K. Bobrowski, and Dariusz Pogocki, C. Schöneich
Nov 26, 1998
Citations
0
Influential Citations
20
Citations
Journal
Journal of Physical Chemistry A
Abstract
The substituent effects on kinetics and yields of specific intermediates and products for the one-electron oxidation by hydroxyl radicals of various (carboxylalkyl)thiopropionic acid derivatives, 3-(methylthio)propionic acid (3-MTPA), 3,3‘-thiodipropionic acid (3,3‘-TDPA), 3-(carboxymethylthio)propionic acid (3-CMTPA), and 2-(carboxymethylthio)succinic acid (2-CMTPA) have been investigated employing pulse radiolysis on the nanosecond to microsecond time scale, and γ-radiolysis. For each derivative, the initial step was a formation of a hydroxysulfuranyl radical proceeding with absolute rate constants of kOH+3-MTPA = 9.1 × 109 M-1 s-1 and kOH+3,3‘-TDPA = 5.8 × 109 M-1 s-1. The subsequent formation of one-electron-oxidized intermediates such as dimeric sulfur−sulfur (S∴S)-three-electron-bonded and monomeric sulfur−carboxylate oxygen (S−O)-bonded sulfide radical cations strongly depended on pH, thioether concentration, and the availability of α- or β-positioned carboxylate functions. A spectral resolution pr...