Efficient Catalytic Cleavage of Reactive Phosphates by an o-Iodosobenzoate Functionalized Surfactant

摘要

5-(N-(n-Hexadecyl)-N,N -dimethyl-N-Beta-ethyloxy)ammoniumO-2-iodosobenzoate, cleaved p-nitrophenyl diphenyl phosphate (PNPDPP), p-nitrophenyl diethyl phosphate (PNPDEP), and p-nitrophenyl isobutyl methylphosphonate (PNIMP) in aqueous cetyltrimethylammonium chloride (CTACl) at pH 8 and 25 C. With .00004 M .0002 M CTACl, second-order cleavage rate constants (L/M-s) were PNPDPP, 28500, PNPDEP, 0.865, and PNPIMP, 215. These represented kinetic advantages of 14700, 43600 and 846, respectively over nonfunctional CTACl-catalyzed cleavages of the substrates. In the presence of excess PNPDPP at pH 8, catalyst 1c/CTACl 'turned over' with k approx. 0.17/s for the hydrolysis of the putative 1c-diphenyl phosphate intermediate. Keywords: Micelles, Kinetics.