Solvent-Free Acetalization of Glycerol with n-Octanal using Combined Bronsted Acid-Surfactant Catalyst

Glycerol, derived from biodiesel production, is a renewable feedstock for the production of value-added chemicals. Herein, we report an investigation of the acetalization of glycerol with n-octanal by homogeneous acid catalysis in the absence of a solvent, using p-dodecylbenzenesulfonic acid, p-toluenesulfonic acid, and sulfuric acid, respectively, as catalysts. p-Dodecylbenzenesulfonic acid, a surfactant-type Bronsted acid, proved to be an excellent catalyst capable of efficiently promoting the reaction under solvent-free conditions, and the yields of glycerol acetals reached 99% under the optimal conditions. The distribution of five-and six-membered cyclic acetal regioisomers varied depending on the reaction time and temperature. Moreover, the amphiphilic properties of the products, with different ratios of five-to six-membered cyclic acetals, have been evaluated by surface tension measurements.