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Isotopic exchange in heterocyclic quaternary salts. II. (1) Hydrogen‐deuterium exchange ln active c‐methyl groups

 

作者: Margareta Bologa,   A. Barabás,   Viorica I. Dénes,   F. Chiraleu,  

 

期刊: Journal of Labelled Compounds and Radiopharmaceuticals  （WILEY Available online 1977）
卷期: Volume 13, issue 1  

页码: 11-22

 

ISSN:0362-4803

 

年代: 1977

 

DOI:10.1002/jlcr.2580130102

 

出版商: John Wiley&Sons, Ltd.

 

关键词: 1H‐nmr chemical shifts;benzothiazolium;benzoselenazolium;benzimidazolium;quinolinium and pyridinium salts

 

数据来源: WILEY

 

摘要:

AbstractThe non‐catalysed H‐D exchange in heterocyclic quaternary ammonium salts (1–3) was studied by1H‐nmr. Exchange occurs only at the C‐CH3group, at a rate decreasing in the order X = C(CH3)2, Se, CH=CH, S, NCH3. In substituted benzothiazolium salts the exchange rates decrease in the series Y = NO2, Cl, H, OCH3. Chemical shifts (δ) of C‐CH3and N‐CH3groups decrease in the same sequence. Both exchange rate constants and chemical shifts can be related ta Hammett σp‐ values of the Y substituents. The mechanism p of the exchange reaction is

 

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