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The accelerated stability of dimethoxy biphenyl monocarboxylate.HCI(DDB-S) was investigated in 6mg/ml water solution in the Ph ranging 2-10 and the temperature of 45-85oC. The observed rate of degradation followed first-order kinetics. The energy of activation for DDB-S degradation was calculated to be 14.1 and 16.5kcal/mole at ph5 and in distilled water, respectively. The degradation rate constant(K25oC) obtained by trending line analysis of Arrenius plots for DDB-S was 5.3 x 10-6h-1. The times to degrade 10%(t10) and 50% (t50) at 25oC were 829 and 5,416 days, respectively.DDB-S exhibited the fastest degradation at Ph 10 and the slowest rate at ph5. In addition, at 65oC, degradation rate constants of DDB-S were 0.066,0.059,5.460,32.1771, and 1.41x10-6h-1 at ph 2,5,8,10 and in distilled water, repectively. These observations indicated that the rate-ph profile of DDB-S showed general acid-base catalysis reaction in the range of ph 2-10.
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