TheWöhler synthesis is the conversion ofammonium cyanate intourea. Thischemical reaction was described in 1828 byFriedrich Wöhler.[1] It is often cited as the starting point of modernorganic chemistry. Although the Wöhler reaction concerns the conversion of ammonium cyanate, thissalt appears only as an (unstable) intermediate. Wöhler demonstrated the reaction in his original publication with different sets of reactants: a combination ofcyanic acid andammonia, a combination ofsilver cyanate andammonium chloride, a combination oflead cyanate and ammonia and finally from a combination ofmercury cyanate and cyanatic ammonia (which is again cyanic acid with ammonia).[2]
The reaction can be demonstrated by starting withsolutions ofpotassium cyanate andammonium chloride which are mixed, heated and cooled again. An additional proof of the chemical transformation is obtained by adding a solution ofoxalic acid which formsureaoxalate as a whiteprecipitate.[3]
Alternatively the reaction can be carried out with lead cyanate and ammonia.[4] The actual reaction taking place is adouble displacement reaction to form ammonium cyanate:
Ammonium cyanatedecomposes toammonia andcyanic acid which in turn react to produce urea:
Complexation withoxalic acid drives thischemical equilibrium to completion.
That Wöhler's synthesis sparked the downfall of the theory ofvitalism, which states that organic matter possessed a certain "vital force" common to all living things, is disputed. Prior to the Wöhler synthesis, the work ofJohn Dalton andJöns Jacob Berzelius had already convinced chemists that organic and inorganic matter obey the same chemical laws. It took until 1845 whenKolbe reported another inorganic – organic conversion (ofcarbon disulfide toacetic 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]
Myth 7. That Friedrich Wöhler's Synthesis of Urea in 1828 Destroyed Vitalism and Gave Rise to Organic Chemistry