Showing papers on "Halogen published in 1996"

Controls on halogen concentrations in sedimentary formation waters

Abstract: Chlorine is the most abundant halogen in sedimentary formation waters with concentrations from 250000 mg/1. Bromine is the second most abundant halogen at 6000 rag/1 with iodine from 100 mg/1 and fluorine from <0.1 rag/1 to 30 mg/L Chlorine and bromine show a strong systematic covariation suggesting that they are subject to the same controlling mechanisms. Fluorine only shows relatively high concentrations at elevated chlorine and bromine concentrations showing that fluorine, chlorine and bromine are possibly controlled by the same processes. Iodine does not correlate with any of the other halogens indicating that unique processes control iodine. Key geological parameters that influence chlorine and bromine (and possibly fluorine) concentrations are the presence of salt in a basin, the age of the reservoir unit and the kerogen-type within the main hydrocarbon source rock in a basin. The presence of salt in a basin shows that sea water was evaporated to halite saturation producing connate waters with high concentrations of chlorine and bromine. The presence of salt also leads to high salinity waters through water-salt interaction during burial and diagenesis. Tertiary reservoirs typically have much lower chlorine and bromine concentrations than Mesozoic or Palaeozoic reservoirs. The age of the reservoir unit may simply reflect the different amounts of time available for formation water to interact with salt. The dominance of type II marine kerogen in a basin leads to higher bromine concentrations. This may reflect the dominance of a marine influence in a basin which is more likely to lead to salt deposition than terrestrial depositional environments. Iodine concentrations are independent of all these parameters. Other geological parameters such as depth of burial, temperature, basin forming mechanism and reservoir lithology have no influence upon halogen concentrations. Key processes that affect halogen concentrations are sea water evaporation and dilution, water-salt interaction and input from organic sources. Chlorine and bromine data lie close to the experimentally-derived sea water evaporation trend showing that sea water evaporation may be an important general control on halogens. Sea water dilution is probably responsible for most low salinity formation water chlorine and bromine concentrations for the same reason. Sea water dilution can occur either by meteoric invasion during burial, or following uplift and erosion, or by diagenetic dehydration reactions. Water can interact with salt in a variety of ways: halite dissolution by congruent processes, halite recrystallization by incongruent processes, sylvite dissolution or recrystallization and halite fluid inclusion rupture. Halite dissolution will lead to high chlorine and relatively low bromine waters because halite contains little bromine. In contrast, halite recrystallization will lead to bromine-enhanced waters because NaBr dissolves preferentially to NaC1. The occurrence of dissolution or recrystallization will depend on the water rock ratio, greater volumes of water will lead to more dissolution and waters with higher C1/Br ratios. Sylvite is usually rich in bromine so dissolution will lead to bromineenhanced waters. Primary aqueous inclusions in halite contain high bromine concentrations so that rupture, during deformation or recrystallization, will lead to bromine-enhanced formation water. A combination of these

Positive Halogens from Halides and Hydrogen Peroxide with Organotellurium Catalysts

Abstract: The oxidations of sodium bromide, sodium chloride, and sodium iodide to positive halogen with hydrogen peroxide in two-phase systems of dichloromethane and pH 6 phosphate buffer were catalyzed by organotellurium catalysts 1−3. The positive halogens were trapped by cyclohexene for bromine and chlorine to give mixtures of the 1,2-dihalocyclohexane (4) and 2-halocyclohexanol (5). For the bromination (4a)/hydrobromination (5a) of cyclohexene, unoptimized turnover numbers of 1010 mol of product per mole of catalyst for 1, 960 for 2, and 820 for 3 were measured with 4a/5a ratios of 55:45, 53:47, and 52:48, respectively. In cyclohexane, the turnover number for 1 was 150 and the 4a/5a ratio was 68:32. In the uncatalyzed process and in the reaction of aqueous bromine with cyclohexene, the 4a/5a ratio is 55:45 in dichloromethane and 67:33 in cyclohexane. The relative rates of catalysis for equimolar amounts of 1−3 were nearly identical to the relative second-order rate constants for oxidation of the organotellurium...

Benzazepine-, benzoxazepine- and benzothiazepine-n-acetic acid derivatives, process for their preparation and pharmaceutical compositions containing them

Abstract: Compounds with neutral endopeptidase (NEP) inhibitory activity corresponding to the formula I I in which R1 is a lower alkoxy-lower-alkyl group whose lower alkoxy radical is substituted by a lower alkoxy group, or a phenyl-lower-alkyl or phenyloxy-lower-alkyl group which can optionally be substituted in the phenyl ring by lower alkyl, lower alkoxy or halogen, or a naphthyl-lower-alkyl group, A is CH2, O or S, R2 is hydrogen or halogen, R3 is hydrogen or halogen, R4 is hydrogen or a group forming a biolabile ester, and R5 is hydrogen or a group forming a biolabile ester, and the physiologically acceptable acid addition salts thereof.

