[Stability of various cephalosporins in solutions. Cefazolin, cefazedone, cefaclor].

The kinetics of splitting out the substitute at C3 in the molecule of beta-lactam antibiotics such as cefazolin, cefaclor, cefazedone and others as well as that of splitting out the chlorine atom in the side radical of the cefazedone molecule was studied within wide ranges of pH and temperature. The destruction processes for all the investigated compounds were shown to be described by the 1st order equations. The values of the activation energy, pre-exponential factors and reaction order by the hydrogen ions were measured. This provided the mathematical description of the destruction processes within wide ranges of pH and temperature. An unusual mechanism of synchronous splitting out the substitute at C3 and one of the chlorine atoms in the side radical of the cefazedone molecule was observed.