A study on the separation and distribution of the chemical forms of131I produced from thermal neutron-irradiated tellurium compounds by thin-layer chromatography

The separation and distribution of the chemical forms of¹³¹I produced from thermal neutron-irradiated tellurium compounds were investigated by thin-layer chromatography using alumina as adsorbent and water as developer as well as the effect of iodine carriers added on the distribution of different chemical forms of¹³¹I was studied. The effects of both atmospheric oxygen and light were investigated on the oxidation of carrier-free iodide on the thin-layer plate.     

Dipole moments of nitro derivatives of indazole

The dipole moments of indazole and a number of its nitro derivatives in dioxane solution were measured. The directions of the vectors of the dipole moments of indazole in the tautomeric 1-H and 2-H forms were determined to solve the problems associated with the tautomerism and the position of the substituents in the molecules. The experimental values of the dipole moments, of the investigated compounds were compared with the values calculated via a vector additive scheme. As a result it was shown that the mononitro and dinitro derivatives of indazole exist primarily in the 1-H tautomeric form, whereas the trinitro and tetranitroindazoles exist in the 2-H tautomeric form. The ratios of the isomers were calculated for compounds that have dipole moments intermediate between the 1-H and 2-H forms. A deviation between the experimental and calculated dipole moments of compounds containing two nitro groups in the ortho position was established; this may be explained by disruption of the coplanarity of the molecules or by deviation from additivity because of the introduction of strong electron-acceptor substituents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1669–1671, December, 1977.     

Reaction of arabinogalactan with isonicotinic acid hydrazide

The reaction of an arabinogalactan and its oxidized forms with the antituberculosis preparation isonicotinic acid hydrazide was investigated. The chemical composition and certain physicochemical properties of the modified compounds were studied. A correlation was found between the concentration of carboxylic acids in the polysaccharides and the drug content in the modified compounds. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 221–223, May–June, 2008.     

3-Diazopyrazolo[3,4-b] pyridine,a versatile synthon for new heterocyclic systems

3-Diazopyrazolo[3,4-b] pyridine was synthesized and its transformations were investigated. With reactive methylene compounds the corresponding hydrazones are formed and they can be cyclized into condensed 1,2,4-triazine derivatives. With amines of thiols the diazo compound forms triazenes or diazosulfides. From hydrazines tetrazenes are formed first and they give upon fragmentation a mixture of N-N or C-N bond fission products. The diazo compound undergoes cycloaddition, reacting as a 1,2-dipole. 3-Azidopyrazolo [3,4-b] pyridine was prepared and converted into the tetrazolo isomer, whereas the 3-amino compound was used for the synthesis of some pyridopyrazolopyrimidines.     

Quantum-chemical investigation of some oligomeric heteroaromatic compounds

Indigo and its dimer, trimer, dehydro, and leuco forms were investigated within the framework of the Pariser-Parr-Pople method. The electronic structures of the compounds in the ground and excited states and the effect of chain lengthening are discussed, and the UV absorption spectra are interpreted. Several characteristics of the chromaticity of the investigated compounds as representatives of vat dyes are examined. The estimated (from calculations) energetic favorability of the indigoid, dehydro, and leuco forms of indigo is used in discussing the observed and experimental ease of redox transformations of indigo.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 794–798, June, 1972.     

Separation of pyridine compounds on ion-exchange resins

The reaction of pyridine compounds (pyridine, 4-methylpyridine, 4-hydroxypyridine, 4-carboxypyridine, pyridine-4-aldehyde, and pyridine-4-aldoxime) with KU-2 cation-exchange resins in the H⁺, K⁺, and NH₄ ⁺ forms and with AV-17 anion-exchange resins in the OH^– and Cl^– forms was investigated. A dependence of the maximum partition coefficients of the pyridine compounds on the composition and concentration of the eluent was found. The chromatogram of the separation of a mixture of pyridine compounds on AV-17 (Cl^– form) is presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 220–224, February, 1971.     

