ATR-IR SPECTROSCOPY FOR THE INVESTIGATION OF SOLUTION REACTION-KINETICS - HYDROLYSIS OF TRIMETHYL PHOSPHATE

ATR-IR spectroscopy is proposed as a versatile technique for the inves tigation of reaction kinetics in solution, particularly in aqueous sol ution. Subtraction of the solvent spectrum and thus quantitative absor ption measurements are possible. In contrast to thin-film transmission spectroscopy, thermostatting is feasible. The high information conten t of IR spectra demands high-resolution spectra measured at many waven umbers, and, for kinetic investigations, series of spectra are measure d. A multivariate nonlinear least-squares fit is proposed that effecti vely overcomes the difficulties related to large numbers of data and p arameters. As a test for the method, the base-catalyzed hydrolysis of trimethyl phosphate in aqueous solution was investigated. The rate con stant is 1.6 x 10(-4) s(-1) at 40 degrees C and pH 13.