Kinetics of Dehydration of Epitetracycline in Solution

The dehydration kinetics of epitetracycline in solution to form epianhydrotetracycline were studied using UV and visible spectrophotometry. The reaction was found to be first order with respect to epitetracycline and hydronium-ion concentrations. The activation energy for the reaction was 28.3 kcal/mole at pH 2.0 in 0.1 M potassium chloride solutions. Dehydration of epitetracycline at pH 2.0 and 70° was found to be slower than that for tetracycline under similar solution conditions, although the activation energy for both reactants is essentially the same. This result is explicable on the basis of conformational differences in the molecules. This paper represents a portion of studies of the rates of various degradation reactions of tetracycline that lead to the toxic material epianhydrotetracycline.