Griess diazotization

What is Griess diazotization?

In 1858, Griess initially reported a reaction that involves the preparation of aromatic diazonium salts from primary aromatic amines, N2O3, and nitric acid HNO3. This reaction is commonly referred to as the Griess diazotization or Griess reaction.

Griess diazotization - general reaction scheme - Griess reaction
Griess diazotization

Over time, other methods for preparing diazonium salts were discovered. Knoevenagel extended the preparation of diazonium salt in 1890 using organic nitrite as a diazotization agent under acidic conditions, which is known as the Knoevenagel method. Witt used Na2S2O5 and nitric acid as the diazotization agents in 1909 (known as the Witt method), and Houston and Johnson used N2O4 as the diazotization agent in 1925. Recently, other reagents have also been developed for diazotization, including NOCl, NaNO2/HBF4, NaNO2/CuCl2, and NOBF4 (or NOPF6, NOSbF6, etc.). However, the most commonly used method for forming diazonium salt involves using nitrous acid generated in situ from sodium nitrite and an acid (HCl, H2SO4, HCOOH, AcOH, etc.), although the Knoevenagel method is also quite popular.

The diazonium salt generated from this reaction is useful for many other reactions, such as the Gatterman reaction and Schiemann reaction.