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Experimentally conducted reactions between CO 2 and various substrates ( i.e. , ethylenediamine (EDA), ethanolamine (ETA), ethylene glycol (EG), mercaptoethanol (ME), and ethylene dithiol (EDT)) are considered in a computational study. The reactions were previously conducted under harsh conditions utilizing toxic metal catalysts. We computationally utilize Brønsted acidic ionic liquid (IL) [Et 2 NH 2 ]HSO 4 as a catalyst aiming to investigate and propose ‘greener’ pathways for future experimental studies. Computations show that EDA is the best to fixate CO 2 among the tested substrates: the nucleophilic EDA attack on CO 2 is calculated to have a very small energy barrier to overcome (TS1EDA, Δ G ‡ = 1.4 kcal mol −1 ) and form I1EDA (carbamic acid adduct). The formed intermediate is converted to cyclic urea (PEDA, imidazolidin-2-one) via ring closure and dehydration of the concerted transition state (TS2EDA, Δ G ‡ = 32.8 kcal mol −1 ). Solvation model analysis demonstrates that nonpolar solvents (hexane, THF) are better for fixing CO 2 with EDA. Attaching electron-donating and -withdrawing groups to EDA does not reduce the energy barriers. Modifying the IL via changing the anion part (HSO 4 − ) central S atom with 6 A and 5 A group elements (Se, P, and As) shows that a Se-based IL can be utilized for the same purpose. Molecular dynamics (MD) simulations reveal that the IL ion pairs can hold substrates and CO 2 molecules via noncovalent interactions to ease nucleophilic attack on CO 2 . 

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 FeCl₂Lewis 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. ZnCl₂was 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.