Alkyl poly glucosides

The industrial pro cess is b ased on the Fischer synthesis and commercial development work started some 25 years ago. Once a route using coconut-based alcohols had been established, full-scale plants became viable and alcohol blends are now used to control hydrophobicity of the molecules produced. Thus, products based on C8 alcohols are water soluble and those based on C18 are virtually insoluble. The critical micelle concentration (CMC) values of pure alkyl glucosides and CulCu alkyl polyglucoside (APG) are comparable with those of a typical non-ionic surfactant and decrease with increasing alkyl chain length. 

The hydrophilic part of the alkyl polyglucoside is derived from a carbohydrate source, and raw material costs increase in the order starch/glucose syrup/glucose monohydrate/water free glucose while plant equipment requirements and hence cost decrease in the same order. 

Direct synthesis is simple and covered by patents with all major producers (Henkel, Huls, Akzo, BASF) having patents in the field from 1988 onwards [49-51]. Here, the carbohydrate is suspended in the alcohol as very fine particles and, in some cases, crystal water is removed to minimise side reactions. 

Highly degraded glucose syrup (dextrose equivalent 96) can be used in a modified direct process where a second solvent or emulsifier is used to provide stable fine droplet dispersions [ 52, 53 ]. The fine droplets/particles are important as the reaction is heterogeneous and good contact between the reactants must be maximised at as low temperature as possible to avoid formation of polymers and charring of the sugars. 

The trans acetylation process is commercially less attractive with higher plant costs and alcohol recycling but several major producers have patents on this process [54-57]. 

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APG = Alkyl poly glucoside, SCI = Sodium cocoyl isethionate,... 

SLES =Sodium lauryl ether sulfate, SDS = Sodium dodecyl sulfate, APG = Alkyl poly glucoside, CAPB = Coco amido propyl betaine,... 

APG = Alkyl poly glucoside, SCI = Sodium cocoyl isethionate, CAPB=Coco amido propyl betaine, SLES = Sodium lauryl ether sulfate, MAP=Mono alkyl phosphate, SDS=Sodium dodecyl sulfate... 

We usually associate antiirritation with amphoteric surfactants however, because other types of surfactants, such as glucamide or alkyl poly glucoside (APG), perform this function and these are structurally not amphoterics or cationics, I suggest that we call this type of surfactant a pseudo-amphoteric surfactant. Furthermore, I would propose that we promote the concept of classifying surfactants on the basis of their function rather than their structure. More on this subject will be presented in the following sections. 

Table 5.11 Examples of commercial poly alkyl glucosides ...

Micelles and cyclodextrins are the most common reagents used for this technique. Micellar electrokinetic capillary chromatography (MECC or MEKC) is generally used for the separation of small molecules [6], Sodium dodecyl sulfate at concentrations from 20 to 150 mM in conjunction with 20 mM borate buffer (pH 9.3) or phosphate buffer (pH 7.0) represent the most common operating conditions. The mechanism of separation is related to reversed-phase liquid chromatography, at least for neutral solutes. Organic solvents such as 5-20% methanol or acetonitrile are useful to modify selectivity when there is too much retention in the system. Alternative surfactants such as bile salts (sodium cholate), cationic surfactants (cetyltrimethy-lammonium bromide), nonionic surfactants (poly-oxyethylene-23-lauryl ether), and alkyl glucosides can be used as well. 

In the presence of chloramine T, the non-reducing end oxime 42 underwent 1,3-polar cycloadditions with terminal alkynes to give 3-glycosyI-5-substituted isoxazoles 43 in moderate yields. Reductive alkylation of pyrroline derivative 44 with methyl 2,3,4-tri-0-benzyl-6-deoxy-6-iodo-a-D-glucopyranoside gave, after ester reduction, osmylation and acetylation-deacetylation, the novel poly-hydroxypyrrolidine 45, containing a methyl glucoside moiety. ... 

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