Showing papers on "Iodide published in 1986"

Upon the structure of room temperature halogenoaluminate ionic liquids

Abstract: The X-ray structure of a monoclinic crystal of 1-methyl-3-ethylimidazolium iodide, [MeEtim]l, reveals the presence of discrete hydrogen-bonded ion-pairs [r{C(2)H ⋯ l–}= 0.293 nm]: the structural implications of the presence of hydrogen-bonding in ionic liquids based upon [MeEtim]X–AlX3(X = Cl or Br) mixtures are discussed.

Iodine kinetic studies during amiodarone treatment.

Abstract: Iodine kinetic studies were performed serially in 15 patients taking 300 mg amiodarone/day for 6 months to assess the biological significance of the high iodine content of the drug. Urinary inorganic iodide excretion increased from 0.25 +/- 0.03 (+/- SE) mumol/mmol creatinine before treatment to over 7 mumol/mmol during therapy. Thyroid iodide clearance fell from 5.93 +/- 0.82 ml/min to less than 0.5 ml/min, while plasma inorganic iodide rose from 0.05 +/- 0.01 mumol/liter to approximately 2.2 mumol/liter during treatment. Thyroid absolute iodide uptake rose from 16.3 +/- 2.7 to 54.6 +/- 5.7 nmol/h after 6 weeks of therapy (P less than 0.001). Thereafter, it progressively declined, but it was still significantly elevated (32.0 +/- 4.3 nmol/h) after 24 weeks (P less than 0.01). The calculated daily excretion of inorganic iodide rose to over 80 mumol during the study, accounting for about 10% of amiodarone iodine. During this time, the patients all had the characteristic plasma thyroid hormone changes associated with amiodarone therapy, i.e. increased T4, free T4, and rT3 and decreased T3, while remaining clinically euthyroid. The massive increase in available inorganic iodide during amiodarone treatment is probably responsible for the induction of both the hypothyroidism and the thyrotoxicosis that can occur in patients receiving the drug.

Process for the preparation of 2-oxo-1,3-dioxolanes

Abstract: A process for the preparation of 2-oxo-1,3-dioxolanes by reaction of epoxides with carbon dioxide in the presence of alkali iodides wherein at least one epoxy compound is reacted in the presence or absence of inert solvent either with a combination of A) at least one alkali iodide and B) at least one compound of the group a) polyol and b) an ether or polyether or, if the epoxy compound already has the structural features of the compounds Ba) and Bb), with the alkali iodide A) alone, at temperatures from 40° to 180° C. while introducing carbon dioxide at normal pressure or at slightly increased pressure, to form the corresponding organic carbonates. The 2-oxo-1,3-dioxolanes obtained are used for the preparation of synthetic resins, containing urethane groups, in the form of coatings of molded bodies.

Reductive coupling of ketones or aldehydes with electron-deficient alkenes promoted by samarium di-iodide

Abstract: Samarium di-iodide is an efficient reagent for the reductive coupling of ketones or aldehydes and electron-deficient alkenes, whereby γ-lactones can be prepared in good yields from ethyl acrylate.

Iodine Suppression of Iodide Uptake in FRTL-5 Thyroid Cells

Abstract: Exposure of FRTL-5 cells to iodide (I−) in excess of 3 μm suppresses the concentrative uptake of I− The depression of I− uptake measured at the steady state is due to a decrease in the rate of I− influx and not to an effect on I− efflux Exposure to Nal is associated with decreased T4 secretion and also depressed Na+-dependent amino acid accumulation The depression in I− and amino acid transports increases proportionately with the duration of exposure and concentration of I′ used but is not associated with alterations in FRTL-5 cell cAMP levels The I− suppression effect is blocked, however, when methimazole is present during the incubation with Nal In agreement with studies in vivo, I− suppression in FRTL-5 cells appears to depend on an intermediate in the organification process and to be independent of a TSH-induced cAMP-mediated action (Endocrinology 118: 2477–2482, 1986)

Electrochemistry in near-critical and supercritical fluids. 3. Studies of bromide, iodide, and hydroquinone in aqueous solutions

Abstract: A new type of apparatus has been constructed for carrying out electrochemistry in near-critical and supercritical aqueous solutions. The following systems have been studied at a platinum electrode: H/sub 2/O/O/sub 2/, I/sup -//I/sub 2/, Br/sup -//Br/sub 2/, and hydroquinone/benzoquinone. The compact alumina flow cell can be heated or cooled quickly and can be recharged with fresh electrolyte solution while at high temperature and pressure. A large reduction in the potential required for the electrolysis of water was observed. Diffusivities have been measured for iodide ions and hydroquinone. General agreement with the Stokes-Einstein model was observed in the temperature range 25-375/sup 0/C.

