Kinetics and mechanism of oxidation of N ,¦Á-diphenylnitrones by 4-(dimethylamino)pyridinium chlorochromate (DMAPCC) in aqueous DMF medium

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• 作者：Govindasamy Rajarajan ; Natesan Jayachandramani ; Subramaniyan Manivarman ; Jayaraman Jayabharathi and Venugopal Thanikachalam
• 刊名：Transition Metal Chemistry
• 出版年：2008
• 出版时间：April, 2008
• 年：2008
• 卷：33
• 期：3
• 页码：393-397
• 全文大小：362.4 KB

文摘

The kinetics of oxidation of aldonitrones by 4-(dimethylamino)pyridinium chlorochromate (DMAPCC) has been studied in aqueous N,N-dimethylformamide in the presence of perchloric acid. The reaction follows first-order kinetics with respect to each of DMAPCC and nitrone. The order with respect to [H+] was found to be close to zero. The rate of oxidation was unaltered by the variation of [NaClO₄] but addition of MnSO₄ decreased the rate. The reaction rate was found to decrease with a decrease in dielectric constant of the medium. Electron-releasing and electron-withdrawing groups perturb the reaction rate with a good Hammett correlation. The oxidation products were found to be benzaldehyde and nitrosobenzene. The reaction was carried out at four different temperatures and the activation parameters have been calculated. On the basis of the experimental findings, a suitable mechanism has been proposed.