THE HISTORY AND CHEMISTRY BEHIND ASPIRINBy Angela Pacheco

PROPERTIES OF ASPIRIN

• Antipyretic: reduces fever

• Analgesic: reduces pain

• Anti-inflammatory: reduces swelling

HISTORICAL PAIN RELIEF

• Some of the earliest pain relievers were parts of plants.

• For example:• The ancient Greeks used bark from willow and poplar trees. Records show

Hippocrates prescribing it around 400 BC. • Native Americans made teas from the bark of the willow.

• In the mid-1700s, these teas were introduced to Europe by Reverend Edward Stone, who dried willow bark and ground it into a powder.

• In the 1800s, the active ingredient, salicylic acid, was identified. It began to be produced in large quantities and not just for pain relief. It was also used as a food preservative.

PROBLEMS WITH SALICYLIC ACID

• However, salicylic acid was hard on the body. Being highly acidic, it caused irritation to the mouth and digestive system.

• Various scientists began to experiment, trying to come up with a suitable alternative.

FELIX HOFFMAN, JR.

• A 25 year old chemist working in Bayer Laboratories in Germany in 1893, Felix Hoffman Jr had a personal interest in finding a replacement for salicylic acid. His father relied on the medicine to treat his arthritis, but suffered from the stomach discomfort it caused.

• Working after hours, Hoffman Jr synthesized acetylsalicylic acid. The Bayer company would patent the drug and call it Aspirin (a- for the acetyl group and the “sprin” for the group of plants that produce salicylic acid.

• In some countries, such as Canada, the name “aspirin” can only be used for the product sold by Bayer.

ASPIRIN = ACETYLSALICYLIC ACID

• Aspirin is formed by reacting salicylic acid with acetic anhydride.

• C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2

• Salicylic acid and acetic anhydride react to form acetylsalicylic acid and acetic acid.

PROBLEMS WITH ASPIRIN

• Though not as badly as its salicylic acid predecessor, aspiring still causes blood loss from the stomach.

• It interferes with the clotting of blood, which can be a good thing for some heart problems. This is one of the reasons why heart patients may take a “baby” aspirin every day.

• Because of the clotting problem, aspirin should not be taken prior to or immediately after surgery.

• Aspirin has been linked to “Reyes Syndrome” in children and young teens suffering from viral infections.

• Aspirin is toxic in large doses.

OUR ASPIRIN SYNTHESIS

• The reaction doesn’t occur quickly, so we will use sulfuric acid as a catalyst.

• This is the same reaction that aspirin companies use to make aspirin!

• Once we have created our aspirin, we will purify it with ice cold water. Aspirin is not soluble in cold water, but the impurities are.

• We will test our product with iron (III) chloride. Iron (III) chloride reacts with a phenol group (found in salicylic acid, but not in aspirin) to produce a colorful result. If your aspirin results look like that of the salicylic acid, then your aspirin is impure.

• We will also test for starch. Starch is added to aspirin power to help it form a tablet. In this way, aspirin serves as a “binder.” Iodine reacts with starch to form a blue or black color.