An unusual reduction route of 2,4,6-trinitrobenzoic acid under conditions of aqueous-phase hydrogenation over Pd/Sibunit catalyst

For the first time it was established that the catalytic hydrogenation of 2,4,6-trinitrobenzoic acid to 1,3,5-triaminobenzene can proceed via the formation of aromatic hydroxyamines and cyclohexane-1,3,5-trione trioxime. As a result of aqueous-phase hydrogenation of sodium salt of 2,4,6-trinitrobenzoic acid in the presence of 5%Pd/Sibunit catalyst at a temperature of 323 K and pressure of 0.5 MPa, a trioxime in high yield (about 70 %) was obtained. Due to high selectivity to cyclohexane-1,3,5-trione trioxime the catalytic hydrogenation of sodium salt of 2,4,6-trinitrobenzoic acid can be considered as a new method for its synthesis.     

Effect of the reduction conditions of the supported palladium precursor on the activity of Pd/C catalysts in hydrogenation of sodium 2,4,6-trinitrobenzoate

The study addresses the effect of the reduction conditions of palladium polynuclear hydroxo complexes (PHC) supported on the Sibunit carbon material on the dispersion of the metal particles and the activity of 0.5%Pd/Sibunit catalysts in the selective hydrogenation of sodium 2,4,6-trinitrobenzoate to 1,3,5-triaminobenzene in an aqueous solution (temperature of 323 or 343 K, pressure of 0.5 MPa). The palladium PHC were reduced using the most common methods pertaining to catalyst preparation: liquid-phase reduction with sodium formate and reduction in a hydrogen flow at elevated temperature. It was found that high-temperature reduction in the gas phase gives rise to Pd particles with a markedly lower dispersion compared with the sample obtained under mild liquid-phase reduction conditions. The catalytic activity of the sample containing large Pd particles proved to be higher than the activity of the catalyst obtained by reduction with sodium formate.     

2,4,6-三对氨基苯氧基-1,3,5-均三嗪的合成

以三聚氯氰和对硝基苯酚为原料,经取代、还原合成了2,4,6-三对氨基苯氧基-1,3,5-均三嗪。对Pd/C水合肼、SnCl2·2H2O-HCl及Pd/C催化加氢三种不同还原体系进行比较。采用1H-NMR、FT-IR和元素分析方法对产物进行结构表征。     

Discotic liquid crystalline hydrazone compounds: synthesis and mesomorphic properties

[reaction: see text] 1,3,5-Trisacetoacetamidobenzene with three 1,3-diketo groups was synthesized by the reaction of 1,3,5-triaminobenzene with diketene. Discotic hydrazone compounds were prepared by the diazo coupling reaction between 1,3,5-trisacetoacetamidobenzene and diazonium salts of 4-alkyloxyphenylamines. The compounds existed in hydrazone forms exclusively, being stabilized by the intramolecular hydrogen bonds, and showed discotic nematic or columnar hexagonal mesophases.     

Two Roomtemperature-stable Trications – Triprotonated Triamino- and Tricyanobenzene

Protonation of 1,3,5-tricyano- and 1,3,5-triaminobenzene was achieved in various superacidic media, resulting in the formation of the respective trinitrilium and triammonium species. Furthermore, the respective N-methyl nitrilium species was synthesized by methylation. Characterization was performed by NMR and vibrational spectroscopy, followed by single-crystal X-ray diffraction analyses of selected species. Fourfold protonation of the amine, which would have led to the triammonium arenium species, could not be achieved. Quantum chemical calculations are employed to enable full vibrational assignment as well to quantify charge localization.     

Free radicals: XXVIII. Reaction of 2,4,6-triphenylpyranyl with (diacetoxy-λ3-iodanyl)benzene

The major product of the reaction of 2,4,6-triphenylpyranyl with (diacetoxy-λ³-iodanyl)benzene in acetonitrile and acetone was 2,4,6-triphenylpyrylium acetate. Analogous reaction in isopropyl alcohol resulted in the formation of methane, carbon dioxide, 1,3,5-triphenylpent-2-ene-1,5-dione, 2-benzoyl-3,5-diphenylfuran, 1,3,5-triphenylpenta-2,4-dien-1-one, and a small amount of 2,4,6-triphenylpyrilium acetate.     

