Ketal-based surfactants

Reaction between a long-chain ketone and a diol will lead to a surfactant that contains a ketal bond. The synthesis is analogous with those given in Figs. 13 and 14 for the preparation of acetal surfactants [52]. Ketal-based surfactants have also been prepared in good yields from esters of keto acids by either of two routes, as shown in Fig. 15 [53-55]. 

Jaeger et al. have studied the kinetics of hydrolysis of cationic ketal-based surfactants [41], A comparison was made between acid hydrolysis of surfactants in nonaggregated form and in the form of either micelles or vesicles. (Ketal surfactants with one hydrophobic tail formed micelles and those with two hydrophobic tails formed vesicles.) It was found that both types of aggregation caused about two orders of magnitude reduction of the hydrolysis rate. Aggregation is evidently a way to protect these acid-labile cationic species from acid hydrolysis just as aggregation is a way to speed up alkaline hydrolysis of cationic alkali-labile surfactants, such as esterquats. 

Ketal-based surfactants have also been prepared in good yields from esters of ketoacids by either of two routes, as shown in Fig. 18 [42,43]. 

Jaeger, D.A. Mohebalian, J. Rose, P.L. Acid-catalyzed hydrolysis and monolayer properties of ketal-based cleavable surfactants. Langmuir 1990, 6, 547-554. 

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