preparation of Aspirin

Experiment # 8:

Preparation of Aspirin

Date: 14-12-10

Muhammad Usman (2008-chem-02-B)

Pyridine: Harmful: Pyridine is harmful if inhaled, swallowed or absorbed through the skin.

Highly flammable: It has a flash point of 21 oC. It can readily catch fire. So care should be taken while handling it. However, pyridine itself is weak carcinogen.

Properties of Pyridine: IUPAC Name Other names Appearance

Pyridine Azabenzene Azine py Colorless liquid

Structure

Molecular formula Molar mass Density Melting point Boiling point Solubility in water Auto-ignition temperature

C5H5N 79.1g mol-1 0.9819g ml-1 -41.6oC 115.2 oC Miscible 21 oC

Salicylic acid:

Harmful: It is a Harmful compound & can cause hearing loss in Zinc deficient individuals.

Properties of salicylic acid: IUPAC name

2-hydroxy Benzoic acid

Other names

Salicylic acid

Structure

Molecular formula Molar mass

Appearance

Density Melting point Boiling point Solubility in water Acidity (Pka) Flash point

C7H6O3 138.12 g/gmol

Colorless crystaline organic acid

1.443 g/cm3 159 oC 211 oC 0.2 g/100 ml H2O (20 oC) 2.97 157 oC

Acetyl-chloride: Harmful: Eyes and skin is specially damaged with acetyl chloride. It can cause pain & vomiting. It also reacts hazardously with ethanol and phosphorus tri-chloride.

Highly flammable: It has a flash point of 13 oC. It can readily catch fire. So care should be taken while handling it because its combustion products include Acetaldehyde which is a strongly carcinogenic substance. However, ethanol itself is not cancer causing.

Corrosive: Acetyl chloride is a corrosive compound. It burns eyes and causes blistering on skin.

Properties of Acetyl chloride: IUPAC Name

Acetyl chloride Ethanoyl chloride Acyl chloride

Other names

Appearance

Colorless liquid

Structure

Molecular formula Molar mass Density Melting point Boiling point Solubility in water Auto-ignition temperature

CH3-CO-Cl 78.49g mol-1 1.104 g ml-1 -112 oC 52 oC Reacts with water 390 oC

Water: It is a non-hazardous compound.

Environmentally safe: Water is an essential part of life. Life cannot be sustained without water. Food & eatables contain some amount of water in them. It is a nonhazardous compound.

IUPAC name

Other names

Water Oxidane

Hydrogen oxide Dihydrogen monoxide Hydrogen monoxide Hydroxylic acid Hydrogen hydroxide R-718 Oxygen dihydride Oxygen hydride Oxane

Structure

Molecular formula Molar mass

H2O 18.0152833 gmol-1

Appearance

Density

1000 kg m-3 (liquid) 917 kg m-3 (solid)

Melting point Boiling point Acidity (Pka) Basicity (Pkb) Viscosity

0 oC 99.98 oC 15.74 15.74 0.001 Pa.S (20 oC)

Preparation of Aspirin Chemicals required: 1) Acetyl Chloride 3) Salicylic acid

2) Dry Pyridine 4) Water

Chemical reaction:

Apparatus Required: Volumetric flask Wire Gauze Filter paper Stirrer

Weigh Balance Tripod stand Beaker

Procedure: 1. Place 10 g Salicylic acid in conical flask & added 7 ml of Pyridine. Finally added 7.5 ml of acetyl chloride at a rate of 1 ml per unit time with shaking continuously. 2. The reaction was exothermic in nature. The heat of reaction is responsible for the rise in temperature of the mixture. Maintain the temperature of the mixture between 50-60 oC. 3. Then the solution was heated on water bath for 5-10 minutes & then cooled. This mixture was poured in 300 ml of cold water. 4. Solution was filtered and aspirin was dried as product.

Precautions: 1. Take special care to avoid fumes evolved during heating or use fuming hood while heating. 2. Solution should be stirred continuously during heating. 3. Water bath should be used for heating purpose.

Uses of Aspirin: Aspirin’s uses lie in the category of Drugs. Its uses in the form of drug are as follows.

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Analgesic: It is used to relieve minor aches and pains.



Antipyretic: It is used to reduce fever.

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Anti inflammatory: Aspirin is also used as an anti-inflammatory drug.