Iodine chemistry in the +1 oxidation state. II. A Raman and uv–visible spectroscopic study of the disproportionation of hypoiodite in basic solutions

Abstract: The kinetics of disproportionation of elemental iodine to iodide and iodate ions has been studied in basic aqueous media using Raman and uv–visible spectroscopy. The IO stretching vibrations for IO...

Acrylamide and Iodide Fluorescence Quenching as a Structural Probe of Tryptophan Microenvironment in Bovine Lens Crystallins

Abstract: Fluorescence quenching using acrylamide and iodide quenchers has been used to investigate the microenvironments of tryptophan residues in bovine alpha-, beta-, and gamma-crystallin fractions Acrylamide quenching is very sensitive to the degree of tryptophan accessibility to the solvent containing the acrylamide Since acrylamide is able to diffuse into the interior of the protein, accessibility to acrylamide may result from Trp residues lying at the surface of the protein or from the existence of channels leading to the interior of the protein Iodide ion is hydrated and is limited by its large size and charge to quenching of tryptophan residues lying at or near the surface of proteins Tryptophan residues in the lens crystallin fractions were found to be highly accessible to acrylamide, yet the rate of quenching by acrylamide was very low, indicating that the tryptophan residues of the lens crystallin fractions occupy predominately hydrophobic environments The high accessibility to acrylamide likely results from diffusion of acrylamide into the interior of the protein Accessibility to iodide was much lower, as was the rate of quenching by iodide, adding support to the conclusions from acrylamide quenching

Liquid crystal compound and composition

Abstract: NEW MATERIAL:A liquid crystal compound of formula I (R is 4W18C alkyl; one of Y 1 and Y 2 is F-substituted phenylene or biphenylene and the other is phenylene or biphenylene which may be substituted with F; X is COO, OCO or O; R* is optically active group containing asymmetric carbon atom). USE: Useful as a component of a liquid crystal composition. It has low viscosity, ready handleability and high stability to heat and moisture. A high-speed display or high-speed printing can be carried out by using the compound as a component of a display element or a printer head. It exhibits broad working temperature range. PREPARATION: The compound of formula I can be produced by reacting an iodine compound of formula II (e.g. p-n-alkyloxy-fluoroiodo-benzene) with propargyl alcohol in the presence of cuprous iodide and a palladium catalyst, treating the reaction product with manganese dioxide and a caustic alkali and reacting the treated product with the compound of formula III in the presence of cuprous iodide and a palladium catalyst. COPYRIGHT: (C)1988,JPO&Japio

Electrodeless high pressure sodium iodide arc lamp

Abstract: High pressure xenon is used as a buffer gas in an elec- rodeless sodium iodide arc lamp. Very high efficacies are achieved by using an arc tube with rounded edges and by surrounding a portion of the arc tube with quartz wool. The arc tube may also contain small amounts of mercury iodide.

A very short ruthenium(II)-nitrogen heterocycle bond: Crystal structures of pentaammine(N-methylpyrazinium)ruthenium(II) iodide and pentaammine(N-methylpyrazinium)ruthenium(III) p-toluenesulfonate pentahydrate

Abstract: [(NH 3 ) 5 Ru(NC 4 H 4 NEH 3 )]I 3 cristallise dans le systeme orthorhombique, groupe d'espace Pnma et sa structure est affinee jusqu'a R=0,041.[(NH 3 ) 5 -Ru(NC 4 H 4 NCH 3 )](CH 3 C 6 H 4 SO 3 ) 4 . 5H 2 O cristallise dans le systeme triclinique, groupe P1, avec R=0,078

Effect of Growth Conditions on Halomethane Production by Phellinus Species: Biological and Environmental Implications

