Preparation of Aspirin from salicylic acid lab.pdf

Preparation of aspirin from salicylic acid

1. lab1
Medicinal chemistryIII practice 4
th
stage

3. Generic Name: Aspirin
Scientific name : Acetylsalicylic acid

4. Aspirin is a salicylate It works by reducing substances
in the body that cause pain, fever, and inflammation.
Aspirin is used to treat pain, and reduce fever or
inflammation. It is sometimes used to treat or prevent
heart attacks, strokes, and chest pain (angina).
Aspirin should be used for cardiovascular conditions
only under the supervision of a doctor.

5. You should not use aspirin if you have :
- a bleeding disorder such as hemophilia.
-a recent history of stomach or intestinal bleeding or if you are
allergic to an NSAID .
Do not give this medicine to a child or teenager with a fever,
flu symptoms, or chicken pox. Aspirin can cause Reye's
syndrome, a serious and some times fatal condition in
children.

6. Taking aspirin during late pregnancy may cause bleeding in
the mother or the baby during delivery. Tell your doctor if you
are pregnant or plan to become pregnant.
Aspirin can pass into breast milk and may harm a nursing
baby. You should not breast-feed while using this medicine.

7. Take aspirin exactly as directed on the label. Do not use in
larger or smaller amounts or for longer than recommended.
Take with food if aspirin upsets your stomach.
Do not crush, chew, break, or open an enteric-coated or
delayed-release pill. Swallow it whole.
If you need surgery, tell the surgeon ahead of time that you are
using this medicine. You may need to stop using it for a short
time.

8. Avoid drinking alcohol while you are taking aspirin. Alcohol
may increase your risk of stomach bleeding.
If you are taking this medicine to prevent heart attack or
stroke, avoid also taking ibuprofen (Advil, Motrin). Ibuprofen
may make this medicine less effective. If you must use both
medications, take the ibuprofen at least 8 hours before or 30
minutes after you take the aspirin (non-enteric coated form).
Ask a doctor or pharmacist before using any cold, allergy, or
pain medication. Many medicines available over the counter
contain aspirin or an NSAID. Taking certain products together
can cause you to get too much of this type of medication.

9. Get emergency medical help if you have signs of an allergic reaction to
aspirin: hives; difficult breathing; swelling of your face, lips, tongue, or
throat.
Stop using this medicine and call your doctor at once if you have:
ringing in your ears, confusion, hallucinations, rapid breathing, seizure
(convulsions);
severe nausea, vomiting, or stomach pain;
bloody or tarry stools, coughing up blood or vomit that looks like coffee
grounds;
fever lasting longer than 3 days; or
swelling, or pain lasting longer than 10 days.
Common aspirin side effects may include:
upset stomach, heartburn;
drowsiness; or
mild headache.

10. Formula: C
9H
8O
4
Systematic name:2-acetoxybenzoic acid
Has a benzene ring backbone
Carboxylic acid
Ester group on the 2nd carbon in benzene
ring.

11. Density: 1.40 g/cm
3
Melting Point: 135 °C
Boiling Point: 140 °C
Aspirin, anacetylderivative of salicylic acid, is a white, crystalline,
weakly acidic substance.

12. Acetylsalicylic acid slowly decomposes by hydrolysis into
acetic and salicylic acids in the aqueous medium.
Hydrolysis of acetylsalicylic acid is accelerated in solutions of
ammonium acetate, or acetates, carbonates, citrates, or
hydroxides of the alkali metals.
Acetylsalicylic acid is a weak acid with an acid dissociation
constant, Ka, of 3.2 x 10^-4.

13. Acetylsalicylic acid is synthesized by producing an esterification reaction
of salicylic acid with acetic anhydride. The products of this reaction are
acetylsalicylic acid, and acetic acid.
Dilute sulfuric acid and sometimes phosphoric acid are used as
catalysts.
Overall Reaction:

14. Reaction Mechanism:

15. 1.Aspirin’s anti-inflamatory, pain relieving, fever relieving, and anti-
coagulant properties arise from its ability to decrease the body’s
production of prostoglandins and thromboxanes.
2.Aspirin inhibits the production of prostoglandins and
thromboxanes by inactivating cyclooxygenase enzymes by
acetylation of their serine residues.
3.Unlike other NSAID’s such as ibuprofen, aspirin’s inactivation of
cyclooxygenase is irreversible.
4.Prostoglandins are responsible for delivering pain responses,
causing fever, and causing inflamation.
5.Thromboxanes are primarily responsible for causing blood to
coagulate. Inhibition of thromboxanes by low doses of aspirin
reduces the risk of heart attack or stroke.

17. There are 2 sub types of cyclooxygenase enzyme; Cox1 and Cox2:
- Cox1 regulates many normal physiological processes in the
body one of these is in the stomach lining where prostaglandin
serves a protective role; preventing the stomach mucosa from
erosion by its own acidity, while cox2 is responsible for
inflammation.
-non selective NSAIDs such as aspirin cause GI irritation due to
cox1 inhibition while selective cox2 inhibitors such as celecoxib
do not cause gastric irritation.
- Aspirin is irreversible inhibitor of cyclooxygenase enzyme.

20. 1.Aspirin is a non-steroidal anti-inflammatory drug (NSAID).
2.Aspirin is used primarily to reduce inflamation, to alleviate
fevers, and to alleviate mild aches and pains.
3.For treatment of post-surgery pain, Ibuprofen has been
shown to be more effective than aspirin.
4.Aspirin is the primary drug used to treat migraines.
5.Aspirin, taken over a long period of time and in low doses,
significantly reduces the risk of heart attack and stroke.
6.Additionally, low doses of aspiring taken over a long period
of time have recently been shown to dramatically reduce the
mortality rate in cancer patients.

22. 1.Aspirin increases the risk of gastrointestinal bleeding.
2.Aspirin increases the risk of bleeding in hemophilic patients.
3.In high doses over a long period of time, aspirin causes iron-
deficiency anemia.
4.Aspirin administered to children with viral infections can cause
Reye’s syndrome, which is characterized by brain injury and by fat
buildup in the liver.
5.Those who have an intolerance to salicylate experience hives when
they take aspirin.

23. Procedure:
1.Weigh out 5.0 g of salicylic acid and place in a 250 ml conical
flask.
2.Measure out 10 ml of acetic anhydride and add this to your
flask, be sure to do this in the hood.
3.Still in the hood, carefully add 5 drops of conc. H
2SO
4, a
catalyst, to the flask and swirl to mix everything thoroughly.
4.Heat the mixture for about 10 min. in a warm water bath (70-
80C
0
).
5.Add 50 ml of distilled water and cool in an ice bath, if crystals
do not appear, you can scratch the walls of the flask with a
stirring rod to induce crystallization.
6.Filter the solid aspirin through a piece of pre-weighed filter
paper.

24. Calculation:
Mwt. Wt.
Salicylic acid 138.12 5 g
Acetyl salicylic acid 180.15 ?
Theoretical wt. =?
Practical weight: by weighing your filtered product after drying