Sulphanilamide: How to prepare and calculate percentage yield?

 

Preparation of sulphanilamide

Object- To synthesize sulphanilamide from acetanilamide and calculate percentage yield.

Sulphanilamide is an organic compound with antimicrobial properties used to treat bacterial infections.

Chemical Formula	C6H8N2O2S
Molecular Weight	172.2 g/mol
Appearance	White or colorless solid
Melting Point	Approximately 164-166°C
Solubility	Soluble in water, ethanol, and acetone
Density	1.41 g/cm³
pKa (Acid Dissociation Constant)	~10.4
Log P (Partition Coefficient)	0.51 (at pH 7.4)
Boiling Point	Decomposes at higher temperatures
UV-Visible Absorbance Maxima	254 nm

Structure

Preparation requirements

• Beaker.
• Funnel.
• Conical flask.
• Buchner funnel.
• Acetanilide.
• Chlorosulphonic acid.
• Aqueous ammonia.

Principle

For the preparation of sulphanilamide, acetanilide is treated with chlorosulphonic acid.

This treatment will give p-acetamido benzene sulphonyl chloride, which on treatment with ammonia gives p-acetamido benzene sulphonamide, followed by hydrolysis.
Reactions involved:

 

Sulphanilamide preparation procedure

1: Synthesis of p-acetamido benzene sulphonyl chloride

• Take 25 grams of powdered acetanilide in a round-bottom flask.
• Slowly add 63 ml of chlorosulphonic acid drop by drop while shaking the flask.
• Attach a calcium chloride guard tube.
• Heat the mixture to 60-70°C for 2 hours.
• Cool the mixture and pour it into crushed ice to separate p-acetamidobenzene sulphonyl chloride.
• Filter the product, wash it with cold water, and dry it.

2: Synthesis of p-acetamido benzene sulphonamide

• Take all the p-acetamidobenzene sulphonyl chloride in a 500 ml round-bottom flask.
• Add 120 ml of concentrated ammonia and 120 ml of water while shaking.
• Heat the mixture at 70°C for 30 minutes.
• Cool the mixture in an ice bath and add dilute sulfuric acid to acidify the mixture.
• Filter the precipitated p-acetamidobenzene sulphonamide, wash with cold water, and dry at 100°C in an oven.

3: Synthesis of sulphanilamide

• Add all the p-acetamidobenzene sulphonamide to a mixture of 10 ml of concentrated hydrochloric acid and 30 ml of distilled water in a 250 ml round-bottom flask.
• Boil the mixture for 1 hour. If no solid separates upon cooling, heat further briefly.
• Add 1 gram of charcoal to the solution to decolorize it, boil for 15 minutes, and then filter.
• Slowly add 6 grams of solid sodium carbonate to the filtrate with stirring until no more effervescence is observed.
• Cool the solution in an ice bath, and sulphanilamide will precipitate.
• Filter the product using a Buchner funnel with suction and then dry it.
• You can recrystallize the sulphanilamide using either water or alcohol.

And the melting point of sulphanilamide will be 163°C.

Now you can calculate the percentage yield and theoretical yield and can write a report: