Acetylsalicylic acid
(more commonly known as Aspirin)
By Viktor Polites
History
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Salicin, derived from Willow Bark, had been used since the time of the
ancient Greek philosopher, Hippocrates, to relieve dull aches and pains.
Salicin is metabolized by the body to produce salicylic acid, which has
similar anti-inflammatory properties to that of aspirin, but causes extreme
stomach discomfort, even stomach bleeding.
In 1897, Felix Hoffman, a researcher from Bayer AG synthesized
acetylsalicylic acid from salicin derived from meadowsweet.
In 1919, Bayer AG lost Aspirin as a registered trademark in the US, the
UK, France, and Russia due to war reparations imposed by the Allies.
Chemical Structure
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Formula: C9H8O4
Systematic name: 2acetoxybenzoic acid
Has a benzene ring backbone
Carboxylic acid
Ester group on the 2nd carbon in
benzene ring.
Physical Properties
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Density: 1.40 g/cm3
Melting Point: 135 °C
Boiling Point: 140 °C
Solubility in Water: 3 mg/mL at 20 °C
Chemical Properties
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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 acetatates, 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.
Synthesis
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Acetylsalicylic acid is synthesized by producing an esterification reaction of salicylic
acid with acetic anyhydride. The products of this reaction are acetylsalicylic acid,
and acetic acid.
Dilute sulfuric acid and sometimes phosphoric acid are used as catalysts.
Overall Reaction:
Salicylic acid
acetic anhydride
acetylsalicylic acid
acetic acid
Synthesis
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Reaction Mechanism:
Uses
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Aspirin is a non-steroidal anti-inflammatory drug (NSAID).
Aspirin is used primarily to reduce inflamation, to alleviate fevers, and to
alleviate mild aches and pains.
For treatment of post-surgery pain, Ibuprofen has been shown to be more
effective than aspirin.
Aspirin is the primary drug used to treat migraines.
Aspirin, taken over a long period of time and in low doses, significantly
reduces the risk of heart attack and stroke.
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.
How Aspirin Works
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Aspirin’s anti-inflamatory, pain relieving, fever relieving, and anticoagulant properties arise from its ability to decrease the body’s
production of prostoglandins and thromboxanes.
Aspirin inhibits the production of prostoglandins and thromboxanes by
inactivating cyclooxygenase enzymes by acetylation of their serine
residues.
Unlike other NSAID’s such as ibuprofen, aspirin’s inactivation of
cyclooxygenase is irreversible.
Prostoglandins are responsible for delivering pain responses, causing
fever, and causing inflamation.
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.
Cyclooxygenase-2
inactivated by Aspirin
Biosynthesis of Prostacyclin
and Thromboxane
Adverse Side Effects
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Aspirin increases the risk of gastrointestinal bleeding.
Aspirin increases the risk of bleeding in hemophilic patients.
In high doses over a long period of time, aspirin causes iron-deficiency
anemia.
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.
Those who have an intolerance to salicylate experience hives when they
take aspirin.
Works Cited
http://en.wikipedia.org/wiki/Aspirin
http://en.wikipedia.org/wiki/Mechanism_of_
action_of_aspirin
http://en.wikipedia.org/wiki/Cyclooxygenas
e
http://en.wikipedia.org/wiki/Prostaglandins
http://en.wikipedia.org/wiki/Thromboxanes