Computational mechanistic studies of the carbon–carbon double bond difunctionalization via epoxidation and subsequent aminolysis in vegetable oils

The industrial importance of the C-C double bond difunctionalization in vegetable oils/fatty acid chains motivates computational studies aimed at helping to improve experimental protocols. The C-C double bond epoxidation is studied with hydrogen peroxide, peracetic acid (CH₃CO₃H), and performic acid (HCO₃H) oxidizing agents. The epoxide ring-opening mechanism is calculated in the presence of ZnCl₂, NiCl₂, and FeCl₂ Lewis acidic catalysts. Computations show that H₂O₂ (∆G^‡ = 39 kcal/mol, TS1_HP) is not an effective oxidizing agent compared to CH₃CO₃H (∆G^‡ = 29.8 kcal/mol, TS1_PA) and HCO₃H (∆G^‡ = 26.7 kcal/mol, TS1_PF). The FeCl₂ (∆G^‡ = 14.7 kcal/mol, TS1_FC) coordination to the epoxide oxygen facilitates the ring-opening via lower energy barriers compared to the ZnCl₂ (∆G^‡ = 19.5 kcal/mol, TS1_ZC) and NiCl₂ (∆G^‡ = 29.4 kcal/mol, TS1_NC) coordination. ZnCl₂ was frequently utilized as a catalyst in laboratory-scale procedures. The energetic span model identifies the FeCl₂ (FC) catalytic cycle as the best option for the epoxide ring-opening.