The thermodynamic properties of the esters of 2,4,6-trinitrobenzoic acid

The thermodynamic properties of the esters of 2,4,6-trinitrobenzoic acid have been investigated using the techniques of hot-stage microscopy and differential scanning calorimetry. In each case an enantiotropic transition process was observed below the melting point. This transition has been explained in terms of restricted rotation and conformational freedon of the flexible alkyl chain in the crystalline solid state.     

Effect of medium acidity on the efficiency of oxidation of 2,4,6-trinitrotoluene to 2,4,6-trinitrobenzoic acid

An effect of boric acid additives on oxidation of 2,4,6-trinitrotoluene (TNT) to 2,4,6-trinitrobenzoic acid (TNBA) with chromic anhydride in concentrated (96—100%) H₂SO₄ has been studied. In the presence of tetrahydrosulfatoboric acid HB(HSO₄)₄ formed in situ (up to 5 mol.%) or added as a preliminary prepared solution (up to 1 mol. %), TNT is selectively oxidized to TNBA in the yields up to 95—99%. The mechanism including formation of TNT dication as a key step of its oxidation at the methyl group has been suggested.     

Generation and reactions of anionic σ-adducts of 1,3-dinitrobenzene and 1,3,5-trinitrobenzene with carbanions in a gas phase,using an electrospray ion source as the chemical reactor

Di- and trinitrophenide anions generated by decarboxylation of the anions of 2,4-, 3,5-, and 2,6-dinitrobenzoic acids and 1,3,5-trinitrobenzoic acid in the medium-pressure region of an electrospray ion source react locally with various C-H acids delivered in the form of vapors mixed with the curtain gas, yielding anionic sigma-adducts. Positive results were obtained for aliphatic aldehydes, ketones, esters and nitriles. All three dinitrobenzoic acids bearing NO(2) groups in the meta position to each other gave the same sigma-adducts which can be rationalized by a reaction sequence including proton transfer from the C-H acid to the nitrophenide anion and subsequent formation of the sigma-adduct by the reaction of 1,3-dinitrobenzene with the carbanion within the ion-molecule complex. It was found that such a reaction is possible only for C-H acids with a gas-phase acidity lying within a narrow, strictly defined range whose location on the acidity scale depends on the acidity of the nitroarene. The sigma-adduct formed in the reaction of the 2,4-dinitrophenide anion with CH(2)Cl(2) undergoes rapid HCl elimination yielding an anion with the same composition as that produced by the Vicarious Nucleophilic Substitution of hydrogen reaction but with a different structure.     

An efficient and facile one-pot synthesis of structurally unique 2,4,6-tris(arylchalcogeno)-1,3,5-triazine and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene

An efficient one-pot synthesis of a novel class of 2,4,6-tris(arylchalcogeno)-1,3,5-triazine (sulfur, selenium and tellurium) and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene (sulfur and selenium)-containing ligands has been developed based on the reaction of 2,4,6-trichloro-1,3,5-triazine and 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene with the corresponding arylchalcogenide anions generated in aqueous tetrahydrofuran.     

Heterogeneous photocatalytic transformations of s-triazine derivatives

Photocatalytic processes arising from irradiated semiconductor oxide suspensions containing 1,3,5-triazine (s-triazine) derivatives are described. Whereas unsubstituted 1,3,5-triazine undergoes hydrolysis, irrespective of the presence of the photocatalyst, other chloro-, amino-, mercapto-, allyloxo-, carboxy- derivatives give rise, in the presence of band-gap excited semiconductor oxide, to nearly stoichiometric formation of 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid). This last compound is stable toward photocatalytic conditions as well as to ^·OH chemically generated in homogeneous solution (H₂O₂/UV or Fenton's reagent). Only partial conversion in cyanuric acid is observed for 2,4,6-tris(2-pyridyl)-1,3,5-triazine and possible explanation is given. The formation of inorganic species (nitrate, chloride, sulfate and ammonium ions) is reported and the mechanism of their evolution presented.     

