Artículos de revistas: "Bromine and iodine"

1

Gilfedder, B. S., M. Petri y H. Biester. "Iodine and bromine speciation in snow and the effect of orographically induced precipitation". Atmospheric Chemistry and Physics 7, n.º 10 (21 de mayo de 2007): 2661–69. http://dx.doi.org/10.5194/acp-7-2661-2007.

Texto completo

Resumen

Abstract. Iodine is an essential trace element for all mammals and may also influence climate through new aerosol formation. Atmospheric bromine cycling is also important due to its well-known ozone depletion capabilities. Despite precipitation being the ultimate source of iodine in the terrestrial environment, the processes effecting its distribution, speciation and transport are relatively unknown. The aim of this study was to determine the effect of orographically induced precipitation on iodine concentrations in snow and also to quantify the inorganic and organic iodine and bromine species. Snow samples were collected over an altitude profile (~840 m) from the northern Black Forest and were analysed by ion-chromatography - inductively coupled plasma mass spectrometry (IC-ICP-MS) for iodine and bromine species and trace metals (ICP-MS). All elements and species concentrations in snow showed significant (r2>0.65) exponential decrease relationships with altitude despite the short (5 km) horizontal distance of the transect. In fact, total iodine more than halved (38 to 13 nmol/l) over the 840 m height change. The results suggest that orographic lifting and subsequent precipitation has a major influence on iodine concentrations in snow. This orographically induced removal effect may be more important than lateral distance from the ocean in determining iodine concentrations in terrestrial precipitation. The microphysical removal process was common to all elements indicating that the iodine and bromine are internally mixed within the snow crystals. We also show that organically bound iodine is the dominant iodine species in snow (61–75%), followed by iodide. Iodate was only found in two samples despite a detection limit of 0.3 nmol/l. Two unknown but most likely anionic organo-I species were also identified in IC-ICP-MS chromatograms and comprised 2–10% of the total iodine. The majority of the bromine was inorganic bromide with a max. of 32% organo-Br.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Gilfedder, B. S., M. Petri y H. Biester. "Iodine and Bromine speciation in snow and the effect of elevation". Atmospheric Chemistry and Physics Discussions 7, n.º 1 (22 de enero de 2007): 995–1016. http://dx.doi.org/10.5194/acpd-7-995-2007.

Texto completo

Resumen

Abstract. Iodine is an essential trace element for all mammals and may also influence climate through new aerosol formation. Atmospheric bromine cycling is also important due to its well-known ozone depletion capabilities. Despite precipitation being the ultimate source of iodine in the terrestrial environment, the processes effecting the distribution, speciation and transport of these elements are relatively unknown. The aim of this study was to determine the effect of orographic lifting on iodine concentrations and also quantify inorganic and organic iodine and bromine species. Snow samples were collected over an altitude profile (~800 m) from the northern Black Forest and were analysed (IC-ICP-MS) for iodine and bromine species and trace metals (ICP-MS). All elements and species showed a significant (r2>0.65) inverse relationship with altitude despite the short (5 km) horizontal distance of the transect. In fact, total iodine more than halved (38 to 13 nmol/l) over the 800 m height change. The results suggest that orographic lifting of cloud masses has a major influence on iodine levels in precipitation and is perhaps more important than lateral distances in determining iodine concentrations in terrestrial precipitation. The microphysical removal process was common to all elements. We also show that organically bound iodine is the dominant iodine species in snow (61–75%), followed by iodide. Iodate was only found in two samples despite a detection limit of 0.3 nmol/l. Two unknown but most likely anionic organo-I species were also identified in IC-ICP-MS chromatograms and comprised 2–10% of the total iodine. The majority of the bromine was inorganic bromide with a max.~of 32% organo-Br.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Spolaor, A., P. Vallelonga, J. M. C. Plane, N. Kehrwald, J. Gabrieli, C. Varin, C. Turetta, G. Cozzi, C. Boutron y C. Barbante. "Halogen species record Antarctic sea ice extent over glacial-interglacial periods". Atmospheric Chemistry and Physics Discussions 13, n.º 2 (12 de febrero de 2013): 3881–913. http://dx.doi.org/10.5194/acpd-13-3881-2013.

Texto completo

Resumen

Abstract. Sea ice is an integral part of the Earth's climate system because it affects planetary albedo, sea surface salinity, and the atmosphere-ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organo-iodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO) and iodine oxide (IO) decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE) ice core (159°11' E, 72°49' S, 2315 m a.s.l.) spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br−) is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I−) and iodate (IO3−), peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial-interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Spolaor, A., P. Vallelonga, J. M. C. Plane, N. Kehrwald, J. Gabrieli, C. Varin, C. Turetta et al. "Halogen species record Antarctic sea ice extent over glacial–interglacial periods". Atmospheric Chemistry and Physics 13, n.º 13 (12 de julio de 2013): 6623–35. http://dx.doi.org/10.5194/acp-13-6623-2013.

Texto completo

Resumen

Abstract. Sea ice is an integral part of the earth's climate system because it affects planetary albedo, sea-surface salinity, and the atmosphere–ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organoiodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO) and iodine oxide (IO) decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE) ice core (159°11' E, 72°49' S; 2315 m a.s.l.) spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br−) is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I−) and iodate (IO3−), peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial–interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Prashanth, Nagaraj, Kanakapura Basavaiah, Sameer Abdulrahman, Nagaraju Rajendraprasad y Basavaiah Vinay. "Application of bromate-bromide mixture as a green brominating agent for the spectrophotometric determination of atenolol in pharmaceuticals". Chemical Industry and Chemical Engineering Quarterly 18, n.º 1 (2012): 43–52. http://dx.doi.org/10.2298/ciceq110721045p.

Texto completo

Resumen

Two highly sensitive spectrophotometric methods are proposed for the quantification of atenolol (ATN) in pure drug as well as in pharmaceutical formulations. The methods are based on the bromination reaction of ATN with a known excess of bromate-bromide mixture in acid medium followed by the determination of unreacted bromine. The residual bromine is determined by its reaction with excess iodide and the liberated iodine (I3?) is either measured at 360 nm (method A) or reacted with starch followed by the measurement of the starch-iodine chromogen at 570 nm (method B). Under the optimum conditions, ATN could be assayed in the concentration ranges of 0.5-9.0 and 0.3-6.0?g mL-1 for method A and method B, respectively, with corresponding molar absorptivity values of 2.36?104 and 2.89?104 L/mol.cm. Sandell?s sensitivity values are found to be 0.0113 and 0.0092 ?g/cm2 for method A and method B, respectively. The proposed methods were successfully applied to the analysis of different commercial brands of pharmaceutical formulations and the results obtained by the proposed methods were in good agreement with those obtained using the reference method. The reliability of the methods was further ascertained by recovery studies using standard- addition method.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Abdel-Moety, Ezzat M., Abdel-Kader S. Ahmad y Mohie Sharaf El-Din. "Determination of Iodine Values of Lipids by Bromide Ion Selective Electrode". Journal of AOAC INTERNATIONAL 69, n.º 1 (1 de enero de 1986): 67–69. http://dx.doi.org/10.1093/jaoac/69.1.67.

