Green production of limonene diepoxide for potential biomedical applications

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, H-1, C-13, and HSQC NMR techniques confirmed the structure of the synthesized and purified limonene diepoxide.

Automated summary

The green catalytic system used in the oxidation of (R)-limonene offers advantages such as low cost, toxicity-free reagents, and water as the only by-product. Through experimental design and analysis, the system was optimized for high efficiency in producing limonene diepoxide. Various analytical techniques confirmed the synthesized and purified product's structure.