Sodium dichromate

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Sodium dichromate
Other names hydrated sodium dichromate
Identifiers
CAS number [7789-12-0]
RTECS number HX7750000
Properties
Molecular formula Na2Cr2O7·2H2O
Molar mass 298.02 g/mol (dihydrate)
Density 2.52 g/cm3
Melting point

356.7 °C
dehydrates at 100 °C
Boiling point

decomposes
Solubility in other solvents 2380 g/L at 0 °C
Hazards
Main hazards carcinogenic
R-phrases R45, R46, R60, R61,
R8, R21, R25, R26, R34,
R42/43, R48/23, R50/53,
S-phrases S53, S45, S60, S61
Related compounds
Related compounds K2Cr2O7,
KMnO4,
CrO3
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Sodium dichromate is the chemical compound with the formula Na2Cr2O7. Usually, however, the salt is handled as its dihydrate Na2Cr2O7·2H2O. Its chemistry, appearance, and behaviour are very similar to those of the more widely encountered potassium dichromate. This chemical is around twenty times more soluble in water than the potassium salt (49 g/L at 0 °C) and its equivalent weight is also lower, which is often desirable.[1]

[edit] Applications in organic chemistry

This compound oxidizes benzylic and allylic C-H bonds to carbonyl derivatives. For example, 2,4,6-trinitrotoluene is oxidized to the corresponding carboxylic acid.[2]. Similarly, 2,3-dimethylnaphthalene is oxidized by Na2Cr2O7 to 2,3-naphthalenedicarboxylic acid (m.p. 239–241 °C).[3]

[edit] Safety

Like all hexavalent chromium compounds, sodium dichromate is considered hazardous. It is also a known carcinogen[4].

[edit] References

  1. ^ Freeman, F. "Sodium Dichromate" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
  2. ^ Clarke, H. T.; Hartman, W. W. (1941). "2,4,6-Trinitrobenzoic Acid". Org. Synth.; Coll. Vol. 1: 543. 
  3. ^ Friedman, L. (1973). "2,3-Naphthalenedicarboxylic Acid". Org. Synth.; Coll. Vol. 5: 810. 
  4. ^ ILO 1369 - Sodium Dichromate [[1]]
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