Solid-state photochromism of chromenes: enhanced photocoloration and observation of unstable colored species at low temperatures

Solid-state photochromism of benzopyrans and naphthopyrans (chromenes) was investigated in the temperature range between 300 and 80 K. Variable-temperature diffuse reflectance spectroscopy of microcrystalline powders showed that the extent of photocoloration was greatly enhanced at low temperatures. All the chromenes examined exhibited solid-state photochromism at low temperatures, even when they showed little or no photocoloration at room temperature. The solid-state photochromic properties of the chromenes were quite similar to those reported for analogous photochromic compounds of spiropyrans and spirooxazines, which indicates that these classes of compounds are generally photochromic even in the solid state. Photobleaching reactions of the colored merocyanine forms proceeded at low temperatures through the formation of a colorless intermediate, instead of directly resuming the original closed form. In addition to two stable planar merocyanine forms, which are usually observed in the photochromic reactions in solution, photoreactions at low temperatures allowed us to observe unstable colored species, which were tentatively assigned as nonplanar cisoid forms, and were stabilized in the solid state at low temperatures.     

Photochromism of 2-benzyl-3-benzoyl-4(1H)-quinolone derivatives

A series of 2-benzyl-3-benzoyl-4(1H)-quinolone derivatives was investigated. The UV–vis spectra of all photochromic derivatives and the corresponding colored photoenols are similar and almost solvent independent. In contrast, the stability of the photoenols depends strongly on the substituents at the quinolone moiety and solvent. We conclude that conversion of the photoinduced forms into the initial quinolones occurs through ionization rather than usual for photochromic compounds thermal relaxation or sigmatropic H-shift. The experimental observations are in good agreement with the results of quantum mechanical calculations.     

Amphiphilic N-benzoyl-1-amino-1-deoxy-D-glucitol derivatives forming thermotropic lamellar, columnar and different types of cubic mesophases

Novel amphiphilic glucamine derivatives have been synthesized. These are N-benzoyl-1-deoxy1-methylamino-D-glucitols and N-benzoyl-1-amino-1-deoxy-D-glucitols carrying one, two or three aliphatic chains (CnH2n 1O- with n 3, 6 and 12) grafted to the benzamido group. The thermotropic mesophases of these compounds were studied by thermal polarizing optical microscopy and differential scanning calorimetry, and some also by X-ray scattering. Depending on the number and the length of the alkyl chains lamellar, bicontinuous cubic, hexagonal columnar or inverted micellar cubic mesophases were detected by analogy with lyotropic systems. In the contact region between lamellar phases of the single chain amphiphiles and micellar cubic phases of the mesomorphic triple chain compounds, hexagonal columnar phases can be induced. A hexagonal columnar phase was also induced in the contact region between a bicontinuous and a micellar cubic mesophase. The lyotropic liquid crystalline behaviour of the dodecyloxy substituted N-benzoyl-1-deoxy-1-methylamino-D-glucitols was investigated by the solvent penetration method using ethylene glycol as protic solvent. On increasing the solvent content, the double chain compound forms a cubic and a lamellar mesophase and the triple chain compound forms a hexagonal columnar lyomesophase. The dodecyloxy substituted compounds were also investigated with respect to their behaviour as thin films at the air-water interface using a Langmuir film-balance. Different types of pi/Aisotherms were observed whereby the molecular areas at collapse were determined either by the size of the carbohydrate head group (single chain compounds) or by the number of alkyl chains (double and triple chain compound).     

Glassy carbon electrodes modified with mixed covalent monolayers of choline, glycine, and glutamic acid for the determination of phenolic compounds

A series of mixed covalent monolayer carbon glassy electrodes (choline/amino acid/GCE) was prepared using choline and amino acids, and the properties were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The oxidations of phenolic compounds including dopamine hydrochloride, epinephrine and phenol have been studied. Electrooxidation of phenols, first leads to the formation of phenoxy radical, which reduces to phenols and hydroquinone; the reaction of polyoxyphenylene is effectively restrained at this electrode, unlike only at chlorine or amino acids modified electrode or bare electrode, which rapidly forms polyoxyphenylene and results in electrode passivation. Owing to significant improvement of electrode passivation shaped insulating polymerization, these mixed covalent monolayer carbon glassy electrodes show themselves excellent resistance ability for pollution, could be successfully used as amperometric sensor for phenolic compounds.     

