DFT Study of (1R,2R,4R)-Limonene-1,2-Diol Synthesized by Hydrolysis of cis and trans Limonene Oxide

In this study, we investigate the reaction between water and the cis and trans limonene oxide mixture in the presence of ethyl carbamate ((R)-N-(α-methyl-benzyl)ethyl-carbamate), producing (1 R, 2 R, 4 R)-limonene-1,2-diol and trans limonene oxide. This study is carried out using the quantum mechanical density functional theory (DFT) method B3LYP-D3/6-31+G (d,p) to theoretically explain that 1,2-limonene diol is the hydrolysis product derived from cis limonene oxide, with trans limonene oxide not reacting (regioselectivity). For this reason, we exploit Fukui`s frontier molecular orbital theory (FMO), local softness and local hardness ratios, transition states of the obtained products, the Fukui indices, and the thermodynamic quantities (enthalpy, entropy, free energy calculations). The theoretical results effectively elucidate the observed regioselectivity and corroborate the experimental findings.