Collect. Czech. Chem. Commun. 1999, 64, 1159-1179

Metal Ion Chelates of Lipophilic Alkyl Diazinyl Ketoximes as Hydrolytic Catalysts

Radek Cibulkaa, František Hampla,*, Tomáš Martinůa, Jiří Mazáčb, Sonja Totevovác and František Liškaa

a Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Ministry of Finance of the Czech Republic, Customs Technical Laboratory, 180 00 Prague 8, Czech Republic
c Department of Biochemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic


A series of lipophilic dodecyl hetaryl ketoximes (hetaryl = pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazin-2-yl as well as their methyl hetaryl homologues was synthesized and hydrolytic activity of their chelates with Co2+, Ni2+, Cu2+ and Zn2+ in a micellar matrix of hexadecyltrimethylammonium bromide or in homogeneous aqueous solutions was investigated using 4-nitrophenyl acetate, 4-nitrophenyl hexanoate and 4-nitrophenyl diphenyl phosphate as model substrates. While Co2+ and Cu2+ chelates are almost inactive, those of Ni2+ and Zn2+ exhibit considerable activity. None of the studied chelates promotes hydrolysis of the used phosphate. The effective species are chelates of the metal : ligand stoichiometry 1 : 3 and 1 : 1 with Ni2+ and Zn2+, respectively, when the ester cleavage proceeds in the micellar matrix. The 1 : 2 stoichiometry was found in aqueous solutions of Ni2+ and Zn2+ chelates of methyl ketoximes.

Keywords: Ester cleavage; Micellar catalysis; Metallomicelles; Coordination chemistry; Diazines; Oximes; Pyridines; Chelates; Nickel; Zinc; Hydrolysis; Phosphates.