Schiff test [SEP] named after
Schiff test
The Schiff test is an early organic chemistry name reaction developed by Hugo Schiff, and is a relatively general chemical test for detection of many organic aldehydes that has also found use in the staining of biological tissues. The Schiff reagent is the reaction product of a dye formulation such as fuchsin and sodium bisulfite; pararosaniline (which lacks an aromatic methyl group) and new fuchsin (which is uniformly mono-methylated "ortho" to the dye's amine functionalities) are not dye alternatives with comparable detection chemistry.
aromatic amine groups then react with the aldehyde being tested to form two aldimine groups; these groups have also been named for their discoverer as Schiff bases (azomethines), with the usual carbinolamine (hemiaminal) intermediate being formed and dehydrated en route to the Schiff base. These electrophilic aldimine groups then react with further bisulfite, and the Ar-NH-CH(R)-SO product (and other resonance-stabilized species in equilibrium with the product) give rise to the magenta color of a positive test. Prior formation of classical bisulfite adducts of