Preparation of amphiphilic sorbitan monoethers through hydrogenolysis of sorbitan acetals and evaluation as bio-based surfactants
Amphiphilic sorbitan acetals have been prepared from sorbitan by acetalisation using linear aliphatic aldehydes or by transacetalisation starting from the corresponding aldehyde diethylacetals. A series of sorbitan acetals has been obtained with 29–81% isolated yields. It has been shown that these sorbitan acetals exist as a mixture of five-membered and six-membered regioisomers. Hydrogenolysis of the mixtures gave the corresponding sorbitan ethers as a mixture of 3 regioisomers with 55–85% isolated yields. A one-pot two-step procedure was also optimized from sorbitan giving similar results. The amphiphilic properties of sorbitan acetals and ethers were evaluated and both families exhibit interesting surfactant properties.