Carbon Dioxide As A Phosgene Replacement: Synthesis And Mechanistic Studies Of Carbamates

The main application of carbamate ester compound as the pesticide, medicine, resin modifying agent and was intermediate of organic synthesis summerized. As intermediate of organic synthesis, carbamates are used in the synthesis of isocyanate, innocuity polyurethane, melamine derivatives, dimethyl carbonate, and polyvinyl- lamine. Carbamates can reacte with unsaturated hydrocarbons, aldehydes and ketones, polyatomic alcohol and aromatic compounds, which generate various derivatives. They are also used in the synthesis of heterocyclic compounds (e.g., pyrrolos, quinazolinones, triazine ect.) and have a good prospect of application. And the application of carbamates in agriculture, architecture and textile was reviewed. The routes to synthesize carbamate was introduced, including phosgene routes and non-phosgene routes (e.g., alcoholysis of CO(NH2)2, catalytic alcoholysis of carbamide by metallic oxides, reductive carbonylation of nitriobenzene to carbamates, catalytic oxidative carbonylation of amine by organic material, synthesis of carbamate by amomomolysis of dimethyl carbonate, catalysis by ionic liquids, synthesis of carbamates in supercritical CO₂, synthesis from amines and aminobenzoate, nucleo- philic substitution).An one-pot synthesis of carbamates from three-components comprising amines, alkyl chlorides and CO₂ instead of phosgene, using nucleophilic substitution, was mainly discussed. Firstly, the route avoid using the virulent chemical of phosgene and prevent the environment pollution, so it complied with the trend of current word developing green chemical industry. Secondly, it does not have the disadvantage of the traditional protocols over the equipment, security and technology, which hamper the production of ordinary medium-small-sized factories. Thirdly, as the green chemical industry is advocated currently, recycling CO₂ from vent gas of cars through utilizing the technique could lessen the greenhouse effect in the whole world, changing the bad into the good. The carbamates satisfying the great requirement from pesticide, medicine and intermediate of organic synthesis fill the gap of the market and decrease the pressure of relying on the long-term import carbomates and it is of great benefit to the economy and society of our country. So that it has wide prospect of application and plays a great part in promoting the development of the economy and the technique of chemical industry.Through using uniform designed experiment and orthogonal designed experiment, the effect of some factors on the reaction yield were studied respectively. Then we do a further reseach to optimize the reaction conditions to find out the best ones(e.g., the ratio of materials, the temperature, the time, the dosage of catalyst and the selection of solvent, ect.). And then we analyzed the products quantitatively and qualitatively (using the figure of NMR 1H and 13C, the figure of FT-IR and the figure of GC-MS), in order to do work over reaction mechanism deeper.