Polarographic reduction and tautomeric structure of 2-amino-5-arylazothiazoles

The polarographic behaviour of a series of 2-amino-4-phenyl-5-arylazothiazoles has been investigated at a dropping mercury electrode. Each of the compounds studied exhibits one wave which was shown to correspond to the reductive cleavage of the azo linkage by a 4e irreversible step. On the basis of the polarographic data, it was concluded that the compounds exist only in one tautomeric form, namely the aminoazo structure 1 . The results of E_1/2 — σ_X correlations and HMO calculations of bonding energies of the various possible tautomeric forms 1–3 indicate that the aminoazo form 1 is the most stable structure of the compounds examined.     

β-thioxo esters—II : Evidence for ester group rotamerism and pertubation of the intramolecular hydrogen-bonding in enethiolized 2-thioxo cycloalkanecarboxylic esters

Ethyl 2-thioxo cycloalkanecarboxylates of ring sizes 5–9 exist in CCl₄ solution in the tautomeric cis-enethiol form, whereas the 10–12 membered ring compounds exist as an equilibrium mixture of several tautomeric forms. On the basis of NMR and IR spectral data it is concluded that the cis-enethiols exist as equilibrium mixtures of two rapidly interconverting rotameric forms, one involving intramolecular H-bonding, the other having the ester group rotated through 180° so that the ester carbonyl group is unable to form an intramolecular H-bond, although still conjugated with the enethiolic double bond. The relative equilibrium concentrations at ～35° of the two rotameric cis-enethiol forms have been determined for all investigated compounds.     

Protonation of imidazo[2,1-b]thiazole and thiazolo[2,3-f]purine

The protonation of imidazo[2,1-b]thiazole and thiazolo[2,3-f]purine was investigated by PMR spectroscopy. In CF₃COOH and D₂SO₄ the imidazothiazole forms a monocation, the structure of which corresponds to the addition of a proton to the nitrogen atom of the imidazole ring. In aqueous D₂SO₄ solutions, the thiazolopurine forms mono- and dications. The first protonation occurs at the nitrogen atom of the pyrimidine ring, while the second protonation occurs at the nitrogen atom of the imidazole ring. The effect of delocalization of the positive charge in the cations of the investigated compounds was examined.     

3-dinitrobenzoylhydrazones of organosilicon carbonyl compounds

Conclusions The reaction of 3,5-dinitrobenzoylhydrazide with organosilicon aldehydes and ketones was investigated. It was shown that this reagent forms readily crystallizing 3,5-dinitrobenzoylhydrazones and is suitable for the identification of organosilicon carbonyl compounds.     

Mass-spectral behavior of substituted 2-alkylaminobenzoxazoles and 3-methyl-2-alkyliminobenzoxazolines

Schemes that reflect the peculiarities of each of the investigated groups of compounds and make it possible to distinguish the amino and imino forms are given on the basis of a study of the dissociative ionization processes of 18 2-alkyl(dialkyl)-aminobenzoxazoles and six 3-methyl-2-alkyliminobenzoxazolines. A qualitative relationship between the electronic properties of the substituents in the aromatic ring and the formation of the imino forms of the molecular ions in the gas phase was found.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 304–308, March, 1981.     

Investigation of the mechanism of the recyclization of furans to thiophenes and selenophenes under acid-catalysis conditions. 3. Investigation of the recyclization of homologs and functional derivatives of furan. Quantum-chemical calculations of the objects of the recyclization

The kinetics of the conversion of di-, tri-, and tetraalkylfurans to the corresponding thiophenes were investigated. A correlation between the reactivities and structures of the investigated furans was established. Quantum-chemical calculations of the objects of the recyclization were made. The calculated and experimental data on the reactivities of the investigated compounds were compared. The most likely pathway of the protonation of furans in their recyclization was determined on the basis of calculations of the total energies of the protonated forms.For Communication 2 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1614–1620, December, 1993.     

