15N NMR study of azo-hydrazone tautomerism of 15N-labelled azo dyestuffs

✍ Scribed by Antonín Lyčka; Dobroslav Šnobl; Vladimír Macháček; Miroslav Večeřa

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 267 KB
• Volume: 16
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270160106

✦ Synopsis

Abstract

^15^N chemical shifts of 3‐methyl‐1‐phenylpyrazole‐4,5‐dione 4‐phenylhydrazone (1), 4‐hydroxyazobenzene (2), 2‐hydroxy‐5‐tert‐butylazobenzene (3) and 1‐phenylazo‐2‐naphthol (4), monolabelled with ^15^N at α‐(compounds prepared from ^15^N‐aniline) and β‐positions (compounds prepared from Na^15^NO~2~), have been measured and the temperature dependence of these chemical shifts followed between 240 and 360 K. For 4, representing a mixture of the azo and hydrazone forms, the hydrazone content has been calculated from the ^15^N chemical shifts of both nitrogen atoms at various temperatures. The two calculations gave identical results.