16273-01-1Relevant academic research and scientific papers
Reactions of Thiols with Phenylglyoxal to Give Thiomandelic S-Esters Formation of Hemithioacetals and Their Rearrangement
Okuyama, Tadashi,Kimura, Kazumasa,Fueno, Takayuki
, p. 1493 - 1497 (2007/10/02)
Equilibrium constants Kh for the addition of 2-mercaptoethanol and glutathione to phenylglyoxal to form hemithioacetals were determined spectrophotometrically over the pH range 7-10.The observed Kh values decrease sigmoidally with pH as the thiol ionizes.Rearrangement of hemithioacetals formed from phenylglyoxal and various thiols was kinetically investigated.The rates increase with thiol concentration following a saturation curve to give Kh identical with the spectrophotometric value.The rearrangement is subject to general base catalysis.The solvent isotope effect on the rate of the rearrangement, kH2O/kd2O, is nearly 1.0; that on the equilibrium, KH2Oh/KD2Oh, is 0.38.The results strongly support the mechanism involving proton transfers through an enediol intermediate.
