GENERAL ACID-CATALYZED DECOMPOSITION OF ALKYL XANTHATES

Xanthates of 2, 2, 2-trifluoroethanol, methoxyethanol, and ethanol have been prepared, and their decomposition in aqueous carboxylic acid buffers has been studied. pH-rate profiles reveal that the pKavalues for the ionization of the xanthic acids are 1.60 for ethyl, 1.30 for trifluoroethyl, and 1.45 for methoxyethyl. Bronsted α values for the general acid catalysis of the breakdown of xanthates are 0.96 for ethyl, 0.88 for methoxyethyl, and 0.79 for trifluoroethyl. These results are interpreted in terms of a concerted process for proton transfer and carbon-oxygen bond breaking. Positive deviations from linearity were observed at high values of mole fraction of the catalyzing acid in plots of vS. mole fraction of HA. These results have been discussed in terms of a general acid-catalyzed breakdown of xanthic acids and solvent-assisted breakdown of xanthate anion. © 1979, American Chemical Society. All rights reserved.