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  • 1 Bhabha Atomic Research Centre Chemistry Division 400 085 Bombay India
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Abstract  

On pulse radiolysis of N2O saturated aqueous solutions of atropine, an optical absorption band (max at 320 nm,e=2.81·103 dm3·mol–1·cm–1) was observed, which is assigned to the product of reaction of OH radicals with the solute. This absorption decayed following second order kinetics with a rate constant of 4.5·108 dm3·mol–1·s–1. The rate constant for the reaction of OH radicals with atropine as estimated by following the build-up kinetics is 2.7·109 dm3·mol–1·s–1. The H atoms also reacted with this compound to produce a transient absorption band behaving similarly to the one observed in the case of reaction with OH radicals. The transient species formed in both cases is assigned to a radical derived by H atom abstraction by H/OH radicals from the parent compound. This radical was unreactive towards 2-mercaptoethanol. e aq was found to react with atropine forming a transient band with max at 310 nm (=3.55·103 dm3·mol–1). Its decay was also second order with a rate constant of 1.64·109 dm3·mol–1·s–1. The bimolecular rate constant for the reaction of e aq with atropine as estimated from the decay of e aq absorption at 720 nm is 3.9·109 dm3·mol–1·s–1. Specific one-electron oxidizing and reducing agents (such as Cl 2 , Tl2+, SO 4 and (CH3)2COH, CO 2 , respectively) failed to oxidize or reduce this compound in aqoues solutions. The radical anion of atropine formed by its reaction with e aq was found to reduce thionine and methyl viologen with bimolecular rate constant of 3.8·109 and 3.2·109 dm3·mol–1·s–1, respectively.