Comparative studies on reaction of bis(p-nitrophenyl) phosphate and α-nucleophiles in cationic micellar media

摘要

We studied the cleave of bis(p-nitrophenyl) phosphate (BNPP) over a pH range of 7.0-12.0 in the presence of cationic micelles of cetyldiethylethanolammonium bromide, cetyldimethylethanolammonium bromide, cetylpyridinium bromide, cetyltrimethylammonium bromide, and cetylpyridinium chloride by using different α-nucleophiles, viz acetohydroxamate, benzohydroxamate, salicylhydroxamate, butane-2,3-dione monooximate, and α-benzoin oximate ions. With the use of α-nucleophiles in cationic micellar media, the hydrolytic cleavage of BNPP was found to be approximately 10 ~5-fold faster than its spontaneous hydrolysis. All reactions followed pseudo-first-order kinetics. The effect of various concentrations of cationic micelles for the reaction of BNPP and α-nucleophiles has been studied. The variation of k _(obs) values of the reactions depends on the micellar structure, that is, head groups, hydrophobic tail length, and counter ion.