Copper chromite

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Copper chromite
Identifiers
CAS number 12053-18-8 YesY
PubChem 3084101
Jmol-3D images Image 1
Properties
Molecular formula Cu2Cr2O5
Molar mass 311.0812 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Copper chromite is the inorganic compound with the formula Cu2Cr2O5. For commercial applications, samples often contain barium oxide and other components. that is used to catalyse reactions in organic synthesis.[1]

Synthesis and structure[edit]

The compound adopts the spinel structure. The oxidation states are Cu(II) and Cr(III).[2]

The material was first described in 1908.[3] A variety of composition are recognized including Cr2CuO4·CuO·BaCrO4 (chemical abstracts registry number is 99328-50-4) and Cr2Cu2O5 (CAS# 12053-18-8). The latter is sometimes intentionally poisoned with quinoline, when the catalyst is used for decarboxylation reactions. The catalyst was developed in North America by Homer Burton Adkins and Wilbur Arthur Lazier partly based on interrogation of German chemists after World War II in relation to the Fischer-Tropsch process.[4] For this reason it is referred to as the Lazier catalyst. The catalyst Cr2CuO4·CuO·BaCrO4 is prepared by addition of a solution containing both barium nitrate and copper(II) nitrate to a solution of ammonium chromate. This resulting precipitate is calcined at 350–400 °C.[5]

Production[edit]

Copper chromite is produced by thermal decomposition of one of three substances. The traditional method is by the uncatalyzed ignition of copper chromate:[6]

CrCuO
4
CrCuO
3
+ O

Copper barium ammonium chromate is the most commonly used substance for production of copper chromite. The resulting copper chromite mixture produced by this method can only be used in procedures that contain materials inert to barium, as barium is a product of the decomposition of copper barium ammonium chromate, and is thus present in the resulting mixture. The by-product copper oxide is removed using an acetic acid extraction, consisting of washing with the acid, decantation and then heat drying of the remaining solid to yield isolated copper chromite. Copper chromite is produced by the exposure of copper barium ammonium chromate to temperatures of 350-450 °C, generally by a muffle furnace:[5]

Ba
2
Cu
2
(NH
4
)
2
(CrO
4
)
5
CrCuO3 + CuO + 2Ba + 4H
2
O
+ 4Cr + N
2
+ 6O
2

Copper ammonium chromate is also used for production of copper chromite. It is generally utilized as an alternative to the route of barium ammonium chromate for usage in chemicals reactive with barium. This can also be washed with acetic acid and dried to remove impurities. Copper chromite is produced through the exposure of copper ammonium chromate to temperatures of 350-450 °C:

Cu(NH
4
)
2
(CrO
4
)
2
CrCuO
3
+ CrO + 4H
2
O
+ N
2

Illustrative reactions[edit]

Reactions involving hydrogen are conducted at relatively high gas pressure (135 atm) and high temperatures (150–300 °C) in a so-called hydrogenation bomb. More active catalysts requiring less vigrous conditions are known but are typically derived from more expensive metals, such as platinum.

References[edit]

  1. ^ Cladingboel, D. E. "Copper Chromite" in Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons. doi:10.1002/047084289X.rc221
  2. ^ Prince, E. "Crystal and magnetic structure of copper chromite" Acta Crystallographica 1957, vol. 10, 554-6. doi:10.1107/S0365110X5700198X
  3. ^ Gröger, M. "Über Ammoniumdoppelchromate" Zeitschrift fur anorganische Chemie volume 58, page 412-426 (1908). doi:10.1002/zaac.19080580138; "Chromite aus basischen Chromaten" ibid. volume 76, page 30-38 (1912). doi: 10.1002/zaac.19120760103
  4. ^ Fischer-Tropsch Archive
  5. ^ a b Lazier, W. A.; H. R. Arnold, H. "Copper Chromite Catalyst" Organic Syntheses, Collective Volume 2, p. 142 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0142.pdf.
  6. ^ Lane, Bray; Laura Silva. "Catalyst recovery method". United States Patent and Trademark Office. Retrieved 8 October 2013. 
  7. ^ Blomquist, A. T.; Goldstein, A. "1,2-Cyclodecanediol" Organic Syntheses Collective Volume 4, p.216. http://www.orgsyn.org/orgsyn/pdfs/cv4p0216.pdf
  8. ^ Kaufman, D.; Reeve, W. "1,5-Pentanediol" Organic Syntheses, Collective Volume 3, p.693 (1955). http://www.orgsyn.org/orgsyn/pdfs/CV3P0693.pdf
  9. ^ Buckles, R. E.; Wheeler, N. C. "cis-Stilbene" Organic Syntheses, Collective Volume 4, p.857 (1963). http://www.orgsyn.org/orgsyn/pdfs/CV4P0857.pdf

External links[edit]

References[edit]

  1. ^ The Copper-Chromium Oxide Catalyst for Hydrogenation Homer Adkins, Edward E. Burgoyne, Henry J. Schneider J. Am. Chem. Soc.; 1950; 72(6); 2626-2629. First Page
  2. ^ CAS registry [7440-47-3] & [1317-38-0]