The Kinetics of Saponification of Iodoacetic Acid

نویسنده

  • R. BRDICKA
چکیده

In studying the reaction which takes place between glycine and iodoacetic acid in certain alkaline buffer solutions (1), it was necessary to consider the saponification of iodoacetic acid by hydroxyl ions. This occurs simultaneously as an independent side reaction. By determining the velocity constants for the saponification in the solutions in which glycine was omitted, the rate of the iodoacetic acid-glycine reaction could be obtained. The study of the kinetics of the saponification reaction of iodoacetic acid forms the subject of the present paper. Holmberg (2) investigated this reaction over a limited range of concentration of the reacting constituents. His measurements have been extended in the present paper to regions of greater alkalinity. His paper appeared before the publication of Brgnsted's (3) hypothesis, and hence his data were not interpreted on this basis. The technique employed is essentially the same as that which was described in the previous paper (1). Certain portions of the iodoacetate and hydroxyl ion containing-solution, whichwas kept in a thermostat at 25 ° :k 0.01, were withdrawn during different time intervals during the saponification. In order to stop the reaction they were brought approximately to neutrality by the addition of HC1. The quantitative estimation of the iodoacetic acid in the samples consisted in recording polarographically the horizontal portions of the current-voltage curves. The concentration of iodoacetic acid can be read from these (see Fig. 1).

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تاریخ انتشار 2003