Beilstein test
The Beilstein test is a simple chemical test used in chemistry as a qualitative test for halides. It was developed by Friedrich Konrad Beilstein.
A copper wire is cleaned and heated in a Bunsen burner flame to form a coating of copper(II) oxide. It is then dipped in the sample to be tested and once again heated in a flame. A positive test is indicated by a green flame caused by the formation of a copper halide.
This test is no longer frequently used. One reason why it is not widely used is that it is possible to generate the highly toxic chloro-dioxins if the test material is a polychloroarene.
An alternative wet test for halide is the sodium fusion test — this test converts organic material to inorganic salts include the sodium halide. Addition of silver nitrate solution causes any halides to precipitate as the respective silver halide.
Standards
Any halogenated compound as a positive standard, such as, 1-Bromobutane, and any non-halogenated compound, such as 1-Butanol, as a negative standard.
Procedure
Heat the tip of a copper wire in a burner flame until there is no further coloration of the flame. Let the wire cool slightly, then dip it into the unknown (solid or liquid" and again, heat it in the flame. A green flash is indicative of chlorine, bromine, and iodine; fluorine is not detected because copper fluoride is not volatile. The Beilstein test is very sensitive, thus halogen-containing impurities may give misleading results.
Positive Test
A green flash is indicative of chlorine, bromine, and iodine, but NOT fluorine.
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