用固体核磁共振和电子能谱研究我国高硫煤的结构

用固体ＮＭＲ和ＸＰＳ技术研究了我国三种（广西合山煤、湖南辰溪煤、浙江长广煤）高硫煤的结构特征。由固体ＮＭＲ测试结果计算出煤的十二种结构参数和芳香簇团的大小，获得了三个样品的结构特征及变化规律，由ＸＰＳ测试结果得到了煤中各种不同形态硫、氮的结合能数值。根据前入所做的模型化合物的结果，得知三咱煤中硫元素主要以噻吩硫形态存在，氮元素主要以吡啶和中的形态存在。     

Three-dimensional supramolecular architecture based on 4,4′-methylene-bis(benzenamine) and aromatic carboxylic acid guests: Synthons cooperation, robust motifs and structural diversity

The two-component solid forms involving 4,4??-methylene-bis(benzenamine) included both salts and co-crystals, while 4,4??-methylene-bis(benzenamine) crystallized exclusively as a salt, in agreement with the differences in the pK _a values. Many of the crystal structures displayed either the neutral or the ionic form of the carboxylic acid-amino heterosynthon, and the similarity in crystal structures between the neutral and the ionized molecules makes the visual distinction between a salt and co-crystal dependent on the experimental location of the acidic proton. A variety of supramolecular hydrogen bonded motifs involving interactions between the aza molecules and carboxylic acid groups are observed rather than just the O-H??N/O-H??O motif. The motifs are identical in all the two compounds analyzed showing the robustness of these supramolecular synthons. In all adducts, recognition between the constituents is established through either N-H??O and/or O-H??O/O-H??N pairwise hydrogen bonds. In all adducts, COOH functional groups available on 1 and 2 interact with the N-donor compounds. The COOH moieties in 1 forms only single N-H??O hydrogen bonds, whereas in 2, it forms pairwise O-H??N/N-H??O hydrogen bonds. The supramolecular architectures are elegant and simple, with stacking of networks in 2, but a rather complex network with a threefold interpenetration pattern was found in 1. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss.     

Study of the reactivity of chalcogen hexafluorides with graphite

The intercalation reaction of chalcogen hexafluorides, EF₆ (E=S, Se, Te), with graphite was investigated. It occured only under a fluorine atmosphere and first stage intercalation compounds were obtained with TeF₆ or SeF₆, as well as a partial graphite fluorination. SF₆ did not intercalate but catalyzed the complete fluorination of graphite. All compounds were characterized by X-ray diffraction, thermogravimetric analysis, infrared and ¹⁹F NMR spectroscopies. Entities, such as TeF₆ and SeF₆ were identified. Others, such as EF₇⁻, EF₈²⁻, …, and possible SeF_n polymeric forms could exist. In all cases, the presence of fluorinated graphite was found.     

Solvent effect on tautomeric equilibria and dipole moments of some alpha substituted benzoylacetanilides

Based on dipole moment measurements, a study was made of the keto-enol equilibria of five alpha substituted benzoylacetanilide derivatives in two non-polar and one polar solvents at 30°C. The enol mole fractions of the compounds investigated were determined by analysis of their ultraviolet spectra. The same type of study was extended to salicylanilide for its resemblance to the enol tautomer of these compounds. A deduction of the most probable configurations of the keto and enol forms was tentatively made through a comparison between the dipole moments of some suggested configurations for these forms of benzoylacetanilide and those measured in benzene for the alpha methyl benzoylacetanilide and salicylanilide, respectively. These inferred configurations were used to calculate the dipole moments of both tautomers of the other compounds, and consequently, the dipole moment values of their tautomeric mixtures in dioxane and chloroform. A comparison between the dipole moment values of their tautomeric mixtures in dioxane and chloroform. A comparison between the dipole moment values calculated in this way and those measured indicated a solute-solvent interaction with dioxane, which chloroform behaved as a non-interacting solvent.