Фридрих Вёлер: Жизнь и открытия немецкого химика

German chemist (1800–1882)

Friedrich Wöhler FRS(For) HonFRSE (31 July 180023 September 1882) was a German chemist known for his work in both organic and 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 also 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 substances contradicted the belief that organic compounds could only be produced by living organisms due to a "life force".

Friedrich Wöhler was born in Eschersheim, Germany, and was the son of a veterinarian. As a boy, he showed interest in mineral collecting, drawing, and science. 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 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 Jacob Berzelius in Stockholm, Sweden. Wöhler's time in Stockholm with Berzelius marked the beginning of a long personal and professional relationship between the two scientists. Wöhler translated many of Berzelius's scientific writings into German for 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, Wöhler became Friedrich Stromeyer's successor as an Ordinary Professor of Chemistry at the University of Göttingen, where he occupied the chair of chemistry for 46 years, until his death in 1882. During his time at Göttingen approximately 8000 research students were trained in his laboratory. In 1834, he was elected a foreign member of the Royal Swedish Academy of Sciences. Although Ørsted published his findings on the isolation of aluminium in the form of small particles, no other investigators successfully replicated 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 convert to solid balls of pure metallic aluminium in 1845. For this work, Wöhler is credited with the first isolation of aluminium in pure form. In 1828 Wöhler was the first to isolate the element beryllium in pure metallic form (also independently isolated by Antoine Bussy). 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. (Elemental titanium was later isolated in completely pure form in 1910 by Matthew A. Hunter.) 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 the preparation of calcium carbide. Wöhler has also been regarded as a pioneering researcher 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 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. 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". Contrary to what was thought in Wöhler's time, cyanate is not a purely inorganic anion, as it is formed in various metabolic pathways. Thus the conversion of ammonium cyanate into urea was not an example of production of an organic compound from an inorganic precursor.

Once Wöhler became a professor at the University of Göttingen, students traveled from around the world to be instructed by him. Wöhler saw particular success in his students after giving them hands on experience in the lab. This practice was later adopted around the world, becoming the chemistry lab co requisite that is required at most universities today. Wöhler also allowed his students to participate and aid him in his research, which was not typical at the time. This practice became nearly universal, normalizing the undergraduate and graduate level research that is a requirement for numerous degrees today.

Wöhler's discoveries had a significant influence on the theoretical basis of chemistry. The journals of every year from 1820 to 1881 contain his original scientific contributions. 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 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. In 1862, Wöhler was elected a member of the American Philosophical Society. The Life and Work of Friedrich Wöhler (1800–1882) (2005) by Robin Keen is considered to be "the first detailed scientific biography" of Wöhler. On the 100th anniversary of Wöhler's death, the West German government issued a stamp depicting the structure of urea with its synthesis formula listed directly below.

Wöhler's first marriage was in 1828, to his cousin Franziska Maria Wöhler (1811–1832). The couple had two children, a son (August) and a daughter (Sophie). After Franziska's death, he married Julie Pfeiffer (1813–1886) in 1834, with whom he had four daughters: Fanny, Helene, Emilie, and Pauline.