Infra-red and electronic absorption spectra of 2-bromopyrimidine

The electronic absorption spectrum of 2-bromopyrimidine in the u.v. region has been recorded in vapour phase and in solution phase in different solvents. Only one system has been observed in vapour phase and it has been identified as π* ← n transition. In solution phase two systems have been identified. The system on the longer wavelength side has been identified as corresponding to the one observed in vapour phase while the other one has been assigned to a π* ← π transition. The infrared spectrum of this molecule has also been recorded and analysed. Help of these i.r. data has been taken to analyse the u.v. spectrum of 2-bromopyrimidine, considering the molecule as belonging to C_2υ point group.     

Radioimmunoassay of human placental lactogen

A sensitive and specific radioimmunossay procedure (RIA) has been developed for the measurement of Human Placental Lactogen (HPL). Pure HPL has been labelled with¹²⁵I and a specific activity of 100 μCi/μgm of HPL has been attained. Dextran-coated charcoal has been employed to separate the bound from the free hormone in radioimmuno-assay. The sensitivity of this technique has been found to be 0.2 ng of HPL. Intraassay and inter assay variations have been found to be less than 10%. This procedure has been adopted to establish the normal range of HPL in pregnant women at different periods of gestation, and to evaluate risk pregnancies.     

Radioimmunoassay of human chorionic gonodotropin

A rapid and sensitive radioimmunoassay has been developed for the measurement of Human Chorionic Gonadotropin (HCG) in serum. Human chorionic gonadotropin has been labelled with¹²⁵I to attain a specific activity between 80–120 μCi/μg. Aqueous dioxane (74 vol. %) has been employed to separate the bound and freehormone in the radioimmunoassay. The sensitivity of this technique has been found to be ∼1.5 mIU/ml of HCG. The intra assay variation has been found to be less than 5% and inter assay variation has been found to be less than 12%.     

Mass spectrometry of the self-association and complexation of triterpene saponins and cholesterol

Electrospray ionization mass spectrometry has been used to study the self-association of α-hederin and hederacoside C (from Hedera) glycosides. The complexation of glycosides with cholesterol has been considered. It has been revealed that α-hederin forms self-associates registered in ESI mass spectra, while no self-associates have been found for hederacoside C and cholesterol. Cholesterol produces molecular complex with α-hederin, while complex formation between cholesterol and bisdesmoside hederacoside has not been observed.     

Chelate formation of ammonium aurintricarboxy-late with bivalent copper : Physico-chemical investigation of the composition,structure and stability

The formation of a coloured chelate, having λmax at 540 mμ, between cupric ions and ammonium aurintricarboxylate has been reported. It has been concluded that only one complex having metal : reagent ratio of 1:2 is formed in solution. The method adopted for investigation has been the continuous variation method, using spectrophotometric and electrical conductance measurements. It has been observed that there is an increase in acidity on mixing the reactants, which shows that hydrogen ions are liberated as a result of chelation It has been suggested that chelation occurs between the phenolic oxygen and the adjacent carboxylic oxygen.A method has been presented for the calculation of formation constant from spectrophotometric data and the value of K in the case of the chelate investigated has been calculated to be 6.45.10⁸. The free energy of formation works out to be —14.6 kcal at 25°C.     

Mechanism of the reaction of CO with NO on palladium catalysts

A mechanism has been proposed for the reaction of CO + NO + (O₂) on palladium catalysts and the elementary stages of the reaction have been subjected to thermodynamic analysis. A kinetic model of the reaction has been constructed. The model of the reaction CO + NO has been analyzed in comparison with the reaction CO + O₂; the existence of a multiplicity of stationary states and critical transitions in the system CO + NO has been demonstrated. Numerical calculation has explained the accelerating influence of oxygen and the inhibiting influence of CO on the rate of the reaction CO + NO, observed experimentally.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 484–489, July–August 1987.     

Effect of temperature on the region of residual rays of CdP2 and ZnP2 single crystals

The technology of growing tetragonal ZnP₂ and CdP₂ single crystals has been presented. The dielectric permittivity dispersion of tetragonal zinc and cadmium diphosphides in the region of residual rays has been studied, and its dependence on temperature has been scrutinized.     

The investigation of the electronic effects of polyfluoro-aryl group by means of nmr spectroscopy

The relationship between NMR ¹⁵N, ¹⁷O, ³¹P, ⁷⁷Se, ¹³C spectral parameters and electronic structure of number of polyfluoroaromatic compounds has been discussed. The increase of the nuclei shielding has been found in all classes of investigated polyfluorinated compounds in respect to the corresponding hydrocarbon analogues. That effect has been discussed in terms of decrease of the conjugation between the unshared electron density of heteroatoms and the π-system of polyfluorinated benzene ring. The conductivity of substituent electronic effects on the π-system of the polyfluoroaryl group by the heteroatom has been estimated from NMR ¹³C data. The sensitivity of nuclei shielding towards interamolecular electronic effects has been noticed to increase from oxygen to selenium and the analysis of the influence of the intramolecular electronic effects on the ¹⁷O and ⁷⁷Se shifts has been given. The influence of the substituents either in pentafluorophenyl ring or adjacent to heteroatom have been shown to correspond those in the hydrocarbon analogues.The conclusion about the influence of polyfluoroaryl group on the character of bonds between different atoms in functional group has been made from the NMR ¹⁷O and ¹⁵N data for aromatic nitro-derivatives. Polyfluorophenyl group in respect to phenyl one deshields the oxygen atom and shields the nitrogen atom. The same effect of pentafluorophenyl group has been observed by other spectral methods.The different screening of ¹⁷O, ¹⁵N, ³¹P and ⁷⁷Se nuclei due to the action of substituents adjacent to the element and variation of the coordination number of heteroatom have been used to the solvation of a number of problems in chemistry of the heteroanalogues of carbenium ions and the detail investigation of the mechanism of electrophylic substitution in the field of polyfluoroaromatic compounds.     

Synthesis and studies of structure and biological properties of D-homoanalogs of steroid estrogens

In order to estimate the potential of steroid estrogens modification, three D-homoanalogs of estrogens have been prepared; their structures and biological properties have been studied. The expansion of D-ring in such compounds has lead to strong decrease if the uterotropic action, however, the unfavorable hypertriglyceridemic effect has been retained. The latter has been eliminated by combined action of the studied steroids and ursolic acid; therewith the hypocholesterolemic activity has been retained.     

Diterpenoids ofPulicaria salviifolia. III. The structure of salvicinin

The new diterpene acid salvicinin has been isolated from the epigeal part ofPulicaria salviifolia and its structure has been established as 15-acetoxy-6α-hydroxy-trans-cleroda-3,13-dien-19-oic acid. A capacity of salvicinin for undergoing lactonization in the presence of acetic anhydride has been revealed, and the lactone formed has been isolated and chracterized.     

Photooxidation of ABS of long-wavelengths

The evolution of the photochemical degradation of ABS has been studied in conditions of long wavelength irradiation (λ's> 300 nm). The main photoproducts involved in the oxidative evolution have been identified by using FTIR spectroscopy and chemical titrations. A particular attention has been devoted to α–β unsaturated ketones that appear as secondary photoproducts. Those ketones present a low photochemical stability when exposed in the range 300–400 nm. Conditions for their formation have been experimentally studied. Formation of oxidation photoproducts has been also studied at the macroscopic level and it has been shown that their repartition in the polymer is heterogeneous. The origins of the heterogenities have been studied.     

Improvement of lactic cell production

The production ofLactobacillus brevis has been improved by changing the medium composition and the physiological conditions. The cellular concentration reaches 8.2 X 10¹⁰ cells/mL in 21 h with a fed-batch technique in MRS medium. Freeze-drying has been used as technology for drying the cells and survival rates have been improved with different additives such as glycerol, CaCO₃, and skimmed-milk powder up to 70%. A model has been developed to predict the stability of freeze-dried cultures during long-term conservation. This model, based on Arrhenius equation, has been confirmed by experimental data.

     

Kinetics and mechanism of oxidation of sugars by quinquevalent vanadium in binary mixture solvents of DMSO–water and acetic acid–water in H2SO4 medium

The kinetics of oxidation of aldosugars and ketosugar by quinquevalent vanadium in binary mixtures of DMSO–water and acetic acid–water in sulfuric acid medium have been studied. The reaction is first order in both oxidant and substrate. The effect of acidity on the reaction kinetics has been determined. The effect of acidity shows a clear difference. The ketose has a unit dependence, whereas aldoses have a 0.5 dependence in H₀. The role of solvent in these reactions has also been studied, and the effect of temperature on these reactions has been determined. A suitable mechanism has been postulated taking all the observed facts into consideration.     

Vibrational and electronic absorption spectra of 4-chloro 2-methyl, 4-chloro 3-methyl and 6-chloro 3-methyl phenols

The infrared spectra of 4-Cl 2-Me, 4-Cl 3-Me and 6-Cl 3-Me phenols have been recorded. The vibrational spectrum has been analysed assuming that the molecules belong toC _s point group and a tentative assignment of the observed frequencies to various modes of vibration has been proposed. The near ultraviolet absorption spectrum of these compounds has also been recorded. Assuming the transition to be electronically allowed the strongest band on the longer wavelength side has been assigned as the (0, 0) band in each case. The spectrum has been analysed in terms of several excited state frequencies which have been correlated with the ground state frequencies observed in the infrared spectrum.     

