Mechanistic study on the formation of the alkyl acrylates from CO 2 , ethylene and alkyl iodides over nickel-based catalyst.

The catalytic conversion of carbon dioxide (CO 2 ) and olefins into acrylates has been a long standing target, because society attempts to synthesize commodity chemicals in a more economical and sustainable fashion. In this work, two alkylation reaction pathways were investigated to explore the role of methylene linkage (-CH 2 -) on the formation of alkyl acrylate from coupling of CO 2 and ethylene, catalyzed by a nickel catalyst in the presence of different alkyl iodides. The energy barrier of Ni-O bond cleavage decreases with increasing methylene linkage of alkyl iodides, which may be due to NPA charge transfer of alkyl iodides. Meanwhile, the O1 (ester sp 3 O atom) attack route leading to the formation of alkyl acrylate competes with the O2 (carboxylic sp 2 O atom) attack route in terms of energy barriers. Further studies on the fluoro-substituted alkyl acrylates show that neither CF 3 I nor CF 3 CH 2 I is effective in releasing trifluoroalkyl acrylates from the nickellacycle, which explains why only negligible amounts of the desired product were detected in the experiment. In addition, we investigated the non-productive pathways leading to byproducts, such as propionic acid, propionates and ion pair complexes, etc. By comparing the results obtained with CH 3 I, the use of C 2 H 5 I as an electrophilic reagent may stabilize the non-productive intermediates. The methylene linkage has little effect on the main productive pathway. However, it has a significant influence on the side reactions, which is detrimental to the formation of alkyl acrylate in competing with the main productive pathway.