title: Amino acid/KI as multi-functional synergistic catalysts for cyclic carbonate synthesis from CO2 under mild reaction conditions: a DFT corroborated study.
abstract: Naturally occurring amino acids were identified as efficient co-catalysts for the alkali metal halide-mediated synthesis of cyclic carbonates from carbon dioxide and epoxides under mild, solvent free reaction conditions. The binary system of histidine/potassium iodide gave an appreciable turnover number of 535 for propylene oxide in 3 h. Detailed studies evaluating a variety of amino acids revealed that the basic amino acids afforded better conversion rates. The formation of a seven membered ring involving the zwitterionic ends of the amino acid, the metal halide, and the epoxide was considered to accelerate the catalysis rate. Density functional theory calculations were performed for the first time on amino acid co-catalyzed cycloaddition to provide further evidence for this hypothesis. The iodide ions of the alkali metal halide displayed excellent synergism with the hydrogen bonding groups of the amino acids in the production of cyclic carbonates, whereas bromide and chloride anions functioned less efficiently. The utilization of amino acids to enhance the catalytic activity of the cheap and eco-friendly alkali metal halides for cyclic carbonate synthesis represents a cost-effective, greener route towards the chemical fixation of carbon dioxide.
authors.affiliation: Division of Chemical and Biomolecular Engineering, Pusan National University, Busan 609-735, Republic of Korea. dwpark@pusan.ac.kr.
authors.forename: Kuruppathparambil Roshith
authors.initials: KR
authors.lastname: Roshan
authors.forename: Amal Cherian
authors.initials: AC
authors.lastname: Kathalikkattil
authors.forename: Jose
authors.initials: J
authors.lastname: Tharun
authors.forename: Dong Woo
authors.initials: DW
authors.lastname: Kim
authors.forename: Yong Sun
authors.initials: YS
authors.lastname: Won
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Park
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D002254:Carbonates / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D004852:Epoxy Compounds / Q000737:chemistry; D015394:Molecular Structure; D011193:Potassium Iodide / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D000596:Amino Acids; D002254:Carbonates; D004852:Epoxy Compounds; D002245:Carbon Dioxide; D011193:Potassium Iodide