Chromyl chloride

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Chromyl chloride
Wireframe model of chromyl chloride Chromyl-chloride-2D.png
Wireframe model of chromyl chloride
Ball and stick model of chromyl chloride Chromyl-chloride-3D-balls.png
Ball and stick model of chromyl chloride
Chromyl chloride.jpg
Names
Preferred IUPAC name
Chromium(VI) dichloride dioxide
Systematic IUPAC name
Dichloridodioxidochromium
Other names
Chromic acid chloride

Chromium oxychloride

Etard Reagent
Chlorochromic anhydride
Chromic oxychloride
Chromium chloride oxide
Chromium dioxide dichloride
Chromium dioxychloride
Chromium oxychloride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.035.491 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 239-056-8
2231
PubChem CID
RTECS number
  • GB5775000
UNII
UN number 1758
  • InChI=1S/2ClH.Cr.2O/h2*1H;;;/q;;+2;;/p-2 Yes check.svgY
    Key: AHXGRMIPHCAXFP-UHFFFAOYSA-L Yes check.svgY
  • InChI=1S/2ClH.Cr.2O/h2*1H;;;/q;;+2;;/p-2
    Key: AHXGRMIPHCAXFP-UHFFFAOYSA-L
  • InChI=1/2ClH.Cr.2O/h2*1H;;;/q;;+2;;/p-2/rCl2CrO2/c1-3(2,4)5
    Key: AHXGRMIPHCAXFP-GRYJOLFGAD
  • Cl[Cr](Cl)(=O)=O
Properties
CrO2Cl2
Molar mass 154.9008 g/mol
AppearanceBlood-red fuming liquid, similar to bromine
Odor Musty, burning, acrid [1]
Density 1.911 g/mL, liquid
Melting point −96.5 °C (−141.7 °F; 176.7 K)
Boiling point 118.5 °C (245.3 °F; 391.6 K)
Reacts with water
Vapor pressure 20 mmHg (20 °C) [1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Toxic, oxidizer, carcinogenic, mutagenic, reacts violently with water [1]
GHS labelling:
GHS-pictogram-rondflam.svg GHS-pictogram-acid.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H271, H314, H317, H340, H350, H410
P201, P210, P280, P303+P361+P353, P305+P351+P338+P310, P308+P313 [2]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W+OX: Reacts with water in an unusual or dangerous manner AND is oxidizer
3
0
2
W
OX
Flash point noncombustible [1]
NIOSH (US health exposure limits):
PEL (Permissible)
none [1]
REL (Recommended)
Ca TWA 0.001 mg Cr(VI)/m3 [1]
IDLH (Immediate danger)
N.D. [1]
Safety data sheet (SDS) Sigma Aldrich - Chromyl Chloride
Related compounds
Related compounds
Sulfuryl chloride
Vanadium oxytrichloride
MoO2Cl2
Tungsten dichloride dioxide
Chromyl fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Chromyl chloride is an inorganic compound with the formula CrO2Cl2. It is a reddish brown compound that is a volatile liquid at room temperature, which is unusual for transition metal compounds. It is the dichloride of chromic acid.

Contents

Preparation

Chromyl chloride can be prepared by the reaction of potassium chromate or potassium dichromate with hydrogen chloride in the presence of sulfuric acid, followed by distillation. [3] [4]

K2Cr2O7 + 6 HCl → 2 CrO2Cl2 + 2 KCl + 3 H2O

The sulfuric acid serves as the dehydration agent.

It can also be prepared directly by exposing chromium trioxide to anhydrous hydrogen chloride gas.

CrO3 + 2 HCl ⇌ CrO2Cl2 + H2O

Usage

Test for the presence of chlorides

The chromyl chloride test involves heating a sample suspected to contain chlorides with potassium dichromate and concentrated sulfuric acid. If a chloride is present, chromyl chloride forms, its presence being indicated by the formation of red smoke. Otherwise, no red smoke will obviously appear. No similar compound is formed in the presence of fluoride, bromide, iodide, or cyanide, making this test specific to chlorides.

Reagent for oxidation of alkenes

Chromyl chloride oxidizes internal alkenes to alpha-chloroketones or related derivatives. [5] It will also attack benzylic methyl groups to give aldehydes via the Étard reaction. Dichloromethane is a suitable solvent for these reactions. [6]

Others

CrO2Cl2 can also be used to test for the absence of nitrate ions.

Safety considerations

Chromyl chloride is often stored in sealed glass ampoules to prevent vapours leaking out of the container Chromyl chloride ampouled.png
Chromyl chloride is often stored in sealed glass ampoules to prevent vapours leaking out of the container

Chromyl chloride is severely corrosive and easily burns the skin and eyes. [7]

Related Research Articles

The compound hydrogen chloride has the chemical formula HCl and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride gas and hydrochloric acid are important in technology and industry. Hydrochloric acid, the aqueous solution of hydrogen chloride, is also commonly given the formula HCl.

Chromic acid is jargon for a solution formed by the addition of sulfuric acid to aqueous solutions of dichromate. It consists at least in part of chromium trioxide.

<span class="mw-page-title-main">Hydrogen bromide</span> Chemical compound

Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.

<span class="mw-page-title-main">Potassium dichromate</span> Chemical compound

Potassium dichromate, K2Cr2O7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health. It is a crystalline ionic solid with a very bright, red-orange color. The salt is popular in laboratories because it is not deliquescent, in contrast to the more industrially relevant salt sodium dichromate.

<span class="mw-page-title-main">Chromium(III) chloride</span> Chemical compound

Chromium(III) chloride (also called chromic chloride) is an inorganic chemical compound with the chemical formula CrCl3. It forms several hydrates with the formula CrCl3·nH2O, among which are hydrates where n can be 5 (chromium(III) chloride pentahydrate CrCl3·5H2O) or 6 (chromium(III) chloride hexahydrate CrCl3·6H2O). The anhydrous compound with the formula CrCl3 are violet crystals, while the most common form of the chromium(III) chloride are the dark green crystals of hexahydrate, CrCl3·6H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

<span class="mw-page-title-main">Cadmium chloride</span> Chemical compound

Cadmium chloride is a white crystalline compound of cadmium and chloride, with the formula CdCl2. This salt is a hygroscopic solid that is highly soluble in water and slightly soluble in alcohol. The crystal structure of cadmium chloride (described below), is a reference for describing other crystal structures. Also known are CdCl2•H2O and the hemipentahydrate CdCl2•2.5H2O.

<span class="mw-page-title-main">Phosphorus trichloride</span> Chemical compound

Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride.

<span class="mw-page-title-main">Chromium(III) oxide</span> Chemical compound

Chromium(III) oxide is an inorganic compound with the formula Cr
2
O
3
. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.

<span class="mw-page-title-main">Phosphoryl chloride</span> Chemical compound

Phosphoryl chloride is a colourless liquid with the formula POCl3. It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phosphorus trichloride and oxygen or phosphorus pentoxide. It is mainly used to make phosphate esters.

<span class="mw-page-title-main">Chromium(III) fluoride</span> Chemical compound

Chromium(III) fluoride is an inorganic compound with the chemical formula CrF3. It forms several hydrates. The compound CrF3 is a green crystalline solid that is insoluble in common solvents, but the hydrates [Cr(H2O)6]F3 (violet) and [Cr(H2O)6]F3·3H2O (green) are soluble in water. The anhydrous form sublimes at 1100–1200 °C.

<span class="mw-page-title-main">Hydrogen fluoride</span> Chemical compound

Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers such as polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, which is much higher of a temperature than other hydrogen halides.