Fluorination of aromatic compounds by halogen exchange with fluoride anions (“halex” reaction)

Abstract: Publisher Summary Halogen exchange with a fluoride anion is one of the two main techniques to introduce a fluorine atom on an aromatic nucleus, which is a useful complement of diazotization of anilines in hydrogen fluoride or thermal decomposition of arenediazonium fluoroborates (Schiemann reaction). It is used on an industrial scale to produce, for example, 2, 6-difluorobenzonitrile (the precursor of the insecticide Diflubenzuron) or 2, 4-difluoroaniline (the precursor of Diflufenican or other herbicides). Because of the high lattice energy of inorganic fluorides, substitutive fluorination with alkaline fluorides in aprotic solvents is always a two-phase reaction which is very dependent on the origin and the preparation of the solid reagent. In order to get new improvements, it is necessary to have a better knowledge of the reaction at the molecular scale and, especially, to determine if the process is limited by physics (that means by the solubilization of the fluoride) or by chemistry. In the latter case, the problem is to know if the reaction occurs in the liquid phase or on the surface of the solid. Some insight could be given by kinetic measurements and comparison of the influences of the reaction parameters on rate values.

Method for etching semiconductor wafers

Abstract: Disclosed is a semiconductor etching method comprising exposing the wafer surface, in a plasma etching apparatus, to a radio-frequency plasma comprising a mixture of a noble gas and a saturated or unsaturated reduced carbon compound selected from the group consisting of acetylene (C 2 H 2 ), benzene (C 6 H 6 ), graphite or buckminsterfullerene (C 60 ) and a halogen compound selected from the group consisting of fluorine, chlorine, bromine, hydrogen chloride, hydrogen fluoride, hydrogen bromide, sulphur hexafluoride and nitrogen trifluoride.

Laser-evaporated aluminum atom reactions with halogen molecules. Infrared spectra of AlXn (X = F, Cl, Br, I; n = 1-3) in solid argon

Abstract: Reactions of laser-evaporated aluminum atoms with molecular fluorine, chlorine, bromine, and iodine in excess argon during condensation onto a CsI window at 11 ± 1 K produced the AlXn (X = F, Cl, Br, I and n = 1−3) and Al2X6 molecules, which were characterized by infrared absorption spectroscopy. Low laser power favored the primary reaction product AlX and AlX2 transient species over the more stable secondary reaction product AlX3 molecules. Chlorine and bromine isotopic structures substantiated the molecular identifications and vibrational assignments. DFT calculations were done for the AlCln and AlBrn series to support the vibrational assignments. Possible Al2Cl4 structures were also explored by DFT calculations, and evidence is presented for a distorted Cl2AlCl2Al structure. The present study provides further evidence for transient aluminum dihalide radicals for the four halogens.

Preparation and Conformation of Monohalotetrahydroxycalix[5]arenes

Abstract: The intraannular introduction of a halogen into a calixarene skeleton is described. Monoaminotetrahydroxy-p-tert-butylcalix[5]arene (2b) was diazotized by treatment with isoamyl nitrite/HCl/EtOH. Thermal dediazoniation of the salt in chloroform yielded monochlorotetrahydroxy-p-tert-butylcalix[5]arene (5a) and the xanthenocalix[5]arene 6. These products result from the capture of an intermediate phenyl cation derivative by chloride ion or intramolecularly, by a neighboring phenol ring. The product ratio 6:5a was not affected by the addition of excess external chloride, suggesting that the reacting intermediate exists as an ion pair. The dediazoniation reaction in the presence of bromide and iodide ions afforded the corresponding halocalixarenes 5b and 5c, while in the presence of a fluoride ion the calixindazole 8 was obtained. X-ray diffraction indicates that 5b exists in a distorted cone conformation (cone-in) in which the extraannular edge of the halophenyl ring is tilted toward the cavity center. The h...

