Alkyl polyglycoside

General chemical structure of an alkyl polyglucoside, a common form of alkyl polyglycoside

Alkyl polyglycosides (APGs) are a class of non-ionic surfactants widely used in a variety of household and industrial applications. They are derived from sugars and fatty alcohols; therefore, they are generally favored for their manufacture from renewable resources.^[1] The raw materials for industrial manufacture are typically starch and fat, and the final products are typically complex mixtures of compounds with different sugars comprising the hydrophilic end and alkyl groups of variable length comprising the hydrophobic end.^[2] When derived from glucose, they are known as alkyl polyglucosides.

Preparation

Alkyl glycosides are produced by direct synthesis from higher monofunctional alcohols and powdered glycoses, in particular anhydrous glucose and/or glucose monohydrate, in the presence of acid catalysts at elevated temperatures. The reaction chamber is maintained under reduced pressure and the glycose is introduced after a delay into the reaction chamber containing an excess of the acid catalyst and alcoholic reagents heated to the reaction temperature. Water released in the reaction mixture is removed from the reaction chamber in the gaseous phase. A partial flow is withdrawn from the liquid reaction mixture and conveyed to a preliminary mixing zone, into which the powdered reactant is introduced simultaneously, where it is processed with the liquid partial flow to a paste and conveyed through a downstream intensive mixer to the reaction chamber. This pressure in the preliminary mixing zone is equalized directly and simultaneously with the reduced pressure in the reaction chamber by the intensive mixer and with atmospheric pressure by the conveying device for the powdered glycose. The consistency of the paste formed in the preliminary mixing zone is chosen so that this paste can be used as a sealant for pressure equalization and hence as a so-called "living seal".

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