Question

Presence of halogen in organic compounds can be detected using:
A.) Liebig's test
B.) Duma's test
C.) Kjeldahl test
D.) Beilstein test

Answer 1

Hint: A material that contains bound or ionic halogens like chlorine, bromine, iodine such as salt or polyvinyl chloride (PVC), often react with a copper wire when they are heated in a flame and produce a brilliant, long lasting green flame and this fact in itself can be used as a condition to check for presence of halogens in organic compounds.

Complete step-by-step answer:
The Beilstein test is a very simple and yet efficient qualitative chemical test for halides. It was proposed by Friedrich Konrad Beilstein. This is a test specifically done for the detection of halogens in the sample. The equipment needed to perform this test are a copper wire and a source of flame.
The copper wire taken for the experiment should be properly cleaned and heated in a Bunsen burner flame to form a coating of copper(II) oxide with utmost caution and care. It is then dipped in the sample which we want to test that is the organic compound respectively and once again heated in a flame.
The copper wire is then heated till it stops imparting blue colour to the flame. After which the compound is touched with wire and again heated. If this time it again imparts blue colour it indicates the presence of some halogen the sample compound. But this test does not describe which particular halogen is present.
Moreover, there are many compounds present which do not contain any halogen but still give this test.
Hence the correct option for the above question is option (D) ie. Beilstein Test.

Note – A strong green color in the flame indicates the presence of halogens (chloride, bromide, iodide but not fluoride) in the given organic compound.The flame will burn green for a long period of time if PVCs are present in the compound.
Impurities, like fingerprints and surface treatments which contain chloride may give a weak green flame that disappears quickly.