Texto completo

Resumen

Abstract A semimicro method for determination of iodine values of lipids is described. An accurately weighed smear of sample (10-20 mg) on a strip of ashless filter paper, 14 × 40 mm, is brominated with bromine vapors for about 5 min. Excess bromine adsorbed on the filter paper is allowed to sublime. Bromine absorbed by the sample is directly related to the degree of unsaturation. Paper with brominated sample is subjected to oxygen flask combustion in the presence of 2 mL 1M sodium hydroxide solution and 10 mL water as absorbing liquid. Bromide formed, which is equivalent to unsaturation, is determined by bromide ion selective electrode. Bromide ions can be also determined by gravimetry or by indirect argentometric titration. The results were statistically analyzed. The iodine values of some fatty acids and oils, determined by this technique, are in accord with those of some officially approved methods.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Spolaor, A., P. Vallelonga, J. Gabrieli, T. Martma, M. P. Björkman, E. Isaksson, G. Cozzi et al. "Seasonality of halogen deposition in polar snow and ice". Atmospheric Chemistry and Physics Discussions 14, n.º 6 (25 de marzo de 2014): 8185–207. http://dx.doi.org/10.5194/acpd-14-8185-2014.

Texto completo

Resumen

Abstract. The atmospheric chemistry of iodine and bromine in polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine is emitted from biological communities hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial-interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine enrichment (relative to sea salt content) and iodine concentrations in polar ice do vary seasonally in Arctic snow and Antarctic ice and we relate such variability to satellite-based observations of tropospheric halogen concentrations. Peaks of bromine enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Rybakova, Anastasiya V., Dmitry G. Kim, Elena I. Danilina, Olesya V. Sazhaeva, Marina A. Ezhikova y Mikhail I. Kodess. "HETEROCYCLIZATION OF 3-PROPARGYLSULFANYL-5 PHENYL-1,2,4-TRIAZINE: TANDEM REACTIONS WITH BROMINE LEADING TO NEW DERIVATIVES OF 7 PHENYL[1,3]THIAZOLO[3,2-B][1,2,4]TRIAZINIUM". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, n.º 6 (12 de mayo de 2020): 19–24. http://dx.doi.org/10.6060/ivkkt.20206306.6102.

Texto completo

Resumen

Derivatives of 1,2,4-triazine-3-thione exhibit biological activity in a wide range. They have optoelectronic properties and can be used as synthons in synthesis of various pyridines by the Diels-Alder reaction. 1,2,4-Triazines are of the greatest interest, for organic synthesis in particular. In the present study we have established that the interaction of 3-propargylsulfanyl-5-phenyl-1,2,4-triazine, obtained by alkylation of 5-phenyl-2,3-dihydro-1,2,4-triazine-3-thione with 3-bromopropyne in acetone in the presence of triethylamine, with halogens leads to annelation of thiazole cycle. At that, [1,3]thiazolo[3,2-b][1,2,4]triazinium systems contain either endo- or exocyclic double bond in their structure, depending on the halogen type. By way of example, iodine acting on propargyl sulfide forms a dark precipitate of (3Z)-3-iodomethylene-7-phenyl-2,3-dihydro-[1,3]thiazolo[3,2-b][1,2,4]triazinium triiodide, the structure of which has been confirmed by 1H and 13C NMR spectroscopy, including two-dimensional 2D 1H-13C HSQC, HMBC and 1H-1H NOESY experiments. Treatment of the obtained triiodide by sodium iodide in acetone leads to synthesis of the corresponding monoiodide, which precipitates from the reaction mixture as a dark red precipitate. Reaction with bromine, as distinct from heterocyclization under iodine action, comprises an unusual cascade reaction including the stages of electrophile heterocyclization, bromine addition, and hydrogen bromide elimination, which leads to formation of 3-dibromomethyl-7-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazinium bromide. It should be pointed out that the identifying feature of 3-propargylsulfanyl-5-phenyl-1,2,4-triazine heterocyclization under iodine and bromine action is the signal bias of the aromatic proton in a triazine ring towards weak field in the 1H NMR spectrum of the reaction products. This is presumably associated with formation of the positively charged nitrogen atom.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Mityusheva, T. P. y O. Ye Amosova. "Industrial brines of the Khoreyver depression of the Pech ora plate". Vestnik of Geosciences 8 (2021): 27–45. http://dx.doi.org/10.19110/geov.2021.8.3.

Texto completo

Resumen

We studied areal distribution of the Khoreyver depression and strontium and lithium-rich iodine-bromine and iodine-boron industrial brines in the hydrogeological section. We presented the potential of the territory for practical use of industrial sodium chloride and calcium-sodium underground brines in the maps of distribution of bromine, iodine, boron and strontium-lithium iodinebromine and iodine-boric industrial brines within three Paleozoic calcareous aquifers (O2–S–D1; D3–C1; C–P1). Separate areas with lithium-strontium iodine - bromine and iodine-boric standard quality brines are designated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Spolaor, A., P. Vallelonga, J. Gabrieli, T. Martma, M. P. Björkman, E. Isaksson, G. Cozzi et al. "Seasonality of halogen deposition in polar snow and ice". Atmospheric Chemistry and Physics 14, n.º 18 (16 de septiembre de 2014): 9613–22. http://dx.doi.org/10.5194/acp-14-9613-2014.

Texto completo

Resumen

Abstract. The atmospheric chemistry of iodine and bromine in Polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine emission is attributed to biological communities in the open ocean and hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial–interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine and iodine concentrations and Br enrichment (relative to sea salt content) in polar ice do vary seasonally in Arctic snow and Antarctic ice. Although seasonal variability in halogen emission sources is recorded by satellite-based observations of tropospheric halogen concentrations, seasonal patterns observed in snowpack are likely also influenced by photolysis-driven processes. Peaks of bromine concentration and Br enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. A secondary bromine peak, observed at the end of summer, is attributed to bromine deposition at the end of the polar day. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions. These findings support previous observations of iodine peaks in winter snow strata attributed to the absence of sunlight-driven photolytic re-mobilisation of iodine from surface snow. Further investigation is required to confirm these proposed mechanisms explaining observations of halogens in polar snow and ice, and to evaluate the extent to which halogens may be applied as sea ice proxies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Sherwen, T., M. J. Evans, L. J. Carpenter, S. J. Andrews, R. T. Lidster, B. Dix, T. K. Koenig et al. "Iodine's impact on tropospheric oxidants: a global model study in GEOS-Chem". Atmospheric Chemistry and Physics Discussions 15, n.º 15 (5 de agosto de 2015): 20957–1023. http://dx.doi.org/10.5194/acpd-15-20957-2015.

Texto completo

Resumen

Abstract. We present a global simulation of tropospheric iodine chemistry within the GEOS-Chem chemical transport model. This includes organic and inorganic iodine sources, standard gas-phase iodine chemistry and simplified higher iodine oxide (I2OX, X = 2, 3, 4) chemistry, photolysis, deposition and parametrised heterogeneous reactions. In comparisons with recent Iodine Oxide (IO) observations the iodine simulation shows an average bias of ~+66 % available surface observations in the marine boundary layer (outside of polar regions), and of ~+73 % within the free troposphere (350 < hPa < 900) over the eastern Pacific. Iodine emissions (3.8 Tg yr−1) are overwhelmingly dominated by the inorganic ocean source, with 76 % of this emission from Hypoiodous acid (HOI). HOI is also found to be the dominant iodine species in terms of global tropospheric IY burden (contributing up to 70 %). The iodine chemistry leads to a significant global tropospheric O3 burden decrease (9.0 %) compared to standard GEOS-Chem (v9-2). The iodine-driven OX loss rate (748 Tg OX yr−1) is by photolysis of HOI (78 %), photolysis of OIO (21 %), and reaction of IO and BrO (1 %). Increases in global mean OH concentrations (1.8 %) by increased conversion of hydroperoxy radicals exceeds the decrease in OH primary production from the reduced O3 concentration. We perform sensitivity studies on a range parameters and conclude that the simulation is sensitive to choices in parameterisation of heterogeneous uptake, ocean surface iodide, and I2OX (X = 2, 3, 4) photolysis. The new iodine chemistry combines with previously implemented bromine chemistry to yield a total bromine and iodine driven tropospheric O3 burden decrease of 14.4 % compared to a simulation without iodine and bromine chemistry in the model. This is a significant impact and so halogen chemistry needs to be considered in climate and air quality models.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Emmanuel Koné, Klègayéré, Amal Bouich, Donafologo Soro y Bernabé Marí Soucase. "Effect of mixed iodine and bromine on optical properties in methylammonium lead chlorine (MAPbCl3) spin-coated on the zinc oxide film". E3S Web of Conferences 412 (2023): 01066. http://dx.doi.org/10.1051/e3sconf/202341201066.

Texto completo

Resumen

The optical influence of mixing methylammonium lead chlorine (MAPbCl3) with iodine and bromine was studied in this work. The spin coating method deposited three layers of perovskites (MAPbCl3, MAPbCl2I, and MAPbCl2Br) on a layer of zinc oxide (ZnO). The zinc oxide solution was prepared by dissolving dehydrated zinc acetate [Zn(CH3COO)2, 2H2O]> 99.5% purity in ethanol to give a 0.5 M solution. The perovskite solutions were prepared using lead chloride (PbCl2), methylammonium chloride (MACl), methylammonium iodide (MAI), and methylammonium bromide (MABr). The precursor containing iodine was dissolved in N, N-dimethylformamide (DMF) and the others in dimethyl sulphoxide (DMSO 99.9%). The films produced were characterized by UV-Visible. The analysis showed that the sample mixed with iodine has good properties. This sample absorbs the most and has a small band gap of 2 eV. The degradation study reveals that the unmixed sample (MAPbCl3) is the most stable.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Okamoto, H. "Br-I (bromine-iodine)". Journal of Phase Equilibria 20, n.º 4 (julio de 1999): 454. http://dx.doi.org/10.1361/105497199770335659.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Thompson, C. R., P. B. Shepson, J. Liao, L. G. Huey, E. C. Apel, C. A. Cantrell, F. Flocke et al. "Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska". Atmospheric Chemistry and Physics Discussions 14, n.º 21 (19 de noviembre de 2014): 28685–755. http://dx.doi.org/10.5194/acpd-14-28685-2014.

Texto completo

Resumen

Abstract. The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, detection of atmospheric I2. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, constrained with measurements from the 2009 OASIS field campaign in Barrow, Alaska. We simulated a 7 day period during late March that included a full ozone depletion event lasting 3 days and subsequent ozone recovery to study the interactions of halogen radicals under these different conditions. In addition, the effects of iodine added to our base model were investigated. While bromine atoms were primarily responsible for ODEs, chlorine and iodine were found to enhance the depletion rates and iodine was found to be more efficient per atom at depleting ozone than Br. The interaction between chlorine and bromine is complex, as the presence of chlorine can increase the recycling and production of Br atoms, while also increasing reactive bromine sinks under certain conditions. Chlorine chemistry was also found to have significant impacts on both HO2 and RO2. The results of this work highlight the need for future studies on the production mechanisms of Br2 and Cl2, as well as on the potential impact of iodine in the High Arctic.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Thompson, C. R., P. B. Shepson, J. Liao, L. G. Huey, E. C. Apel, C. A. Cantrell, F. Flocke et al. "Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska". Atmospheric Chemistry and Physics 15, n.º 16 (28 de agosto de 2015): 9651–79. http://dx.doi.org/10.5194/acp-15-9651-2015.

Texto completo

Resumen

Abstract. The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, observation of snowpack photochemical production of I2. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, constrained with measurements from the 2009 OASIS field campaign in Barrow, Alaska. We simulated a 7-day period during late March that included a full ozone depletion event lasting 3 days and subsequent ozone recovery to study the interactions of halogen radicals under these different conditions. In addition, the effects of iodine added to our Base Model were investigated. While bromine atoms were primarily responsible for ODEs, chlorine and iodine were found to enhance the depletion rates and iodine was found to be more efficient per atom at depleting ozone than Br. The interaction between chlorine and bromine is complex, as the presence of chlorine can increase the recycling and production of Br atoms, while also increasing reactive bromine sinks under certain conditions. Chlorine chemistry was also found to have significant impacts on both HO2 and RO2, with organic compounds serving as the primary reaction partner for Cl atoms. The results of this work highlight the need for future studies on the production mechanisms of Br2 and Cl2, as well as on the potential impact of iodine in the High Arctic.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Jameson, Alexander y Elod Gyenge. "Comparison of Zinc Bromine and Zinc Iodine Flow Batteries: From Electrolde to Electrolyte". ECS Meeting Abstracts MA2022-01, n.º 48 (7 de julio de 2022): 2000. http://dx.doi.org/10.1149/ma2022-01482000mtgabs.

