Over the past few decades, governments have imposed increasingly stringent environmental regulations on the chemical industry with the aim of reducing waste generation and energy requirements. Therefore, the company's top priority has become to maintain high process performance through an eco-compatible approach using non-toxic and biodegradable dimethyl carbonate chemicals, and the chemistry of organic carbonates, which was only marginally developed at the time, seemed very attractive in this prospect force. In fact, dialkyl carbonates (DAC) are safe and effective alternatives to chlorine (halogen) reagents1 because they can replace toxic substances: (1) methyl and acid halides and sulfuric acid in alkylation and carbonylation reactions Dimethyl esters; 2 (2) phosgene in the synthesis of carbamates, carbamates, and isocyanates; 3 (3) dichloromethane and chloroform as solvents. In addition, both chlorine and carbonate moieties are sacrificial groups (i.e., leaving groups) in nucleophilic displacements; however, the latter do not generate salts and hazardous wastes that require disposal, and exhibit low toxicity and high biodegradation properties, making organic carbonates green solvents and reagents
Currently, DACs, especially dimethyl carbonate (DMC), are synthesized by clean processes (Scheme 2, equations (2) and (3)); therefore, these compounds are particularly attractive to chemical companies, as more and more The number of patents registered, as indicated by the industrial applications of phytochemicals (such as the synthesis of herbicides and fungicides, pharmaceuticals, fragrances, varnishes, adhesives and biofuel additives)4. 5 It is worth mentioning that DMC is initially produced by the reaction of phosgene with methanol (as a nucleophile) under basic conditions (Scheme 2, equation (1)), 6 resulting in the dissolution of a large amount of NaCl in water for disposal. In the mid-80s, Enichem7 and UBE8 finally developed a cleaner process involving the catalytic oxidative carbonylation of methanol with oxygen (Scheme 2, Equation (2)), which actually paved the way for the green industrial-scale production of DMC the way. Today, DMC is primarily produced by intercalating CO2 into ethylene oxide to produce ethylene carbonate, which reacts with methanol under alkaline conditions to produce DMC and ethylene glycol (Scheme 2, Equation (3)). 9