Flash Photolysis Observation of Aryl, 2,3-Dihydrocyclohexadienyl, and Halogen Anion Radicals in Aqueous Solution: Photohomolytic Radical Cyclization of Aryl Halide1

Abstract: A thorough investigation of the transient species from the laser flash photolysis of haloarene tethered arenes has been performed Some transient species in the laser photolysis of N-benzyl-2-halopyridinium and N-(2-halobenzyl)pyridinium bromides have been investigated as an effort to understand the photocyclized reaction mechanism as well as to know the properties of the transients themselves Pyridinium σ, 2,3-dihydrocyclohexadienyl π, and halogen anion radicals are detected in the photolysis of a N-benzyl-2-halopyridinium salt (1 or 2) in water: the absorption maxima are 250, 310, and 355 (Br−Cl•-) nm, respectively The lifetimes of 2-pyridinium σ radical, 2,3-dihydrocyclohexadienyl π, and bromine chloride (in the case of 1) anion radicals are 072 ms, 12 ms, and 93 μs, respectively Phenyl σ, 2,3-dihydropyridinium π, and halogen anion radicals are also detected in the laser photolysis of an aqueous solution of a N-(2-halobenzyl)pyridinium salt (3 or 4): the absorption maxima are 250, 310, and 360

Reactivity of mono-halogen carbene radical anions (CHX–˙; X = F, Cl and Br) and the corresponding carbanions (CH2X–; X = Cl and Br) in the gas phase

Abstract: The gas-phase reactions of mono-halogen substituted carbene radical anions, CHX–˙(X = F, Cl and Br) and the corresponding carbanions, CH2X–(X = Cl and Br) with halomethanes and organic esters have been examined with the use of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The chlorine and bromine containing (radical) anions react by SN2 substitution with the parent chloro- and bromo-urethanes, whereas an SN2 and/or a BAC2 reaction occurs with the methyl ester of trifluoroacetic acid and dimethyl carbonate. The main features of the results are: (i) the SN2 substitution of a given carbene radical anion with CH3Cl or CH3Br is less efficient than this reaction of the corresponding carbanion, (ii) the radical anions react less efficiently with dimethyl carbonate than the carbanions, (iii) the SN2 substitution is less important for the radical anions than for the carbanions in the reactions with the two carbonyl compounds, (iv) for both types of ions, the BAC2 pathway becomes relatively more important as the halogen atom is changed from chlorine to bromine. These findings are discussed in terms of the thermodynamics of the overall processes in combination with considerations of the potential energy surfaces which can describe these gas-phase processes.

Halogen exchange reactions

Abstract: An essentially anhydrous agitated mixture of (i) finely-divided essentially anhydrous alkali metal fluoride (e.g., KF), (ii) haloaromatic compound having at least one halogen atom of atomic number greater than 9 on an aromatic ring (e.g., C 6 Cl 6 ), and (iii) an aminophosphonium catalyst (e.g., (Et 2 N) 4 PBr), is heated at a temperature at which fluorine replaces one or more of the ring halogen atom of the haloaromatic compound.

Method for producing oxygen and hydrogen

Abstract: There are provided a method of producing a hydrogen halide and oxygen by reacting water with a halogen using activated carbon as a catalyst, a method of producing hydrogen by thermal decomposition of a hydrogen halide using chromium oxide as a catalyst, and a method of producing oxygen and hydrogen by combining these two methods.

17O- and 1H-NMR Studies of the Water Structure in Binary Aqueous Mixtures of Halogenated Organic Compounds

Abstract: The chemical shifts of water (17O- and 1H-NMR) and the spin-lattice relaxation time of water (17O-NMR) were measured on binary aqueous mixtures of halogenated ethanols, propanols, acetamide and acetone to investigate the effect of their halogen groups on water structure. The solute molecules were 2-chloroethanol, 2-bromoethanol, 2-iodoethanol, 2,2-dichloroethanol, 3-chloropropan-1-ol, 2,3-dichloropropan-1-ol, chloroacetamide, and chloroacetone together with ethanol, propan-1-ol, acetamide and acetone. The results give clear evidence of the fact that the hydrogen bonds of the water molecules become weaker around the halogen group irrespective of the presence of an OH group in the molecules.

Method for preserving olefin polymerization catalyst

Abstract: PROBLEM TO BE SOLVED: To inhibit an olefin polymerization catalyst from being inactivated by preserving a catalyst comprising a specified transition metal compound and a specified promoter in the presence of an olefin. SOLUTION: A catalyst comprising a compound (A) containing a group 8-10 transition metal in the periodic table and represented by the formula and at least one compound (B) selected among organoaluminumoxy compounds (B-1), alkylboric acid derivatives (B-2) and Lewis acids and ionic compounds (B-3) is preserved in the presence of an olefin (C). In the formula, M is a group 8-10 transition metal atom in the periodic table; X and X are each nitrogen or phosphorus; R and R are each hydrogen or a hydrocarbon group; m and n are each 1 or 2 and is a number satisfying the valence of X or X ; R is a group represented by formula II (R , R , R , R , R and R are each hydrogen or a hydrocarbon group); and R and R are each hydrogen, a halogen, a hydrocarbon group or the like.

Facile conversion of perfluoroacyl fluorides into other acyl halides

Abstract: Nine perfluoroacyl fluorides underwent halogen exchange when treated with anhydrous lithium halides to give acyl chlorides, bromides and iodides in high yields. The temperature dependence of this reaction is described. In the reaction with perfluorodiacyl fluoride, the diacyl halides possessing different acyl halide-groups were also produced. Of the alkaline metal salts used halogen exchange was successful only with lithium salts because of the interaction between lithium and fluorine.

Method of manufacturing group iii-v compound semiconductor

Abstract: The present invention provides for a method of manufacturing a Group III-V compound semiconductor, which grows a nitrogen-contained Group III-V compound semiconductor of the p-type conductivity, without performing any particular post-processing after growing the compound semiconductor, and which prevents a deterioration in the yield of manufacturing light emitting elements due to post-processing. A first embodiment is directed to a method of manufacturing a Group III-V compound semiconductor which contains p-type impurities and which is expressed by a general formula InxGayAlzN (0≧x≧1,0≧z≧1, x+y+z=1), by thermal decomposition vapor phase method using metalorganics, the method being characterized in that carrier gas is inert gas in which the concentration of hydrogen is 0.5 % or smaller by volume. A second embodiment is directed to a method of manufacturing a Group III-V compound semiconductor which contains p-type impurities and which is expressed by a general formula InxGayAlzN (0≧x≧1, 0≧y≧1,0≧1, x+y+z=1), by thermal decomposition vapor phase method using metalorganics, the method being characterized in that after etching within a reaction furnace using at least one compound which is selected from a compound group consisting of compounds of halogenated hydrogen, compounds of halogen and Group V elements and compounds of halogen, hydrogen and Group V elements, inert gas in which the concentration of hydrogen is 0.5% or smaller by volume is used as carrier gas.

Process for removing noxious compounds

Abstract: A process is described for removing noxious compounds such as hydrocarbons which may or may not contain halogen and/or may or may not be aromatic, from solids (soil), water or gas, according to which process the solid, the water or the gas is treated with a complex of a transition metal and an alkaline polyamine in the presence of a peroxide. The complex is, for example, a complex of iron chloride and 1,4,7-trimethyl-1,4,7-triazonane. The peroxide is preferably electrochemically produced hydrogen peroxide.

Halogen ion electric field assisted diffusion in fluorite and polyvinyl chloride during electron irradiation

Abstract: Fluorite CaF2 and polyvinyl chloride specimens coated with a grounded thin gold layer have been irradiated with 12 and 30 keV electrons, respectively. The change of the halogen x‐ray signal intensity (F Kα and Cl Kα) has been measured as a function of time and for various incident doses. The experimental results are fully explained by a simple model for the anion migration driven by the electrostatic field. An Auger process is suggested for the initial escape of anions from their lattice site. To our knowledge, the migration of halogen ion is reported for the first time.

Substituted phenyl compounds as endothelin antagonists

Abstract: Compounds of formula (I) are described, wherein: R1 is CN, CH?2?CN, CH=CHCN, CHO, or CH=CHCO2H; R?2? is aryl lower alkoxy, heteroaryl lower alkoxy, aryl lower alkylthio or heteroaryl lower alkylthio in which each of the aryl and heteroaryl moieties is optionally substituted; R3 is halogen; R4 is optionally substituted aryl or optionally substituted heteroaryl; R5 is carboxy or an acid isostere; X is oxygen or sulphur; and n is zero or 1; and their N-oxides and prodrugs, and pharmaceutically acceptable salts thereof. The compounds have endothelin antagonist activity and are useful as pharmaceuticals.

Sulfonium salts of pyrrolylbenzimidazoles

Abstract: Compounds of formula (1): ##STR1## wherein m is an integer 1, 2 or 3, R 1 and R 2 are the same or independently different alkyl groups, each having 1-5 carbon atoms, R 3 is a hydrogen atom, alkyl group having 1-3 carbon atoms, alkoxy group having 1-3 carbon atoms or halogen atom, and X - is an acid residue of acid selected from a group consisting of methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid and trifluoromethanesulfonic acid, and their salts are useful as an effective component of anticancer agents.

