An improved spectrophotometric determination of chloride via chromyl chloride formation

Chloride (? 1 μg) is extracted into carbon tetrachloride as chromyl chloride. It is back-extracted into pH 3.2 buffer where it oxidizes iodide to tri-iodide ions, which are measured at 288 nm or 351 nm. The relative standard deviation is 0.8% for 10 μg of chloride.     

A simple method for the spectrophotometric determination of chloride by solvent extraction as chromyl chloride

Summary A simple and direct method for the spectrophotometric determination of chloride, based on the formation of chromyl chloride and its extraction into carbon tetrachloride has been developed. The absorption spectrum of the organic extract shows two bands at 300 and 415 nm; Beer's law is obeyed at both wavelengths over the range 20–320g of chloride. The best conditions for the spectrophotometric determination of chloride are determined and a procedure is recommended. Interferences from some of the most common anions are studied.

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Zusammenfassung Eine neue Methode für die Bestimmung von Chloridionen wurde angegeben. Sie beruht auf der Bildung von Chromylchlorid und dessen Extraktion mit Tetrachlorkohlenstoff. Der Extrakt hat spektrale Maxima bei 300 und 415 nm. Das Beersche Gesetz ist zwischen 20 und 320g Chlorid erfüllt. Die besten Bedingungen für die spektrophotometrische Bestimmung wurden ermittelt und ein Verfahren empfohlen. Störungsmöglichkeiten einiger üblicher Anionen wurden untersucht.

     

Chrysomelidial by chromyl chloride oxidation: A revised structure for gastrolactone

Non-conjugated $\text{gem}$-dialkylated alkenes were oxidized to aldehydes in the presence of α,β-unsaturated carbonyl functional groups, providing a new synthesis of $\text{1}$ and a synthesis of $\text{2}$ that led to a revised structure for gastrolactone.     

Indirect determination of chloride as chromyl chloride by atomic-absorption spectrophotometry

Summary A method for the determination of chloride in aqueous solution by atomic-absorption Spectrophotometry is described. The chloride is converted into chromyl chloride, which is extracted into carbon tetrachloride and subsequently back-extracted and determined in a solution buffered with NH₄H₂PO₄/(NH₄)₂HPO₄. Calibration plots of the atomic absorption of the aqueous back-extracted phase at the chromium 425.4 nm resonance line are linear in the range 5–270g of chloride. The calibration graph can be obtained directly with aqueous solutions of Cr(VI). The proposed method can be applied directly to mineral and medicinal water samples.

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Indirekte AAS-Bestimmung von Chlorid als Chromylchlorid

Zusammenfassung Eine Methode zur Bestimmung von Chlorid durch Atom-Absorptions-Spektroskopie wurde entwickelt, deren Basis die Bildung von Chromylchlorid, dessen Extraktion mit Cl₄C und die anschließende Bestimmung des rückextrahierten Chroms in einer Lösung von NH₄H₂PO₄/(NH₄)₂HPO₄ ist. Das lineare Verhältnis zwischen Absorbanz und Chromkonzentration ermöglicht die Bestimmung des Chlorids im Bereich 5–270g; zur direkten Eichung dienten wäßrige Lösungen von Chrom(VI). Die vorgeschlagene Methode wurde für die Chlorid-Bestimmung in Mineral-und Medizinalwasser benutzt.

     

Mechanism of chromyl chloride alkane oxidation

Modern electronic structure methods, including complete active space-perturbation theory to second order (CASPT2) and a range of density functional (DFT) methods, are used to characterize the intermediates and transition states associated with chromyl chloride alkane oxidation. Computed energetics for radical abstraction are found to be inconsistent with experimental activation energetics. The alcohol product is also found to be too endothermic to be viable. A novel zwitterionic direct pathway is characterized which, when coupled with a dinuclear complex, exothermically produces alcohol consistent with experiment.     

Mechanism of chromyl chloride epoxidation

Modern electronic structure methods including complete active space perturbation theory to second order (CASPT2), and a range of density functional (DFT) methods are used to characterize the intermediates and transition states associated with ethylene epoxidation by chromyl chloride. A novel zwitterionic direct addition pathway is characterized which, when coupled with a dinuclear complex, exothermically produces epoxide through a pathway with a small kinetic barrier.     

Reaction of fluoroole fins with chromyl chloride

Conclusions The reactions of chromyl chloride with various fluoroolefins were investigated. The character of the process does not agree with the mechanism suggested for the reaction of chromyl chloride with olefins not containing halogen atoms at the double bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 379–383, February, 1970.     

Some aspects of the polymerization of n-butyl vinyl ether by chromyl chloride

The rate of n-butyl vinyl ether polymerization by chromyl chloride is first order in [catalyst] and second order in [monomer]. Added H₂O (after a certain concentration) and HCl increase the rate, thiophene retards the rate, while pyridine inhibits the rate. DP is independent of [chromyl chloride] and increases with increasing [monomer] up to 1M, thereafter becoming independent of it. Both rate and DP increase over the range 10?32°C and decrease at higher temperatures.     

Theoretical investigation of internal conversion in chromyl chloride

The internal conversion process from single vibronic levels in the first excited electronic state S₁ of chromyl chloride was theoretically investigated. On the basis of this analysis certain important features of the experimentally observed fluorescence decay from S₁ have been understood. Implications of the obtained results to multiphoton chemistry are discussed.     

Kinetics and mechanism of acid-catalyzed oxidation of bromide ions by the aqueous chromyl(IV) ion

The reaction between the aqueous chromyl ion, CraqO2+, and Br- is acid-catalyzed and generates Br2. Kinetic studies that utilized a superoxochromium ion, CraqOO2+, as a kinetic probe yielded a mixed third-order rate law, -d[CraqO2+]/dt=k[CraqO2+][Br-][H+], where k=608+/-11 M-2 s-1. Experimental data strongly favor a one-electron mechanism, but the reaction is much faster than predicted on the basis of the reduction potential for the Br*/Br- couple. The reduction of CraqO2+ by transition-metal complexes, on the other hand, exhibits "normal" behavior, that is, k=(1.37x10(3)+1.94x10(3) [H+]) M-1 s-1 for Os(1,10-tris-phenanthroline)(3)2+ and <10 M-1 s-1 for Ru(2,2'-bipyridine)3(2+) at 0.1 M H+. The reduction of CraqOO2+ by Br2*- takes place with a rate constant k=(1.23+/-0.20)x10(9) M-1 s-1, as determined by laser-flash photolysis.     

Photoelectron spectrum and ground state electronic structure of chromyl chloride vapor

The electronic structure of chromyl chloride CrO₂Cl₂ has been investigated by ultraviolet (HeI) photoelectron spectroscopy. Mulliken-Wolfsberg-Helmholtz molecular orbital calculations have been performed in order to provide a model for interpretation of the photoelectron spectra and to assist in assigning the low-energy optical absorption and emission transitions. The first ionization potential of CrO₂Cl₂ at 11.8 eV is due to ionization of the near-degenerate oxygen and chlorine nonbonding 2a₂, 4b₁, and 4b₂ MO's. The first unoccupied orbital is basically a chromium dπ^* orbital. The excitations (2a₂, 4b₁, 4b₂)→ 7a₁^* correlate well with the three low energy absorption transitions observed.     

A new class of meta-pyridine-urea oligomers for selective identification of mercury(II) ions

A series of new pyridine-urea oligomers were synthesized and tested for their ability to recognize ions in PBS or Ac buffer solution by fluorescence. The results showed that the ability of oligourea urea to selectively recognize Hg²⁺ was gradually enhanced with the increase of chain, which was further proved by DFT calculation. The 1:2 stoichiometry was established for the L7-Hg²⁺ complex on the basis of Job's plot. The binding constant (K_B) and the lowest detection limit for Hg²⁺ were also determined. DFT calculations were used to optimize the structures of L2-7 and its Hg²⁺ complexes. Highly sensitive and selective probes for the recognition of Hg²⁺ based on this report are expected to be developed and used for in vivo detection.     

Emitter lifetime and velocity distribution in the collisionless IR multiphoton excitation of chromyl chloride

The collisionless infrared multiphoton exeitation of chromyl chlonde is studied systematically. An attempt is made to find the parentage of the induced visible emission.     

Alkylation of benzyl chloride by gaseous carbenium ions

The alkylation of benzyl chloride has been studied in the gas phase using radiolytically formed carbenium ions as the charged reagents. The intramolecular selectivity of the electrophilic attack, deduced from the composition of the neutral products, is characterized by the comparable reactivity of the aromatic ring and of the halogen atom of the substrate toward the gaseous cations. As to ring alkylation, the reactivity of the ortho positions of benzyl chloride is considerably lower than those of chlorobenzene. The results are compared with pertinent mass-spectrometric data, and discussed in connection with existing models of gas phase aromatic substitution by charged electrophiles.