<span class="mw-page-title-main">Chromium(II) chloride</span> Chemical compound

Chromium(II) chloride describes inorganic compounds with the formula CrCl2(H2O)n. The anhydrous solid is white when pure, however commercial samples are often grey or green; it is hygroscopic and readily dissolves in water to give bright blue air-sensitive solutions of the tetrahydrate Cr(H2O)4Cl2. Chromium(II) chloride has no commercial uses but is used on a laboratory-scale for the synthesis of other chromium complexes.

<span class="mw-page-title-main">Disulfur dichloride</span> Chemical compound

Disulfur dichloride is the inorganic compound of sulfur and chlorine with the formula S2Cl2. It is an amber oily liquid.

<span class="mw-page-title-main">Arsenic trichloride</span> Chemical compound

Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.

<span class="mw-page-title-main">Chromium compounds</span> Chemical compounds containing chromium

Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist.

Antimony pentasulfide is an inorganic compound of antimony and sulfur, also known as antimony red. It is a nonstoichiometric compound with a variable composition. Its structure is unknown. Commercial samples are contaminated with sulfur, which may be removed by washing with carbon disulfide in a Soxhlet extractor.

<span class="mw-page-title-main">Potassium chlorochromate</span> Chemical compound

Potassium chlorochromate is an inorganic compound with the formula KCrO3Cl. It is the potassium salt of chlorochromate, [CrO3Cl]. It is a water-soluble orange compound is used occasionally for oxidation of organic compounds. It is sometimes called Péligot's salt, in recognition of its discoverer Eugène-Melchior Péligot.

<span class="mw-page-title-main">Jones oxidation</span> Oxidation of alcohol

The Jones oxidation is an organic reaction for the oxidation of primary and secondary alcohols to carboxylic acids and ketones, respectively. It is named after its discoverer, Sir Ewart Jones. The reaction was an early method for the oxidation of alcohols. Its use has subsided because milder, more selective reagents have been developed, e.g. Collins reagent.

<span class="mw-page-title-main">Chromyl fluoride</span> Chemical compound

Chromyl fluoride is an inorganic compound with the formula CrO2F2. It is a violet-red colored crystalline solid that melts to an orange-red liquid.

<span class="mw-page-title-main">Chromium(II) fluoride</span> Chemical compound

Chromium(II) fluoride is an inorganic compound with the formula CrF2. It exists as a blue-green iridescent solid. Chromium(II) fluoride is sparingly soluble in water, almost insoluble in alcohol, and is soluble in boiling hydrochloric acid, but is not attacked by hot distilled sulfuric acid or nitric acid. Like other chromous compounds, chromium(II) fluoride is oxidized to chromium(III) oxide in air.

References

  1. 1 2 3 4 5 6 7 NIOSH Pocket Guide to Chemical Hazards. "#0142". National Institute for Occupational Safety and Health (NIOSH).
  2. "Chromyl chloride 200042" (PDF). Sigma-Aldrich. Archived from the original on 2020-09-01.
  3. Moody, B.J. (1965). "22". Comparative Inorganic Chemistry (1 ed.). London: Edward Arnold. p. 381. ISBN   0-7131-3679-0.
  4. Sisler, Harry H. (1946). Chromyl Chloride [Chromium(VI) Dioxychloride]. Inorganic Syntheses. Vol. 2. pp. 205–207. doi:10.1002/9780470132333.ch63. ISBN   9780470132333.
  5. Freeman, Fillmore; DuBois, Richard H.; McLaughlin, Thomas G. (1971). "Aldehydes by Oxidation of Terminal Olefins with Chromyl Chloride: 2,4,4-Trimethylpentanal". Org. Synth. 51: 4. doi:10.15227/orgsyn.051.0004.
  6. F. Freeman (2004). "Chromyl Chloride". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rc177. ISBN   0471936235.
  7. Prof CH Gray, ed. (1966). "IV". Laboratory Handbook of Toxic Agents (2 ed.). London: Royal Institute of Chemistry. p. 79.