The Wöhler synthesis is the conversion of

ammonium cyanate Ammonium cyanate is an inorganic compound with the formula . It is a colorless, solid salt. Structure and reactions The structure of this salt was verified by X-ray crystallography. The respective C–O and C–N distances are 1.174(8) and 1.192 ...

into

urea Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...

. This

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

was described in 1828 by Friedrich Wöhler. It is often cited as the starting point of modern

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

. Although the Wöhler reaction concerns the conversion of ammonium cyanate, this

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

appears only as an (unstable) intermediate. Wöhler demonstrated the reaction in his original publication with different sets of reactants: a combination of cyanic acid and

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

, a combination of silver cyanate and

ammonium chloride Ammonium chloride is an inorganic chemical compound with the chemical formula , also written as . It is an ammonium salt of hydrogen chloride. It consists of ammonium cations and chloride anions . It is a white crystalline salt (chemistry), sal ...

, 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).

Modified versions of the Wöhler synthesis

The reaction can be demonstrated by starting with solutions of potassium cyanate and

which are mixed, heated and cooled again. An additional proof of the chemical transformation is obtained by adding a solution of oxalic acid which forms

oxalate as a white precipitate. Alternatively the reaction can be carried out with lead cyanate and ammonia. The actual reaction taking place is a double displacement reaction to form ammonium cyanate: : Ammonium cyanate decomposes to

and cyanic acid which in turn react to produce urea: : Complexation with oxalic acid drives this chemical equilibrium to completion.

Debate

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

vitalism Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...

, which states that organic matter possessed a certain ''vital force'' common to all living things. Prior to the Wöhler synthesis, the work of

John Dalton John Dalton (; 5 or 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. He introduced the atomic theory into chemistry. He also researched Color blindness, colour blindness; as a result, the umbrella term ...

and Jöns Jacob Berzelius had already convinced chemists that organic and inorganic matter obey the same chemical laws. It took until 1845 when Kolbe reported another inorganic – organic conversion (of carbon disulfide to

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

) before vitalism started to lose support. 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.

References

{{DEFAULTSORT:Wohler Synthesis Organic reactions Inorganic reactions Name reactions