At room temperature, a new three-dimensional organic-inorganic coordination polymer [Cd(C4H2O4)(C3H4N2)3]n?2nH2O was synthesized by the reaction of Cd(CH3COO)2?2H2O, imidazole and fumaric acid. It was characterized by EA, IR, TG-DTA and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 8.980(3), b = 15.803(5), c = 13.415(4) ?, α = γ = 90.00°, β = 98.450(5)°, F(000) = 936, Mr = 466.73, Z = 4, V = 1883.0(10) ?3, Dc = 1.646 g/cm3, μ(MoKα) = 1.201 mm-1, S = 1.041, the final R = 0.0237 and wR = 0.0469. The crystal structure shows that the cadmium has a distorted octahedral environment with three carboxyl oxygen donors and three imidazole nitrogen donors. Each cadmium atom is linked by a fumatate as bridging ligand to afford a one-dimensional framework, and then an infinite three- dimensional supramolecular network is formed through hydrogen bonding interactions.
Toluene dicarbamate(TDC)is an important precursor for preparing toluene diisocyanate(TDI). The biological enzyme catalyst for the synthesis of TDC from toluene diamine(TDA) and dimethyl carbonate(DMC) is investigated. It is found that papain exhibits the best catalgtic activity and the most suitable solvent is tetrahydrofuran. The optimal reaction conditions over papain are as follows: reaction temperature, 40 ℃; reaction time, 40 minutes; n(TDA)/n(DMC)=1/20, the enzyme concentration, 17.4mg/mL; the yield of TDC is 3.94%.
