Preparation of Methyl Orange from Sulfanilic Acid

MATERIALS REQUIRED:

a) test tube

b) test tube holder

c) Funnel

d) Beaker.

CHEMICALS REQUIRED:

a) Dimethyl aniline

b) Sodium carbonate

c) Sodium nitrate

d) Sulphuric acid

e) Conc. HCI

THEORY:

Methyl orange is a light orange coloured solid soluble in alcohol. It is an important Indicator in acid-base solution titration. It is prepared by diazotization of sulphonic acid followed by coupling with dimethyl aniline in presence of acid at ice cold temperature.

PROCEDURE:

0.5 gm of Na₂CO₃ was dissolved in 20 ml H₂O and 29m Sulphanilic acid was added in a beaker and was immersed in cold water. In a test tube 19m of NaNO₂ was dissolved in 2 ml H₂O. Then the solution in the beaker and the test tube was mixed slowly and concentrated conc. HCI was added to the mixture. Now, 1 ml dimethyl aniline 1ml galactic acetic acid and 5-10 ml NaOH was slowly added. Then, the resulting solution was filtered. The residue was filtered with cold water, and was dried-Light orange crystal methyl orange obtained.

RESULT:

The light orange crystals of methyl orange were prepared from Sulphanilic acid.

CONCLUSION:

Thus, by this experiment methyl oranges can be prepared in the laboratory from sulphanilic acid.

PRECAUTIONS:

1) Apparatus should be handled carefully.

2) Chemicals should be handled carefully.