Thermolysis of Triazoles as Melts − Is the 3,5-Diphenyl-1,2,4-triazole Group a Good Leaving Group?

• Published in: European journal of organic chemistry Vol. 2000; no. 22; pp. 3749 - 3753
• Main Authors: Gautun, Odd R., Carlsen, Per H. J.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01.11.2000; WILEY‐VCH Verlag GmbH; Wiley
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Reaction mechanisms; Rearrangements; Science & Technology; Thermochemistry; Triazole; rearrangements; reaction mechanisms; 4-ALKYL-4H-1,2,4-TRIAZOLES; ENERGIES; thermochemistry; triazole; THERMAL REARRANGEMENT; C4H7; CATIONS
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/1099-0690(200011)2000:22<3749::AID-EJOC3749>3.0.CO;2-X

The mechanism of the rearrangement of 4‐alkyltriazoles to the corresponding 1‐alkyltriazoles on thermolysis at 330 °C is shown to involve initial formation of an intermediate 1,4‐dialkyltriazolium triazolate salt. The triazolate ion subsequently attacks at the alkyl group bearing 1‐ and 4‐positions of the dialkyltriazolium ion, yielding the observed products. No evidence for unimolecular reaction steps has been found. The triazole moiety in these compounds is only a weak leaving group, which requires activation by alkylation. Unimolecular reaction steps never take place, neither from neutral triazole species nor from activated dialkyl‐substituted triazolium species.