Green production of limonene diepoxide for potential biomedical applications

Abstract The green catalytic system (Al2O3/H2O2/ethyl acetate) used in the oxidation of (R)-limonene has many advantages since the reagents have low cost, it is toxicity-free (no heavy metals and no toxic solvents are utilized), and water is the only by-product. The synthesized epoxide may have applications in several industrial segments like adhesives, polymers, resins, and others that require a clean process, especially as a precursor for medical biomaterial applications. An experimental design 23 with 17 assays (6 axial points and central point triplicate) has been carried out for the optimization of the conversion and selectivity towards limonene diepoxide. The assessed variables included the quantities of alumina, limonene, and hydrogen peroxide (70% aq). The analysis of variance (ANOVA) confirmed the validity of the mathematical model obtained with a 90% confidence interval in the studied range. The conversion and selectivity towards limonene diepoxide was >99 %, with a reaction time of 10 h, showing the high efficiency of this catalytic system. FTIR, Raman, GC/MS, 1H, 13C, and HSQC NMR techniques confirmed the structure of the synthesized and purified limonene diepoxide.