The reactions of OH radicals with toluene diisocyanate, toluenediamine and methylenedianiline under simulated atmospheric conditions

Abstract The reactions of OH radicals with vaporized toluene diisocyanate (TDI), toluenediamine (2,4- and 2,6-TDA) and methylenedianiline (MDA) in synthetic air were studied in a 420 l photoreactor at ambient pressure and temperature (298 ± 2 K) by in situ long-path Fourier transform IR absorption spectroscopy, using a competitive rate technique. Rate constants of ⩾7.4, 190 ± 70, ⩾ 100 and 30 ± 10 (units: 10 −12 cm 3 s −1 ) were determined for TDI, 2,4-TDA, 2,6-TDA and MDA respectively. These data show that under atmospheric conditions the (half) lifetimes for OH radical reactions, with 10 6 OH cm −3 as the mean concentration, range from 26 h for TDI to 1 h for 2,4-TDA.