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
SO2Cl2; VOCl3; MoO2Cl2; WO2Cl2; CrO2F2
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.

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

The method used to prepare chromyl chloride is the basis for a qualitative test for chloride: a sample suspected of containing chloride is heated with a mixture of potassium dichromate and concentrated sulfuric acid. If chloride is present, chromyl chloride forms as evidenced by red fumes of CrO2Cl2. Analogous compounds are not formed with fluorides, bromides, iodides and cyanides.

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

In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively charged sodium ions and negatively charged chloride ions.

Chromic acid is an inorganic acid composed of the elements chromium, oxygen, and hydrogen. It is a dark, purplish red, odorless, sand-like solid powder. When dissolved in water, it is a strong acid. There are 2 types of chromic acid: molecular chromic acid with the formula H
2
CrO
4
and dichromic acid with the formula H
2
Cr
2
O
7
.

Cyanogen chloride is a highly toxic chemical compound with the formula CNCl. This linear, triatomic pseudohalogen is an easily condensed colorless gas. More commonly encountered in the laboratory is the related compound cyanogen bromide, a room-temperature solid that is widely used in biochemical analysis and preparation.

<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. 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">Praseodymium(III) chloride</span> Chemical compound

Praseodymium(III) chloride is the inorganic compound with the formula PrCl3. Like other lanthanide trichlorides, it exists both in the anhydrous and hydrated forms. It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green heptahydrate.

Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms may need to be brought to this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes.

<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">Thionyl chloride</span> Inorganic compound (SOCl2)

Thionyl chloride is an inorganic compound with the chemical formula SOCl2. It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately 45,000 tonnes per year being produced during the early 1990s, but is occasionally also used as a solvent. It is toxic, reacts with water, and is also listed under the Chemical Weapons Convention as it may be used for the production of chemical weapons.

<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">Trimethylsilyl chloride</span> Organosilicon compound with the formula (CH3)3SiCl

Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound, with the formula (CH3)3SiCl, often abbreviated Me3SiCl or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. It is widely used in organic chemistry.

Benzyl chloride, or α-chlorotoluene, is an organic compound with the formula C6H5CH2Cl. This colorless liquid is a reactive organochlorine compound that is a widely used chemical building block.

<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">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 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.

<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.