Triazolone derivatives

Diethyl malonate reacts with azides to form triazolone derivatives, noteworthy because of their interesting tautomeric relationships (Dimroth). 

Oxidation of 5-anilino-4-phenyl- -triazole may give a 4 -triazolone derivative as an intermediate (Scheme 39). ... 

Brand Name(s) Emend, Emend 3-Day Chemical Class Triazolone derivative... 

Heating bromide 30c in the absence of solvent gave oxadiazoline hydrobromide 158, which yielded, after basification, the free base 159. However, treatment of 30c with sodium hydroxide solution at room temperature or at reflux furnished a mixture of the triazolone derivative 162 (75% yield) and 5-bromothenoic acid 163, presumably via intramolecular displacement of the bromine atom to give 161, followed by alkaline cleavage of the thenoyl group (78JHC1393). 

C NMR spectra of 3-nitro-l,2,4-triazol-5-one and seven of its salts with different amines have been studied. The chemical shifts of C-3 and C-5 are independent of the nature of the cation (Table 3.21) [560], NMR spectra of 1-nitro-1,4-dihydro-1-7/-l,2,4-triazol-5-one, 5-(3-azido-l,2,4-triazol-3-yl)-3-nitro-l,2,4-triazoles [611], l-alkyl-3-nitro-l,2,4-triazol-5-one [612], some 3-nitro-2-methyl-l,2,4-triazolone derivatives [613-615], and their mono- and dinitro energetic salts [616] have been discussed. 

Azolone anions are readily alkylated at nitrogen, e.g. 2-triazolone with methyl iodide gives the 1-methyl derivative. 

The 3-(4-chloro-2-nitrophenyl)triazole derivative (110) undergoes nucleophilic displacement of chloride by azide ion <89JCS(P2)1425>. The thermal and photochemical decomposition of 3-nitro-triazolone have been shown to occur via radical cations <9UPC5509>. 

Derivatives containing the s-triazolone ring are among the most active members of this class of compounds showing crop selectivity, whereas the introduction of alkylthio, sulfinyl, and sul-fonyl groups cause total loss of activity. Hydroxy derivatives which are tautomers of urazole are likewise inactive. 

An example of synthesis of N-fluoro-1,2,4-triazole was described in the patent of Strazdina and Grinstein [6, 17]. Here l-flnoro-3,5-dibromo-l,2,4-triazole 8 was obtained by treating the heterocyclic substrate with the hypohalous acid or its derivatives at -40 to -h50 C in water or an organic solvent in the presence of bases. Langlet and Oslmark in a patent [18] have described the application of isomeric fluoro-triazolones 9,10 as components of explosive compositions, but the data on the synthesis of these substances have been not reported. 

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