3.5- Dimethyl-l,2,4-triazole

Deamination into 2,4,6-trimethylpyrimidine, together with a simultaneous formation of 3,5-dimethyl-l,2,4-triazole, occurs when A-amino-2,4,6-trimethylpyrimidinium mesitylenesulfonate reacts with liquid ammonia... 

However, when the transmetalation was carried out at reOux temperature in wet solvent with access to air, the pentanuclear complexes [Cu5(L )2(dmt)2][C10J3 (70),and[Cuj(L )2(dmt)2][C104]3 (71), (dmt = 3,5-dimethyl-l,2,4-triazolate anion) were obtained. The structures of these complexes were confirmed by an X-ray diffraction analysis of complex 71 (Fig. 11) [44], Separate experiments established... 

In the series of 1,2,3-triazoles fast rearrangement of Af-bromo-4-methyl-1,2,3-triazole 33c to 4-methyl-5-bromo-l,2,3-triazole 57 is described [55LA(593)207], 1-Iodo-l, 2,3-triazole 34a yields 4,5-diiodo-l,2,3-triazole 58 on heating to 110°C in the presence of 3,5-dimethyl-l, 2,4-triazole as a halogen carrier (70ZC220) (Scheme 31). 

TV-Iodo-1,2,4-triazole 49 in contrast to N-chloro and A -bromo derivatives does not react under these conditions (69KGS1114). Formation of 3-iodo-and 3,5-diiodo-l,2,4-triazole proceeds on heating to 150°C in the presence of 3,5-dimethyl-l,2,4-triazole as the halogen carrier (69ZC300 70ZC220). 

Leukazone 23 is not 3,6-dimethyl-4//-l,2,4,5-oxatriazine as originally reported, but is in fact 3,5-dimethyl-l, 2,4-triazole 4-oxide.24... 

G. Kurek, E. Konig, K. Nachtkamp, and T. Engbeit. Polyisocyanates blocked with 3,5-dimethyl-l,2,4-triazole. US Patent 6005046, assigned to Bayer Ak-... 

Dimethyl-l,2,4-triazole is acolorless solid with a melting point of 144 °C. 1-Vinyl-1,2,4-triazole can be prepared by the reaction of 1,2,4-triazole with... 

Hydrazinium hydrazine carboxylate is used in the preparation of 4-amino-3,5-dimethyl-l,2,4-triazole, a useful compound in agriculture and medicine. When a mixture of viscous liquid hydrazinium hydrazine carboxylate and acetonitrile is kept at room temperature, two layers appear the top layer being acetonitrile and the lower one N2H5COON2H3. A pink color develops in the acetonitrile layer after about 12 h. After two to three weeks, a white crystalline compound is formed in the hydrazinium hydrazine carboxylate layer, and the pinkish acetonitrile layer disappears. The white crystals are those of 4-amino-3,5-dimethyl-l,2,4-triazole. 

The synthesis of 4-amino-3,5-dimethyl-l,2,4-triazole is also carried out using hydrazinium hydrazine carboxylate as the starting material it is boiled under reflux with acetonitrile (20 ml) for 4h [5]. The resultant solution is evaporated over a water bath to afford colorless crystals of the triazole. The crystals are separated by filtration and washed with a small amount of acetone followed by acetonitrile, and then dried in air to give the product (1.3 g). The compound is freely soluble in DMSO and water, slightly soluble in acetone, and insoluble in benzene, carbon tetrachloride, chloroform, and acetonitrile. 

Hydrazine hydrate is known to react with acetonitrile in the presence of sulfur or ethanol to form 4-amino-3,5-dimethyl-l,2,4-triazole or 3,6-disubstitued-l,2-dihydro-l,2,4,5-tetrazines. The initial product, which is disubstituted l,2-dihydro-l,2,4,5-tetrazine, is readily oxidized to the pink colored 1,2,4,5-tetrazine it may also rearrange at elevated temperature or on treatment with an acid to the corresponding 1,2,4-triazole. The triazole compound is obtained by the reaction of hydrazine hydrate and acetonitrile in the presence of CO2. The presence of CO2 in the formation of the six-membered ring intermediate is essential, and has been confirmed by repeating the experiments in the absence of CO2. However, the exact role of CO2 in this reaction is not clear. Figure 6.1 gives a possible mechanism for the formation of the triazole from hydrazinium hydrazine carboxylate and acetonitrile. 

Vittal, J.J., Angadi, V.B., and Patil, K.C. (1989) Reactivity of hydrazinium hydrazi-necarboxylate-synthesis of 4-amino-3,5-dimethyl-l,2,4-triazole. Journal of the Indian Institute of Science, 69, 119-124. 

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