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WM5 The synthesis of salicylicacid and aspirin

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Synthesis is better than harvesting

Chemists can synthesise (artificially produce)

compunds, once the structure is known. Phenol¶s germicidal properties were well

known by the end of 19th Century.

Phenol (a product from heating coal) was

readily available. 2-hydroxybenzoic acid has 1 extra functional

group, compared to phenol.

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How is phenol converted into 2-hydroxybenzoic acid?

Draw the structures of phenol and 2-

hydroxybenzoic acid. What extra atoms need to be added to

phenol?

What conditions and reagents are needed?

(research this).

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Kolbe ±Schmitt synthesis

Kolbe (1874) producedsalicylic acid from drysodium phenoxide in astream of carbon dioxideat 150 ± 160 °C. Hefound that the yield wasonly 50%.

Schmitt (1884) increased the yield to 90% byincreasing the pressure to 5 bar (7atm), until no moreCO2 was taken up.

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On an industrial scale«

Felix Hoffmann developed process for the

Bayer company. Unpleasant side-effects on mouth, gullet and

stomach.

Hoffmann modified the structure and tested

products on his rheumatic father! 1898 ± 2-ethanoylhydroxybenzoic acid (aka

acetylsalicylic acid OR aspirin) produced

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