A Study On Novel Cobalt Complex Catalysis System For Double Carbonylation Reaction Of Benzyl Chloride

α-Keto acids are active intermediates with double functional groups in organic synthesis and biosynthesis. The double carbonylation of organic halides to α-keto acids and their derivatives is an important catalyzed reaction. Traditional catalyst Co2(CO)8 used in the double carbonylation of benzyl chloride has some shortages such as difficult to synthesize, less stability and very expensive. In view of these problems, a novel catalyst system CoCl2 / potassium pyrazine-2-carboxylate (KPzca) is found to have high stability, high catalytic activity and high selectivity for the double carbonylation of benzyl chloride to β-benzyl-α-phenylpyruvic acid (BPPA). At the same time, double carbonylational catalysis ability of the catalysis systems which are composed of the other ligands and cobaltous chloride is researched. The main research contents are followed:(1) The conditions and catalysis activity of CoCl2/KPzca are studied in this paper. Optimal reaction conditions are established through experiments. In the case of CoCl2 0.03 mol/l, KPzca 0.156mol/l, the mol ratio of Ca(OH)2/PhCH2Cl 2.7, the V(dioxane)/V(H2O) 5:1, the corresponding yield of BPPA is 77.3% with selectivity 99.6% when the reaction is carried out for 10h at 343Kand 2.0MPa.. The single carbonylation product phenyl acetic acid (PAA) is efficiently inhibited in this novel catalyst system and reaction product is almost all BPPA. Thus, the reaction selectivity for double carbonylation and conversion rate of benzyl chloride are better. At the same time the double carbonylation mechanism of the catalysis system CoCl2/Kpzca is discussed.(2) The catalysis performance of the catalysis systems which are composed of the other ligands and cobaltous chloride in the double carbonylation of benzyl chloride is studied. When the ligand differs, the double carbonylation products of benzyl chloride is different. On the other hand, the substituent's sorts and its position on ligand rings has a great effect to reaction result, product yield and reaction selectivity. Otherwise, ligands'intervening fashion has definite effect on the reaction. All of those experiments results have enriched contents of double carbonylation reaction research.(3) Synthesis of 2,3-pyrazinedicarboxylic acid(Pzdc) by means of quinoxaline oxidation—acidation—subcooling crystallization has been carried out. The influencing factors of synthesis are discussed. When the quinoxaline synthesis reaction is carried out at 1100C, the molar ratio of potassium permanganate to quinoxaline is 6:1 and reaction temperature 90-1000C in oxidizing reaction, circumfluence time is 45 minutes and the HCl concentration is 20%, the corresponding yield of Pzdc is 82.7%,which is higher than that of literatures.(4) Potassium carbonate/ CoCl2 is found to have definite catalysis ability in the double carbonylation of benzyl chloride, and reaction product is phenylpyruvic acid (PPA) with yield 8.8%.(5) Chemical structures of the products have been characterized.