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Thermal Rearrangement of 4‐Alkyl‐4 H ‐1,2,4‐triazoles to 1‐Alkyl‐1 H ‐1,2,4‐triazoles − A Study of the Mechanism by Cross‐over Experiments
Author(s) -
Gautun Odd R.,
Carlsen Per H. J.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200011)2000:22<3745::aid-ejoc3745>3.0.co;2-k
Subject(s) - chemistry , alkyl , tetrafluoroborate , nucleophile , thermal decomposition , medicinal chemistry , ionic bonding , triazole , ionic liquid , organic chemistry , ion , catalysis
The mechanism for the thermal rearrangement of 4‐alkyl‐1,2,4‐triazoles to the corresponding 1‐alkyl‐1,2,4‐triazoles, was studied by cross‐over experiments with mixtures of 4‐ethyl‐3,5‐diphenyl‐4 H ‐1,2,4‐triazole and 3,5‐bis(4‐methylphenyl)‐4‐propyl‐4 H ‐1,2,4‐triazole. This gave support to a proposed mechanism involving the formation of an ionic triazolium triazolate intermediate, and a subsequent nucleophilic attack of the triazolate anion at the 1‐ and 4‐alkyl‐group positions to form the observed products. Further support was obtained by thermolysis of a mixture of 1‐ethyl‐3,5‐bis(4‐methylphenyl)‐4‐propyl‐1,2,4‐triazolium tetrafluoroborate and potassium 3,5‐diphenyl‐1 H ‐triazolate.