Abstract: Production of the gaseous secondary metabolite chloromethane (CH,Cl) by the fungus Phellinus pomaceus has been measured on a variety of media using headspace techniques. On glucosebased media, CH3C1 production was linearly related to the logarithm of chloride ion concentration. At concentrations less than 4 mM, over 90% of the chloride ion in the medium was converted to CH3C1. Bromide and iodide, but not fluoride, were substrates for the methylating system. The pH range 5 to 7 was optimal for CH3C1 biosynthesis and the presence of ammonium ions stimulated the process. Supplementation of the medium with methionine, serine or folic acid did not affect overall CH3CI production. With cellulosic media, CH3C1 yields based on chloride ion present in the medium were high, ranging from 75% at 0.4 mM to 90% at 50m~. Bromomethane yields from bromide averaged 70% between 0.5 and 25 mM. Iodomethane yields of approximately 60% were obtained with up to 1 mM-iodide but declined sharply above this concentration. When equimolar concentrations of the three halide ions were present, the different halides were methylated sequentially, iodide being the most preferred substrate and chloride the least. Gas chromatography/mass spectrometry of other headspace volatiles from P. pomaceus mycelia revealed, amongst the main components, methyl esters of 2-furoic, benzoic and salicylic acids. The pseudohalide ion thiocyanate acted as a specific inhibitor of not only halomethane biosynthesis but also methyl benzoate formation, suggesting that methylation of halide and benzoate may be mediated by the same biochemical system. Of five other species of Phellinus previously reported to produce CH,Cl, only P. ribis and P. occidentalis exhibited high efficiency conversion of chloride ion to CH3Cl. P. robiniae converted only a small proportion of available chloride to CH3Cl, whilst no CH3Cl production by P. conchatus or P. vinosus could be demonstrated on any of the media employed. The biochemical, ecological and environmental significance of fungal halomethane biosynthesis is discussed.

Titrimetric determination of catecholamines and related compounds via bromine oxidation and substitution.

Abstract: A titrimetric method for the determination of 0.1–10 mg of catecholamines and related compounds as pure substances and in their dosage forms was investigated and found to offer improvements with regard to ease, speed and accuracy. The method is based on bromine oxidation of the catecholamines (adrenaline, noradrenaline, L-dopa, dopamine and methyldopa) to the corresponding benzoquinones; related compounds (octopamine, tyramine and tyrosine) undergo substitution to the dibromoaryl hypobromites. The benzoquinones and hypobromites oxidise iodide to liberate stoicheiometric amounts of iodine, which can be determined titrimetrically with thiosulphate, using starch as an indicator.

1,2-Regioselective reduction of α,β-unsaturated carbonyl compounds with lithium aluminium hydride in the presence of lanthanoid salts

Abstract: An α,β-unsaturated carbonyl compound when reduced by lithium aluminium hydride in the presence of lanthanoid chloride, bromide, iodide, or acetylacetonate gives, selectivity, an allylic alcohol, while in its absence saturated alcohol formation predominates. Such reactions can be applied to various α,β-unsaturated carbonyl compounds such as aldehydes, ketones, esters, and lactones. In addition to its wide applicability, this reagent appears to be easier to use, than other known reducing reagents.

The role of compound III in reversible and irreversible inactivation of lactoperoxidase

Abstract: In the presence of iodide (I-, 10 mM) and hydrogen peroxide in a large excess (H2O2, 0.1-10 mM) catalytic amounts of lactoperoxidase (2 nM) are very rapidly irreversibly inactivated without forming compound III (cpd III). In contrast, in the absence of I- cpd III is formed and inactivation proceeds very slowly. Increasing the enzyme concentration up to the micromolar range significantly accelerates the rate of inactivation. The present data reveal that irreversible inactivation of the enzyme involves cleavage of the prosthetic group and liberation of heme iron. The rate of enzyme destruction is well correlated with the production of molecular oxygen (O2), which originates from the oxidation of excess H2O2. Since H2O2 and O2 per se do not affect the heme moiety of the peroxidase, we suggest that the damaging species may be a primary intermediate of the H2O2 oxidation, such as oxygen in its excited singlet state (1 delta gO2), superoxide radicals (O-.2), or consequently formed hydroxyl radicals (OH.).

Radiolysis of Poly(U) in Oxygenated Solution

Abstract: SummaryAqueous N2O/O2-saturated solutions of poly(U) were irradiated at 0·C and the release of unaltered uracil determined. Immediately after irradiation G(uracil release) was 1·5 which increased to a value of 5·3 ± 0·3 upon heating to 95°C. Thereby all of the organic hydroperoxides (G = 6·8 ± 0·7) and some of the hydrogen peroxide (G = 1·7 ± 0·2) was destroyed leaving G(peroxidic material; mainly hydrogen peroxide) = 1·0 ± 0·7. G(chromophore loss) = 8 − 11 was measured immediately after irradiation, but no increase was observed upon heating. Addition of iodide destroyed the hydroperoxides and caused immediate base release to rise to G = 4 and further heating brought the value to that observed in the absence of iodide. In contrast, on reducing the hydroperoxides with NaBH4, immediate uracil release rose to only G = 2·8 and no further increase was observed on heating. A major product (G = 2·7) is carbon dioxide. There are also osazone-forming compounds produced (G = 2·7), all of which are originally bound ...

