Science and Mathematics Faculty Publications

Title

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

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

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