(mercapto-triazolylmethyl) cyclopentanol microbicides

Abstract: Novel triazolyl methyl cyclopentanols of formula (I) in which R?1 and R2? are mutually independently hydrogen or alkyl with 1 to 6 carbon atoms, R3 is hydrogen or alkyl with 1 to 4 carbon atoms, X is halogen, alkyl with 1 to 5 carbon atoms, alkoxy with 1 to 4 carbon atoms, phenyl, phenoxy, halogen alkyl with 1 to 4 carbon atoms and 1 to 5 halogen atoms, halogen alkoxy with 1 to 4 carbon atoms and 1 to 5 halogen atoms or halogen alkylthio with 1 to 4 carbon atoms and 1 to 5 halogen atoms, and n is 0, 1 or 2, and their acid addition salts and metal salt complexes, a process for producing these substances and their use as microbicides in plant and material protection.

Catalysts which can be used in conversion reactions of hydrocarbons and containing silicon

Abstract: The invention relates to a catalyst comprising: a matrix consisting of 0 and 100% by weight of λ transition alumina, the complement up to 100% by weight of the matrix being in γ transition alumina, and relative to the total weight of the catalyst, from 0.001 to 2% by weight of silicon, from 0.1 to 15% by weight of at least one halogen chosen from the group formed by fluorine, chlorine, bromine and iodine, from 0.01 to 2% by weight of at least one noble metal from the platinum group, from 0.005 to 10% by weight of at least one promoter metal chosen from the group formed by tin, germanium, indium, gallium, thallium, antimony, lead, rhenium, manganese, chromium, molybdenum and tungsten, and if required from 0.001 to 10% by weight of a doping metal.

Method for destroying organohalogen compounds

Abstract: A process is provided for the destruction of organohalogen compounds, such as methyl chloride, chloroform, carbon tetrachloride, etc., by mixing the organohalogen compounds with a heated carrier gas, such as nitrogen, argon or air, and either steam or water to form a mixture; supplying the mixture to a catalyst, such as titanium oxide/tungsten oxide, to decompose the organohalogen compounds into halogens and hydrogen halides, such as chlorine, hydrochloric acid, fluorine and hydrofluoric acid; conducting the halogen and hydrogen halide contaminated gas through a bent path, created by a baffle that prevents the entry of mist or droplets into the catalyst chamber, into a cooling section where the halogen and hydrogen halide contaminated gas is sprayed with water to cool the gas to a temperature low enough to prevent the formation of dioxines. An alkaline agent, such as sodium hydroxide, can be added to the cooling water to neutralize the halides and hydrogen halides.

Halogen-magnesium-aluminum hydridohalides, methods for their synthesis and their use as reducing agents

Abstract: Halogen magnesium aluminum hydridohalides of the general formula Mg.sub.2 X.sub.3 (ether).sub.y !.sup.+ AlH.sub.4-n X.sub.n !.sup.- wherein X is chlorine, bromine or iodine, y is a number from 0 to 6, n is a number from 1 to 3 and ether is an aliphatic or cylcoaliphatic ether with 2 to 30 carbon atoms, with the exception of t-butyl ether, with a dipole moment>0.5 Debye and a melting point of<0° C. are prepared. The invention furthermore relates to a method for the synthesis of these compounds and to a method of reducing functional organic compounds utilizing the inventive compounds.

Process for preparing alkylsilanes having bulky alkyl radicals

Abstract: Di- and trialkylsilanes of the formula R.sub.a R.sup.1 R.sup.2.sub.b SiX.sub.c (I), which comprises reacting mono- and dialkylsilanes of the formula R.sup.1 R.sup.2.sub.b SiH.sub.a X.sub.c (II), with alkenes A having at least 4 carbon atoms, which alkenes are unsubstituted or substituted by fluorine, chlorine or bromine atoms or cyano groups, in the presence of a transition metal catalyst and a hydrocarbon as activator, which hydrocarbon has at least one functional group selected from among aldehyde, keto and epoxy groups or halogen atoms, where in the above formulae (I) and (II), R is a branched or cyclic hydrocarbon radical having at least 4 carbon atoms, which radical is unsubstituted or substituted by fluorine, chlorine or bromine atoms or cyano groups, R 1 is an alkyl radical having at least 2 carbon atoms, which radical is unsubstituted or substituted by fluorine, chlorine or bromine atoms or cyano groups, R 2 is a hydrocarbon radical having at least 2 carbon atoms, which radical is unsubstituted or substituted by fluorine, chlorine, or bromine atoms or cyano groups, X is a fluorine, chlorine or bromine atom or an alkoxy radical having from 1 to 18 carbon atoms, which radical is unsubstituted or substituted by fluorine, chlorine or bromine atoms or cyano groups, a is 1 or 2, b is 0 or 1 and c is 1 or 2.