Verification of phenol with the Liebermann-Test
sodium nitrite O T N R 8-25-50 S (1/2)-45-61
phenol C T R 24/25-34 S (1/2)-28-45
sulphuric acid 96% C R 35 S (1/2)-26-30-45
Information concerning dangerous substances
4-nitrosophenol Xn N R 22-40-41-51/53 S (2)-26-36/37/39-47-49-61
a not too small test tube
- Safety goggles! Exhaust hood or good ventilation! Work especially carefully!
- Add a small spatula-tipful phenol and a small spatula-tipful sodium nitrite to the test tube.
- Add a drop of concentrated sulphuric acid.
- After the appearance of a red intermediate stage, which can only briefly be observed, a dark blue almost black color arises, the mixture appears tarry.
- Add several ml water. Caution! Due to overwarming a caustic and toxic mix can foam up and possibly spatter. One should add the water quickly at once (not too much because of foaming), in order to limit the formation of toxic vapors due to warming.
- The color is still very dark, but becomes red again.
- Caution, during the reaction 4-nitrosophenol, which is suspected to cause cancer, develops!
- The reaction mixture can be disposed of as halogene-free organic waste, due to foaming it is possible that it can scarely be removed from the test tube, therefore if necessary add acetone or rinse with this.
See the literature
The reaction mixture after adding concentrated sulphuric acid.
The reaction mixture after adding water.
derived from XV.3 "Phenolnachweis durch die Liebermann-Probe", p. 172,