1.2.3- Triazole, 2-phenyl-, nitration

Amino-3-phenyl-1,2,4-triazole, Nitrous acid, 2952 Benzenediazonium chloride, 2230 Benzenediazonium iodide, 2250 Benzenediazonium nitrate, 2275... 

The first study of the nitration of 2-phenyl-1,2,3[2//]-triazole suggested that the products, using mixed acid at 20°C, were the ortho and para isomers (48JOC815). However, later work showed the two products to be the para isomer and the 4-nitro-2-(4-nitrophenyl) dinitrated product. Further nitration gives the 4-nitro-2-(2,4-dinitrophenyl) trinitrated product. Exclusive mononitration to produce the 4-nitrophenyl product can be effected using nitric acid in acetic anhydride (63CJC274). 

The nitration of 1-phenyl-1,2,4-triazole and 4-phenyl-1,2,4-triazole using mixed acid, as well as the nitration of 3-phenyl-1,2,4-triazole, each gives the 4-nitrophenyl product with no mention of other isomers (69ZC378). 3-Methyl-1-phenyl, 5-methyl-l-phenyl, and 3-methyl-4-phenyl-l,2,4-triazole have also been reported to yield 4-nitrophenyl products (67BSF2634). 

The presence of three heteroatoms in the azole ring reduces its reactivity in electrophilic substitution reactions more. 1,2,3-Triazole itself could not be nitrated [240], An attempt to introduce a nitro group into the heterocyclic ring 1-phenyl- and 4-phenyl-... 

Amino-l-nitro-l,2,4-triazole (581), obtained by nitration of 5-amino-triazole with acetyl nitrate, rearranges, on heating, to the nitramino-triazole (582). ° The combined action of sodium hydroxide, potassium iodide, tri-ethylamine, and sodium dihydrogen phosphite on the chloro-nitro-triazole (583) results in a mixture of the rearranged triazole (584), 3-chloro-l,2,4-triazole, and the coupled product (585). The stable betaine (586) has been prepared by treatment of 4-phenyl-1,2,4-triazole with phenacyl bromide, followed by tri-ethylamine. The meso-ionic triazolium thiolate (537 X = S) reacts with chlorine to form the dichloride (587 X = SCU), which has been converted into the betaine (588) by the action of diethyl bromomalonate in the presence of triethylamine. ... 

Methyl-1,2,3-triazole can be brominated at C-4, but the 2-methyl isomer is less reactive, requiring the use of an iron catalyst the lower reactivity of the latter is probably related to the presence of two azomethine units. Nitration of 2-phenyl-1,2,3-triazole proceeds first on the benzene ring, but then does bring about hetero-ring substitution. ... 

Phenyl-l,2,3-triazole (9) undergoes nitration first on the benzene ring (—>10) and then at the triazole system (- 11) ... 

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