Synthesis of 1H-1,5,7-triazacyclopenta[<Emphasis Type="Italic">c,d</Emphasis>]phenalenes by the electrophilic amination of perimidines using sodium azide in PPA

A method was developed for the synthesis of 1H-1,5,7-triazacyclopenta[c,d]phenalenes by the electrophilic amination of perimidines using the new sodium azide/PPA reagent system and a subsequent one-pot reaction with 1,3,5-triazines. A multicomponent variant of this reaction is possible in the case of 2,4,6-trimethyl- and 2,4,6-triphenyl-1,3,5-triazines.     

Synthesis of cyclo-2,4,6-triarsa-1,3,5-triazanes from cyclo-2,4-diarsa-1,3-diazanes demonstrating the general influence of substituent steric strain on the relative stability of pnictazane oligomers

2,4-Dichloro-1,3-diaryl-cyclo-2,4-diarsa-1,3-diazanes (aryl = 2,6-dimethylphenyl, Dmp, or 2,6-diisopropylphenyl, Dipp) have been transformed into the corresponding 2,4,6-trichloro-cyclo-2,4,6-triarsa-1,3,5-triazanes on reaction with GaCl(3) followed by 4-(dimethylamino)pyridine (DMAP). The nitrogen bound Dmp and Dipp substituents impose "medium" substituent steric strain on the heterocycles influencing the relative thermodynamic stability of potential oligomers in favor of the trimers. This ring expansion disproportionation reaction is initiated by chloride ion abstraction, and the intermediate 2,4-dichloro-1,3,5-tris(2,6-diisopropylphenyl)-cyclo-2,4-diarsa-1,3,5-triazane-6-arsenium tetrachlorogallate has been isolated and structurally characterized. Subsequent reaction with 4-(dimethylamino)pyridine (DMAP) effects release of chloride ion from the gallate anion and consequential formation of a covalent As-Cl bond in the trimer. The observations are analogous to those for the phosphorus derivatives demonstrating a general applicability of this new synthetic procedure for the development and diversification of cyclopnictazane chemistry.     

Nucleophilic Substitution Reactions of 2,4,6-Tris(trinitromethyl)-1,3,5-triazine. 3. Reaction of 2,4,6-Tris(trinitromethyl)-1,3,5-triazine with Azides and Hydrazine

As a result of nucleophilic substitution of the trinitromethyl groups in 2,4,6-tris(trinitromethyl)-1,3,5-triazine, the corresponding monoazido and diazido derivatives have been synthesized. The reaction of the starting triazine with hydrazine acetate in the presence of trifluoroacetic acid leads to 1-acetyl-2,2-bis[4,6-bis(trinitromethyl)-1,3,5-triazin-2-yl]hydrazine.     

Synthesis of 2-arylpyrrolidines by reaction of γ-ureidoacetals with benzene-1,3,5-triol

New 2,2′-(2,4,6-trihydroxybenzene-1,3-diyl)dipyrrolidine derivatives have been synthesized by reaction of benzene-1,3,5-triol (phloroglucinol) with γ-ureidoacetals in the presence of trifluoroacetic acid as catalyst.     

