Bromination and iodination of trialkylethynylsilanes

Conclusions The addition of bromine and iodine to trimethyl- and dimethylethylethynylsilanes has been studied. The halogenation of these compounds takes place stepwise. The first molecule of bromine adds at 30–50° and the second at 70–90°. In the case of bromination under UV irradiation, hydrogen bromide is eliminated as a side-reaction. The addition of iodine ceases at the stage of the formation of the diiodovinylsilanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 693–694, March, 1967.     

Polarographic investigation of the mobility of halogen atoms in halogen-substituted components of nucleic acids

In order to establish quantitatively the reducibility of halogen-substituted components of nucleic acids, the half-wave potentials (E_1/2) of their electrochemical reduction have been determined. The electrochemical reduction of all compounds takes place in the interval from –0.5 to –1.8 V and consists in the splitting off of the halogen atom (iodine, bromine) from the given molecule. The iodine derivatives are reduced much more readily (500–800 mV) than the bromine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1408, October, 1992     

Halogenation of the components of nucleic acids

Summary Preparative methods have been worked out for the bromination of unprotected deoxy-AMP, deoxy-GMP, and deoxy-CMP and methods have been devised for the isolation and purification of the bromine derivatives.Some physicochemical characteristics (UV spectra, R_f values on thin-layer and paper chromatography, coefficients of millimolar extinction) of the bromine derivatives of the DNA components obtained have been determined.Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 524–527, July–August, 1976.     

Degree of solid-phase oxidation of nickel and cobalt phthalocyanines by halogens

Electronic and IR transmission spectroscopy and ESR have been used to investigate the products obtained in the oxidation of layes of nickel and cobalt phthalocyanines by halogen vapors. It has been established that cobalt phthalocyanine in chlorine or bromine vapor forms stable cation radicals in which one electron has been detached from the cobalt and the other from the phthalocyanine ligand; in iodine vapor, a partially oxidized product is formed, with a positive charge on the ligand. Nickel phthalocyanine in bromine vapor at high pressure of bromine, and also in chlorine or iodine vapor, nickel phthalocyanine forms partially oxidized products with various degrees of oxidation of the ligand. An interpretation is given for the spectra of the ionic species that have been investigated; the interpretation can be used in particular to determine the degree of the ionic species on the basis of their spectra.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 528–534, September–October, 1989.The authors wish to thank A. V. Baranov for measuring the Raman spectrum of the bromine-oxidized Copc.     

Determination of Au,Sb, As,Br, Na,K, Cd,Mn and Cl in rice from Vietnam by neutron activation analysis

Gold, antimony, arsenic, bromine, sodium, potassium, cadmium, manganese and chlorine were determined by neutron activation analysis in various rice seed, brand layer and husk from Vietnam. The following concentration values were found: Au 0.05–0.28 ppm, Sb 0.05–1.08 ppm, As 0.08–0.94 ppm, Br 0.82–6.72 ppm, Na 16.71–25, 71 ppm, K 2582–5163 ppm, MN 19.26–33.43 ppm, Cd 0.51–2.42 ppm and Cl 205.20–828.61 ppm in rice seed. These elements were also determined in brand layer and rice husk. Statistically significant differences /t=0.05/ in Au, Sb, Cd contents were detected in rice seed and rice husk, as well as brand layer with rice husk.     

Absorption spectra of 2,3-dihydrothionaphthen-3-one and its derivatives

A number of new thioindigoid dyes have been synthesized. They have been subjected to photochemical isomerization. The absorption spectra of the dyes synthesized have been compared with the absorption spectra of analogous dyes not containing bromine. The spectra of the cis forms are less sensitive to the introduction of a bromine atom than those of the trans forms.For Communication XI, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 8, pp. 1031–1033, August, 1970.     

Liquid-liquid extractions with metal diethyldithiocarbamates as reagents

The liquid-liquid extraction of about twenty ions with metal diethyldithiocarbamates in chloroform from citrate buffers of pH 2–6 and the most common inorganic acids has been studied. Several backextraction reagents have been examined: hydrochloric acid (1–12M), dilute nitric acid saturated with bromine and a mixture of concentrated hydrochloric acid and hydrogen peroxide. A short review of metal diethyldithiocarbamates as extraction reagents and a mathematical model for these extractions are also included.     

Solubility of Solid 2,3-Dimethylbutane and Cyclopentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 2,3-dimethylbutane and cyclopentene in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in solutes. The experimental value of the mole fraction solubility of solid 2,3-dimethyl-butane in liquid argon at 87.3 K is (8.26 ± 1.60) × 10^–6 and (2.77 ± 0.94) × 10^–8 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid cyclopentene in liquid argon at 87.3 K is (5.11 ± 0.44) × 10^–6 and (4.60 ± 0.76) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for investigated solid hydrocarbons than is liquid nitrogen.     

A method for functional analysis of organosilicon compounds containing silacyclobutane groups

A method of determining quantitatively silacyclobutane rings in organosilicon compounds is worked out. It is based on addition of bromine or iodine to a Si-C bond in the ring, followed by determination of those elements in the resultant Si-Br or Si-I group. The error in determining bromine or iodine numbers by the method is 0.5–2.0%; the error in determining percentage bromine (iodine) is 0.5–2.0%. A determination takes 3–4 hr. The silacyclobutane group does not react with thiocyanogen, so that it is possible to determine separately multiple bonds and silacyclobutane groups present in one and the same molecule.     

