TITLE:
Aminolysis of 1-(1-Hydroxybenzotriazolyl)-2,4-dinitrobenzene and 2-(1-Hydroxybenzotriazolyl)-5-nitropyridine
AUTHORS:
Sherine N. Khattab, Mohamed A. H. Kharaba, Amal El-Hawary, Ayman El-Faham, Ezzat A. Hamed
KEYWORDS:
Nucleophilic Aromatic Substitution Reactions; Kinetic Measurements, 1-Hydroxybenzotriazole; Solvent Effect; Morpholine; Cyclohexylamine and Aniline; Uncatalyzed and Specific Base Catalyzed Mechanisms
JOURNAL NAME:
Open Journal of Physical Chemistry,
Vol.2 No.3,
August
31,
2012
ABSTRACT: The reaction 1-(1-hydroxybenzotriazolyl)-2,4-dinitrobenzene 1 and 2-(1-hydroxybenzotriazolyl)-5-nitro-pyridine 2 with amines undergoes amination followed by elimination of the 1-hydroxyl benzotriazolyl anion. The kinetic data for the reaction of 1 and 2 with Mo, CHA and An in MeOH and AN proceeded by uncatalysed mechanism in which the rate limiting step is the leaving group departure, whereas the reaction with Mo in toluene proceeded by uncatalysed mechanism in which the formation of the zwitterionic intermediate is the rate determining step. While the reactions of 1 with CHA and An and the reaction of 2 with CHA in toluene proceeded by SB mechanism in which the rate determining step is the proton transfer process. The reactions of 1 and 2 with Mo in the three solvents and with CHA and An in MeOH and AN is greatly depended on the stability of the zwitterionic intermediate. The effect of ring activation is due to the ground state stabilization and the more efficient delocalization of the negative charge with a nitro group than with a ring-nitrogen in the transition state. The low activation enthalpies ΔH# and the highly negative activation entropies ΔS# are due to the intramolecular hydrogen bonding with the ammonio hydrogen present in the transition state.