Texto completo

Resumen

Research in flow batteries and their application in large scale energy storage has received a growing amount of attention and promise over the past two decades. Although the energy density of flow batteries is low relative to the Li-ion battery, their comparatively lower costs, preferred safety, and ease of scalability has made flow batteries some of the most promising contenders for large-scale stationary energy storage, and are currently commercially available for this purpose. The zinc-bromine flow battery (ZBFB), despite being one of the first proposed flow batteries in the 1980s, has only recently gained enough traction to compete with the well established all-vanadium redox flow batteries. This is largely due to the high solubility of the bromine redox species in aqueous electrolytes, which has allowed the ZBFB is achieve double the energy density of the all-vanadium technology. Recently, an analogue to the zinc-bromine flow battery was introduced: the zinc-iodine flow battery (ZIFB). Similar to the ZBFB, the main advantages of this technology arose from the high solubility of the electroactive species in the electrolyte (iodine/tri-iodide). The solubility of the iodine redox species is even higher than that of analogous bromine electrolytes, and accordingly, the highest energy densities of all aqueous flow batteries to date has been for the ZIFB. Despite the similarities between the two technologies, they are held back by different issues, and so different approaches have been taken to improving the performances of the ZBFB and ZIFB. The ZBFB primarily suffers from a low power-density due to the sluggish kinetics of the bromine redox couple. Therefore, a majority of research on the ZBFB has focused on identifying new, low cost electrode materials that minimize kinetic losses at the bromine half-cell. In contrast, a majority of research on the ZIFB has been on improvements to the electrolyte composition. The ZIFB is plagued by issues of a thick, high impedance iodine film that forms at the positive electrode on charge. Due to the strong Lewis acid nature of the iodine species, a variety of charge-transfer complexes can be formed in the electrolyte, having a variety of effects on the battery performance. This presentation provides an overview on the similarities and differences between the ZBFB and ZIFB technologies. We performed a variety of half-cell and flow battery tests varying the electrode and electrolyte compositions. A number of low cost carbon materials are used as electrode materials, along with a variety of modifications to the bromine and iodine electrolytes. Through the use of high-surface area carbon blacks, the exchange current of the bromine redox couple is able to be increased by two orders to magnitude in comparison to glassy carbon. Additions of MSA or other acids to the ZBFB increases the oxidation kinetics greatly, and accordingly the overall energy efficiency of the ZBFB. For the ZIFB, the presence of high surface area catalysts have little to no effect on the overall performance. We found that in aqueous electrolytes, the iodine electrode is largely held back by the iodine film that forms on charge. Therefore, by adding ions to the electrolyte such as Br-, Cl-, and SO4 2-, we were able to increase the solubility of the iodine film and the reversibility of the battery, and accordingly its efficiency. Although the ZIFB initially performs better than the ZBFB, after making systematic adjustments to both the electrode and electrolyte compositions, the discrepancy between their performances is largely minimized, demonstrating both can be viable for the future of large-scale energy storage. Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Biester, H., D. Selimović, S. Hemmerich y M. Petri. "Halogens in porewater of peat bogs – the role of peat decomposition and dissolved organic matter". Biogeosciences Discussions 2, n.º 5 (20 de septiembre de 2005): 1457–86. http://dx.doi.org/10.5194/bgd-2-1457-2005.

Texto completo

Resumen

Abstract. Peatlands are one of the largest active terrestrial reservoirs of halogens. Formation of organo-halogens is a key process for the retention of halogens by organic matter and halogen enrichment in peat is strongly influenced by climatically controlled humification processes. However, little is known about release and transport of halogens in peat bogs. In this study we investigated the release of halogens from peat in three peat bogs located in the Magellanic Moorlands, southern Chile. Peat porewaters were collected using a sipping technique, which allows in situ sampling down to a depth of more than 6 m. Halogens and halogen species in porewater were determined by ion-chromatography (IC) (chlorine) and IC-ICP-MS (bromine and iodine). Results show that halogen concentrations in porewater are 15–30 times higher than in rainwater suggesting that their release from peat during diagenesis is the major source of halogens in porewater. Mean concentrations of chlorine, bromine and iodine in porewater were 7–15 mg l−1, 56–123μg l−1, and 10–20μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organo-bromine and organoiodine were predominant in porewaters, whereas the release of organo-chlorine compounds from peat appears to be of minor importance. Results show that the release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC) was also the most intensive. Here, proportions of released iodine and bromine follow proportions of released dissolved organic matter (DOM) indicating that the release of halogenated DOM is the predominant process of iodine and bromine release from peat.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Sherwen, T., M. J. Evans, L. J. Carpenter, S. J. Andrews, R. T. Lidster, B. Dix, T. K. Koenig et al. "Iodine's impact on tropospheric oxidants: a global model study in GEOS-Chem". Atmospheric Chemistry and Physics 16, n.º 2 (2 de febrero de 2016): 1161–86. http://dx.doi.org/10.5194/acp-16-1161-2016.

