220px-FountainSpringsWintergreen.pngHistory and Current Process

Aspirin - History
Aspirin is the world's most recognizable drug with over 25 million kilograms produced annually. Aspirin is the trade name for acetyl salicylic acid. It is used as a Non Steroidal Anti-inflammatory, analgesic and anti pyretic drug. The drug was originally patented by Bayer in 1897 after the acetylation of the cousin compound salicylic acid was achieved. Salicylic acid is produced by many plants such as willow and wintergreen in times of stress, and has been used for therapeutic purposes’ for over two millennia. The Greek physician Hippocrates wrote in the 5th Century of the willows bark curative properties.

The Current Process
The current manufacturing process involves the use of petrochemical products and a number of inefficient reactions. One of these processes starts with the petrochemical derived carcinogen, benzene and through the sulphonation produces benzene sulphonic acid.

Benzene --------------------------------------Benzenesulphonic acid

The second stage is to react the benzenesulphonic acid with a strong base producing phenol.


Benzene sulphonic acid ----------------------Phenol

The next reaction is called the Kolbe- Schmitt reaction, a nucleophilic addition reaction to produce salicylic acid.


Phenol ----------------------------------------Sodium phenolate ---------------------------Salicylic acid

And the final step is the acetylation of the salicylic acid to produce the acetyl salicylic acid. The commercial process uses acetyl chloride to acetylize the salicylic acid. This produces hydrochloric acid as a byproduct which is an example of the undesirable waste products of the process.


Salicylic acid-------------------------------- acetyl salicylic acid

These multiple steps produce a number of unwanted by products and therefore a more greener process needs to be derived.

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