Beilstein test

The Beilstein test, named after Friedrich Konrad Beilstein ( also known by its Russian name Fyodor Fyodorovich Beilstein ) is a method of analytical chemistry to test organic compounds of halogens is. With this sensitive qualitative detection to low molecular weight and high molecular weight organic compounds can be investigated, including plastics or organic pigments. The detectable polymers include polyvinyl chloride, polyvinylidene chloride, chloroprene and epichlorohydrin rubber, polychlorotrifluoroethylene, ethylene- chlorotrifluoroethylene copolymers, chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated polypropylene, polyvinyl chloride and various copolymers containing.

Implementation

First, a copper plate or a long Kupferöse is annealed can be seen until no blue or green coloring of the flame. This is absolutely necessary, since even traces of halogens can cause a false- positive result. For example, can easily be formed from hydrochloric acid and ammonia, ammonium chloride, which - unnoticed deposited on copper sheet or wire - also produces a blue-green flame coloration.

Still hot - - Next, the sample is annealed to the copper plate or the Kupferöse applied and maintained in the non-luminous area of ​​a gas burner flame. If the flame is colored it green to blue-green, the sample likely contains a halogen.

Explanation

The organic halogen compounds decompose during the pyrolysis and form, for example, hydrogen chloride or hydrogen bromide. This form of copper volatile copper halogen compounds, which turn the flame.

Safety concerns

Since in this reaction, even if only in very small quantities, may form dioxins, the experiment must be carried out under a fume hood. In some North Rhine-Westphalia schools of this experiment should therefore no longer be performed.