2,1,3-Oxadiazol 3,4-dinitro

Ethyl-4-hydroxy-l,2,5-oxadiazole, 1504 4-Oximino-4,5,6,7-tetrahydrobenzofurazan A-oxide, 2357 Potassium 4-hydroxyamino-5,7-dinitro-4,5-dihydrobenzofurazanide 3-oxide, 2176... 

Cyano-l,2,4-oxadiazol-5-yl)-4-cyanofurazan 2- (or 5-) oxide, 2630 4,5 -Cy clopentanofurazan-A-oxide, 1871 Dicyanofurazan A-oxide, 1804 4,6-Dinitrobenzofurazan A-oxide, 2089 3-Ethyl-4-hydroxy-l,2,5-oxadiazole, 1504 4-Oximino-4,5,6,7-tetiahydrobenzofurazan A-oxide, 2357 Potassium 4-hydroxyamino-5,7-dinitro-4,5-dihydrobenzofurazanide 3-oxide, 2176... 

Bromination of the phenyl group in 5-(4-nitrophenyl)-2-phenyl-l,3,4-oxadiazole in the presence of potassium bromate yielded o- (16%), m- (14%), and /)-bromo (26%) products, together with low yields of dibromo products <84JCR(S)382>. Similar results were obtained on nitration of 2,5-diphenyl-1,3,4-oxadiazole with fuming nitric acid to give dinitro products. The ratio of o- w-.-/ -nitration... 

Phenyl-hydrazino)- , 3,4-oxadiazole konnen aus 2-(2-Benzyliden-l-phenyl-hydr-azino)-l,3,4-oxadiazolen durch limhydrazonisierung mit 2,4-Dinitro-phenylhydrazin in miiBi-gen Ausbeuten synthetisiert werden547 (vgl. Synthesen anderer 2-Hydrazino-l,3,4-oxadiazole S. 607) ... 

The 1,3,4-oxadiazole unit was initially incorporated into PAE in 1967 by reacting 2,5-di(4-fluorophenyl)-l,3,4-oxadiazole with bisphenol A [1]. The same route and same difluoro monomer were used more recently to prepare a series of polyfarylene ether l,3,4-oxadiazole)s [33]. The corresponding dinitro or di-chloro compounds, 2,5-di(4-nitro or chlorophenyl)-1,3,4-oxadiazole [33], were... 

Dinitrobenzene-oxadiazole see 2,6-Dinitro-benzene-2-diazo-l-oxide 2 B59... 

The products of the thermolysis of 3-phenyl-5-(arylamino)-l,2,4-oxadiazoles and thiazoles have been accounted for by a radical mechanism.266 Flash vacuum pyrolysis of 1,3-dithiolane-1-oxides has led to thiocarbonyl compounds, but the transformation is not general.267 hi an ongoing study of silacyclobutane pyrolysis, CASSF(4,4), MR-CI and CASSCF(4,4)+MP2 calculations using the 3-21G and 6-31G basis sets have modelled the reaction between silenes and ethylene, suggesting a cyclic transition state from which silacyclobutane or a trcins-biradical are formed.268 An AMI study of the thermolysis of 1,3,3-trinitroazacyclobutane and its derivatives has identified gem-dinitro C—N bond homolysis as the initial reaction.269 Similar AMI analysis has determined the activation energy of die formation of NCh from methyl nitrate.270 Thermal decomposition of nitromethane in a shock tube (1050-1400 K, 0.2-40 atm) was studied spectrophotometrically, allowing determination of rate constants.271... 

The nitration of 2,5-diphenyl-l,3,4,-oxadiazole (44a) was first investigated by Grekov and Azen (61JGU1796), who reported that fuming nitric acid (d 1.51) alone results in a mixture of three isomers, the 2,5-bis(2-nitrophenyl), bis(3-nitrophenyl), and bis(4-nitrophenyl) products in yields of 40, 20, and 27%, respectively. They found that fuming nitric acid in sulfuric acid gives a preponderance of 3-nitrophenyI products with both the mononitro and the dinitro derivatives being obtained in yields of 31 and 38%, respectively. 

The chemistry of cyclopentafurazans (cyclopen-ta-1,2,5-oxadiazoles) and furazans fused to five-membered heterocycles with one to four heteroatoms has been reviewed (95JHC371). Treatment of 3-amino-4-nitro-l,2,5-oxadiazole with dinitrogen pentoxide yields dinitro-1,2,5-oxadiazole 89 (95MC102). The latter reacts normally with benzenethiol to give the sulfide 90,... 

The mass spectral characteristics of 4,7-dibromo-5,6-dinitro-2,l,3-benzothiadiazoles and 4-bromo-5-nitro-6,7-(2, l, 3 -oxadiazole)-2,l,3-benzothiadiazole have been considered [1361],... 

The reaction of 3-(2-nitroaryl)-2,3-dihydro[l,2,4]oxadiazol-2-ones (385) with phosphorus pentasulfide in refluxing xylene transforms the oxadiazole ring into the thiadiazole ring concomitant reduction of the nitro group and closure of the imidazole ring affords [l,3,4]thia-diazolo[3,2-a]benzimidazoles (386). The reaction of l,3-dinitro-4,6-bis[(5-(l,l-dimethylethyl)-2-oxo-2,3-dihydro[l,3,4]oxadiazol-3-yl)benzene (387) is only partially successful and gives some 2-( 1,1 -dimethyl-ethyl)-5-[5-( 1,1 -dimethylethyl)-2-thioxo-2,3-dihydro-[l,3,4]oxadiazol-3-yl]-6-nitro-5-[l,3>4]thiadiazolo[3,2-a]benzimidazole (388) (Equation (132)) <88PS(36)139>. 

Some current preparations of poly(arylene ether)s are carried out by nucleophilic displacements of activated aromatic dihalides or dinitro groups by alkali metal bisphenates. The reactions take place in polar aprotic solvents. The glass transition temperatures, tensile strengths, and tensile moduli of these materials tend to increase when heterocyclic units are incorporated into the backbones. Poly(arylene ether)s containing imide, phenylquinoxaline, imidazoles, pyrazoles, l,3,4-oxadiazoles, benzoxazoles, and benzimidazoles groups were prepared. 

I, 4-dinitro-2-methylpyrrole, ethylnitroHc acid and a derivative of furoxan (1,2,5-oxadiazole 2-oxide) 3-(5-methyl-4-furoxanyl)prop-2-enoic acid, which undergo decomposition to other products. Ascorbic acid completely eliminates the mutagenicity of 1,4-dinitro-2-methylpyrrole by reduction of the C-4 nitro group to a C-amino group. The l-nitro-2-methyl-4-amino pyrrole formed is non-mutagenic (Figure 11.1). 

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