Reinecke's salt

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Reinecke's salt
IUPAC name Chromate(1-), diaminetetrakis-
(thiocyanato-N)-, ammonium, (OC-6-11)-
Other names ammonium tetrathiocyanato-
diamminechromate(III),

Reinecke salt,
ammonium reineckate
Identifiers
CAS number [13573-16-5]
RTECS number na
Properties
Molecular formula C4H12N7OCrS2
Molar mass 354.42 g/mol
Appearance dark red solid
Density  ? g/cm3, ?
Melting point

270 °C
Boiling point

decomposes
Solubility in water soluble in hot water
Structure
Coordination
geometry		 octahedral
Dipole moment 0 D
Hazards
Main hazards toxic
R-phrases 20/21/22
S-phrases 36
Related compounds
Related compounds [Co(NH3)6]Cl3,
KSCN,
Chromium(III) chloride
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Reinecke's salt is a chemical compound with the formula NH4[Cr(NCS)4(NH3)2].H2O. The dark-red crystalline compound is soluble in boiling water and ethanol.

[edit] Structure

The chromium atom is surrounded by six nitrogen atoms in an octahedral geometry; the NH3 ligands are mutually trans. The salt crystallizes with one molecule of water. It was first reported in 1863.[1]

According to Organic Syntheses, NH4[Cr(NCS)4(NH3)2] is prepared by treatment of molten NH4SCN (ca. 145–150 °C) with (NH4)2Cr2O7.[2]

This salt was once widely used to precipitate primary and secondary amines as their ammonium salts. Included in the amines that effectively form crystalline precipitates are those derived from the amino acids, including proline and hydroxyproline. It also reacts with Hg2+ compounds, giving a red color or a red precipitate.

[edit] References

  1. ^ Reinecke, A. "Über Rhodanchromammonium-Verbindungen" Annalen der Chemie und Pharmacie, volume 126, pages 113-118 (1863). DOI: 10.1002/jlac.18631260116.
  2. ^ Dakin, H. D. "Reinecke Salt" Organic Syntheses, Collected Volume 2, p.555 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0555.pdf
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