In vitro culture of Vitis: the effects of light spectrum, manganese sulfate and potassium iodide on morphogenesis

Abstract: The effects of blue and red light, manganese sulfate concentration (100 and 5 μM), and potassium iodide (5 and 0 μM) on shoot and root production from subcultured shoots of the Vitis hybrid “Remaily Seedless” were studied. Shoot production was greater in blue light. It was increased by lowering the manganese sulfate concentration. The response to manganese in blue light was greatest when there was no potassium iodide addition. Root production was decreased by red light and lower manganese concentration. The effects of manganese, iodide and light spectrum on morphogenesis are discussed in relation to their known effects on IAA metabolism.

The anion specificity of the sodium-potassium-chloride cotransporter in rabbit kidney outer medulla: studies on medullary plasma membranes.

Abstract: Plasma membrane vesicles were isolated from rabbit kidney outer medulla and employed in sodium, rubidium, and chloride flux studies. Chloride dependence and bumetanide sensitivity of (part of) the sodium and rubidium flux indicate that this plasma membrane fraction can be used to study the properties of Na−K−2Cl cotransport system present in the luminal membrane of the medullary thick ascending limb. The anion specificity of the cotransporter was investigated by determining the effect of anion replacement on sodium fluxes. When chloride was completely replaced by bromide, iodide, nitrate, or thiocyanate only bromide could effectively substitute for chloride (90% activity), whereas sodium uptake in the presence of iodide, nitrate, and thiocyanate amounted to only 25% of the sodium uptake observed in the presence of chloride. When similar replacement experiments were performed in the presence of 10 mmol/l chloride, bromide could substitute for chloride by 110%, iodide and nitrate by 60%, and thiocyanate by 70%. In the presence of 10 mmol/l bromide iodide, nitrate, and thiocyanate were similarly effective. The effect of nitrate and chloride on sodium flux was additive. Bumetanide-sensitive chloride uptake was inhibited by nitrate, the inhibition was however only partly, amounting to 60%. The results obtained are compatible with the view that the two anion binding sites of the Na−K−2Cl cotransporter can exhibit a different substrate specificity and that the transporter in addition to a 2Cl mode can also operate in a 2Br, Cl−, A− and Br−, A− mode, A− representing iodide, nitrate, or thiocyanate.

Mechanisms in hydride generation AAS

Abstract: Results of recent studies on the mechanisms playing a role in hydride generation AAS are discussed and compared with results obtained elsewhere. Within 10 ms after mixing the alkaline NaBH4 solution with the acid sample solution, the NaBH4, is decomposed, so hydride formation proceeds even faster. The separation of the hydride from the liquid takes much more time, however. The interference by heavy metal ions is caused by their catalytic action on the NaBH4 decomposition: the reagent is decomposed before it has reacted with the analyte. In the determination of selenium the presence of iodide has a beneficial effect on the interference of heavy metals. This is attributed to a catalytic effect of iodide on the reaction between NaBH4 and Se(IV). The presence of iodide in the NaBH4 solution also has the effect that the concentration of NaBH4 required for complete conversion of Se(IV) to SeH2 is reduced from 0.16 to 0.001%. A discussion is given on some mechanisms that have been proposed for the atom formation in the cuvette. The mechanism may depend on the analyte considered, the temperature and other parameters, and radicals are probably involved. At high analyte concentrations or long residence times of the gas mixture in the cuvette analyte losses may occur by dimerization (As, Se) or condensation (possibly after oxidation). Such effects are promoted by the tube walls. In developing procedures and apparatus, results mentioned should be considered. Several suggestions are discussed.

Trans-effect in extraction kinetics: palladium extraction by 7-(1-vinyl-3,3,5,5-tetramethylhexyl)-8-quinolinol

Abstract: SUMMARY The rate of palladium extraction from chloride solutions by 7-(1-vinyl)-3,3,5,5-tetramethylhexyl)-8-quinolinol (KELEX 100) increased more than six hundred times when as little as 2 × 10−4M thiocyanate was added to the aqueous solution. Similar but smaller effects were produced by iodide and bromide. The influence of pH and the concentration of thiocyanate and ligand on the extraction rate indicated that the homogeneous chemical reaction of the type: is the rate determining step. The enhancement in the extraction rate parallels the size of the “trans-effect”, which decreases in the order of SCN¯> I¯>Br¯, in easing the replacement of a coordinated chloride ion by KELEX 100.