Friedrich Wöhler


Friedrich Wöhler FRS HFRSE was a German chemist, known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the first to prepare several inorganic compounds including silane and silicon nitride.
Wöhler is known for seminal contributions in organic chemistry, in particular the Wöhler synthesis of urea. His synthesis of the organic compound urea in the laboratory from inorganic precursors refuted the prevailing belief that organic compounds could only be produced by living organisms due to a "life force". Wöhler also introduced the concept of a functional group, which was a new concept that advanced understanding of organic compounds.

Biography

Friedrich Wöhler was born in Eschersheim, Germany, and was the son of a veterinarian. His secondary education was at the Frankfurt Gymnasium. During his time at the gymnasium, Wöhler began chemical experimentation in a home laboratory provided by his father. He began his higher education were at Marburg University in 1820.
On 2 September 1823 Wöhler passed his examinations as a Doctor of Medicine, Surgery, and Obstetrics at Heidelberg University, having studied in the laboratory of chemist Leopold Gmelin. Gmelin encouraged him to focus on chemistry, and arranged for Wöhler to conduct research under the direction of chemist Jöns Jakob Berzelius in Stockholm, Sweden. Wöhler's time in Stockholm with Berzelius marked the beginning of a long professional relationship between the two scientists. Wöhler translated some of Berzelius's scientific writings into the German language for the purpose of international publication.
From 1826 to 1831 Wöhler taught chemistry at the Polytechnic School in Berlin. From 1831 until 1836 he taught at the Polytechnic School at Kassel. In the spring of 1836, he became Friedrich Stromeyer's successor as Ordinary Professor of Chemistry in the University of Göttingen, where he served as chemistry professor for 21 years. He remained affiliated with the University of Göttingen until his death in 1882. During his time at the University of Göttingen, approximately 8000 research students trained in his laboratory. In 1834, he was elected a foreign member of the Royal Swedish Academy of Sciences.

Contributions to chemistry

Inorganic chemistry

Wöhler investigated more than twenty‐five chemical elements during his career.
Hans Christian Ørsted was the first to separate out the element aluminium, in 1825, using a reduction of aluminium chloride with a potassium amalgam. Although Ørsted published his findings on the isolation of aluminium in the form of small particles, no other investigators were able to replicate his findings until 1936. Ørsted is now credited with discovering aluminium. Ørsted's findings on aluminium preparation were developed further by Wöhler, with Ørsted's permission. Wöhler modified Ørsted's methods, substituting potassium metal for potassium amalgam for the reduction of aluminium chloride. Using this improved method, Wöhler isolated aluminium powder in pure form on 22 October 1827. He showed that the aluminium powder could be solidified balls of pure metallic aluminium in 1845. For this work, Wöhler is credited with the first isolation of aluminium metal in pure form.
In 1828 Wöhler was the first to isolate the element beryllium in pure metallic form. In the same year, he became the first to isolate the element yttrium in pure metallic form. He achieved these preparations by heating the anhydrous chlorides of beryllium and yttrium with potassium metal.
In 1850, Wöhler determined that what was believed until then to be metallic titanium was in fact a mixture of titanium, carbon, and nitrogen, from which he derived the purest form isolated to that time. He also developed a chemical synthesis of calcium carbide and silicon nitride.
Wöhler, working with French chemist Sainte Claire Deville, isolated the element boron in a crystalline form. He also isolated the element silicon in a crystalline form. Crystalline forms of these two elements were previously unknown. In 1856, working with Heinrich Buff, Wöhler prepared the inorganic compound silane (SiH4. He prepared the first samples of boron nitride by melting together boric acid and potassium cyanide. He also developed a method for preparation of calcium carbide.
Wöhler had an interest in the chemical composition of meteorites. He showed that some meteoric stones contain organic matter. He analyzed meteorites, and for many years wrote the digest on the literature of meteorites in the Jahresberichte über die Fortschritte der Chemie. Wöhler accumulated the best private collection of meteoric stones and irons then existing.

