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Thin Layer Chromatography

Melting Point

Simple Distillation

Column Chromatography

Infrared Spectroscopy

Polarimetry

Solubility Testing

Reflux

Extraction

Gas Chromatography-Mass Spectrometry

Classification Tests-Halides

Fractional Distillation

ChemDraw

 

 

Tests for Halides

Silver Nitrate in Ethanol Test

Sodium Iodide in Acetone Test

Beilstein Test


Silver Nitrate in Ethanol Test


Standards, as done in the Classification Tests for Halides lab

1-chlorobutane
1-bromobutane
1-iodobutane
2-chlorobutane
2-bromobutane
2-iodobutane
2-chloro-2-methylpropane
2-bromo-2-methylpropane
benzyl chloride
bromobenzene

Procedure
Place approximately 0.25 mL of each compound into a test tube. Add 2 mL of a 1% ethanolic silver nitrate solution to the material in each test tube, noting the time of addition. After the addition, shake the test tube well to ensure adequate mixing of the compound and the solution. Record the time required for any precipitates to form. If no precipitates are seen after 5 minutes, heat the solution on the steam bath for approximately 5 minutes. Note whether a precipitate forms in the test tube. Continue slow reactions for up to 45 minutes at room temperature.

Complications
Carboxylic acids have been known to react in this test, giving false positives.

 

Sodium Iodide in Acetone Test


Standards
Reference tests done in Classification Tests for Halides Lab

Procedure
In a test tube place 0.25 mL or 0.2 g of your unknown. Add 2 mL of a 15% solution of sodium iodide in acetone, noting the time of addition. After the addition, shake the test tube well to ensure adequate mixing of the unknown and the solution. Record the time needed for any precipitate to form. After about 5 minutes, if no precipitate forms, place the test tube in a 50oC water bath. Be careful not to allow the temperature of the water bath to go above this temperature since the acetone will evaporate, giving a false positive result. After 6 minutes more in the bath, if no precipitates are visible, remove the test tube and let it cool to room temperature. Note any change that might indicate that a reaction has occurred. Continue slow reactions for up to 45 minutes at room temperature.

Positive Test
The formation of a white precipitate indicates the presence of halides.

Complications
When the sodium iodide solution is added to the unknown, a precipitate of sodium iodide might occur leading to a false positive test. Upon mixing, the precipitate of sodium iodide should dissolve.

Beilstein Test

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.