Nucleophilic substitution in benzo-1,2,3,4-tetrazine 1,3-dioxides

Nucleophilic substitution in nitro- and bromobenzo-1,2,3,4-tetrazine 1,3-dioxides (BTDOs) was studied. In most cases, the bromo and nitro groups are replaced by methylamino, dimethylamino, azido, and methoxy groups without opening of the tetrazine ring. It was illustrated with the reactions of dibromo-BTDOs with sodium methoxide that the reactivity of positions 5 to 8 in their benzene ring as regards nucleophilic substitution changes in the following order: 6 > 8 > 7 > 5. The structures of the BTDOs obtained were confirmed by ¹H, ¹³C, and ¹⁴N NMR data.     

Cationic complexes of Eu(III) and Sr(II) with diphosphine dioxides in organic extracts

IR spectroscopy was used to study the structure and composition of Eu(III) and Sr(II) complexes formed by cation-exchange extraction of these metals from their aqueous nitrate solutions with dichlorethane solutions of mixtures of chlorinated cobalt(III) dicarbollide (CCD) as a superacid with diphenyldiphosphine dioxides containing a methyl (Me-DPDO), ethyl (Et-DPDO), or polyoxyethylene bridge between two phosphorus atoms of phosphine oxide groups. At molar ratios DPDO/CCD ≤ 1, [Eu(H₂O)_nL₄]³⁺ complexes are formed in organic phases, whereas with an excess of DPDO relative to CCD, Eu(NO₃)L ₄ ²⁺ complexes are formed, where L = Me-or Et-DPDO. Polyoxyethylenediphosphine dioxide forms anhydrous complexes of composition Eu:L = 1:1 and 1:2 with Eu(III) and outer-spheric complexes of composition Sr:L = 1:1 and 1:2 with Sr(II), where the organic ligand molecules envelop the hydrated Sr(H₂O) _n ²⁺ cation. The peculiarities of extraction of the complexes are explained based on data about their composition and structure.     

Electrophilic reactions of 3-hydroxyisonicotinic acid

Conclusions The aminomethylation, azo-coupling, and nitration of 3-hydroxyisonicotinic acid and its ester are directed to the 2 position, whereas their iodination proceeds with the formation of the 2-iodo and 2,6-diiodo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–454, February, 1977.     

Activating Mixing in Modification of Rubbers in Solution

The applicability of the previously developed principles of activating mixing to modification of rubbers in solutions was tested, and a process was developed for mechanochemical modification of cis-1,4-polyisoprene in rotary pulsation apparatus.     

Infrared spectra of cyclic ethers and their derivatives

Data for the characteristic bands of cyclic ethers are reviewed. The infrared spectra of a number of 2-mono- and 2, 5-di-substituted derivatives of tetrahydrofuran are investigated. Absorption bands at about 900 cm⁻¹ are related to pulsation vibrations, and those at about 1200 cm⁻¹ to antisymmetric skeletal vibrations, of the tetrahydrofuran ring. It is shown that to confirm the presence of a tetrahydrofuran ring in a molecule, it is necessary to take into account not only the band of valence antisymmetric vibrations of the group C-O-C (ν _C-O-C ^as 1075 cm⁻¹), but also bands due to ring pulsation vibrations (ring symmetric valence vibrations ν _sk ^s ∼ 900 cm¹).     

PMR spectroscopic study of the kinetics of H/D exchange in methyl groups in a series of heterocyclic azines

The rate of H/D exchange among methyl group protons in a series of substituted 3-hydroxypyridines, 5-hydroxypyrimidines, and their N-oxides has been shown to increase with increasing acidity of the medium. The most reactive form of these molecules is the cationic form at pH<2. The rate of H/D exchange of CH₃ group protons in 3-hydroxypyridine derivatives has also been found to be several orders of magnitude lower than the rates of exchange for methyl-substituted 5-hydroxypyrimidine and its N-oxide. Effective rate constants for methyl group proton exchange have been estimated. In the case of methyl-substituted 5-hydroxypyrimidine N-oxide derivatives it has been established that the rate of proton exchange is greater for an ortho-methyl group than for a methyl group in the para-position relative to the N-oxide site.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 93–96, January, 1991.     

Fluorine absorption spectra and some fluorides in condensed state

The absorption spectra of liquid F₂, NF₃, N₂F₄, CF₄, BF₃, NF₃, SF₆ have been obtained at diminished temperatures in the near ultra-violet region of the spectrum. It is shown that the absorption spectrum does not differ from the spectra in the gaseous phase, therefore the elementary absorption act is characterized by the cross section of photon absorption by an individual molecule. The absorption cross sections of the above mentioned molecules are represented in the liquid phase, which do not differ strongly from absorption cross sections of these molecules in the gaseous phase. The dependence of the absorption cross sections of liquid fluorine on its concentrations in solutions with N₂, Ar, NF₃, O₂ at - 196°C has been studied. The cross sections of photon absorption by the fluoride molecule in different liquid media with small fluorine concentrations have been obtained.     

Heterocyclic bioantioxidants. 2. Interaction of 3-nitro-4-substituted coumarins with mercaptans

3-Nitro-4-chlorocoumarin forms 3-nitro-4-substituted coumarins when it reacts with an equimolar quantity of benzyl mercaptan or thiosalicylic acid; with excess benzyl mercaptan, it forms 3,4-di-S-benzyl coumarin. 3-Nitro-4-methoxycoumarin under the same conditions, with an equimolar ratio of reagents, forms a mixture of monosubstituted and disubstituted products. A mechanism is proposed for these reactions.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1476–1479, November, 1991.     

Synthesis of 3-Aryl[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3]benzothiazole-6,7-dicarbonitriles from 5-Aryl-4H-triazole-2-thiols and 5-Bromo-5-nitrophthalonitrile

New 3-aryl-substituted [1,2,4]triazolo][3,4-b][1,3]benzothiazole-6,7-dicarbonitriles have been synthesized by successive interaction of 5-aryl-4H-triazole-2-thiols with 4-bromo-5-nitrophthalonitrile in the presence of K₂CO₃ initially at the bromine atoms and then at the nitro group.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 270–272, February, 2005.