Thermal behaviour of 3-phenyl-1,2,4-oxadiazol-5-ylhydrazines

Abstract

Depending on the substitution on the hydrazine moiety, thermolysis of 3-phenyl-l,2,4-oxadiazol-5-ylhydrazines(1)-(5) gives variable amounts of 1 -amino-A2-1,2,4-triazolin-5-ones (1 3) or (1 7), AZor A3-1,2,4-triazolin-5ones (1 2), (1 8), or (1 9), and the s-triazine (20). A possible mechanism accounting for the products and the effects is discussed. A diradical intermediate and a hydrogen transfer from the reaction medium are suggested on the basis of the effect of benzoyl peroxide on the reaction and on the behaviour of the hydrazines (1)-(4) towards catalytic h yd rog en at i on.

Photoinduced Molecular Rearrangements. The Photochemistry of Some 1,2,4-Oxadiazoles in the Presence of Nitrogen Nucleophiles. Formation of 1,2,4-Triazoles, Indazoles, and Benzimidazoles

“…Irradiation of the Oxadiazole 1 in the Presence of Hydrazine or N , N -Dimethylhydrazine. Irradiation of 1 (0.5 g) in the presence of hydrazine for 1.5 h and chromatography, besides starting material (0.05 g; 10%), gave compound 5 (0.1 g; 20%) and then 1-amino-3-phenyl-1,2,4- triazolin-5-one ( 9 ) (0.2 g; 37%), mp 235−240 °C (lit . mp 235−238 °C).…”

“…Irradiation of 1 (0.5 g) in the presence of hydrazine for 1.5 h and chromatography, besides starting material (0.05 g; 10%), gave compound 5 (0.1 g; 20%) and then 1-amino-3-phenyl-1,2,4-triazolin-5-one (9) (0.2 g; 37%), mp 235-240 °C (lit. 26 mp 235-238 °C). Irradiation of 1 (0.5 g) in the presence of N,N-dimethylhydrazine (5 mL) for 1.5 h and chromatography, besides starting material (0.05 g; 10%) and minor components which were discarded, gave 12 (0.3 g; 60%).…”

“…Irradiation for 6 h and chromatography, besides starting material (0.05 g; 10%), gave 24 (0.08 g; 16%), 26 (0.06 g; 10%), and 17 (0.15 g; 30%). N-(Methylaminocarbonyl)-N′-phenylbenzamidine (26) (or/and its tautomer): mp 160-164 °C (from benzene-light petroleum); IR 3210, 3100, 1680, 28 Similarly, irradiation of 13 (0.5 g) in the presence of methanolic ammonia for 2 h and chromatography, together with starting material (0.3 g; 60%) and traces of 24, gave 3,5diphenyl-1,2,4-triazole (20) (0.05 g; 10%), mp 190 °C (from aqueous ethanol) (lit. 27 mp 191.5-192.5 °C).…”

Heteroaryl-susbstituted phenols as potential antioxidants

“…All reagents were reagent grade and were used without purification. The halo-heteroaryl derivatives 1a, 1b (Donati et al 1991) and 1d (Argibas et al 1992), 1e (Adembri et al 1981), 1f, 1g (Adembri et al 1975), 1h (Camparini et al 1977), were known compounds and were prepared and purified as reported previously. Compound 1c (oil) was prepared from 4-phenyl-3-methylisoxazole following the procedure reported for the synthesis of compounds 1a and 1b.…”