L- triazoles

Treatment of 3-rncthyl A-cthoxycarbonyl-5-aryIidcnchydrazono-l//-pyrazolcs 194 with bromine, in the presence of sodium acetate, in acetic acid gives substituted ethyl 3-aryl-7-cthoxycarbonyI-6-rncthyl-1 //-pyrazolo[5,1 -/ -[l,2,4]triazoles 55 (Equation 35) <2002ARK133>. Analogously, the reaction of compounds 194 with lead tetracetate [Pb(OAc)4] in acetic acid also gives l//-pyrazolo[5,l-c][l,2,4]triazoles 55 (unreported yield) (Equation 35) <2002ARK133>. 

Nitric acid may be precipitated by nitron [2218-94-2] (4,5-dihydro-l,4-diphenyl-3,5-phenylimino-l,2,4-triazole). The yellow precipitate maybe seen at dilutions as low as 1 60,000 at 25°C or 1 80,000 at 0°C. To prevent nitrous acid from interfering with the test results, it may be removed by treating the solution with hydrazine sulfate, sodium azide, or sulfamic acid. 

Fig. 1. HeterocycHc amines usedia azo dyes, (a) 2-Amino-6-nitrohenzothiazo1e [6285-57-0], (b) 3-amiao-5-nitro-2,l-benzisothiazole [14346-19-1], (c) 3-amiQo-4JT-l,2,4-triazole [65312-61 -0], (d) 5-amiQo-l,2,4-thiadiazole [7552-07-0, (e) 4,4 -diamiQo-2,2 -biphenylsulfone [6259-19-4], (f)...

Halogeno-l-methyl-l,2,3-triazoles undergo substitution reactions with amines, but the 4-halogeno analogs do not. 5-Chloro-l,4-diphenyl-l,2,3-triazole with sodium cyanide in DMSO gives the cyano derivative (63JCS2032). 1-Substituted 3-chloro- and 5-chloro-l,2,4-triazoles both react with amines. 

Nitropyrazoles rearrange to 4-nitropyrazoles in H2SO4 and to 3-nitropyrazoles thermally. Similar rearrangements are known for 7V-nitro-l,2,4-triazoles. 

Amino-l,2,4-triazole has been prepared by evaporating formylguanidine nitrate with sodium carbonate, and from 5(3)-amino-1,2,4-triazole carboxjdic acid-3(S) by heating above its melting point, or by a long digestion with acetic acid. ... 

Amino-l,2,4-triazole [61-82-5] M 84.1, m 159 , pKj 4.04, pK 11.08. Crystd from EtOH (charcoal), then three times from dioxane [Williams, McEwan and Henry J Phys Chem 61 261 1957]. 

Amino-l,2,4-triazole undergoes a cyclocondensation with 3-etlioxyacrolein (7) to form 1,2,4-triazolo[l,5-a]pyrimidine (3) or its [4,3-u] isomer (5), according to whether it reacts as IH or 4H tautomer 2 or 4. Moreover, the pyrimidines 3 and 5 can interconvert by a Dimroth rearrangement. Since the H NMR spectrum 30a does not enable a clear distinction to be made AMX systems for... 

A mixture of 300 ml. of water, 150 ml. of concentrated nitric acid, and 0.2 g. of sodium nitrite (Note 2) is placed in a 2-1. threenecked flask equipped with a stirrer and a thermometer. The stirred mixture is warmed to 45°, and 2 g. of l,2,4-triazole-3(5)-thiol is added. When oxidation starts, as indicated by the evolution of brown fumes of nitrogen dioxide and a rise in temperature, a bath of cold water is placed under the reaction flask to provide cooling and an additional 99 g. (total, 101 g. 1 mole) of 1,2,4-triazole-3(5)-thiol is added in small portions over the course of 30-60 minutes. The rate of addition and the extent of cooling by the water bath are so regulated as to keep the temperature close to 45 7° all during the addition. The water bath is kept cold by the occasional addition of ice. 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

Three skeleton atoms of a hetero-l,3-diene are incorporated into a five-membered ring system on reaction with 1,2 [n,n] compounds (e.g., hydrazines, reaction type 4, equation 10). On further heating in the presence of azobisiso-butyronitrile (AIBN), the bis(trifluoromethyl)-substituted 1,2,4-triazolines are transformed into 5-tnfluoromethyl-l,2,4-triazoles in high yield [t02 (equation 22). 

