Effect of Pyridine Type Nitrogen (=N-) on Hammett ρ: Invoking the Reactivity-Selectivity Principle: A Chemical Education Perspective

R. Sanjeev¹ and V. Jagannadham^2,

¹Department of Chemistry, Geethanjali College of Engineering and Technology, Cheeryal-501301, Telangana, India

²Department of Chemistry, Osmania University, Hyderabad-500007, India

Cite this paper:
R. Sanjeev and V. Jagannadham. Effect of Pyridine Type Nitrogen (=N-) on Hammett ρ: Invoking the Reactivity-Selectivity Principle: A Chemical Education Perspective. World Journal of Chemical Education. 2022; 10(3):91-94. doi: 10.12691/wjce-10-3-1

Abstract

Hammett ρ values are estimated for the two acid dissociation equilibriums eqn. 1 and 2 of pyridinium and pyridazenium ions from the Hammett plots of log K_aH versus Hammett σ values. The Hammett ρ values are found to be 5.94 and 5.29 for the two equilibriums eqns. 1 and 2 respectively. The effect of extra pyridine type nitrogen (=N-) on Hammett ρ is discussed. Similarly, the average lone pair ionization potentials (IP) of pyridines and pyridazines also followed Hammett equation with Hammett ρ of 1.18 for pyridines and 0.38 for pyridazines respectively. This article is useful in an undergraduate and graduate classroom who tries to study the substituent effects and reactivity-selectivity principle.

Keywords:
pyridiene pyridazine hammett equation pK_a lone pair ionization potentials

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