Catalytic Activity of Various Salts in the Reaction of 2,3-Epoxypropyl Phenyl Ether and Carbon Dioxide under Atmospheric Pressure

Article abstract of DOI:10.1021/jo00075a011

Reaction of 2,3-epoxypropyl phenyl ether (1) with carbon dioxide was carried out under atmospheric pressure in N-methylpyrrolidinone (NMP) at 100 deg C in the presence of 5 mol percent of various salts to obtain a five-membered cyclic carbonate, 4-(phenoxymethyl)-1,3-dioxolan-2-one (2), selectively.Only halide salts showed high catalytic activity, and the order of intrinsic activity was found to be as follows: chloride > bromide > iodide which is the order of nucleophilicity of the anion.Furthermore, the order of the activity was found to be lithium salt > sodium salt > benzyltrimethylammonium salt, which is in accord with the order of Lewis acidity of the cation.Kinetic analyses show that the reaction rate can be represented by -d<1>/dt=k<1>, where the carbon dioxide pressure shows no effect on the reaction rate.The reaction proceeds via nucleophilic attack of halide to oxirane to form β-haloalkoxide 4 which reacts with CO2 followed by cyclization.The presence of key intermediate 4 was indirectly proved by the reaction of 1 with 1 equiv of LiBr in the absence of CO2 at 100 deg C for 2.5 h in NMP which leads to 1-phenoxy-2-propanone (6) in 20percent yield as the rearrangement product of 4.