Ionization in Liquid Ammonia of Methyl and Amino Groups Bonded to Pyridine and Pyrazine. A Method of Determining Their pKa Values

Authors

John A. Zoltewic
Larry S. Helmick, Cedarville UniversityFollow

Document Type

Article

Publication Date

1973

Journal Title

Journal of Organic Chemistry

Volume

38

Issue

4

First Page

658

Last Page

662

Abstract

Proton magnetic resonance spectra of ionized 2-methyl and 2-amino derivatives of pyridine and pyrazine along with spectra of 2-pyridone and 2-pyrazinone in liquid ammonia are reported. Changes in chemical shifts produced by ionization of the pyridines are linearly related to those for the pyrazines. Competition experiments show that 2-methyl- is less acidic than 4-methylpyridine; estimates of the pK, values for these two acids are given. It is suggested that the results provide a basis for determining the equilibrium acidities of weak heterocyclic acids.

Keywords

ionization, liquid ammonia, pyridine, pyrazine

Recommended Citation

Helmick, L. S. (1973). Ionization in Liquid Ammonia of Methyl and Amino Groups Bonded to Pyridine and Pyrazine. A Method of Determining Their pKa Values. Journal of Organic Chemistry, 38, 658-662.