Texto completo

Resumen

Abstract. We present a global simulation of tropospheric iodine chemistry within the GEOS-Chem chemical transport model. This includes organic and inorganic iodine sources, standard gas-phase iodine chemistry, and simplified higher iodine oxide (I2OX, X = 2, 3, 4) chemistry, photolysis, deposition, and parametrized heterogeneous reactions. In comparisons with recent iodine oxide (IO) observations, the simulation shows an average bias of ∼ +90 % with available surface observations in the marine boundary layer (outside of polar regions), and of ∼ +73 % within the free troposphere (350 hPa < p < 900 hPa) over the eastern Pacific. Iodine emissions (3.8 Tg yr−1) are overwhelmingly dominated by the inorganic ocean source, with 76 % of this emission from hypoiodous acid (HOI). HOI is also found to be the dominant iodine species in terms of global tropospheric IY burden (contributing up to 70 %). The iodine chemistry leads to a significant global tropospheric O3 burden decrease (9.0 %) compared to standard GEOS-Chem (v9-2). The iodine-driven OX loss rate1 (748 Tg OX yr−1) is due to photolysis of HOI (78 %), photolysis of OIO (21 %), and reaction between IO and BrO (1 %). Increases in global mean OH concentrations (1.8 %) by increased conversion of hydroperoxy radicals exceeds the decrease in OH primary production from the reduced O3 concentration. We perform sensitivity studies on a range of parameters and conclude that the simulation is sensitive to choices in parametrization of heterogeneous uptake, ocean surface iodide, and I2OX (X = 2, 3, 4) photolysis. The new iodine chemistry combines with previously implemented bromine chemistry to yield a total bromine- and iodine-driven tropospheric O3 burden decrease of 14.4 % compared to a simulation without iodine and bromine chemistry in the model, and a small increase in OH (1.8 %). This is a significant impact and so halogen chemistry needs to be considered in both climate and air quality models. 1 Here OX is defined as O3 + NO2 + 2NO3 + PAN + PMN+PPN + HNO4 + 3N2O5 + HNO3 + BrO + HOBr + BrNO2+2BrNO3 + MPN + IO + HOI + INO2 + 2INO3 + 2OIO+2I2O2 + 3I2O3 + 4I2O4, where PAN = peroxyacetyl nitrate, PPN = peroxypropionyl nitrate, MPN = methyl peroxy nitrate, and MPN = peroxymethacryloyl nitrate.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Biester, H., D. Selimović, S. Hemmerich y M. Petri. "Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter". Biogeosciences 3, n.º 1 (27 de enero de 2006): 53–64. http://dx.doi.org/10.5194/bg-3-53-2006.

Texto completo

Resumen

Abstract. Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC) (chlorine) and IC-ICP-MS (bromine and iodine). Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC) was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM) is the predominant mechanism of iodine and bromine release from peat.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Struble, Mark D., Michael T. Scerba, Maxime Siegler y Thomas Lectka. "Evidence for a Symmetrical Fluoronium Ion in Solution". Science 340, n.º 6128 (4 de abril de 2013): 57–60. http://dx.doi.org/10.1126/science.1231247.

Texto completo

Resumen

Halonium ions, in which formally positively charged halogens (chlorine, bromine, and iodine) are equivalently attached to two carbon atoms through three-center bonds, are well established in the synthetic chemistry of organochlorides, bromides, and iodides. Mechanistic studies of these ions have generated numerous insights into the origins of stereoselectivity in addition and displacement reactions. However, it has not been clear whether fluorine can form a halonium ion in the same manner. We present chemical and theoretical evidence for the transient generation of a true symmetrical fluoronium ion in solution from an appropriately configured precursor.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Fan, X., E. C. Dickey, A. A. Puretzky, D. B. Geohegan y S. J. Pennycook. "STEM Observation and EELS Analysis of Dopant and Catalyst Particles in Carbon Nanotubes". Microscopy and Microanalysis 6, S2 (agosto de 2000): 48–49. http://dx.doi.org/10.1017/s1431927600032736.

Texto completo

Resumen

Doping carbon nanotubes with either electron donors or acceptors can improve their electrical conductivity [1-2]. In order to fully understand the doping mechanisms and the corresponding changes in the electronic properties, it is essential to reveal the spatial distribution of the dopants within the carbon nanotubes. In this study we have investigated both iodine- and bromine-doped single wall carbon nanotubes(SWNT) by Z-contrast scanning transmission electron microscopy (STEM). The SWNT bundles were made by arc-discharge method and doped with either molten iodine or bromine vapor. Both iodine and bromine were incorporated linearly within the nanotube bundles as shown in Fig. l and Fig.2 respectively. Higher resolution images of iodine doped nanotubes reveals that two iodine atomic chains are inside each individual SWNT as shown in Fig. lc. This unexpected result is contrary to the common belief that dopants can only enter interstitial site of the SWNT bundles.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Iskander, Felib Y. "Determination of Iodine Value by Bromine/Instrumental Neutron Activation Analysis". Journal of AOAC INTERNATIONAL 72, n.º 3 (1 de mayo de 1989): 498–500. http://dx.doi.org/10.1093/jaoac/72.3.498.

Texto completo

Resumen

Abstract A new microanalytical method has been developed to measure iodine value (IV) of oils and fats. Bromine vapor was used to saturate the ethylenic double bonds, and reacted bromine was determined by instrumental neutron activation analysis. The method was applied to measure the iodine values of 7 commercially available vegetable oils: almond oil, sunflower oil, peanut oil, soy oil, sesame oil, corn oil, and olive oil. No significant difference was observed between the iodine value determined by the proposed method and that determined by an officially approved (Hübl) method. Bromine measurements can be performed up to 150 days after bromination with no significant variation in iodine value; thus, availability of an irradiation facility on the premises is not a limitation. No corrosive and toxic reagents are required, and the method is faster than the official methods. The method is also applicable to measuring iodine values of free or esterified fatty acids.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Novakova, Gergana, Presian Bonev, Mary Duro, Rui Azevedo, Cristina Couto, Edgar Pinto y Agostinho Almeida. "Serum Iodine and Bromine in Chronic Hemodialysis Patients—An Observational Study in a Cohort of Portuguese Patients". Toxics 11, n.º 3 (6 de marzo de 2023): 247. http://dx.doi.org/10.3390/toxics11030247.

Texto completo

Resumen

Background: Patients on chronic hemodialysis therapy are at high risk of disturbances in trace element status due to both the underlying disease and the hemodialysis process itself. Data on iodine and bromine levels in these patients are scarce. Methods: Using an ICP-MS analytical procedure, serum iodine and bromine levels were determined in a cohort (n = 57) of end-stage renal disease patients on chronic hemodialysis. The results were compared with those of a control group (n = 59). Results: Hemodialysis patients presented serum iodine levels within the normal range, slightly lower than in controls, but without reaching a statistically significant difference (67.6 ± 17.1 µg/L vs. 72.2 ± 14.8 µg/L; p = 0.1252). In contrast, serum bromine levels were much lower in patients (1086 ± 244 µg/L vs. 4137 ± 770 µg/L; p < 0.0001), at values only about 26% of the values observed in controls. Conclusions: Hemodialysis patients had normal serum iodine levels, but highly decreased serum bromine levels. The clinical significance of this finding requires further investigation, but it may be associated with sleep disturbances and fatigue that affect hemodialysis patients.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Francke, Robert, Nayereh Mohebbati, Igors Sokolovs y Edgars Suna. "Electrochemistry of Hypervalent Bromine(III) Compounds". ECS Meeting Abstracts MA2022-01, n.º 42 (7 de julio de 2022): 1822. http://dx.doi.org/10.1149/ma2022-01421822mtgabs.