The conversion of a 4-arylazo-5-oxazolone into a 1,2,4-triazole by reaction with a Grignard reagent is mentioned in Section II, B, 3. In HiTnilar fashion, the rearrangement of compound 30 to derivatives of 3-carboxy-l,5-diphenyl-lfl -l,2,4-triazoles (40) proceeds readily in the presence of strong nucleophiles [Eq. (26)]. This transformation undoubtedly occurs by ring opening and dehydrative cychzation, and, indeed, the acyclic amide and hydrazide 41 have been isolated. ... 

In solutions of 3-mercapto-l, 2,4-triazoles the tautomeric equilibrium is shifted to the thione forms 181b (Scheme 65) [76AHC(S1), pp. 404, 415 96UK326]. Such an equihbrium was observed for 3-mercapto-5-ferrocenyl-4-phenyl-1,2,4-triazole 182 (94MI1121 96UK326). The thione tautomers 183 of 5-mercapto-l,2,4-triazoles are predominant [76AHC(S1), pp. 405, 414 97SA(A)699]. 

Similarly to aminoazoles, diaminoazoles prefer their amino forms 210 for 3,5-diaminopyrazole [76AHC(S1), p. 460 84CHEC-I(5)167 96CHEC-11(3)1] 211 for 3,5-diamino-l,2,4-triazole and 212 for 3,5-diaminoisothiazole [76AHC(S1), p. 460]. Ilie triamino structure 213 was proven by an X-ray crystallographic study of 4-aminoquinazine hydrobromide [73JCS(P2)lj. 

Cyclization of the 3-(2-aminoethyl)-l,2,4-triazoles 60 with aromatic aldehydes gave a mixture of the corresponding Schiff bases 61 and the 5,6,7,8-tetrahydro-l,2,4-triazolo[l,5-c]pyrimidines 62. Cyclization of 60 with car-bonyl-1,1 -diimidazole (CDI) afforded the 5-oxo analogs 63 (92JPR630) (Scheme 22). 

Dimethyl-1,2,4-triazolium iodide with nickel(II) acetate gives the carbene complex l2Ni( 1,4-dimethyl-l,2,4-triazol-5-ylidene)2 (97OM2209). 

Dimethyl-1,2,4-triazolium iodide with palladium acetate yields the carbene adduct 182 (97JOM(530)259). Under water it undergoes cis-trans isomerization to 183. Some other derivatives were reported in 1981 (81BCSJ800). 1,1 -Methylenebis(4-alkyl-l,2,4-triazolium)diiodides (alkyl = /-Pr, n-Bu, octyl) with palladium(II) acetate give the mononuclear complexes [L Pdl ] (99EJIC1965), where L2= l,l -methylenebis(4-R-l,2,4-triazol-2-ylidene) (R = /-Pr, n-Bu, octyl). Thermolysis of the products in THF gives the rran -dinuclear complexes 184... 

The same compound treated with 3-nitro-1,2,4-triazole (52) in alkaline solutions provided a mixture of the corresponding l,2,4-triazol-5-one (53), 5-substi-tuted 1,2,4-triazole 54 and the product of denitrocyclization 55 (Scheme 9) (95ZOR1223). 

Fragmentary ultraviolet spectral data are available for 3-amino-1,2,4-triazole. Early chemical data on 3,5-diamino-2-phenyl-l,2,4-triazole were interpreted on the basis of the diimino structure 201, but ultraviolet spectral evidence was later stated to favor either structure 202 or 203. ... 

From purine (51a), 9-methyl purine (51b) is formed. b. Triazoles. 3(5)-Phenyl-1,2,4-triazole (52) is converted by diazomethane into l-methyl-5-phenyl-l,2,4-triazole (53). ... 

Since both oxepin and its valence isomer benzene oxide contain a x-tb-diene structure they are prone to Diels-Alder addition reactions. The dienophiles 4-phenyl- and 4-methyl-4//-l,2,4-triazole-3,5-dione react with substituted oxepins at room temperature to give the 1 1 adducts 7 formed by addition to the diene structure of the respective benzene oxide.149 190,222... 

---