Search results for "Bromine"
showing 10 items of 102 documents
Scanning electron microscopy characterization of ZnSe single crystals grown by solid-phase recrystallization
2000
ZnSe single crystals were grown from n-type microcrystalline boules by a Solid Phase Recrystallization (SPR) method. The recrystallizations were performed under different atmospheres, Ar or Se, and pressures to investigate the influence of growth conditions on the structural features of the resulting crystals. The samples were mechanically and mechano-chemically polished in a bromine methanol solution and, then, etched in HCl for a short time, before characterization. The homogeneity and the nature of defects in the crystals were studied by Cathodoluminescence (CL) in the scanning electron microscope (SEM). CL measurements show the existence of slip bands in the recrystallized samples, like…
Laser-induced plasma spectroscopy in near vacuum ultraviolet using ordinary spectrograph and ICCD
2002
An experimental setup to measure laser-induced plasma emission spectra with an ordinary Czerny-Turner spectrograph and intensified charge-coupled device in the near vacuum ultraviolet down to 130 nm is described. Spectra of bromine, chlorine and iodine were recorded to demonstrate the performance of the setup.
Synthesis of chiral 1,5-disubstituted pyrrolidinones via electrophile-induced cyclization of 2-(3-butenyl)oxazolines derived from (1R,2S)- and (1S,2R…
2006
Starting from (1R,2S)- and (1S,2R)-norephedrine, enantiomers of the corresponding 2-(3-butenyl)oxazolines were prepared in a two-step process. The cyclization of the intermediate alkenylamides with phenylselenyl bromide afforded cyclic imidates instead of the expected pyrrolidinones. The electrophile-induced cyclizations of 2-alkenyloxazolines with bromine or iodine produced diastereomeric mixtures of chiral 1,5-disubstituted pyrrolidinones. The ring closure of the all-cis (1R,2S,5R)-diastereomer 7 with NaH resulted in the tetrahydropyrrolo[2,1-b]oxazol-5-one derivative 18, which was alternatively prepared by the cyclocondensation of (1R,2S)-norephedrine with levulinic acid.
Towards controlling PCDD/F production in a multi-fuel fired BFB boiler using two sulfur addition strategies. Part II: Thermodynamic analysis
2014
Abstract A staged equilibrium process model was developed for a bubbling fluidized bed boiler firing SRF, bark and sludge. The model was used to study the influence of sulfur addition strategies (S-pellet additive and peat co-firing) on the behavior of copper, bromine, and alkalis. Aerosol samples collected from the backpass of the boiler were used to validate the chemistry predicted by the model. The model revealed that Cu existed as Cu 2 S (s3) in the reducing zone, and CuCl (g) (for all test cases) and CuO (s) (during peat co-firing) in the oxidation zones. CuBr 3(g) was also present after the introduction of tertiary air. However the model failed to predict the formation of CuSO 4 , an …
Size, Form and Flexibility of the Rubber Molecule
1962
Abstract Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 ti…
Copper(II) complexes with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-(N6)-benzoylhydrazone: synthesis, spectral and XRD studi…
1999
Abstract From reactions between different Cu(II) salts and the Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone (H2BEZDO) in alcohol, six new copper complexes with simplified formulas [Cu(HBEZDO)(H2O)(MeOH)]NO3 (1), [CuCl(HBEZDO)(DMF)] (2), [CuBr(HBEZDO)]·2H2O (3), CuBr(HBEZDO) (4), Cu(ClO4)(HBEZDO)·H2O (5), and Cu(SO4)1/2(HBEZDO)·1 1 2 H2O (6) were isolated. The structures of compounds 1, 2 and 3 have been established by means of XRD diffraction methods. In the three compounds, the Schiff base acts as a tridentate monodeprotonated ligand through the N(6), N(51) and O(52) atoms, making two five- and six-membered chelate rings. In the structure of 1 and 2, the solvent molecul…
Bromine chemistry of volcanic plumes
2012
Volcanic gas studies are an established tool for volcanic monitoring and enhance the understanding of volcanic manifestations. The central question of the project, which we will introduce here, is whether the ratio between bromine monoxide (BrO) to sulphur dioxide (SO2) can potentially serve as indicator for volcanic activity. Both species have the advantage that they can be remotely measured by Differential Optical Absorption Spectroscopy (DOAS) at safe distances from the emission source. To answer the question above, it is of great importance to link the measurements of halogen oxides to the total emission flux of individual halogen species and to understand the influences of meteorologic…
Über zinn-haltige heterocyclen
1981
Abstract A complete series of diphenyl and mixed methyl/chlorine/bromine/iodinephenyl substituted oxadithia- and trithiastannocanes has been prepared by reactions between the respective disodium dithiolates and tin dihalides. The 13C NMR chemical shifts of these compounds and the coupling constants J(119Sn13C) are dependent upon the magnetic anisotropy of the substituents and the bond angles at the tin atom. The crystal structure of 2,2-diphenyl-1,3,6-trithia-2-stannocane has been determined and refined to R = 0.039. The environment of Sn is a monocapped tetrahedron (transannular distance Sn⋯S 324.6(1) pm). This type of coordination, intermediate between a tetrahedron and a trigonal bipyra…
OH–π and halogen–π interactions as driving forces in the crystal organisations of tri-bromo and tri-iodo trityl alcohols
2008
The trityl alcohols bearing three bromine or three iodine atoms at the para-positions of the aromatic units, have been known for more than a hundred years. In our case these compounds have been synthesized in one-pot sequence starting from the 1,4-dihalogenobenzenes via mono-lithiation and the successive reaction with diethylcarbonate. The compounds have been crystallized from different solvent mixtures leading to one structure of bromo- (A) and three structures of iodo trityl alcohols (B–D). The inclusion of dichloromethane (C) or benzene (D) in the crystalline lattices has been observed. In all cases the OH–π and halogen–π (and in one case the halogen-halogen and CH-O weak) contacts play …
Mass spectra of halogenated esters: 8. Methyl esters of 2,3-dichloro-, bromochloro- and dibromopropenoic acids
1988
The mass spectral fragmentation of methyl esters of E and Z isomers of 2,3-dichloro-, 2-bromo-3-chloro-, 3-bromo-2-chIoro- and 2,3-dibromopropenoic acids have been investigated. The M+˙ peak is shown with all isomers, the [M − OCH3]+, [M − X]+, [M − OCH3 − CO]+, [M − OCH3 − CO − X]+˙ and [M − OCH3 − CO − X − X]+ ions constituting abundant peaks in all spectra. The results, particularly from the bromochloro isomers, show that a halogen atom is eliminated from the 3- rather than the 2- position and from the Z rather than the E isomer. Bromine as a bulky atom is preferentially lost.