Determination and prediction of the average polymerization degree of alkyl polyglucosides

Synthetic alkyl polyglucosides (APG) result from the Fischer reaction of glucose with a fatty alcohol. Monoalkylated glucose further reacts with free glucose under the same conditions to yield APG. Determination of the average polymerization degree (PD) is a problem that has no simple and practical solution. The proposed method relies on gas chromatography measurements. The PD calculation uses the Flory polymerization model and requires the experimental evaluation of the molar fractions of monoglucosides and unreacted fatty alcohol. The number of truly reactive centers in glucose is a key parameter, whose value is determined from a thorough analysis of literature data. The results show that glucose behaves as a bifonctional molecule. Kinetic simulations support the employed methodology.