Sodium dichromate

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.

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. . Similarly,  2,3-dimethylnaphthalene is oxidized by Na2Cr2O7 to 2,3-naphthalenedicarboxylic acid (m.p. 239–241 °C).

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