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The results of the reaction between Ba atom and HBr are studied by using the quasi-classical trajectory (QCT) calculation on extended London-Eyring-Polanyi-Sato (LEPS) potential-energy surface (PES). The vibrational distribution, reaction cross section, and rotational alignment of the product BaBr have been calculated. The calculations predict that the reaction cross section decreases, while the translation energy and rotational energy increase with the increasing of collision energy. It has been found that low collision energy favors the abstraction reaction, whereas high collision energy leads to an insertion reaction. The calculated results agree with the experimental data and some relative theoretical results as well. Key words: QCT, LEPS PES, vibrational distribution, reaction cross section, rotational alignment. On a realise une etude theorie de la reaction entre un atome de baryum et du HBr en faisant appel a des calculs de trajectoire quasi-classique (TQC) sur une surface d'energie potentielle (SEP) etendue de London-Eyring-Polanyi-Santo (LEPS). On a calcule la distribution vibrationnelle, la section droite de la reaction et l'alignement rotation du produit BaBr. Les calculs ont permis de predire que, une augmentation de l'energie de collision s'accompagne d'une diminution de la section droite de la reaction alors que l'energie de translation et l'energie de rotation augmentent. On a trouve qu'une faible energie de collision favorise une reaction d'abstraction alors qu'une energie de collision elevee conduit a une insertion. Les resultats calcules sont en bon accord avec les donnees experimentales ainsi qu'avec certains resultats theoriques. Mots-cles : trajectoire quasi-classique (TQC), LEPS SEP, distribution vibrationnelle, section droite de reaction, alignement reactionnel., [Traduit par la Redaction] Introduction Along with the interaction of experiments and theories in the field, the study of molecular reaction dynamics has obtained great development and extraordinary achievements in [...]

Several crystalline polymorphs have been discovered for picryl bromide. Among the several forces that control the formation of such polymorphs are the interactions among the nitro groups and phenyl rings of those crystals. Although there are >300 structures to be found in the Cambridge Structural Database displaying the nitro-phenyl interaction, nonetheless this interesting and apparently important, interaction, seems not to have been discussed within any of the papers reporting the structures. In this article, quantum calculations are reported that assess the strength of these nitro-phenyl interactions within a crystal of picryl bromide. The rather flat molecules of picryl bromide are arranged in layered planes within the crystal, and we examine the attractive interactions that occur within a given plane, and between adjacent planes. Calculations of Hartree Fock and Moller Plesset perturbation theory carried to a second-order expansion are used. Both quantum mechanical approximations are implemented with 6-31G* basis functions. Hartree Fock | Moller Plesset perturbation theory | quantum mechanics

Aryl allylic alcohols are converted to hydrogenated unsaturated ketones or allylic halides by using excess Moffatt-Swern reagent. The oxidation/halogenation reaction has performed well with both oxalyl chloride and oxalyl bromide, thus providing access to the corresponding chlorides or bromides, respectively.

The bromination of 6,7,8,9-tetrahydro-5H-5,9-ethenobenzo[a][7]annulene has yielded regio- and stereospecifically formed dibromides arising from the alkyl shift where the bromine exclusively attacks the double bond from the endo face of the double bond. The results have shown that the pyramidalization of the double bond and steric repulsion caused by the methylene protons are responsible for the stereo- and regioselective addition of bromine.

1-Arylmethyl-2-(cyanomethyl)aziridines are transformed into 4-(N,N-bis(arylmethyl)amino)-3-(pyrrolidin-1-yl)butanenitriles and 4-(N,N-bis(arylmethyl)amino)-2-butenenitriles through 4-(N,N-bis(arylmethyl)amino)-3-bromobutanenitriles in high yields. The main steps have involved the unprecedented regiospecific ring opening of intermediate 2-(cyanomethyl)aziridinium salts by bromide and pyrrolidine in acetonitrile at the substituted aziridine carbon atom.

Bromo- and iodoalkenes have undergone trifluoromethylation in N,N-dimethylacetamide (DMA) with 'C[F.sub.3]Cu' generated from [(C[F.sub.3]).sub.2]Hg and Cu. Variable stereochemical inversion is seen with substrates having a gem-carbonyl group, while substrates with gem-hydrogen, -alkyl, or -alkenyl groups have provided products with stereochemical retention.

The electrosynthesis, isolation and characterization of reaction products between [C.sub.60.sup.2-] and benzyl bromide in PhCN are reinvestigated. The visible and near-infrared spectra of the monoanion and dianion of 1,2-[(PhC[H.sub.2]).sub.2][C.sub.60] are described.

An experiment was carried out by subjecting molecular clusters of B[Br.sub.3] (Boron tribromide) to electron ionization and mass analysis in a reflectron time-of flight mass spectrometer. The results have predicted that fragment ions smaller than B[Br.sub.3.sup.+] undergo reactions with neutral B[Br.sub.3] molecules to form covalently bound adduct species that function as core ions within the clusters.

The freeze/thaw procedure is used to prepare the surfactant-containing poly(vinyl alcohol) (PVA) cryogels by drying and reswelling hydrogel patches in decyltrimethylammonium ([C.sub.10]TAB) aqueous solutions. It is shown that ([C.sub.10]TAB) micellization is unperturbed by the confinement of the surfactant molecules within the polymeric network of a freeze/thaw PVA hydrogel, and there is no direct surfactant-polymer interaction taking place.

A laboratory-scale model is developed to study the mechanism involved in the horizontal transport of Escherichia coli under saturation-excess flow conditions, focusing on the potential for E. coli to attach to soil particles during transport. The results have shown that in runoff generated by saturation-excess conditions, bacteria are rapidly transported across the surface and have little opportunity to interact with the soil matrix.

The thermal decomposition of quaternary ethylammonium chloride, bromide, and iodide is studied using the experimental techniques of thermal gravimetry coupled to Fourier transform infrared spectroscopy (TG- FTIR) and differential scanning calorimetry (DSC) as well as the density functional theory (DFT) and MP2 quantum- chemical methods. The respective experimental enthalpies of dissociation of the chloride, bromide, and iodide are 158, 181 and 195 kJ/mol.

The outcome of reactions of 1-bromo-4-tert-butylbenzene, a representative aryl bromide, with n-BuLi or t-BuLi at 0 degree Celsius in a variety of solvent systems is investigated. The products of reactions of 1-bromo-4-tert-butylbenzene with n-BuLi vary significantly with changes in solvent composition.

The influence of interface reactions on gas-phase molecular halogen production from pure NaCl and NaBr aerosols is examined with the help of the Model of Aerosol, Gas and Interfacial Chemistry (MAGIC 2.0). The main source of Cl2 is the interface process involving Cl-(sub surf) and OH(g).

The resonance Raman (RR) and surface--enhanced resonance Raman scattering (SERRS) of 4'-(N,N'-dimethyl-aminostyryl)-4-proplypyridinium bromide in acetonitrile solution and on a colloidal silver surface is discussed. The interaction with the silver surface is found to occur through the nitrogen lone pair of the pyridyl or the dimethylamino group of the molecule with a tilted orientation.

The 1-fluoro-1-haloalkenes undergo Pd-catalyzed Negishi cross-couplings with primary alkylzinc bromides to give multisubstituted fluoroalkenes and the alkylation was transselective giving pure Z-fluoroalkenes in most cases. The highest yields were obtained with Pd2(dba)3 and PdCl2(dppb) catalysts but the best stereochemical outcome was obtained with less reactive Pd(PPh3)4.

Nitrogen electrode reaction is studied in a LiBr-KBr-CsBr melt containing Li(sub 3)N. The results of quantitative analysis of anodically evolved gas from a LiBr-KBr-CsBr-Li(sub 3)N melt shows that the oxidation of N(super 3-) ions proceeds to produce pure nitrogen gas almost quantitatively at potentials more positive than 0.3 V versus Li(super +)/ Li and the standard formal potential of the N(sub 2)/N(super 3-) redox couple is evaluated and the thermodynamic quantities for Li(sub 3) is estimated.

The novel vanadium thiobromide, V(sub 4)S(sub 9)Br(sub 4), with a square-planner metal cluster core was synthesized and characterized by single-crystal X-ray diffraction, measurements of magnetic property and the heat capacity, and density functional theory (DFT) calculation of the electronic structure. The electronic structure of V(sub 4)S(sub 9)Br(sub 4) is characterized by a high spin state, that is, the electronic system is in the excited state.

The supersaturational ratio, S, was theoretically related to the supply rate of solute, Q, from growth rate and mass-balance equations in the quasi-steady state in the growth process of isotropic monodisperse particles. The results revealed that the supersaturation ratio was found out to be 1.28 as an average.

A high-yielding cross-coupling reaction of unactivated alkyl bromides possessing beta-hydrogens with alkylzinc halides utilizing a Pd/N-heterocyclic carbene (NHC) catalyst at room temperature is described. An investigation of different NHC precursors reveals that the bulky 2,6-diisopropylphenyl moiety is necessary to achieve high coupling yields.

Molecular dynamics simulations are used to study the solid and liquid properties and to predict the melting point of 1-n-propy1-4-amino-1,2,4-triazolium bromide ([patr][Br]) using force field based on Canongia Lopes and coworkers. The structures of the solid and liquid phases are characterized with radial distribution functions, which show that there are strong spatial correlations among neighboring ion pairs in liquid [patr][Br].

A convenient and chemoselective formation of functionalized benzofurans containing remote bromide functionality is reported. The products are formed by a new BBr3-mediated domino 'ring-cleavage-deprotection-cyclization' reaction.

Potential energy surface based on ab initio calculations are scaled, shifted, and dilated to generate three-dimensional morphed potential for Ar-HBr that reproduces the measured value of D0. These calculations provide a basis for making a comprehensive comparison of the different morphed potentials using the methodologies applied.

1,2-Dipyridiniumditribromide-ethane is synthesized and explored as a new efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as a safe source of bromine requiring just 0.5 equiv for complete bromination.

Glyoxal bis(N-methyl-N-phenylhydrazone) and its related compounds such as 2-pyridine-carboxaldehyde N-methyl-N-phenylhydrazone were prepared and examined as ligands for the Suzuki-Miyaura cross-coupling reaction of aryl halides and arylboronic acids. It was concluded that the Suzuki-Miyaura reaction of aryl bromide and arylboronic acids can be performed under mild phosphine-free conditions, based on Pd(OAc)(sub 2)/hydrazone and its related compounds with cesium carbonate in the DMF-water system under an aerobic atmosphere at room temperature.

The mechanism of forming silica spherical particles with radially orientated mesopores is investigated. Both intermediate and final products formed during precipitation of silica and cetytrimethylammonium bromide (CTAB) from solutions of ethanol, water, and ammonia are also examined.

A theoretical study on the torquoselectivity of the electrocyclic ring opening of 2,3-disubstitutedmono and dibromo cyclopropanes was carried out at the B3LYP/6-311++G level. As a result of charge donation from the dissociating C-C bond to the antibonding orbital of the breaking C-Br bond, only one of the two allowed disrotatory paths for the disrotatory ring opening that takes place in concert with the C-Br bond cleavage, is energetically accessible, both in gas phase and in solution.

Kinetics of excited-state proton-transfer reactions and proton-induced fluorescence quenching of 1-naphthol and 2-octadecyl-1-naphthol in micellar solutions of cetyltrimethylammonium bromide, polyoxyethylene(23) lauryl ether (Brij 35), and sodium dodecyl sulfate is studied by using stationary and time-resolved fluorescence techniques.

The effect of a positively charged dodecyl trimethylammonium bromide (DTAB) surfactant on the aqueous solvation of coumarin 314 (C314), a solvatochromic molecule, at the air/water interface was investigated. Steady-state and femtosecond time-resolved second harmonic generation (SHG) spectroscopy was employed as a surface-selective tool to characterize the solvation of C314.

The discovery of one-pot, three-step system involving the reaction of a range of primary amines with 2-bromoethyl-phenanthridinium bromide and leading to an unprecedented class of dihydro-imidazo-phenanthridinium (DIP) compounds, which exhibit DNA affinity and high cytotoxic activity is reported. A methodology is developed by means of a biphasic system using N-bromosuccinimide as a co-oxidizing agent and it has also been extended to other N-heterocyclic cation derivatives such as quinolinium and quinazolinium.

The synthesis of micelle-templated silicas is described. The self-assembly of inorganic silica and micelles of cetyltrimethylammonium bromide containing different amounts of 1,3,5-trimethylbenzene micelles used for this purpose is also examined.

Solvation dynamics of coumarin 480 (C480) is studied in a nanoporous sol-gel matrix. Its effect in the presence of cetyltrimethylammonium bromide is studied.

The interaction between dioctadecyldimethylammonium bromide (DODAB), chloride (DODAC), or acetate (DODAAc) cationic bilayer fragments (BF) and polystyrene sulfate (PSS) particles is examined, by means of zeta-potential, and particle diameter analysis, at and above equivalence of total surface areas for bilayers and particles (A(sub b)/A(sub p)) over a range of low NaCl and lipid concentrations.

The functionalization of carbon nanotubes with pyrene-containing dendra is investigated to examine the difference between Single-walled (SWNTs) and multiple-walled carbon nanotubes (MWNTs), and to assess the effect of the tether length. The results revealed that a significant emission contributions is from pyrene excimers in all functionalized carbon nanotubes samples in solution, and both SWNTs and MWNTs serve as efficient quenchers for the pyrene photoexcited states.

The interaction of the positively charged surfactant DDAB (didodecyldimethyl ammonium bromide) with preformed vesicles from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), and negatively charged surfactant oleate, are investigated. In both cases the matrix effect are shown by DDAB with the formation of mixed vesicles of size distribution depending on reactant concentrations.

Solid state solvation of HCl and HBr (HX acids) was investigated by FRIR spectroscopy, with methanol (MeOH), dimethyl ether (DME), and tetrahydrofuran (THF) acting as solvents. Effort was devoted to finding those composition ratios for which the acid and the solvent readily form mixed crystalline and amorphous solids and to the study of the extent of acid solvation in these solids.

An attempt is made to examine 'sulfur-sensitized' AgBr microcrystals, which enabled to produce a picture of photophysical processes that can occur when sulfide is deposited on an AgBr surface. The structure and energy levels with respect to the conduction and valence bands of AgBr of several species that may be formed during sulfur sensitization are calculated.

The study of the interaction of HBr with an ice surface via electronic structure calculations on a semiconstrained HBr.(H2O)13 model cluster at the MP2 level of theory using effective core potentials for all the heavy atoms. The resulting acid dissociation of HBr is found to be barrierless and energetically spontaneous.

The uptake kinetics of HOBr on NaBr and NaCl particle film surfaces are studied in a flow reactor coupled with a differentially pumped quadrupole mass spectrometer. The results are interpreted in terms of the mechanism HOBr(ad) + NaX -> BrX + NaOH, which involves the adsorption of HOBr on the surface with the reactions occurring mainly on a NaX surface domain without water coverage at low RH.

A study of the kinetics of the reactions of dibromide radical with methylarenes, aldehydes and carboxylic acids in acetic acid is presented. The results suggest that the variation of rate constant can be correlated with the reported rates for the overall catalytic conversions and investigation of several compounds with diuterium labels in the methylside chains show presence of a significant kinetic isotope effect.

Triton X-100 (TX-100) molecules coaggregate with cetyl trimethylammonium bromide (CTAB) molecules in aqueous solutions. In uniformly mixed solutions of TX-100 and CTAB, mixed micelles were formed and it was observed that there was interaction between the hydrophobic protons and hydrophilic protons of the 2 surfactants.

The pyrolysis of vinyl bromide was examined in the temperature range 637-733 K and at pressures from 6 to 86 kPa. The kinetic analysis indicates that the activation energy of the new free radical initiation channel is approximately 150 kJ mol(super -1), much less than the C-Br bond energy.

The appearance of energy of BrO(super +) from the dissociative ionization of OBrO was determined from the photoionization efficiency spectrum of BrO(super +) over the wavelength range 90-122 nm by using a discharge flow-photoionization mass spectrometer apparatus coupled to a vacuum-ultraviolet synchrotron radiation source. The results are perturbed by a signal from BrO(Super +) formed by direct photoionization of BrO and by the dissociative ionization of Br2O.

Research is done on the properties of the interface region of bulk, vapor-deposited, and single-crystal ice which are examined in a Knudsen cell flow reactor in the range 190-210 K using repetitive pulse experiments (RPEs) at variable frequency. Results of the experiment are presented that are in according to the laws of diffusion which leads to values of the HCl diffusion coefficient DHCl ranging from (4.0+- 1.0) x 10-14 to (2.8 +- 1.0) x 10-12 cm2 s-1 for single-crystal and bulk ice, respectively.

Phase response analysis of light-perturbed closed and aging Ru-catalyzed Belousov-Zhabotinsky (BZ) reactions is reported. The experimentally observed phase response curves agree well with the calculations performed with the Oregonator model.

The photodissociation of CHBr(sub 3) at 193 nm was investigated using photofragment translational spectroscopy with VuV ionization detection. The ab initio calculation provided important thermochemical information about the fragmentation of CHBr(sub 2) including the transition state associated with HBr elimination.

The influence of added electrolytes (NaBr, NaCl, Na2SO4, Na3PO4, Na2HPO4, NaSCN) on the lyotropic mesophase behavior of triethylammoniodecyloxycyanobipenyl bromide (OCB-C10NEt3) is studied by using the optical microscopy, X-ray diffraction, and NMR. The effects of the electrolytes are seen to follow the Hofmeister series and are attributed to adsorption or desorption of anions at the aggregate surface rather than to changes in 'water structure'.

The C-HCOSY, H-H COSY, and NOESY spectra of 2-[(cyclohexylhydroxyphenylacety)oxy]-N, N-diethyl-N-methylethanaminium bromide (OB), an antiacetylcholine drug, in D(sub 2)O are studied. Calculations of molecular mechanics, molecular dynamics, and molecular hydrophobic and hydrophilic surface areas are made for the prediction of its solution structure. A pair of the corresponding protons and carbons of the cyclohexyl group are magnetically nonequivalent with one another is established.

The solubility of HBr in H2SO4/H2O and HNO3/H2SO4/H2O solutions was determined by calculating the HBr vapor pressure over, stirred bulk solutions using tunable diode laser spectrometry. The relations derived in the experiment can be used for atmospheric modeling of the influence of heterogeneous HBr reactions on atmospheric ozone destruction.

The substituted reactions of phenancyl compounds with pyridines (XC5H4N) are investigated in acetonitrile at 45.0 degrees C. and the stepwise mechanism is described. This mechanism is supported by the faster rates with pyridines than with anilines.

The photochemistry of 3,5-dimethoxybenzyl compounds with the leaving groups acetate (1a), chloride (1b), bromide (1c), iodine (1d), diethyl phosphate (1e), and trimethylamine (1f), as the chloride, was examined by both product studies and flash photolysis. The reactive trienes produced in the photochemistry of 3,5-dimethoxybenzyl derivates are formed in only low yield (~ 16% for the acetate 2a, and the phosphate 2e) if at all (chloride, bromide and iodide).