Wöhler synthesis

Source: Wikipedia, the free encyclopedia.

The Wöhler synthesis is the conversion of

cyanic acid and ammonia, a combination of silver cyanate and ammonium chloride, a combination of lead cyanate and ammonia and finally from a combination of mercury cyanate and cyanatic ammonia (which is again cyanic acid with ammonia).[2]

Modified versions of the Wöhler synthesis

The reaction can be demonstrated by starting with

precipitate.[3]

Alternatively the reaction can be carried out with lead cyanate and ammonia.

double displacement reaction
to form ammonium cyanate:

Pb(OCN)2 + 2 NH3 + 2 H2O → Pb(OH)2 + 2NH4(OCN)

Ammonium cyanate

cyanic acid
which in turn react to produce urea:

NH4(OCN) → NH3 + HOCN ⇌ (NH2)2CO

Complexation with oxalic acid drives this chemical equilibrium to completion.

Debate

Further information: Vitalism § 19th century

It is disputed that Wöhler's synthesis sparked the downfall of the theory of

Kolbe reported another inorganic – organic conversion (of carbon disulfide to acetic acid) before vitalism started to lose support.[5][6] Wöhler also did not, as some textbooks have claimed, act as a "crusader" against vitalism. A 2000 survey by historian Peter Ramberg found that 90% of chemical textbooks repeat some version of the Wöhler myth.[7]

References

  1. ^ Friedrich Wöhler (1828). "Ueber künstliche Bildung des Harnstoffs". Annalen der Physik und Chemie. 88 (2): 253–256
  2. doi:10.1021/ed073p883
    .
  3. doi:10.1021/ed073p539.2
    .
  4. S2CID 95650676
    .
  5. ^ "Introduction", Newton's Apple and Other Myths about Science, Harvard University Press, pp. 59–66, 31 December 2015, retrieved 29 July 2022, Myth 7. That Friedrich Wöhler's Synthesis of Urea in 1828 Destroyed Vitalism and Gave Rise to Organic Chemistry
  6. ISBN 978-0-674-08916-7
    .
  7. S2CID 44613876
    .
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