12381-48-5

Basic information

• Product Name: dioxido(dioxo)chromium
• Synonyms: chromium, diolatodioxo-; Dioxido(dioxo)chromium
• CAS NO: 12381-48-5
• Molecular Formula: CrO₄
• Molecular Weight: 115.9948
• EINECS: 231-639-5
• Mol File: 12381-48-5.mol
• Article Data: 16

Chemical Properties

• CAS DataBase Reference: dioxido(dioxo)chromium(CAS DataBase Reference)
• NIST Chemistry Reference: dioxido(dioxo)chromium(12381-48-5)
• EPA Substance Registry System: dioxido(dioxo)chromium(12381-48-5)

Safety Data

• Hazardous Substances Data: 12381-48-5(Hazardous Substances Data)

Upstream product

• 14866-68-3 chlorate 
• 13907-47-6 dichromate anion 
• 80937-33-3 oxygen 
• 7722-84-1 dihydrogen peroxide 

Downstream Products

• 14333-16-5 chromate(V) ion 
• 16065-83-1 chromium (III) ion 

Relevant articles and documents

Nucleophilic catalysis by HPO42- in the hydrolysis of Cr2O72-. Formation and decay of HO3POCrO32-

The initial reaction of Cr2O7(2-) in phosphate buffer (pH 6.03-8.54, 25.0°C, I = 1.0 M NaClO4) follows the rate law kobs = kK[HPO4(2-)]/(1+K[HPO4(2-)]). This is interpreted as arising from the reversible and rapid formation of a chromium(VI)-phosphato intermediate of increased coordination number (K = 5.5±1.3 M-1), and rate-determining loss of CrO4(2-) from this species (k = 4.4±0.5 s-1) to give HO3POCrO3(2-) (pKac = 6.96). This appears to be the first clear demonstration of an addition-elimination (stepwise) mechanism for substitution at chromium (VI). Subsequent equilibration of HO3POCrO3(2-) to give HCrO4- and H2PO4- (K = 5.95±1.90 M-1) is seen as a separate process which is subject to specific H+ and OH-, and general base (HPO4(2-)) catalysis, in addition to a spontaneous reaction.

Biomimetic oxidation of chromium(III): Does the antidiabetic activity of chromium(III) involve carcinogenic chromium(VI)?

The insulin-enhancing activities of some CrIII complexes, such as [Cr3O(OCOEt)6-(OH2)3]+ (1), previously attributed to specific interactions of CrIII ions with cellular insulin receptors, are more likely to be caused by the formation of [CrO4]2- (2). Oxidation of 1 to 2 by biologically relevant oxidants, including enzymes (see scheme), and inhibition of an isolated protein tyrosine phosphatase by a CrVI complex are reported.

Characterization and oxidation of chromium(III) by sodium hypochlorite in alkaline solutions

Chromium exists in nuclear waste sludges and is a problematic element in the vitrification process of high-level nuclear wastes. It is therefore necessary to treat the waste sludges to remove chromium prior to vitrification, by caustic leaching or oxidation of Cr(III) to Cr(VI). The objective of this study is to investigate the effect of oligomerization of Cr(III) on its oxidation by hypochlorite in alkaline solutions. Monomeric, dimeric and trimeric Cr(III) species in solution were separated by ion exchange. The kinetics of the oxidation of the separated species by hypochlorite in alkaline solutions was studied by UV/Vis absorption spectroscopy, and compared with the oxidation by hydrogen peroxide previously studied. Results indicate that hypochlorite can oxidize Cr(III) to Cr(VI) in alkaline solutions, but the rate of oxidation by hypochlorite is slower than that by hydrogen peroxide at the same alkalinity and concentrations of oxidants. The rate of oxidation of Cr(III) by both oxidants decreases as the concentration of sodium hydroxide is increased, but the oxidation by hypochlorite seems less affected by the degree of oligomerization of Cr(III) than that by peroxide. Compared with the oxidation by hydrogen peroxide where the major reaction pathway has an inverse order with respect to CNaOH, the oxidation by hypochlorite has a significant reaction pathway independent of [OH-].

Chromium(V) peptide complexes: Synthesis and spectroscopic characterization

A series of stable Cr(V) model complexes that mimic the binding of Cr(V) to peptide backbones at the C-terminus of proteins have been prepared for N,N-dimethylurea derivatives of the tripeptides Aib3-DMF, AibLAlaAib-DMF, and AibDAlaAib-DMF (Aib = 2-amino-2-methylpropanoic acid, DMF = N,N-dimethylformamide). The Cr(II) precursor complexes were synthesized by the initial deprotonation of the amide and acid groups of the peptide ligands in DMF with potassium tert-butoxide in the presence of CrCl2. The Cr(II) intermediates thus formed were then immediately oxidized to Cr(V) using tert-butyl hydroperoxide. Spectroscopic and mass-spectrometric analyses of the Cr(V) complexes showed that a new metal-directed organic transformation of the ligand had occurred. This involved a DMF solvent molecule becoming covalently bound to the amine group of the peptide ligand, yielding a urea group, and a third coordinated deprotonated urea nitrogen donor. A metal-directed oxidative coupling has been proposed as a possible mechanism for the organic transformation. The Cr(V/IV) reduction potential was determined for the three Cr(V) complexes using cyclic voltammetry, and in all cases it was quasi-reversible. These are the first isolated and fully characterized Cr(V) complexes with non-sulfur-containing peptide ligands.

Kinetcs of Metal Oxide Dissolution

A detailed study of the oxidative dissolution of chromium(III) oxide (Cr2O3) in potassium permanganate is reported.The kinetics of the reaction follow an inverse-cubic rate law under both acid and alkaline conditions; no inhibition by MnO2 product is observed.In alkaline solution, in the temperature range 43-140 degC, the rate exhibits dependences on permanganate and hydroxide concentrations which are explained in terms of a Langmuirian adsorption mechanism.The rate of dissolution is controlled by electron transfer within a surface complex in which bot OH(1-) and MnO4(1-) are bound.Thermodynamic parameters imply chemical bond formation between permanganate and ions in the oxide surface.A study in dilute HNO3 shows that adsorption of MnO4(1-) is also a prerequisite for reaction under acid conditions.

Hydrolytic and redox transformations of chromium(III) bis-oxalato complexes with glutaminic acid and glutamine: A kinetic, UV-Vis and EPR, study

The title complexes have been synthesized, chromatographically isolated and characterized by their ligands to metal ratio determinations and spectroscopic analyses. The kinetics of the first aquation stage, i.e., the amino acid chelate ring opening via the Cr-N bond cleavage, has been studied spectrophotometrically in acidic and alkaline media. Hydrogen peroxide oxidizes the complexes in alkaline media to CrO 42- anion and a relatively stable Cr(V) complex. Consecutive biphasic kinetics through two first-order steps were observed for the base hydrolysis and the oxidation process, whereas the acid-catalyzed aquation obeys a simple first-order pattern. Based on the kinetic and spectroscopic data, mechanisms of the coordinated amino acid liberation and chromium(III) oxidation are discussed.