title: Stopped-flow spectrophotometric study of the kinetics and mechanism of CO₂ uptake by cis-[Cr(C₂O₄)(BaraNH₂)(OH₂)₂]+ cation and the acid-catalyzed decomposition of cis-[Cr(C₂O₄)(BaraNH₂)OCO₂]- anion in aqueous solution.
abstract: The kinetics of CO(2) uptake by the cis-[Cr(C(2)O(4))(BaraNH(2))(OH(2))(2)]+ complex cation and the acid hydrolysis of the cis-[Cr(C(2)O(4))(BaraNH(2))OCO(2)]- complex anion (where BaraNH(2) denotes methyl 3-amino-2,3-dideoxy-b-D-arabino-hexopyranoside) were studied using the stopped-flow technique. The reactions under study were investigated in aqueous solution in the 288-308 K temperature range. In the case of the reaction between CO(2) and cis-[Cr(C(2)O(4))(BaraNH(2))(OH(2))(2)]+ cation variable pH values (6.82-8.91) and the constant ionic strength of solution (H+, Na+, ClO(4)- = 1.0) were used. Carbon dioxide was generated by the reaction between sodium pyruvate and hydrogen peroxide. The acid hydrolysis of cis-[Cr(C(2)O(4))(BaraNH(2))OCO(2)]- was investigated for varying concentrations of H+ ions (0.01-2.7 M). The obtained results enabled the determination of the number of steps of the studied reactions. Based on the kinetic equations, rate constants were determined for each step. Finally, mechanisms for both reactions were proposed and discussed. Based on the obtained results it was concluded that the carboxylation (CO(2) uptake) reactions of cis-[Cr(C(2)O(4))(BaraNH(2))(OH(2))(2)]+ and the decarboxylation (acid hydrolysis) of the cis-[Cr(C(2)O(4))(BaraNH(2))OCO(2)]- are the opposite of each other.
authors: Department of General and Inorganic Chemistry, University of Gdańsk, Sobieskiego 18/19, 80-952 Gdańsk, Poland. dagmara@chem.univ.gda.pl
authors: Dagmara
authors: D
authors: Jacewicz
authors: Aleksandra
authors: A
authors: Dąbrowska
authors: Lech
authors: L
authors: Chmurzyński
mesh_terms: D002245:Carbon Dioxide / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009942:Organometallic Compounds / Q000737:chemistry*; D019289:Pyruvic Acid / Q000737:chemistry; D012996:Solutions; D013053:Spectrophotometry; D014867:Water
chemical_list: D005609:Free Radicals; D009942:Organometallic Compounds; D012996:Solutions; C568724:cis-(Cr(C2O2)(BaraNH2)OCO2); C568723:cis-(Cr(C2O4)(BaraNH2)(OH2)2); D014867:Water; D002857:Chromium; D002245:Carbon Dioxide; D019289:Pyruvic Acid; D006861:Hydrogen Peroxide