Studies of Nucleophilic Substitution Reactions of p‐Nitrophenyl Acetate with Some Dihydroxamate Ions in Cationic Micellar Media

Pseudo‐first‐order rate constants have been determined for the nucleophilic substitution reactions of p‐nitrophenyl acetate with oxalo, malono, and succinodihydroxamate ions (⁻ONHC(O)(CH₂)_nC(O)NHO⁻) in phosphate buffer (pH=7.9) at 27°C. The rate data of the reaction revealed that the nucleophilic reactivity sequence of these hydroxamate ions is generally ODHA>MDHA>SDHA. The k_obs value increases upon addition of cationic surfactants to the reaction medium which is typical behavior of micelle‐assisted bimolecular reactions. The pseudo‐phase ion exchange model has been successfully applied to determine binding constant.

Keywords:

• Nucleophilic substitution
• dihydroxamic acid
• hydroysis of carboxylate ester

Acknowledgment

Financial support from the Council of Scientific and Industrial Research (New Delhi, INDIA is gratefully acknowledged (Grant No: 01(1825)/02/EMR‐I). SB thanks Pt. Ravishankar Shukla University, Raipur for sanctioning scholarship. The authors are thankful to Professor G. L. Mundhara, Head, School of Studies in Chemistry, for providing laboratory facilities.