Collect. Czech. Chem. Commun.
1995, 60, 883-893
https://doi.org/10.1135/cccc19950883
Quaternary Heteroarenium Aldoximes as Catalysts for Cleavage of Phosphate Esters
František Hampla, Jiří Mazáčb, František Liškaa, Jiří Šrogla, Lubomír Kábrtc and Miloslav Suchánekc
a Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Central Laboratories, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
c Department of Analytical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
Abstract
1-Methyl- (Ia - Id) and 1-dodecyl-2-, 3- and 4-hydroxyiminomethylpyridinium salts (Ie - Ih), as well as 1-methyl- (IIa) and 1-dodecyl-3-hydroxyiminomethylpyridazinium salts (IIb, IIc), were synthesized as catalysts for hydrolytic cleavage of organophosphates. The activities of the prepared catalysts were evaluated by measuring rate constants of hydrolysis of 4-nitrophenyl diphenyl phosphate (PNPDPP) under conditions of a pseudo-first-order reaction. The observed reactivity of pyridinium aldoximes Ia - Ih towards PNPDPP in neutral or slightly basic aqueous solutions (pH 7.2 and 7.8) depends on the acidity of the hydroxyimino group. The cleavage of PNPDPP is strongly accelerated in solutions of 1-dodecylhydroxyiminomethylpyridinium salts Ie - Ih above their critical micellar concentration (CMC). Considerable effect on the velocity of PNPDPP cleavage was observed when quaternary pyridinium aldoximes Ie - Ih were comicellized with inert cationic tenside hexadecyltrimethylammonium bromide (CTAB). 1-Dodecyl-3-hydroxyiminomethylpyridazinium salts IIb and IIc were unstable in aqueous solutions under the above-mentioned conditions.
