Friedrich Wöhler, along with Jöns Jacob Berzelius (1779-1848) and Justus von Liebig (1803-1873), were pioneers in applying the techniques of organic chemistry to the parts and products of living things. Their work, originally known as "animal chemistry," established the foundations of modern biochemistry. Wöhler and Liebig are important in the history of chemistry for their recognition of the benzoyl radical. Wöhler is best known for demonstrating that the isomerization of ammonium cyanate produced urea, thus making him the first to synthesize an organic compound from an inorganic compound.
Wöhler, the son of a schoolmaster, was born in Eschersheim, near Frankfurt-am-Main. Although Wöhler studied medicine at Marburg and Heidelberg and earned the M.D., he came under the influence of Leopold Gmelin (1788-1853) and decided to make chemistry his career. He never practiced medicine. Wöhler was not a distinguished student, but flourished at Heidelberg when he was given permission to abandon routine coursework and devote himself to research. A year of work with Berzelius in Sweden (1823-24) established the future course of his research career. He taught at technical schools in Berlin (1825) and Cassel (1831) before being appointed Professor of Chemistry in Göttingen in 1835. He remained at that university until his death in 1882. Wöhler was greatly respected as a teacher and exerted tremendous influence on the development of organic chemistry though his numerous students.
As a medical student, Wöhler initiated an investigation of the derivatives of cyanogen and subsequently discovered cyanic acid. In 1828 he carried out his most famous experiment, in which he demonstrated that ammonium cyanate, the ammonium salt of cyanic acid, could be isomerized (transformed) into urea. This was the first time that a chemical normally produced only by living beings was synthesized from materials that could be obtained, at least in theory, from nonliving matter. In a famous letter to a colleague Wöhler wrote that he could "make urea without kidney of man or dog." Although Wöhler's preparation of urea is often seen as proof that inorganic and organic chemicals are theoretically equivalent, many other demonstrations were needed to abolish the ancient belief that "animal chemistry" was fundamentally different from inorganic chemistry. Indeed, Wöhler never claimed that his synthesis of urea signaled the death of vitalism. The synthesis of acetic acid by Hermann Kolbe (1818-1884) is generally considered the first complete in vitro synthesis of an organic compound.
The study of cyanogen compounds also led to the isolation of benzaldehyde from pure oil of bitter almonds. In 1832 Wöhler and Liebig found that when they put benzaldehyde through a variety of reactions, a cluster of atoms seemed to act like a chemical element. That is, it apparently remained unchanged throughout all the reactions of benzaldehyde that they were able to test. They named this the group of atoms benzoyl. This concept brought order and direction to further work in organic chemistry. Eventually, other examples of such "compound radicals" were discovered. Wöhler published a landmark article on the chemistry of metabolism in 1842. He demonstrated that when benzoic acid was consumed with food, it was excreted in the urine as hippuric acid. Other investigations involved the quinones, alkaloids, and derivatives of uric acid.
Although Wöhler's most famous achievements were in organic chemistry, he also remained interested in inorganic chemistry. His many admirers said that there were hardly any known elements that he had not studied. Indeed, his work included the isolation of aluminum, beryllium, silicon hydrides, analyses of various minerals, and studies of meteorites.
LOIS N. MAGNER
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