Texto completo

Resumen

The chemistry of hypervalent halogen species has experienced remarkable advancement in the recent decades [1]. However, in comparison to the well-explored hypervalent iodine(III) compounds, little research has been done on the isoelectronic bromine(III) counterparts [2]. This is mainly due to the difficult-to-control reactivity of λ 3-bromanes as well as to the challenges associated with the conventional protocol for their preparation from the highly toxic and corrosive precursor BrF3 [3]. In this context, we present a straightforward and scalable approach to λ 3-bromanes by anodic oxidation of parent aryl bromides. A series of para-substituted λ 3-bromanes with remarkably high redox potentials spanning a range from 1.86 V to 2.60 V vs. Ag/AgNO3 was synthesized by the electrochemical method. We demonstrate that the bench-stable bromine(III) species can be activated by addition of a Lewis or a Brønsted acid and used for various synthetic applications [4]. The developed electrochemical approach to λ 3-bromanes offers considerable advantages compared to previously established methods since stoichiometric reagents are replaced by electric current and the use of hazardous precursors is omitted. Therefore, our approach may open the door to the development of unprecedented synthetic transformations that would benefit from the unique properties of hypervalent bromine(III) species. Mechanistic studies on formation and activation of the bromanes are underway [5]. References: 1. Yoshimura, A.; Zhdankin, V. V., Chem Rev 2016, 116, 3328-435. 2. Miyamoto, K., Chemistry of Hypervalent Bromine. In PATAI'S Chemistry of Functional Groups 2018, pp 1-25. 3. Farooq, U.; Shah, A. A.; Wirth, T., Angew. Chem. Int. Ed. 2009, 48, 1018-1020. 4. Sokolovs, I.; Mohebbati, N.; Francke, R.; Suna, E., Angew. Chem. Int. Ed. 2021, 60, 15832-15837. 5. Mohebbati, N.; Sokolovs, I.; Woitke, P.; Leito, I.; Roemelt, M.; Suna, E.; Francke, R.; 2022, manuscript in preparation. Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Winterson, Bethan, Tuhin Patra y Thomas Wirth. "Hypervalent Bromine(III) Compounds: Synthesis, Applications, Prospects". Synthesis 54, n.º 05 (21 de octubre de 2021): 1261–71. http://dx.doi.org/10.1055/a-1675-8404.

Texto completo

Resumen

AbstractHypervalent compounds play a prominent role in homogeneous oxidation catalysis. Despite the higher reactivity of hypervalent bromine compounds when compared to their isoelectronic iodine analogues, the corresponding λ3-bromanes are much less explored. This can be attributed to the discernible lack of convenient strategies for their synthesis. This short review highlights the available methods for the synthesis of various organo-λ3-bromanes, with a major focus on the recent developments and reactivities in the last few years. Additionally, limitations and future prospects of hypervalent bromine chemistry are discussed.1 Introduction2 Diaryl-λ3-bromanes3 Dialkyl-λ3-bromanes4 Dihetero-λ3-bromanes5 Alkenyl-λ3-bromanes6 Alkynyl-λ3-bromanes7 Conclusion and Prospects

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Meletis, Chris D. "Iodine". Journal of Evidence-Based Complementary & Alternative Medicine 16, n.º 3 (25 de agosto de 2011): 190–94. http://dx.doi.org/10.1177/2156587211414424.

Texto completo

Resumen

Iodine levels in the United States have dropped precipitously over the past few decades, whereas antagonists such as bromine, perchlorate, and fluoride have become more ubiquitous. These changes have placed a nutritional burden on the human body and increased the potential for pathophysiological change at the cellular level. This review examines the clinical and peer-reviewed literature and provides perspective related to health-compromising trends that warrant close scrutiny in clinical practice and future research mandates.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Cleaver, Brian y David H. Condlyffe. "The effect of pressure on the electrical conductivity of liquid iodine, iodine chloride, iodine bromide and bromine trifluoride". Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 85, n.º 8 (1989): 2453. http://dx.doi.org/10.1039/f19898502453.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Tarasova, N. M., I. D. Yushina, D. G. Kim y V. V. Sharutin. "Synthesis, structure and non-covalent interactions of 5-methyl-2,3-dihydrothiazolo[2,3-<i>b</i>]thiazolium halides". Журнал общей химии 93, n.º 1 (15 de enero de 2023): 58–66. http://dx.doi.org/10.31857/s0044460x23010079.

Texto completo

Resumen

2,3-Dihydrothiazolo[2,3- b ]thiazolium iodides and bromide were obtained for the first time by the cyclization of corresponding metallyl- and propinylsulfanyl derivatives of 1,3-thiazole with iodine and bromine in dichloromethane without heating and the use of strong acids. The structure of the obtained compounds was studied by 1H, 13C{1H} NMR spectroscopy. Structure of the 3-iodomethyl-3,5-dimethyl-2,3-dihydrothiazolo[2,3- b ][1,3]thiazolium heterocyclic system is characterized by the X-ray analysis. The bonding in the heterocyclic system and non-covalent cation-anion interactions are analyzed on the basis of quantum chemical calculations with periodic boundary conditions; I···S chalcogen bond is discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Spolaor, A., T. Opel, J. R. McConnell, O. J. Maselli, G. Spreen, C. Varin, T. Kirchgeorg, D. Fritzsche y P. Vallelonga. "Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)". Cryosphere Discussions 9, n.º 4 (24 de agosto de 2015): 4407–36. http://dx.doi.org/10.5194/tcd-9-4407-2015.

Texto completo

Resumen

Abstract. The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of AD 1950 to 1998 sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The halogens bromine (Br) and iodine (I) are strongly influenced by sea ice processes. Bromine reacts with the sea ice surface in auto-catalyzing "Bromine explosion" events causing an enrichment of the Br / Na ratio and the bromine excess (Brexc) in snow compared to that in seawater. Iodine is emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. These two halogens are therefore good candidates for extended reconstructions of past sea ice changes in the Arctic.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Kopylov, S. N., P. S. Kopylov, I. P. Eltyshev y I. R. Begishev. "Effect of the State of the Reactor Surface on the Characteristics of Combustion of Gas Mixtures Containing Halogen-Substituted Hydrocarbons". Журнал физической химии 97, n.º 8 (1 de agosto de 2023): 1207–12. http://dx.doi.org/10.31857/s0044453723080113.

Texto completo

Resumen

The influence of the reactor walls on combustion of gas mixtures containing halogenated hydrocarbons at atmospheric pressure has been studied experimentally. When the wall is contaminated with combustion products, the additional amounts of bromine or iodine that passed from it into the volume reduce the efficiency of combustion inhibition of hydrogen–air mixtures by bromine- and iodine-containing hydrocarbons (the effect was more pronounced for iodinated substances) and weakens the self-inhibition of the combustion of ethyl bromide in a mixture with air, leading to the expansion of the concentration region of flame propagation. Based on the analysis of the known kinetic data, the experimentally observed picture was explained by a diminished role of the HI regeneration cycle during the inhibition of hydrogen combustion in air by iodinated hydrocarbon and decreased rate of the reaction of brominated hydrocarbons with atomic hydrogen when additional amounts of I2 and Br2 are supplied from the reactor wall.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Harris, Gordon S. y J. S. McKechnie. "Conductometric titration study of the reactions of some trialkylphosphines with bromine, iodine and iodine bromide". Polyhedron 4, n.º 1 (enero de 1985): 115–20. http://dx.doi.org/10.1016/s0277-5387(00)84230-8.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Giscard, M. "Bromine and Iodine-bromine Mineral Waters in the Voronezh Region". Вестник ВГУ Серия География Геоэкология, n.º 4 (2022): 131–40. http://dx.doi.org/10.17308/geo/1609-0683/2022/4/131-140.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Gaude, Didier, Gisèle Gellon, Raymond Le Goaller y Jean-Louis Pierre. "Influence de la complexation sur la réactivité de nitrates d'halogènes". Canadian Journal of Chemistry 67, n.º 1 (1 de enero de 1989): 104–8. http://dx.doi.org/10.1139/v89-018.

Texto completo

Resumen

Iodine nitrate or bromine nitrate in acetonitrile or in chloroform react with a variety of phenolic substrates to form both halogenated and nitrated products. In the presence of strong complexing agents of halonium ions, no reaction occurs, while in the presence of pyridine or triethylamine, only halogenated phenols exhibiting a strong ortho-directing effect of the phenolic function are produced. Keywords: phenols, iodine nitrate, bromine nitrate, halogenation, nitration.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Spolaor, A., T. Opel, J. R. McConnell, O. J. Maselli, G. Spreen, C. Varin, T. Kirchgeorg, D. Fritzsche, A. Saiz-Lopez y P. Vallelonga. "Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)". Cryosphere 10, n.º 1 (26 de enero de 2016): 245–56. http://dx.doi.org/10.5194/tc-10-245-2016.

Texto completo

Resumen

Abstract. The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere–ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The chemistry of halogens bromine (Br) and iodine (I) is strongly active and influenced by sea ice dynamics, in terms of physical, chemical and biological process. Bromine reacts on the sea ice surface in autocatalyzing "bromine explosion" events, causing an enrichment of the Br / Na ratio and hence a bromine excess (Brexc) in snow compared to that in seawater. Iodine is suggested to be emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. The correlation coefficients obtained between Brexc and spring sea ice (r = 0.44) as well as between iodine and summer sea ice (r = 0.50) for the Laptev Sea suggest that these two halogens could become good candidates for extended reconstructions of past sea ice changes in the Arctic.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Kayi, Hakan y Timothy Clark. "AM1* parameters for bromine and iodine". Journal of Molecular Modeling 15, n.º 3 (5 de diciembre de 2008): 295–308. http://dx.doi.org/10.1007/s00894-008-0419-4.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Liu, Xiaodong, Qinghua Xu, Lifen Zhang, Zhenping Cheng y Xiulin Zhu. "Visible-light-induced living radical polymerization using in situ bromine-iodine transformation as an internal boost". Polymer Chemistry 8, n.º 16 (2017): 2538–51. http://dx.doi.org/10.1039/c7py00366h.

Texto completo

Resumen

A new visible-light-induced methodology, termed as “bromine-iodine transformation activated living radical polymerization”, was successfully established to build a “bridge” between ATRP and iodine-mediated LRP techniques.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Kato, Shinzi, Kouichi Kaga, Masaru Ishida y Toshiaki Murai. "Preparation of Haloselenium and Halotellurium Trithiocarbonates". Zeitschrift für Naturforschung B 40, n.º 2 (1 de febrero de 1985): 273–76. http://dx.doi.org/10.1515/znb-1985-0221.

Texto completo

Resumen

Abstract Selenium (1) and tellurium bis(trithiocarbonates) (2) were found to react with bromine and iodine to give the corresponding haloselenium (11) and halotellurium trithiocarbonates (7, 8). Reaction of 2 with excess of bromine give tribromotellurium trithiocarbonates (9).

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Sokolovs, Igors, Edgars Suna y Robert Francke. "(Invited) Electrochemical Synthesis of Chelation-Stabilized Organo-Λ ³-Bromanes". ECS Meeting Abstracts MA2023-02, n.º 52 (22 de diciembre de 2023): 2503. http://dx.doi.org/10.1149/ma2023-02522503mtgabs.

Texto completo

Resumen

The chemistry of hypervalent halogen species has made enormous progress over the last few decades, and hypervalent iodine(III) compounds have become common reagents in nowadays organic synthesis. The related isoelectronic hypervalent bromine(III) species feature superior reactivity to the I(III) counterparts due to the higher oxidizing ability, stronger electrophilicity and better leaving group ability (nucleofugality) of the bromanyl moiety. However, the hypervalent bromine chemistry appears to be significantly less developed than that of the iodine(III) compounds. This notable imbalance appears to be due to the relatively low stability and high oxidizing power of bromine(III) reagents, resulting in reactivity that is difficult to control. Furthermore, there is a clear shortage of simple method for the synthesis of bromine (III) species, but known methods often require handling of the highly toxic and corrosive BrF3 precursor. In this context, we have proposed the electrochemical generation of chelation-stabilized hypervalent bromine(III) compounds as a possible solution to the above problems. This presentation will give an overview of our current progress in this field.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Worden, Richard H. "Controls on halogen concentrations in sedimentary formation waters". Mineralogical Magazine 60, n.º 399 (abril de 1996): 259–74. http://dx.doi.org/10.1180/minmag.1996.060.399.02.

