Aspirin is a salicylate (sa-LIS-il-ate). It is known as acetylsalicylic acid (ASA).
Aspirin is used to treat pain, and reduce fever or inflammation. It is sometimes used to treat or prevent heart attacks, strokes, chest pain (angina) and blood clot formation in people at high risk of developing blood clots.
Aspirin may be effective at preventing certain types of cancer, particularly colorectal cancer.
Aspirin blocks the effects of an enzyme, cyclooxygenase which in turn prevents the synthesis of prostaglandin. This gives it its pain-relieving and anti-inflammatory properties. It also has an effect on the way platelets stick together which helps it to prevent blood clots from forming in the heart. It is a type of nonsteroidal anti-inflammatory drug (NSAID).
Physical properties
Aspirin, an acetyl derivative of salicylic acid, is a white, crystalline, weakly acidic substance, with a melting point of 136 °C (277 °F), and a boiling point of 140 °C (284 °F). Its acid dissociation constant (pKa) is 3.5 at 25 °C (77 °F).
Synthesis
The synthesis of aspirin is classified as an esterification reaction. Salicylic acid is treated with acetic anhydride, an acid derivative, causing a chemical reaction that turns salicylic acid's hydroxyl group into an ester group (R-OH → R-OCOCH3). This process yields aspirin and acetic acid, which is considered a byproduct of this reaction. Small amounts of sulfuric acid (and occasionally phosphoric acid) are almost always used as a catalyst. This method is commonly employed in undergraduate teaching labs.
Reaction mechanism
Formulations containing high concentrations of aspirin often smell like vinegar because aspirin can decompose through hydrolysis in moist conditions, yielding salicylic and acetic acids.
Side effects
- Increased blood fibrinolytic activity.
- Hepatotoxicity and cholestatic hepatitis.
- Dehydration and hyperkalemia.
- Respiratory alkalosis and metabolic acidosis.
- Agitation, cerebral edema, coma, confusion, dizziness, headache, cranial hemorrhage, lethargy and seizures.
- Reye's syndrome.
- Hyperpnea, pulmonary edema, and tachypnea.
- Rhabdomyolysis.
- Hypoglycemia and hyperglycemia.
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