Benzene Bromide Research Articles

On the Dependence of the Rate of Deactivation of Triplet Excitations of a Number of Molecules on Their Ionization Potential and the Charge of the Nucleus of Heavy Atoms of the Solvent

Purpose. Establish the nature and reasons for the dependence of the change in the radiative rate constant of deactivation of triplet excitations of a number of molecules, caused by the effect of an external heavy atom, on their ionization potential from the ground state and the energy of the first excited singlet state.Methods. Kinetic methods were used to determine the rate constant for the deactivation of triplet excitations of organic molecules in solid solutions at 77 K. The solvents were n-heptane (neutral), carbon tetrachloride and benzene bromide (containing heavy chlorine and bromine atoms). The molecules studied were coronene, triphenylene, phenanthrene, naphthalene and biphenyl.Results. A linear relationship has been established between an increase in the ionization potential, the energy value of the first excited singlet state, and an increase in the change in the rate of radiative deactivation of triplet excitations of the studied molecules in carbon tetrachloride. It is shown that the increase in the change in the radiative deactivation rate of these molecules with an increase in their ionization potential is due to a decrease in the difference between the ionization energies and the first excited singlet state.Conclusion. The results of the study showed that there is a linear relationship between the increase in the radiative deactivation rate of triplet excitations of the studied molecules and their ionization potential. A linear relationship is also observed between the increase in the rate of radiative deactivation of triplet excitations of these molecules and the first excited singlet state. As the ionization potentials of the molecules under study increase, the difference between the ionization energy and the energy of the first excited singlet state decreases. This is the reason for the increase in the rate of deactivation of triplet excitations of molecules with an increase in their ionization potential.

Nickel Complexes of Pyridine‐Functionalized N‐Heterocyclic Carbenes: Syntheses, Structures, and Activity in Electrocatalytic Hydrogen Production

Two bis(benz)imidazolium salts alkylated with pyridyl side arms, H2L1Br2 (1,2‐bis{[1‐(2‐pyridylmethyl)benzimidazolium‐3‐yl]methyl}benzene bromide) and H2L2Br2 (1,2‐bis{[1‐(2‐pyridylmethyl)imidazolium‐3‐yl]methyl}benzene bromide) have been prepared and were used as precursors in the synthesis of novel nickel compounds of N‐heterocyclic carbenes (Ni‐NHCs). The four Ni‐NHC complexes [Ni(L1)Br]Br (1a), [Ni(L1)](PF6)2 (1b), [Ni(L2)]Br2 (2a) and [Ni(L2)](PF6)2 (2b) were isolated and characterized by various methods, and the X‐ray crystal structures of 1a, 2a and 2b are reported. The nickel ion in 1a is in a square‐pyramidal geometry with one of the bromide ions in the apical position, the nickel ions in 2a and 2b are in square‐planar geometries. The compounds of the ligand with an imidazole‐based carbene revealed much higher activity in electrocatalytic proton reduction and better acid tolerance, although their overpotentials are higher than those of the benzimidazole‐based compounds. The presence of bromide ions has an adverse effect on the redox potentials as well as the overpotentials for proton reduction. Complex 2b, having the most planar coordination geometry, appeared to have the highest catalytic efficiency for proton reduction in DMF (ic/ip = 50, kobs = 490 s–1 at 0.1 V/s) when using acetic acid as the proton source. To the best of our knowledge, this is the first report of Ni‐NHC complexes that are active in electrocatalytic proton reduction.

Effect of Halogen Doping on Optical Properties for ZnO Thin Film Prepared by Thermal Oxidation

Undoped and halogen-doped zinc oxide thin films are prepared by the thermal oxidation process. Zinc acetate dihydrate, ethanol, and Diethanolamine are used as precursor, solvent, and stabilizer, respectively. In the case of ZnO:Hal. dopant Ammonium chloride NH4Cl 99%, Benzene Bromide C6H5Br, or Benzene Iodide C6H5I for making dopant ZnO thin film with Cl, Br, I respectively is added to the precursor solution with an atomic percentage equal to 2-10.% hal. The transparent solution sprayed onto glass substrates, and are transformed into ZnO upon annealing at 500°C. XRD spectra of ZnO thin films, and optical properties of them as a function of halogen content have been investigated using U.V spectroscopy ( transmittance , refractive index, extinction coefficient and energy band gap ) for undoped and halogen-doped zinc oxide thin films.

Effect of Halogen Doping on Optical Properties for ZnO Thin Film Prepared by Thermal Oxidation

Undoped and halogen-doped zinc oxide thin films are prepared by the thermal oxidation process. Zinc acetate dihydrate, ethanol, and Diethanolamine are used as precursor, solvent, and stabilizer, respectively. In the case of ZnO:Hal. dopant Ammonium chloride NH4Cl 99%, Benzene Bromide C6H5Br, or Benzene Iodide C6H5I for making dopant ZnO thin film with Cl, Br, I respectively is added to the precursor solution with an atomic percentage equal to 2-10.% hal. The transparent solution sprayed onto glass substrates, and are transformed into ZnO upon annealing at 500°C. XRD spectra of ZnO thin films, and optical properties of them as a function of halogen content have been investigated using U.V spectroscopy ( transmittance , refractive index, extinction coefficient and energy band gap ) for undoped and halogen-doped zinc oxide thin films.

Highly precise detection, discrimination, and removal of anionic surfactants over the full pH range via cationic conjugated polymer: an efficient strategy to facilitate illicit-drug analysis.

A water-soluble cationic conjugated polyelectrolyte (CPE), poly(1,4-bis(6-(1-methylimidazolium)-hexyloxy)-benzene bromide) (PMI) displays extraordinary stability over the full pH range of 1-14 as well as in seawater, brine, urine, and other solutions and carries out efficient detection, discrimination, and removal of moderately dissimilar anionic surfactants (viz., sodium dodecyl benzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS)) at very low levels (31.7 and 17.3 parts per billion (ppb), respectively). PMI formed stable hydrogels in the presence of SDS that remained unaffected by strong acids/bases, heating, ultrasonication, or exposure to light, whereas SDBS formed precipitate with PMI as a result of its different interpolymer cofacial arrangement via Columbic attraction. The complex-forming ability of PMI with SDS and SDBS facilitated their elimination from water or drug-doped urine samples without the use of any organic solvent, chromatographic technique, or solid support. This protocol, the first of its kind for the removal of anionic surfactants at very low concentrations from any type of solution and competitive environments, demonstrates an original application using a CPE. The surfactant-free sample solutions could be precisely analyzed for the presence of illicit drugs by any standard methods. Using PMI, a newly developed CPE, a rapid and practical method for the efficient detection, discrimination, and removal of SDS and SDBS at ppb levels from water and urine, under harsh conditions, and in natural chemical environments is demonstrated.

Synthesis of some new 2,4,6-trisubstituted phenyl pyrimidines using 4-nitro and 4-fluorophenacyldimethylsulfonium bromides with aromatic aldehydes

4-Nitrophenacyldimethylsulfonium bromide and 4-fluorophenacyldimethylsulfonium bromide have been prepared by the reaction of dimethyl sulfide with 4-substitutedphenacyl bromide in benzene at reflux temperature under nitrogen atmosphere. These sulfonium salts on treatment with NaOH gave 4-nitrophenacylidenedimethylsulfurane and 4-fluorophenacylidenedimethylsulfurane. The reaction of these sulfonium salts and sulfuranes with various aromatic aldehydes is carried out in presence of ammonium acetate and acetic acid at reflux in an atmosphere of nitrogen to give 2,4,6-triarylpyrimidines in 35-80% yields. Ammonium acetate in acetic acid was used as aza cyclization agent. The structures of new pyrimidines were confirmed on the basis of IR and NMR spectral data.

Sound speed and density measurements for tetra- n-butylammonium bromide in benzene and carbon tetrachloride solutions at T = 298.15 K

The density and sound speed measurements have been carried out for the binary systems consisting of tetra- n-butylammonium bromide (Bu 4NBr) as a solute in benzene and CCl 4 at T = 298.15 K (concentration range 0.01 mol · kg −1 to ∼0.8 mol · kg −1). The apparent molar volumes ( ϕ V) and apparent molar isentropic compressibility ( ϕ K S ) have been calculated and the values at infinite dilution are estimated. These data for Bu 4NBr in benzene and CCl 4 solutions are combined with the literature data of Bu 4NBr in water to obtain transfer compressibility of Bu 4NBr molecules from non-aqueous to aqueous solutions. The ϕ V behaviour as a function of concentration in benzene solutions indicates formation of reverse micelles and having critical micelle concentration (cmc) around 0.01 x 2 of Bu 4NBr (∼0.13 mol · kg −1). The compressibility data are further used to estimate hydration number of Bu 4NBr in aqueous solutions by applying Shiio’s method. The hydration number calculated for compressible organic electrolyte shows good agreement with the number obtained for clathrate hydrate of Bu 4NBr using the chemical analysis and X-ray diffraction.

Crystal structure of 1-(2-pyridiniomethyl)-2,4-bis(phenylsulfonyl)benzene bromide

The crystal structure of 1-(2-pyridiniomethyl)-2,4-bis(phenylsulfonyl)benzene bromide, (C24H20NO4S2)+. Br− (I) has been investigated by X-ray diffraction (XRD)analysis. The triclinic structure of I (space group P1, a = 7.863 A, b = 8.350 A, c = 9.043 A, α = 94.00°, β = 97.81°, γ = 104.62°, Z = 1) was solved by direct methods and refined by full-matrix least-squares analysis in an anisotropic approximation to R = 0.048 for all 4570 reflections collected (CAD-4 automatic diffractometer, λCuKα). The geometrical parameters of the organic cation were determined with a sufficient degree of accuracy. The crystal structure of I involves a very strong interionic hydrogen bond N+-H⋅⋅⋅Br−.

Solubility of Tetrabutylammonium Bromide in Benzene between 298.15 K and 323.15 K

Tetrabutylammonium bromide, a weak organic salt, is used as a phase-transfer catalyst in a phase-transfer catalytic reaction producing the desired product, benzyl bromide in the organic phase. The solubility of tetrabutylammonium bromide in benzene (used as the organic phase solvent) is the possible dominant factor influencing benzyl bromide yield. In this study, the solubility of tetrabutylammonium bromide in benzene was measured in the temperature range between 298.15 K and 323.15 K, and a theoretical approach for the solid−liquid equilibrium of this binary mixture was proposed. The experimental data were then correlated with the Pitzer−Debye−Huckel equation, accounting for the ionic interaction, and with the UNIQUAC model, taking into account the ion−molecule and molecule−molecule interactions. An empirical parameter was introduced to represent the degree of partial dissociation of tetrabutylammonium bromide into ions in the solvent.

GL-MS Spectroscopy of a Xylene Electrolyte for Aluminum Plating

GL-MS spectroscopy and conductivity measurements were used to study solutions of aluminum bromide in benzene, toluene, xylene, and methyl iodide. It was shown that AlBr3is transformed most considerably in xylene solutions. Aluminum began to precipitate from xylene-based electrolytes immediately after their preparation. The current efficiency increased from 40 to 80% with the electrolysis time. The resulting solutions contained about 20 compounds. Aluminum precipitation is accompanied by transalkylation, alkylation, bromination, and polymerization, suggesting the electrolytic mechanism of aluminum plating.

Synthesis of α-phenylchalcogeno acetic acids, ethyl-α-phenylchalcogeno acetates and ethyl-α-halo-α-phenylchalcogeno acetates

Reaction of phenyltellurolate or phenylselenolate anion with α-bromoacetic acid under phase transfer conditions using a liquid—solid system affords the α-phenyltelluro acetic acid and the α-phenylseleno acetic acid in 44 and 50% yields respectively. Under similar reaction conditions, phenyl chalcogenate anions react with ethyl α-bromoacetate to give the corresponding ethyl-α-phenyltelluro acetate in 52% and ethyl-α-phenylseleno acetate in 47% yield. Reaction of phenylselenenyl chloride with ethyl diazoacetate in THF at 0°C yields exclusively the ethyl-α-chloro-α-phenylseleno acetate in 88% yield. Similar reactions performed by addition of phenylselenenyl bromide in THF or benzene to the ethyl diazoacetate at different temperatures result in mixtures of ethyl-α-bromo-α-phenylseleno acetate and ethyl-α,α-bis(phenylseleno) acetate in different ratios. However, when the ethyl diazoacetate was slowly added to a solution of phenylselenenyl bromide in benzene under reflux, the ethyl-α-bromo-α-phenylseleno acetate was obtained in 84% yield as the only product. Reaction of ethyl diazoacetate with phenyltellurenyl bromide in benzene at room temperature results in formation of ethyl-α-bromo-α-phenyltelluro acetate that decomposes rapidly into the corresponding tellurone. Addition of ethyl diazoacetate to a mixture of diphenyldiselenide and copper sulfate in benzene under reflux results in a mixture of ethyl-α-phenylseleno acetate: ethyl-α,α-bis(phenylseleno) acetate (10:1). Using an alternative route, the ethyl-α-phenylseleno acetate was obtained in 74% yield by esterification of α-phenylseleno acetic acid in benzene with ethanol / sulfuric acid. The ethyl-α-phenylseleno acetate was transformed into the ethyl-bromo-α-phenylseleno acetate in 41% yield by treatment with N-bromosuccinimide. On the other hand, the copper-catalyzed thermal reaction of ethyl diazoacetate with diphenyl ditelluride in benzene afforded the corresponding ethyl-α-phenyltelluro acetate as the only product.

Synthesis and characterization of methyl 6- O-α- and -β- d-galactopyranosyl-β- d-galactopyranoside

Sequential tritylation, acetylation and detritylation of methyl β- d-galactopyranoside gave crystalline methyl 2,3,4-tri- O-acetyl-β- d-galactopyranoside ( 4) and methyl 2,3,6-tri- O-acetyl-β- d-galactopyranoside, the latter being the minor product resulting from acetyl migration. Reaction of 4 with 2,3,4,6-tetra- O-acetyl-α- d-galactosyl bromide in benzene, in the presence of mercuric cyanide and mercuric bromide, gave the α- and β- d-(1→6)-linked disaccharides ( 7 and 9, respectively) in high yield, and their structure was confirmed by 1H- and 13C-n.m.r. 1d. and 2d. spectroscopy. O-Deacetylation of 7 gave the hitherto unknown, crystalline methyl 6- O-α- d-galactopyranosyl-β- d-galactopyranoside. O-Deacetylation of 9 gave the corresponding, β- d-linked disaccharide methyl glycoside, the physical constants of which are discussed with respect to controversial data in the literature.

Homogeneously catalyzed hydrogenation and gas‐liquid chromatographic analysis of the methyl esters of cyclopropene fatty acids

AbstractVarious concentrations of cyclopropene fatty acids have been determined down to 0.2% by the use of gas liquid chromatographic (GLC) analysis of the methyl esters of fatty acids that have been quantitatively hydrogenated using a homogeneous transition metal complex catalyst. The effectiveness of the use of bromotris(triphenylphosphine)‐rhodium(I), Br(P(C6H5)3)3Rh, as a homogeneous hydrogenation catalyst to convert the cyclopropene ring to a cyclopropane ring has been evaluated and compared with the analogous chloro‐ and iodo‐complexes. The hydrogenation/GLC method of analysis has been compared with the method of titration with hydrogen bromide in benzene and with the method involving the use of high resolution nuclear magnetic resonance (NMR).

2-amino-7-β- d-arabinofuranosyl-4-methoxy-7 H-pyrrolo[2,3- d]pyrimidine: A facile preparation and anomerisation of a 7-deazapurine nucleoside

Phase-transfer glycosylation of 2-amino-4-methoxy-7 H-pyrrolo[2,3- d]pyrimidine with 2,3,5-tri- O-benzyl- d-arabinofuranosyl bromide in benzene—50% aqueous sodium hydroxide—tetrabutylammonium hydrogensulfate gave two anomeric glycosylation products ( 1 and 3). Removal of the benzyl groups from 1 and 3, respectively, with boron trichloride yielded 2-amino-7-(α- and β- d-arabinofuranosyl)-4-methoxy-7 H-pyrrolo[2,3- d]pyrimidine ( 4 and 2). Treatment of 2 and 4 with 2 m hydrochloric acid under nitrogen caused anomerisation and demethylation without glycosylic cleavage, and reflected the extraordinary stability of pyrrolo[2,3- d]pyrimidine nucleosides towards hydrolysis. The conversion of 2 and 4 into ara-7-deazaguanosine or its α anomer was accomplished with anhydrous acid.

Polymerizations of 1‐(4‐pyridyl)‐1,3‐butadiene

AbstractPolymerization of 1‐(4‐pyridyl)‐1,3‐butadiene (PyBu) initiated by 2,2′‐azoisobutyronitrile (AIBN) or butyllithium (BuLi) was studied. Radical polymerization gave poly(PyBu) of low molecular weight, soluble in chloroform, tetrahydrofuran, or methanol. PyBu was polymerized by BuLi more rapidly than by AIBN, but the produced polyanion was not living. IR and 1H NMR spectra of poly(PyBu) indicate the presence of trans‐1,4‐and trans‐3,4‐units. The content of trans‐1,4‐units was found to be 75 mole‐% (for radical polymerization) or 90 mole‐% (for anionic polymerization). From radical copolymerization with styrene the following reactivity ratios resulted: r1 (PyBu) = 7,21, r2 (styrene) = 0,12; Q = 6, 1 and e = −0,42 (for PyBu). Reaction of PyBu with ethyl bromide in benzene at 30°C produced a polyelectrolyte, as observed in the case of 4‐vinylpyridine.

ChemInform Abstract: THE USE OF GRIGNARD REAGENTS IN THE SYNTHESIS OF CARBOHYDRATES. III. THE ONE‐WAY ANOMERIZATION OF METHYL GLYCOFURANOSIDES AND THE OPENING OF THEIR FURANOSE RINGS

AbstractDie Anomerisierung von Methylglycofuranosiden.

The Use of Grignard Reagents in the Synthesis of Carbohydrates. III. The One-way Anomerization of Methyl Glycofuranosides and the Opening of Their Furanose Rings

Abstract The anomerization of methyl glycofuranoside derivatives with methylmagnesium iodide or t-butylmagnesium bromide occurred in a one-way manner. For example, methyl 5-O-benzyl-β-d-ribofuranoside (3β) was converted into the corresponding α-anomer (3α) in a 95% yield when a mixture of 3β and t-butylmagnesium bromide in benzene–ether was heated at about 75 °C to remove the ether; the reverse reaction (from 3α to (3β) did not proceed. The reaction of 3β with methylmagnesium iodide gave open-chain products (33%), besides 3α (30%). Twenty kinds of anomers were tested, and the mechanisms of the reactions were discussed. The cleavage of a benzyl- or trityl-protecting group with the Grignard reagent was also observed during the reaction.

ChemInform Abstract: 7,8‐BENZO‐11‐CHLORO‐(5)METACYCLOPHANE

AbstractDas Dichlorcyclopropan (I) ergibt bei der Behandlung mit Silberperchlorat in Tetrahydrofuran in Gegenwart von 2,6‐Lutidin das Benzo‐chloro‐metacyclophan (II), das sich in Gegenwart von Essigsäure in das Isomere (III) umlagert.

7,8-Benzo-11-chloro[5]metacyclophane

The [5]metacyclophane derivative (3) was obtained in 55% isolated yield by treatment of (2) with silver perchlorate in the presence of 2,6-lutidine in tetrahydrofuran solution; (3) isomerizes to (6) in acidic solution and is converted by hydrogen bromide in benzene–acetic acid–water into a mixture consisting mainly of (6), (8a), and (8b).

ChemInform Abstract: CYCLIZATION OF O‐NITROSOACYLBENZENES TO ANTHRANILS

5-Bromo- and 5-methoxy-3-ethylanthranils, respectively, were obtained by cyclization of o-nitrosopropiophenone under the influence of hydrogen bromide in benzene and hydrogen chloride in methanol. In these reactions, the starting nitroso ketone undergoes redox transformations that also proceed readily in an inert solvent in the absence of any cyclizing reagents.