Texto completo

Resumen

AbstractChlorine is the most abundant halogen in sedimentary formation waters with concentrations from <100 to >250000 mg/l. Bromine is the second most abundant halogen at <1 mg/l to >6000 mg/l with iodine from <0.1 mg/l to >100 mg/l and fluorine from <0.1 mg/l 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 NaCl. 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 Cl/Br ratios. Sylvite is usually rich in bromine so dissolution will lead to bromine-enhanced 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 processes are responsible for the very limited range of Cl/Br ratios although congruent halite dissolution must have a limited role due to the absence of waters with high Cl/Br ratios.Iodine is strongly concentrated in organic materials in the marine environment; oils and organic rich-source rocks have high I/Cl and I/Br ratios relative to sea water or evaporated sea water. All formation waters are enriched in iodine relative to sea water implying that there has been input from organic matter or interaction with oil. However, hydrocarbon source rock type in a basin has no discernible effect upon iodine concentrations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Upmann, Daniel y Peter G. Jones. "Bromination and iodination of diphosphane dichalcogenides". Dalton Transactions 47, n.º 8 (2018): 2748–58. http://dx.doi.org/10.1039/c7dt04531j.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Maffezzoli, Niccolò, Andrea Spolaor, Carlo Barbante, Michele Bertò, Massimo Frezzotti y Paul Vallelonga. "Bromine, iodine and sodium in surface snow along the 2013 Talos Dome–GV7 traverse (northern Victoria Land, East Antarctica)". Cryosphere 11, n.º 2 (17 de marzo de 2017): 693–705. http://dx.doi.org/10.5194/tc-11-693-2017.

Texto completo

Resumen

Abstract. Halogen chemistry in the polar regions occurs through the release of halogen elements from different sources. Bromine is primarily emitted from sea salt aerosols and other saline condensed phases associated with sea ice surfaces, while iodine is affected by the release of organic compounds from algae colonies living within the sea ice environment. Measurements of halogen species in polar snow samples are limited to a few sites although there is some evidence that they are related to sea ice extent. We examine here total bromine, iodine and sodium concentrations in a series of 2 m cores collected during a traverse from Talos Dome (72°48' S, 159°06' E) to GV7 (70°41' S, 158°51' E) analyzed by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) at a resolution of 5 cm. We find a distinct seasonality of the bromine enrichment signal in most of the cores, with maxima during the austral spring. Iodine shows average concentrations of 0.04 ppb with little variability. No distinct seasonality is found for iodine and sodium. The transect reveals homogeneous air-to-snow fluxes for the three chemical species along the transect due to competing effects of air masses originating from the Ross Sea and the Southern Ocean.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Müller, Holger S. P. y Michael C. L. Gerry. "Hyperfine constants of bromine and iodine monofluoride". Journal of Chemical Physics 103, n.º 2 (8 de julio de 1995): 577–83. http://dx.doi.org/10.1063/1.470092.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Shi, Min, Ming Ma, Zhi-Bin Zhu y Li Wei. "Reactions of Arylvinylidenecyclopropanes with Bromine and Iodine". Synlett 2006, n.º 12 (agosto de 2006): 1943–47. http://dx.doi.org/10.1055/s-2006-947337.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Zlotin, S. G., P. G. Kislitsin y O. A. Luk'yanov. "Synthesis of bromine-and iodine-containing perhaloisothiazoles". Russian Chemical Bulletin 46, n.º 10 (octubre de 1997): 1792–94. http://dx.doi.org/10.1007/bf02495138.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Sturges, W. T. y L. A. Barrie. "Chlorine, Bromine AND Iodine in arctic aerosols". Atmospheric Environment (1967) 22, n.º 6 (enero de 1988): 1179–94. http://dx.doi.org/10.1016/0004-6981(88)90349-6.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Rodger, P. Mark, Anthony J. Stone y Dominic J. Tildesley. "Intermolecular interactions in halogens: Bromine and iodine". Chemical Physics Letters 145, n.º 5 (abril de 1988): 365–70. http://dx.doi.org/10.1016/0009-2614(88)80191-x.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Abdelbassit, Mohammed S. y Owen J. Curnow. "Construction of Ternary Iodine–Bromine–Chlorine Octahalides". Chemistry – A European Journal 25, n.º 58 (24 de septiembre de 2019): 13294–98. http://dx.doi.org/10.1002/chem.201903913.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Philips, Aimee, Christopher Cunningham, Kajal Naran y Tanay Kesharwani. "Synthesis of 3-Halo-7-azaindoles through a 5-endo-dig Electrophilic Cyclization Reaction". Synlett 30, n.º 10 (20 de mayo de 2019): 1246–52. http://dx.doi.org/10.1055/s-0037-1611827.

Texto completo

Resumen

Biologically useful 7-azaindoles were synthesized by electrophilic cyclization of 3-alkynyl-N,N-dimethylpyridine-2-amines with molecular iodine. By this simple atom-economical approach under ambient reaction conditions, a library of interesting 3-iodo-7-azaindoles were synthesized in high yields. To synthesize the corresponding 3-bromo- and 3-chloro-7-azaindoles, an environmentally benign copper-mediated cyclization was employed, with inexpensive, nontoxic, and noncorrosive sodium chloride and sodium bromide as the sources of chlorine and bromine, respectively.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Fusswinkel, Tobias, Christopher Giehl, Oliver Beermann, Johan R. Fredriksson, Dieter Garbe-Schönberg, Lea Scholten y Thomas Wagner. "Combined LA-ICP-MS microanalysis of iodine, bromine and chlorine in fluid inclusions". Journal of Analytical Atomic Spectrometry 33, n.º 5 (2018): 768–83. http://dx.doi.org/10.1039/c7ja00415j.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Meena, Bashdar I., Hawbash H. Karim, Kurdistan F. Aziz, Faten A. Chaqmaqchee, Dashne M. Kokhasmail y Khabat N. Hussein. "Structural Characterization of Salts Using X-ray Fluorescence Technique". ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY 12, n.º 1 (6 de enero de 2024): 1–7. http://dx.doi.org/10.14500/aro.11418.

Texto completo

Resumen

This study investigates the structure of 21 table salts that were collected from different local markets in the Kurdistan region of Iraq. The major trace elements and iodine concentrations in tablesalt are analyzed through the X-ray fluorescence (XRF) technique and the titration method, respectively. The study shows that using XRF spectral analysis, the collected table salt samples are rich in chlorine, sodium, and contain a lower percentage of bromine, strontium, tin, tellurium, and iodine. Moreover, these samples have a high percentage of sulfur and sirconium, where the molybdenum is >0.2%. Other elements such as zinc and copper are essential and found in low concentrations <0.0086% and 0.001%. Iodine is a trace element that is necessary nutrients for human life, and it is naturally present in some foods. Iodine deficiency is brought on by a lack of iodine consumption. Iodized salt is highly recommended as a source of iodine to prevent iodine deficiency disease. Iodine is added to table salt in two different ways, either through iodate or through iodine. The results show that only 25% of the salt samples have an adequate level of iodine, while the other samples have low or no iodine content. According to the World Health Organization, quality of salt depends on iodine concentration and other trace elements, which are necessary for human health.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Bromine and iodine"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros