PREPARATION OF ACETYL SALICYLIC ACID

OBSERVATION AND CALCULATIONS:-

Molecular weight of 2-Amino-benzoic acid = 137.0g

Molecular weight of Acetyl salicylic acid = 180.0g

137.0g of 2-amino benzoic acid yields acetyl salicylic acid = 180.0g

1.0g of 2-amino benzoic acid yields acetyl salicylic acid = 180/137g

6.9g of 2-amino benzoic acid yields acetyl salicylic acid = 180/137 ´ 6.9

= 9.06g

Theoretical yield = 9.06g

Practical yield = 7.92g

Percentage yield = Practical yield/Theoretical yield ´ 100

= 7.92/9.06 ´ 100

= 87.4%

RESULT:- Percentage yield of acetyl salicylic acid is 87.4%.

APPARATUS:- Round bottom flask, Burner, Stand, Beaker, Funnel, Condenser, Water bath, stirrer etc.

CHEMICALS:-

Sodium nitrite

2-Amino benzoic acid

PROCEDURE:-

1. 6.0g of sodium nitrite was mixed with 20.0ml of water and placed in ice (solution No. 1).

2. 6.9g of 2-Amino benzoic acid was mixed with 100.0ml of ice cold 70% HCl (solution No. 2).

3. Solution No. 1 was added to solution No. 2, gradually by constant stirring (temperature should be less than 5^oC).

4. The mixture was allowed to remain in the ice for 15 minutes. Copper turnings were then added.

5. The solution was then heated in a water bath for 20 minutes at temperature not more than 50⁰C.

6. Precipitates of salicylic acid were formed. These were filtered, dried and added to 30.0ml of acetylating mixture (15.0ml of glacial acetic acid & 15.0ml of acetyl chloride).

7. Reflux condensation was carried out for 30 minutes.

8. The condenser was removed and the reaction mixture was transferred to 50.0ml of ice-cold water.

9. Precipitates of acetyl salicylic acid were obtained, which were filtered and dried.

10. Precipitates were weighed and percentage yield was calculated.

PREPARATION OF P-NITROSOPHENOL

OBSERVATION AND CALCULATIONS:-

Molecular weight of Phenol = 94.0g

Molecular weight of P-nitrosophenol = 123.0g

94.0g of phenol yields P-nitrosophenol = 123.0g

1.0g of phenol yields P-nitrosophenol = 123/90g

6.0g of phenol yields P-nitrosophenol = 123/90 ´ 6

= 7.85g

Theoretical yield = 7.85g

Practical yield = 6.40g

Percentage yield = Practical yield/Theoretical yield ´ 100

= 6.40/7.85 ´ 100

= 81.5%

RESULT:- Percentage yield of P-nitrosophenol is 81.5%.

APPARATUS:- Round bottom flask, Burner, Stand, Beaker, Funnel, Condenser, Water bath, stirrer etc.

CHEMICALS:-

Phenol

Sodium Nitrite

Sulfuric acid

Sodium Hydroxide

PROCEDURE:-

1. Dissolved 15.0g of concentrated sulfuric acid in 10.0 ml of water (solution No. 1).
2. Dissolved 2.7g of NaOH in 150.0ml of water (solution No. 2).
3. 6g of phenol and 5.4g of NaNO₂ were mixed (solution No. 3).
4. Solution No. 3 was added into Solution No. 2 then that mixture was dissolved in solution No. 1.
5. A big china dish was filled with crushed ice and the reaction mixture was transferred to the ice bath, and was kept for 1 hour and 45 minutes without stirring.
6. Precipitates of p-Nitrosophenol were obtained.
7. Filtration was done and the precipitates were collected.
8. Precipitates were weighed and percentage yield was calculated.

PREPARATION OF BENZILIC ACID

OBSERVATION AND CALCULATIONS:-

Molecular weight of benzil = 210.0g

Molecular weight of benzilic acid = 228.0g

210.0g of benzil yields benzilic acid = 228.0g

1.0g of benzil yields benzilic acid = 228/210g

3.0g of benzil yields benzilic acid = 228/210 ´ 3

= 3.25g

Theoretical yield = 3.25g

Practical yield = 2.5g

Percentage yield = Practical yield/Theoretical yield ´ 100

= 2.5/3.25 * 100

= 76%

RESULT:- Percentage yield of benzilic acid is 76%.

APPARATUS:- Round bottom flask, Burner, Stand, Beaker, Funnel, Condenser, Water bath, stirrer etc.

CHEMICALS:-

Benzil

Potassium hydroxide

Ethyl Alcohol

Hydrochloric Acid

PROCEDURE:-

1. Took 3.0g of benzil in round bottom flask.

2. Took 3.0g of potassium hydroxide dissolved in 10.0ml of water, added to it 10.0ml of ethanol (90%).

3. Added alcoholic potassium hydroxide solution (as in no.2) in benzil (as in no.1).

4. Refluxed the reaction mixture for 20 minutes over water bath.

5. Transferred the reaction mixture (in a small beaker) immediately into the ice bath. Stirred continuously until solution was cooled. The potassium salt of benzilic acid was precipitated out.

6. Filtered the precipitates.

7. Precipitates were dissolved in 30.0ml of water and acidified with 3 drops of concentrated hydrochloric acid with stirring.

8. Re-filtered and dried the precipitates.

9. PURIFICATION:- Dry precipitates were washed with 10.0ml of cold water and filtered, dried and again washed with 5.0ml of benzene, re-filtered and dried.

10. Precipitates were weighed and percentage yield was calculated.