Dimethyl Carbonate Participated Green Reactions Catalyzed By Ionic Liquids

Dimethyl carbonate(DMC) is a versatile compound that represents an attractive eco-friendly alternative to both methyl halides(or dimethyl sulfate) and phosgene for methylation and carbonylation processes,respectively.DMC has attracted much more attention.Room temperature ionic liquids,a new kind of green solvents and catalysts with unique chemical and physical properties,have attracted growing interest,and many catalytic reactions proceeded in ionic liquids were reported with excellent performance.This thesis combined the advantages of ionic liquid and dimethyl carbonate.It was composed with two sections.The first section was about N-heterocyclic carbomethoxylation catalyzed by ionic liquids in the presence of dimethyl carbonate. The second section was about the selective mono-C-methylation of arylacetonitriles catalyzed by ionic liquids in the presence of dimethyl carbonate.In the first section,an efficient,environmentally friendly procedure for synthesis of N-heterocyclic carbamates from N-heterocycles and dimethyl carbonate catalyzed by ionic liquids was investigated.[Bmim]OH was found to be the most active catalyst among the applied ionic liquids.Effects of the amount of ionic liquid,reaction temperature and the amount of water were also investigated.96%yield and 100% selectivity was obtained under the optimal conditions when using indole as reactant. The possible reaction mechanism was discussed based on the reaction results,the results show that proton in 2-position in imidazolium played a dominating role in catalyzing the reaction of indole and DMC.[Bmim]OH could be reused at least up to 4 times without any decrease of activity.In the second section,an efficient,environmentally friendly and highly selective mono-C-methylation of arylacetonitriles to produce 2-arylprionitriles was studied in the presence of dimethyl carbonate as an alkylating agent and various ionic liquids as catalysts.[Bmim]OAc as catalyst exhibited better caralytic activity compared with other catalysts.The effects of the amount of ionic liquid,reaction temperature, reaction time and the amount of water were also investigated.Under the optimal reaction conditions,the yield and selectivity of 2-phenylpropionitrile was 98%and 100%when using phenylacetonitrile as reactant.The possible mechanism was also studied by using various ionic liquids.The results showed that proton in 2-position in imidazolium played a dominating role in catalyzing the reaction of phenylacetonitrile and DMC.[Bmim]OAc could be reused at least up to 5 times with slight decrease of activity.