Tautomerism of hydroxypyridines (II). Bromination of 2,4-dihydroxypyridine and its ethyl derivatives

✍ Scribed by C. R. Kolder; H. J. den Hertog

• Book ID: 104586170
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 288 KB
• Volume: 79
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19600790505

✦ Synopsis

Abstract

2,4‐Dihydroxypyridine, 2‐ethoxy‐4‐hydroxypyridine, 4‐ethoxy‐2‐hydroxypyridine and 2,4‐diethoxypyridine were brominated in pyridine as solvent. It appeared that bromine enters the 3‐position during the bromination of the three first mentioned substances whereas from 2,4‐diethoxypyridine the 5‐bromo derivative is formed.

Ultraviolet absorption spectra of substrates and reaction products in 50% aqueous ethanolic solution were measured. Comparison of these spectra with the known spectra of the mono‐ and dimethoxy derivatives of 2,4‐dihydroxypyridine enabled the tautomeric structures of the substances to be investigated. The course of the brominations is connected with the structure of the substrates.