Efficient epoxidation of (R)-(+)-limonene to limonene dioxide through peracids generated using whole-cell Rhizopus oryzae lipase

[Display omitted] •We developed a biocatalytic system for directly epoxidation of limonene to limonene dioxide.•A relatively high yield of 93 % for limonene dioxide achieved.•Cell wall and membrane lipases in Rhizopus oryzae drive slow percid production.•Optimal conditions include a high H2O2 concentration and trisodium citrate addition. Limonene dioxide (LDO) is essential for manufacturing bio-based polycarbonate and non-isocyanate polyurethanes. Herein, we report a strategy for the chemoenzymatic epoxidation of (R)-(+)-limonene to LDO with high selectivity using Rhizopus oryzae whole cells. The presence of sufficient excess acid in the system is essential, in addition to overcoming the hydrolysis of the intermediate product, 1,2-limonene oxide, to accomplish the double epoxidation of limonene. When using a high concentration of H2O2 and trisodium citrate, the conditions were effectively established, even when Novozym 435 was substituted, which had previously been reported to be ineffective in achieving high-yield double epoxidation of limonene. The transfer of H2O2 and peracids between the cell and solvent slowed production. The total amount of peracids generated remained constant, but their concentrations remained moderate, favoring the double epoxidation of limonene. An LDO yield of 93 % and no intermediate product, limonene oxide, were obtained under optimized conditions within 20 h.