Entirely solvent-free biocatalytic synthesis of solketal fatty esters from soybean seeds

Solvent-free reactions are the systems of choice in green chemistry. In addition to contributing to lowering the environmental impact of chemical processes, solvent-free systems can reduce production costs, reaction times, and the dimensions of reactors, thereby decreasing investment costs. An improved procedure to prepare 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane (solketal) fatty esters from soybean seeds has been developed. Yields higher than 90% were achieved by combining 15 h of hydrolysis with 6 h of esterification with a stepwise addition of solketal. The synthesis was performed in a solvent-free medium, and the final extraction was accomplished using supercritical CO₂. Hence, we have successfully prepared these esters from soybean beans without using organic solvents. In addition, given the non-toxicity of Rhizopus oryzae and the composition of the remaining solid, it might be used as a raw material for feedstock production.