Determination of rate constants in second-order kinetics using UV-visible spectroscopy

A general method for estimating reaction rate constants of chemical reactio ns using ultraviolet-visible (UV-vis) spectroscopy is presented. The only r equirement is that some of the chemical components involved be spectroscopi cally active. The method uses the combination of spectroscopic measurements and techniques from numerical mathematics and chemometrics. Therefore, the method can be used in cases where a large spectral overlap of the individu al reacting absorbing species is present. No knowledge about molar absorban ces of individual reacting absorbing species is required for quantification . The reaction rate constants and the individual spectra of the reacting ab sorbing species of the two-step consecutive reaction of 3-chlorophenylhydra zonopropane dinitrile,vith 2-mercaptoethanol were estimated simultaneously from UV-vis recorded spectra in time. The results obtained were excellent.