Organic chemistry

In 1832, lacking his own laboratory facilities at Kassel, Wöhler worked with Justus Liebig in his Giessen laboratory.
In 1834, Wöhler and Liebig published an investigation of the oil of bitter almonds. Through their detailed analysis of the chemical composition of this oil, they proved by their experiments that a group of carbon, hydrogen, and oxygen atoms can behave chemically as if it were the equivalent of a single atom, can take the place of an atom in a chemical compound, and can be exchanged for other atoms in chemical compounds. Specifically, in their research on the oil of bitter almonds, they showed that a group of elements with chemical composition C7H5O can be thought of as a single functional group, which came to be known as a benzoyl radical. In this way, the investigations of Wöhler and Liebig established a new concept in organic chemistry referred to as compound radicals, a concept which had a profound influence on the development of organic chemistry. Many more such functional groups were later identified by subsequent investigators with wide utility in chemistry.
Liebig and Wöhler explored the concept of chemical isomerism, the idea that two chemical compounds with identical chemical compositions could in fact be different substances because of different arrangements of the atoms in the chemical structure. Aspects of chemical isomerism had originated in the research of Berzelius. Liebig and Wöhler investigated silver fulminate and silver cyanate. These two compounds have the same chemical composition, yet are chemically different. Silver fulminate is explosive, while silver cyanate is a stable compound. Liebig and Wöhler recognized these as being examples of structural isomerism, which was a significant advance in the understanding of chemical isomerism.
Wöhler has also been regarded as a pioneer in organic chemistry as a result of his 1828 demonstration of the laboratory synthesis of urea from ammonium cyanate, in a chemical reaction that came to be known as the "Wöhler synthesis". Urea and ammonium cyanate are further examples of structural isomers of chemical compounds. Heating ammonium cyanate converts it into urea, which is its isomer. In a letter to Swedish chemist Jöns Jacob Berzelius the same year, he wrote, 'In a manner of speaking, I can no longer hold my chemical water. I must tell you that I can make urea without the use of kidneys of any animal, be it man or dog.'
Wöhler's demonstration of urea synthesis has become regarded as a refutation of vitalism, the hypothesis that living things are alive because of some special "vital force".
It was the beginning of the end for one popular vitalist hypothesis, the idea that "organic" compounds could be made only by living things.
In responding to Wöhler, Jöns Jakob Berzelius clearly acknowledged that Wöhler's results were highly significant for the understanding of organic chemistry, calling the findings a "jewel" for Wöhler's "laurel wreath". Both scientists also recognized the work's importance to the study of isomerism, a new area of research.
Wöhler's role in overturning vitalism is at times said to have become exaggerated over time. This tendency can be traced back to Hermann Kopp's History of Chemistry. He emphasized the importance of Wöhler's research as a refutation of vitalism, but ignored its importance to understanding chemical isomerism, setting a tone for subsequent writers.
The notion that Wöhler single-handedly overturned vitalism also gained popularity after it appeared in a popular history of chemistry published in 1931, which, "ignoring all pretense of historical accuracy, turned Wöhler into a crusader".

Final days and legacy

Wöhler's discoveries had significant influence on the theoretical basis of chemistry. The journals of every year from 1820 to 1881 contain original scientific contributions from him. The Scientific American supplement for 1882 stated that "for two or three of his researches he deserves the highest honor a scientific man can obtain, but the sum of his work is absolutely overwhelming. Had he never lived, the aspect of chemistry would be very different from that it is now".
Wöhler's notable research students included chemists Georg Ludwig Carius, Heinrich Limpricht, Rudolph Fittig, Adolph Wilhelm Hermann Kolbe, Albert Niemann, Vojtěch Šafařík, Wilhelm Kühne and Augustus Voelcker.
Wöhler was elected a Fellow of the Royal Society of London in 1854. He was an Honorary Fellow of the Royal Society of Edinburgh.
The Life and Work of Friedrich Wöhler by Robin Keen is considered to be "the first detailed scientific biography" of Wöhler.

Family

Wöhler's first marriage was in 1828, to his cousin Franziska Maria Wöhler. The couple had two children, a son and a daughter. After Franziska's death, he married Julie Pfeiffer in 1834, with whom he had four daughters: Fanny, Helene, Emilie and Pauline.

Further works

Further works from Wöhler: