Friedrich Wöhler is in history of chemistry famous with its experiment (1852) in
which he succeeded to prepare organic compound, urea, from the inorganic precursor ammonium-cyanate:
NH 4 OCN
H 2 NCONH 2
CH 4 ON 2
heating
Until that experiment, the chemical theories were mostly focused (and valid) to
inorganic compounds. Behaviour of compounds isolated from plants or animals has
been unexplainable within the old theories by Stahl and Lavoisier. In his book
about chemistry, Systéme des connaissances chimiques (1800) Antoine Fourcroy
(1755–1809) describes organic compounds only in the last two chapters. However,
just this orientation to the systematic investigation of this class of compounds will
represent the key step for the final development of structural theory.
Far-reaching of Wohler’s discovery is not only in the rejection of dualistic
hypothesis by which the chemistry in living beings is different from the chemistry
in inorganic world, but also in the knowledge that the same elemental composition
(represented by formula CH 4 ON) can possess very different substances. The conclusion is that, if the difference between substances is not only in their composition,
it must be in something else: the micro organization of atoms that we call the
Crystals of sodium-chloride NaCl (the figure is copied from the public internet pages)
82
10 Systematization, Classification, Structure, and Elements
which he succeeded to prepare organic compound, urea, from the inorganic precursor ammonium-cyanate:
NH 4 OCN
H 2 NCONH 2
CH 4 ON 2
heating
Until that experiment, the chemical theories were mostly focused (and valid) to
inorganic compounds. Behaviour of compounds isolated from plants or animals has
been unexplainable within the old theories by Stahl and Lavoisier. In his book
about chemistry, Systéme des connaissances chimiques (1800) Antoine Fourcroy
(1755–1809) describes organic compounds only in the last two chapters. However,
just this orientation to the systematic investigation of this class of compounds will
represent the key step for the final development of structural theory.
Far-reaching of Wohler’s discovery is not only in the rejection of dualistic
hypothesis by which the chemistry in living beings is different from the chemistry
in inorganic world, but also in the knowledge that the same elemental composition
(represented by formula CH 4 ON) can possess very different substances. The conclusion is that, if the difference between substances is not only in their composition,
it must be in something else: the micro organization of atoms that we call the
Crystals of sodium-chloride NaCl (the figure is copied from the public internet pages)
82
10 Systematization, Classification, Structure, and Elements