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《》 1984-02
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STUDIES ON STABILITY OF MEDEMYCIN IN AN AQUEOUS SOLUTION

Wang Yubou Li Liyan Department of Antibiotics  
In the experiment, we studied the stability of medemycin by means of spectrophotometry.The results showed that medemycin is stable at 55℃, 70℃ over a pH range of 2—9, but not stable at 50℃,55℃, 65℃, or when pH=1.0,pH=12. The hydrolytic reaction of medemycin complies with a first—order reaction of kinetic equation.According to the kinetic equation, we determined: pH=12 50℃, K=4.00×10~(-3)min~(-1), 55℃, K=7.68×10~(-3)min~(-1) 65℃, K=4.12×10~(-2)min~(-1) pH=1.0 50℃, K=1.76×10~(-3)min~(-1), 55℃, K=6.41×10~(-3)min~(-1), 65℃, K=2.14×10~(-2)min~(-1), It was also proved that the action of temperature on the rate constant complies Arrhenius equation.Calculating E. and A for the Arrhenius equation: pH=12, E_a=3.27×10~4cal/mol A=3.98×10~(19) pH=1.0 E_s=3.43×10~4cal/mol A=3.98×10~(20) Then the Arrhenius equation was definitely established: pH=12 lg K=-7.1×10~31/T+19.6 pH=1.0 lg K=-7.5×10~31/T+20.6
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