User:Enix150/ReagentTables/Liebermann

The Liebermann reagent was originally developed to give intense colours with phenols:

• Orange colours are given by substances that contain a monosubstituted benzene ring not joined to C¼O, N–C(¼O)– or to a ring that contains a C¼N–O– group.

• Orange or brown colours are given by some substances that contain two monosubstituted benzene rings (or some disubstituted compounds in which fluorine is the second substituent) that are joined either to one carbon atom or to adjacent carbon atoms.

• A wide range of colours is given by compounds that contain –OH, O–alkyl or –O–CH2O– groups attached to a benzene ring or to a ring in a polycyclic structure that contains a benzene ring. The benzene ring must not bear –NO2, or be halogenated, or contain an –O– substituent ortho to the oxy groups. Compounds that contain ring sulfur give a similar range of colours.

• Barbiturates should test yellow.

Recipes:
 * 1 g of sodium (or potassium ) nitrite to 10mL of concentrated sulfuric acid (with cooling and swirling to absorb the brown fumes)
 * 10% w/v sodium nitrite in sulfuric acid, added with cooling in water bath and swirling to absorb brown fumes