions of fatty acids with polyhydric alcohols derived from reduction of sugars such as sorbitol results in a mixtnre of esters of both the sorbitol and its dehydrated ethers sorbide and isosorbide. Ethoxylation of this complex mixtnre of esters involves insertion of ethoxylation and transesterification ethoxylation as described earlier, resulting in a highly complex composition with performance properties that are dependent on the precise conditions for both the esterification and the ethoxylation steps. This is described classically as a product-by-process, which is difficult to reproduce due to the affect of the commercial-scale manufacturing kit on the precise conditions of each step of the reaction. 

FIG- 2 Examples of enzyme-mediated products of ethoxylated sugar fatty acid esters. (From Ref. 61.)... 

Description. Surfactants of this class are better known as sugar esters or sucrose esters. The sucrose esters are obtained by transesterification of sucrose with fatty acid methyl esters or triglycerides, leaving methanol or glycerol as by-products, respectively- Mono- and diesters are the major products. Due to the steric effects,-primary hydroxyl groups are almost exclusively subject to esterification. Both types of esters exhibit the general properties of common nonionics (i.e., ethoxylated alcohols). 

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