Synthesis of acetaminophen (paracetamol) from p- aminophenol by using microwave system

5/5 - (2 votes)

BACKGROUND

Principle:

Microwave synthesis involves use of microwave radiation to carry out reaction at a higher rate. The wavelength of microwave lies between 0.01-1 meters. Aniline undergoes acetylation when irradiated with microwaves in dilute acetic acid solution has led to a simplified version of the Schotten-Baumann reaction.

Telegram	Subscribe
Facebook	Follow
Website	Click here

Acetaminophen (Tylenol) can be produced in good yield in a few min from commercially available p-aminophenol. p-aminophenol is reacted with 80% of acetic acid in a domestic microwave oven leads to formation of acetaminophen by acetylation reaction.^1,2

Aim: To prepare acetaminophen (paracetamol) from p- aminophenol by using microwave system.

Reaction:

Mechanism:

Uses:

1. It is an effective antipyretic and analgesic. Activity on the hypothalamic heat-regulating centre is the cause of antipyretic effect, whereas elevation of the pain-threshold is the reason for analgesic action.

2. It is also found to be useful in diseases accompanied by pain, discomfort, and fever, for instance the common cold and other viral infections.

3. It is also effective in a wide spectrum of arthritic and rheumatic conditions involving musculoskeletal pain as well as the pain caused due to headache, dysmenorrhea, myalgia, and neuralgia.

REQUIREMENTS

Chemicals:

p-Aminophenol – 2 g

Acetic acid – 15 ml

Chloroform/hexane

Apparatus:

Conical flask

Beaker

Pipette

Glass rod

Buchner funnel

PROCEDURE

Take 2 g of this substituted aniline (p-aminophenol), add a mixture of 4 ml water and 2 ml acetic anhydride (or 15 ml of 80% acetic acid) in a 100 ml beaker and mix well. Cover the beaker with a watch glass and place it in a microwave oven at 600W for 3 min or at a power level of 30% (probably level 3) or at 70°C for five min. or at 90°C, for 4 min.

Allow the contents of the flask to attain room temperature, and pour it directly into a beaker having 30 ml of cold water (with a few chips of crushed ice) and stir it vigorously. The crude product obtained is filtered onto a Büchner funnel using suction, wash it with plenty of cold water, drain well and dry the product either between the folds of filter paper and air-dry it or dry it in an electric oven maintained at 100°C.

Recrystallisation: Dissolve the crude product in 70% (v/v) ethanol and warm it to 60°C; add 1 g of powdered animal charcoal (decolourizing carbon). Filter and concentrate the filtrate over a water-bath.

Calculation:

Here limiting reagent is p-aminophenol; hence yield should be calculated from its amount taken.

C₆H₇NO = Molecular formula of p-aminophenol

C₈H₉NO₂ =Molecular formula of paracetamol

Molecular weight of p-aminophenol = 109 g/mole

Molecular weight of paracetamol = 151 g/mole

Theoretical yield:

109 g p-aminophenol forms 151 g paracetamol

Therefore, 2 g p-aminophenol will form ………? (X) g paracetamol

X =( 151 × 2)/109 = 2.77 g

Theoretical yield = 2.77 g

Practical yield = ————- g

% Yield = (Practical Yield)/(Theoretical Yield) × 100

CONCLUSION

Paracetamol was synthesized and the percentage yield was found to be………..%

REFERENCES

Shao Yan-dong, Li Yong-hong, Yu Ying-hua, Zhao Qi-peng,Wei Jia (Department of Chemistry and Life Science, Chuzhou University,Chuzhou 239012,China); Microwave-assisted synthesis of acetaminophen; Applied Chemical Industry;2010-02
Loupy, A. Microwaves in Organic Synthesis, 1st edition; Wiley-VCH Verlag GbH & Company KGaA, Weinheim, 2002, pp. 35, 115-116.

Also read:

🔴 Would you like to attempt Labmonk Daily quiz? Click here

🔵 Check out Jobs & Exam Notices. Labmonk Notice Board

🔴 Labmonk Scholarships. Click here

🔵 Labmonk Blog. Click here

🔴 Do you need notes? Click here

Watch Career related videos on Youtube: Watch now !!