01 The birth of organic chemistry and the vital-force theory
In ancient times
- Since antiquity humans used substances from animals and plants: fats, oils, sugar, vinegar, alcohols and perfumes.
- The ancient Egyptians used drugs in mummification and fast dyes still visible on the walls of temples.
Berzelius's division (1806)
- Organic compounds: extracted from a plant or animal origin.
- Inorganic compounds: obtained from mineral sources in the earth.
The vital-force theory
Berzelius held that an organic compound is formed inside the cells of a living organism by a vital force, and therefore cannot be prepared in the laboratory.
Wöhler's experiment (1828)
The German chemist Friedrich Wöhler prepared urea — an organic compound found in the urine of mammals — from two inorganic compounds. He mixed ammonium chloride with silver cyanate to form ammonium cyanate, then heated it and obtained urea:
- NH₄Cl + AgCNO → AgCl ↓ + NH₄CNO
- NH₄CNO —(heat)→ H₂N–CO–NH₂ (urea)
This was the death blow to the vital-force theory; scientists then went on to prepare drugs, detergents, dyes, plastics, fertilisers and pesticides.
The modern definition
- An organic substance is defined by its composition, not its source, because most laboratory-prepared compounds do not exist in living organisms.
- Organic chemistry is the study of the compounds of carbon, excluding oxides of carbon, carbonates and cyanides.
- Inorganic chemistry is the study of the remaining elements and their compounds.