Theoretical study of reaction pathways to borazine

Four reaction pathways from diborane and ammonia to borazine, (HBNH)3, have been studied computationally at the density functional level (B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d)). The cycloaddition of H2BNH2 to 1,3-diaza-2,4-diborabuta-1,3-diene and subsequent elimination of two molecules of H2 was found to be the lowest-energy pathway to (HBNH)3. In the other pathways, the formation and conversion of the intermediates 1,3,5-triaza-2,4,6-triborahexatriene, cyclotriborazane, and 1,3,5-triaza-2,4,6-triborahexa-1,5-diene into (HBNH)3 were investigated. The formation of 1,3-diaza-2,4-diborabuta-1,3-diene and, subsequently, the formation and electrocyclization of 1,3,5-triaza-2,4,6-triborahexatriene and the cycloaddition of H2BNH2 to 1,3-diaza-2,4-diborabuta-1,3-diene are predicted to be the kinetically favored pathways to (HBNH)3 in the gas phase. At low concentrations of 1,3-diaza-2,4-diborabutene, high concentrations of H2BNH2, and a temperature of 298.15 K, the formation of the polyolefins H3BNH2(H2BNH2)nNHBH2 (n=1,2) is predicted to be competitive with the formation of 1,3-diaza-2,4-diborabuta-1,3-diene.     

Selective reduction of one, two, or three nitro groups in 1,3,5-trinitrobenzene with hydrazine hydrate

A method was developed for successive selective reduction of one, two, or three nitro groups in 1,3,5-trinitrobenzene with hydrazine hydrate in the presence of iron chloride and charcoal. This method provides an approach to the one-pot synthesis of 3,5-dinitroaniline, 1,3-diamino-5-nitrobenzene, or 1,3,5-triaminobenzene from 1,3,5-trinitrobenzene. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 904–905, May, 2006.     

Thermal C1-C5 diradical cyclization of enediynes

Computational studies at the BLYP/6-31G(d) level (supplemented by BCCD(T)/cc-pVDZ calculations) suggest that in aryl-substituted 1,2-diethynylbenzenes, steric effects disfavor the thermal C1-C6 diradical cyclization reaction (Bergman) and electronic effects favor the regiovariant C1-C5 cyclization to the extent that the C1-C5 process should become an important reaction pathway in the thermolyses of such compounds. Experimentally, thermolyses of 1,2-bis(2,4,6-trichlorophenylethynyl)benzene, a particularly favorable case, yields only products derived from C1-C5 cyclization [specifically, 1-(2,4,6-trichlorobenzylidene)-2-(2,4,6-trichlorophenyl)-1H-indene and its hydrogenation product 3-(2,4,6-trichlorobenzyl)-2-(2,4,6-trichlorophenyl)-1H-indene], and even for the parent hydrocarbon 1,2-bis(phenylethynyl)benzene, the formation of C1-C5 cyclization products is competitive with the major Bergman reaction. Although some C1-C5 cyclization products are probably formed by transfer hydrogenation from 1,4-cyclohexadiene (commonly included in such reactions), thermolyses in the absence of 1,4-CHD as well as deuterium labeling studies confirm the existence of direct C1-C5 diradical cyclizations for diaryl-substituted enediynes.     

制备2,4,6-三甲基苯甲醛的新方法

1,3,5-三甲苯与溴素在水溶液中反应生成2,4,6-三甲基溴苯(1,收率90%);1制备成格氏试剂再与甲醛反应得到2,4,6-三甲基苄醇(2,收率79%)。2经铬酸氧化得2,4,6-三甲基苯甲醛(3,收率90.3%)。3的总收率达64.2%,纯度97%。2和3的结构经1H NMR和MS确证。     

具有三角架结构的丙二酸、β-二酮和吡唑衍生物的合成、结构及超分子自组装

本文系统的探讨了1,3,5-丙二酸衍生物取代基（2-5）,戊烷-2,4-二酮取代基(6),3,5-二甲基-1H-吡唑取代基-2,4,6-三乙基苯(7)的合成和结构。1H NMR分析表明,这些化合物在溶液中具有高度的对称性;X-单晶衍射分析确认这些化合物在固态均采取1,3,5-交替构象,即三个功能取代基团处在中心苯环平面的一边,而三个乙基则位于该中心苯环平面的另一边。分子内和分子间氢键是化合物4,5,7实现超分子自组装的主要作用力。化合物7（L）的吡唑取代基与铜离子（II）通过Cu-N的配位键作用形成笼状配合物8 (Cu3L2),在配合物8中,两配体分子7（L）采取了顺式面面相向的构象。