Halogenide ion

The conversion of a primary amino substituent into a halogeno substituent is usually done by diazotization in the presence of an excess of the appropriate halogenide ion, by treatment in a nonaqueous solvent with alkyl nitrite and copper (II) halogenide, or by treatment with a freshly made solution of bromopyridinium perbromide [(CH)5N+ Br. Br2 ] or the like. These routes are illustrated in the following examples. 

In the CeSI (115) and NdSBr (334) type of structure, bromine and iodine are coordinated to five metal ions (four of the same layer, and one of the opposite layer) and four halogen ions of the double layer. In the SmSI type (335), iodine is coordinated to three metal ions of a [LS] layer and three other iodine ions of the double layer. In the FeOCl type of compound, such as ErSCl (355) and LuSBr (85), the halogen is surrounded by a polyhedron formed by six sulfur and four halogenide ions. 

Fig. 13-1.—Drawing snowing the distribution of electrons in the alk li and halogenide ions.

Work on the direct determination of the electron affinities of halogen atoms was begun by Mayer,7 who, with his students, measured directly the equilibrium constant for dissociation of alkali halogenide gas molecules into ions or of gas halogenide ions into atoms and electrons. Other methods have also been used, especially some involving mass... 

It is possible by assigning suitable values to r+ and r for the nine alkali and halogenide ions to calculate, with Equations 13-12 and 13-13, values of Bo for the 17 alkali halogenides with the sodium chloride structure at room temperature that agree with the experimental values to within 0.001 A on the average. The comparison of calculated and... 

In all of these crystals the ratio of number of oxygen atoms to number of aluminum atoms and silicon atoms is 2 1, as required for a complete tetrahedral framework, and the number of alkali and alkaline-earth atoms is that required by the argument given above. (In a few cases, such as sodalite, described below, more alkali ion is present, balanced by halogenide ion or a similar anion.)... 

The values of the free energy of formation of the negative halogenide ions (plus hydrogen ion) in aqueous solution might be expected to depend in a simple way on the electronegativity of the atoms. It is found (Fig. XI-1) that there is a linear relation, represented by the equation... 

Reaction of 4,5-disubstituted imidazole 1-oxides 263 with POCl3 or POBr3 produces 2-chloro or 2-bromoimidazole 301 (Hal = Cl or Br) (1975JCS(P1)275, 2002AG(E)2290). A possible mechanism in line with that in play by acylation comprises O-phosphorylation to be followed by addition of halogenide ion and subsequent elimination of halophosphoric acid as outlined in Scheme 89. 

Various 3-halopyruvate derivatives have been reported to be decarboxylated and simultaneously dehalogenated, yielding acetate, carbon dioxide and a halogenide ion as the only reaction products [133,158], A similar reaction may occur upon enzymatic decarboxylation of 3-hydroxypyruvate, which is an alternative substrate and a strong competitive inhibitor of PDC [159],... 

Russel, H. A. Gas chromatographic determination of halogenid ions. Angew. Chem. 

For tin(IV) bromide, the halogenide ion detachment apparently takes place much more readily compared with that of SnF4. However, the bulky bromine atom causes steric hindrances due to its interaction with the substituents at the a-dioxime fragments. In particular, attempts to obtain clathrochelate tribromotin-capped cobalt(III) a-benzyldioximate and a-furyldioximate were not successful, whereas the corresponding trichlorotin-capped complexes were obtained [45]. 

Die Halogene nehmen als gute Oxidationsmittel tatsachlich leicht ein Elektron auf und bilden die Halogenid-Ionen. Diese besitzen Edelgaskonfiguration (8 Valenzelektronen), so dass die Aulhahme eines weiteren Elektrons durch ein Halogenid-Ion sehr ungiinstig ist. 

If a free halogen is reduced, the product of reduction must be the halogenide ion (charge— — 1). If a metal that has only one positive oxidation state is oxidized, the oxidation state of the product is obvious. 

For a long time the principle was assumed to be valid that solid electrolytes for gas analysis have to contain such ions as the migrating species which could be formed from particles of the gas phase [6]. According to that, oxide-ion-conducting solid electrolytes are useful for electrode reactions as quoted in Equations (25-8) and (2S-9), and in connection with halogenide ion-conducting solid electrolytes electrode reactions such as... 

Quite early. Ingold and coworkers (Baker et al., 1928) proposed carbocations as intermediates in these reactions, as the product pattern and the stereochemistry display similarities to those of nucleophilic aliphatic substitutions of molecules with anionic leaving groups like halogenide ions, arenesulfonate ions, etc. (7-2). 

Chlorobutyl rubber sample was burned in oxygen atmosphere in the presence of platinum catalyst with the following absorption of burning products by alkali. The amount of formed halogenide-ions was determined by mercurrometric titration (titrant - Hg2(N03>2, indicator -... 

Soft-sphere ionic radii for alkali and halogenide ions. J. Chem. Soc. Dalton Trans. (1980), p. 645. 

NOx as it is in the gas phase, in spite of the fact that the nature of nitrate at the ice surface is not well established. Recent spectroscopic experiments indicate that nitrate exists at the ice surface in solvated form with a local environment similar to that in concentrated solution [302]. Still, this does not rule out a reduced solvent cage compared to dilute nitrate solution that would allow NO2 to escape, more likely due to recombination being suppressed, as has been suggested based on quantum yield measurements for frozen nitrate solutions [192]. Since in snow the nitrate anion is often co-located with other ions, e.g., halogenide ions, in a brine solution, ion specific effects may lead to enhancement of nitrate ions at the aqueous brine-air interface. Such effects have been shown to lead to enhanced nitrate photolysis rates in aqueous solution [303, 304]. In some contrast to the case of H2O2, the particular enviromnent in snow or ice makes photolysis of nitrate more efficient than in solution. Such effects would help to explain the significant cycling of NOx mediated by nitrate photolysis in polar snow [276, 298, 305-308]. 

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