Cycloaddition of carbon dioxide to 1,2-epoxypropane catalyzed by tetra-t-butylphthalocyaninatoaluminium(III) hydroxide

Carbon dioxide was fixed as propane-1,2-diol carbonate (PDC) with 1,2-epoxypropane (EP) catalyzed by AI(OH) {pc(t-Bu)(4)} in the presence of such a quaternary ammonium halide (HAX) as THO(CH2)(2)N(CH3)(2)(C4H9)]X (X = Cl, Br, I). Although the yield was scarcely affected by the structure of HAX, it was dependent on the kind of halide ion. While PDC was formed in chloroform or dichloromethane, the yield decreased extremely in DMSO or pyridine, and PDC was not prepared in methanol. Although halohydrin was formed in a chloroform solution of EP, Al(OH){pc(t-Bu)(4)}, and HAX, it was not an intermediate. The formation of a hexa-coordinate complex of Al(OH){pc(t-Bu)(4)} with HAX and EP was spectroscopically confirmed, and the complex catalyzed the preparation of PDC from carbon dioxide and EP.