IR spectroscopy study of the radiation-thermal decomposition of water on nanosized zirconium dioxide

Radiation-thermal decomposition of water on nanosized ZrO₂ in the temperature range of 300–673 K has been studied by FTIR spectroscopy. It has been revealed by the X-ray diffraction method that the sample used has the centrsymmetric monoclinic crystal structure. It has been shown that nanosized zirconium dioxide adsorbs water on via the molecular and dissociative mechanisms. Intermediate products of the radiation-induced heterogeneous decomposition of water, namely, the molecular oxygen and hydrogen peroxide radical ions, zirconium hydride, and hydroxyl radicals have been detected. A comparative analysis of changes in the absorption bands of molecular water and surface hydroxyl groups with temperature has been conducted, and the stimulating role of radiation in the radiation-thermal process of water decomposition has been revealed.     

Polyelectrolyte Configuration of Low Molecular Weight Sodium Amylose Xanthate in Aqueous and Salt Solutions

The polyelectrolyte chain configuration of low molecular weight sodium amylose xanthate (NaAX) in aqueous and salt solutions has been studied by viscometry and light scattering. The viscometric results in aqueous solution have been found to be in accordance with the Fuoss's modified equation. The intrinsic viscosities of NaAX in salt solutions from 0.00125 to 0.25 M NaCl have been determined and the expansion factor a at each ionic strength has been determined. The dependence of a on ionic strength has been studied according to the theories of Hermans and Overbeek, Flory, etc. But though qualitative agreement between experimental and theoretical results has been found, quantitative agreement was far from expectations. The frictional coefficient per monomer unit | has been calculated from the relationship of Kirkwood and Riseman. The NaAX macromolecule has been found to have the polydispersed random coil chain configuration in 0.25 M NaCl. Some macromolecular configurational parameters such as effective bond length b, Kuhn-Kuhn equivalent chain length A_m, and steric factor α has been determined.     

Physicochemical analysis of a protein with nerve growth activity from the muscle tissue of Rana ridibunda

A protein nerve growth factor has been isolated in the pure form from the muscles of the lake frogRana ridibunda. The individuality of the substance obtained has been shown, its molecular mass (106.0–110.0 kDa) and pI value (9.2–9.4) have been determined, and lysine and valine have been found as the N- and C-terminal amino acid residues of its polypeptide chain. In view of the detection of the presence of sugars (about 1%), the substance has been identified as a glycoprotein. Its absorption spectra in the UV region has been obtained and the amino acid composition of the isolated protein has been determined. Information on the amino acid composition of various proteins with nerve growth activity has been subjected to comparative analysis with the aid of computer programs, and on this base their phylogenetic tree has been constructed.Institute of Biochemistry, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 251–257, March–April, 1992.     

Study of the lignin of cotton plants of the variety AN Bayaut-2. I

The dioxane lignin has been isolated from ripe stems of a cotton plant of the variety AN Bayaut-2. Its developed empirical formula has been derived, its UV, IR, and PMR spectra have been recorded, and its molecular weight has been determined. It has been shown that the dioxane lignins of the stems of cotton plants of different varieties differ in chemical structure.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 101–104, January–February, 1986.     

Elucidation of the Structure of Products of Triphenylphosphine Electrooxidation in the Presence of Camphene

The structure of the products of anodic oxidation of triphenylphosphine in the presence of camphene carried out in acetonitrile with sodium perchlorate as supporting electrolyte has been studied. The major product, triphenylphosphine oxide, has been isolated from the solution in the form of cocrystals of free triphenylphosphine oxide and its complex with sodium perchlorate. The molecular structure of the cocrystals has been studied by X-ray diffraction analysis. Triphenylcamphenylphosphonium perchlorate, bornylacetamide, and a terpene compound with triphenylphosphonium and acetamide substituents in the cycle have been detected by NMR ¹³C as the electrolysis side products.

     

Carbohydrates of allium IX. Polysaccharides of A. suvorovii

The carbohydrate compositions of all the organs ofAllium suvorovii Rgl have been determined and it has been established that the bulk of the fructose accumulates in its bulbs. The dynamics of the accumulation of glucofructans in the bulbs has been studied and it has been found that this accumulation is a maximum in the dormancy stage.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedienii, No. 6, pp. 622–624, November–December, 1992.