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Substituent effects on thermal rearrangement of 3‐ (substituted phenyl)‐4‐( p ‐tolyl)‐1,2,4‐oxadiazole‐5(4 H )‐thiones
Author(s) -
Agirbas Hikmet,
Toker Alev
Publication year - 2001
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200101)14:1<58::aid-poc337>3.0.co;2-o
Subject(s) - heterolysis , chemistry , oxadiazole , homolysis , bond cleavage , substituent , medicinal chemistry , cleavage (geology) , cope rearrangement , sigmatropic reaction , catalysis , carroll rearrangement , organic chemistry , radical , geotechnical engineering , fracture (geology) , engineering
The kinetics of the rearrangement of 3‐(substituted phenyl)‐4‐( p ‐tolyl)‐1,2,4‐oxadiazole‐5(4 H )‐thiones in solution were determined in the temperature range 160–200 °C. From the correlation of log k against σ, it was found that for m ‐Me, p ‐Cl and p ‐CN, the compounds rearrange with the homolytic cleavage of the N—O bond, whereas for p ‐Me, H and m ‐NO 2 , the rearrangement occurs with the heterolytic cleavage of the N—O bond. In comparison with the uncatalysed rearrangement, Cu catalysis greatly increased the rate of the rearrangement of 3‐( m ‐chlorophenyl)‐4‐( p ‐tolyl)‐1,2,4‐oxadiazole‐5(4 H )‐thione at 166 °C. Copyright © 2000 John Wiley & Sons, Ltd.