Synthesis of biologically active bromine derivatives of quercetin

The synthesis of a series of bromine derivatives of quercetin differing by the number of bromine atoms introduced is described. It has been shown that in the dynamics of the bromination process the deciding factors affecting the qualitative and quantitative compositions of the reaction products are the temperature regime and the ratio of the reactants. Thus, the use of equimolar amounts of the reactants in dioxane in the temperature interval from 20 to 25° C gives a monobromo derivative, while all other conditions give mixtures of bromo derivatives. The antiviral and antitumoral activities of the mono- and dibromo derivatives of quercetin have been studied.Al-Farabi Kazakh State National University, Almaty, fax (3272) 47 26 09. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 709–711, September–October, 1996. Original article submitted February 27, 1995.     

13C NMR spectra of bromine derivatives of fatty acids

Summary The¹³C spectra of the methyl esters of the cis and trans isomers of 9,10-dibromostearic, of cis,cis-9,10,12,13-tetrabromostearic, and of 10,11-dibromoundecanoic acid have been obtained, and the assignment of all the signals has been performed. It has been shown that the presence of bromine atoms in the chain of a fatty acid leads to the magnetic non-equivalence of the¹³C nuclei of the methylene groups present at a distance of three carbon-carbon bonds from the nucleus to which the halogen is directly attached. A dependence has been found of the shift parameter of the carbon nuclei in a fatty acid chain on the relative arrangement of the bromine atoms.V. I. Lenin Tashkent State University. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 26–30, January–February, 1977.     

Kinetic investigation of the textile bleaching process

Volumetric H₂-uptake measurements on an Mo₂N (79 m²g^–1) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308–623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature. The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The H_IR/Mo ratio calculated from the uptakes obtained in the temperature range of 308–623 K varies in the range of 0.0010–0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N paris, in which the molybdenum atoms are in unsaturated coordination.     

Theoretical investigation of the electronic structure of graphite + LiNH2 intercalation compounds by the MNDO method

The electronic structures of the clusters C₄₈H₂₄, C₄₈H₂₄Li, and C₄₈H₂₄LiNH₂, which are models of intercalation compounds of graphite, have been calculated by a semiempirical quantum-chemical method in the cluster approximation. It has been shown that an Li atom is strongly polarized in a graphite lattice. When a molecule of LiNH₂ is inserted into a graphite matrix, the charge states of the intercalant molecule and the surrounding carbon atoms change. The cause of the strong increase in the inter planar distances in the intercalation compound of LiNH₂ is the antibonding interaction of the MO's of graphite and the intercalant.Institute of Chemistry, Academy of Sciences of the USSR, Far-Eastern Branch. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 12–16, March–April, 1991.     

Solubility of Solid 1-Hexyne in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 1-hexyne in liquid argon at 87.3 and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in 1-hexyne. The experimental value of the mole fraction solubility of solid 1-hexyne in liquid argon at 87.3 K is (0.85 ± 0.19) × 10^–7 and (1.25 ± 0.08) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for solid 1-hexyne than is liquid nitrogen.     

A Raman study of multiferroic LuMnO3

Magnetic and dielectric measurements confirm the multiferroic nature of LuMnO₃. Raman spectra of LuMnO₃ have been recorded in the 77–800 K range covering both the antiferromagnetic transition at 90 K and the ferroelectric–paraelectric transition at 750 K. The changes in the phonon modes frequencies and band-widths indicate the presence of phonon–spin coupling in the antiferromagnetically ordered phase. The ferroelectric–paraelectric transition is accompanied by the broadening and disappearance of many of the phonon modes. Some of the phonon modes also show anomalies at the ferroelectric transition.     

Microdetermination of ascorbic acid using bromine monochloride in water-acetic acid medium

A micromethod for the determination of ascorbic acid has been developed. A 2–10 mg sample dissolved in glacial acetic acid is reacted with a known excess of bromine monochloride at ice-bath temperature, and the excess reagent is back-titrated iodometrically. The maximum deviation in the results is ± 1.5%.     

Solubility of 1-Pentene Ice in Liquid Nitrogen and Argon at the Standard Boiling Points of the Solvents

The solubilities of 1-pentene ice in liquid nitrogen at a temperature of 77.4 K and in liquid argon at 87.3 K have been measured by the filtration method. The 1-pentene content in solution was determined using gas chromatography. The experimental value of the mole fraction solubility of 1-pentene ice in liquid nitrogen at 77.4 K is: (1.28±0.25)×10^–7 and (4.11±0.44)×10^–7 in liquid argon at 87.3 K. The Preston–Prausnitz method was used for calculation of the solubilities of 1-pentene ice in liquid nitrogen in the temperature range 64.0–90.0 K and in liquid argon in the temperature range 84.0–90.0 K. The parameters l ₁₂ were also calculated. At 90.0 K liquid argon is the better solvent for 1-pentene ice than is liquid nitrogen.     

Cobalt-Selective Electrode Based on Titanium Ditelluride Intercalated with Cobalt

A cobalt-selective solid-contact electrode was prepared on the basis of titanium ditelluride. The electrode exhibits the slope of the electrode function –(29 ± 1) mV/pC and provides the determination of 1 × 10^–5–1 × 10^–1 M cobalt(II) in the pH range 4.5–6.5. The electrode was used for the potentiometric indication of the titration end point in the determination of cobalt(II) in lanthanum–strontium cobaltite La_0.5Sr_0.5CoO₃. The intercalant concentration range providing optimal ion-selective properties was determined.     

Study of radical rearrangement during bromination of 3,3,3-trichloropropene

Conclusions It was shown by the EPR method that in the photochemical bromination of 3,3,3-trichloropropene at 77°K a bromine atom adds to the compound with the formation of the CCl₃CHCH₂Br radical, which is then converted to the CCl₂CHClCH₂Br radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 179–181, January, 1973.     

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.