Substituted o-Iodoso- and o-Iodoxybenzoic Acids: Synthesis and Catalytic Activity in the Hydrolysis of Active Phosphorus Esters and Related Systems

Article abstract of DOI:10.1021/jo00252a017

2-Iodoso- and 2-iodoxybenzoic acids containing alkyl, alkyloxy, nitro, carboxyl, and water-solubilizing substituents have been synthesized, and their influence on the rates of hydrolysis of p-nitrophenyl diphenyl phosphate (PNPDPP), p-nitrophenyl isopropylphenylphosphinate (NPIPP), and p-nitrophenyl hexanoate (PNPH) has been determined in the presence of added cetyltrimethylammonium chloride (CTAC).All the compounds are true catalysts, with rates increasing with increasing catalyst concentration. 2-Iodoxybenzoic acids possess 60-110percent of the activity of their 2-iodosobenzoic acid analogues in 0.001 M CTAC.The effects of substituents of variable electronic and aqua/lipophilic character upon catalytic activity have been determined.Lipophilic substituents significantly enhanced the rates while simple ring substitution with electron-releasing and -withdrawing and water-soluble groups had only moderate effects.Extraordinary rate enhancements were obtained with 5-(2-hydroxyethoxy)-2-iodoxybenzoic acid and 5-(alkyloxy)-2-iodosobenzoic acid and -2-iodoxybenzoic acid derivatives, giving second-order rate constants of 400-5000 M^-1 s^-1.The efficient catalysis of the hydrolysis of active phosphorus derivatives renders these aromatic 2-iodoso- and 2-iodoxybenzoic acids potentially useful decontaminants.