August Wilhelm von Hofmann
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August Wilhelm von Hofmann
The German chemist August Wilhelm von Hofmann (1818-1892) was one of the most influential organic chemists and teachers of the century.
August Wilhelm von Hofmann was born on April 8, 1818, in the small university town of Giessen. In 1836 he entered the University of Giessen, where he studied law, philosophy, and mathematics. However, in 1843 he turned to the study of chemistry. He received his doctorate summa cum laude with a thesis entitled Chemical Investigation of the Organic Bases in Coal Tar, a field in which he was destined to achieve worldwide fame.
In 1845, while holding a professorship at the University of Bonn, Hofmann derived analine from benzene and thus laid one of the foundations of the synthetic dye industry. He also worked out the problem of substituting atoms of chlorine for the hydrogen atoms of the aromatic compounds. This work won the coveted Gold Medal of the Parisian Societé de Pharmacie and made Hofmann famous. He received and accepted an invitation from Queen Victoria in 1845 to transfer his scientific activities to London.
Working in England as researcher and teacher for 20 years, Hofmann trained a generation of brilliant chemists, including Frederick Abel, Warren de La Rue, E.C. Nicholson, Charles Mansfield, William H. Perkins, and Sir William Crookes, and a host of future leaders of the German chemical industry such as Peter Griess, George Merck, C.A. Martius, and Jacob Vilhard. In 1865 Hofmann became professor of chemistry at the University of Berlin.
Honored by the leading scientific societies of Europe, Hofmann worked in a spacious new laboratory built by a grateful government. During this period his researches were directly related to the meteoric rise of the German dye and pharmaceutical industries, which with coal and iron were the foundations of the industrial supremacy of Wilhelmine Germany. Critical to this success was what became known as the Hofmann degradation process, the successive reduction of the length of a carbon chain through treating the amides of fatty acids with bromine and alkali. Indigo was produced industrially by precisely these steps. Another of Hofmann's industrially significant accomplishments was the production of formaldehyde by passing vapors of methyl alcohol over hot platinum.
Though most of Hofmann's 360 major papers grew out of his work with the derivatives of coal tar and the synthesis of related organic compounds, he also contributed to the chemistry of cadmium, antimony, phosphorus, and titanium. He discovered the quaternary ammonium salts and was thus led to classify all amines as formal derivatives of ammonia - an idea which was the foundation of the later "theory of types" of Charles F. Gerhardt.
Hofmann was married four times and was the father of 11 children. In 1868 he helped found the German Chemical Society and served as its president 14 times. Never spoiled by fame or fortune, he continued his teaching and writing until the very end, on May 2, 1892, in Berlin.
Further Reading
Eduard Farber, ed., Great Chemists (1961), contains a section on Hofmann. See also Archibold Clow, The Chemical Revolution: A Contribution to Social Technology (1952); Eduard Farber, The Evolution of Chemistry: A History of Its Ideas, Methods, and Materials (1952; 2d ed. 1969); and James R. Partington, A History of Chemistry, vol. 4 (1964).
Hofmann, August Wilhelm von (ou'gʊst vĭl'hĕlm fən hôf'män), 1818-92, German organic chemist. He was professor at the Univ. of Berlin from 1865 and was a founder (1868) of the German Chemical Society. He studied the constitution of aniline and was the first to prepare rosaniline and its derivatives, thereby laying the basis for the aniline dye industry. He also discovered a reaction for deriving amines from amides and developed the Hofmann method of finding the vapor densities, and from these the molecular weights, of liquids. He also helped to popularize the concept of valence (the word comes from his term quantivalence).
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August Wilhelm von Hofmann
| August Wilhelm von Hofmann | |
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 August Wilhelm von Hofmann |
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| Born | 8 April 1818 Giessen, Germany |
| Died | 5 May 1892 (aged 74) Berlin, Germany |
| Residence | Germany England |
| Nationality | German |
| Fields | Chemistry |
| Institutions | University of Bonn, Royal College of Chemistry, Berlin University |
| Alma mater | University of Göttingen |
| Doctoral advisor | Justus von Liebig |
| Doctoral students | Richard Abegg, Adolf Pinner, Fritz Haber, Karl Friedrich von Auwers, Rudolf Hugo Nietzki, Ferdinand Tiemann, Eugen Bamberger |
| Known for | Hofmann rearrangement Hofmann elimination Hofmann-Löffler reaction |
| Influenced | William Henry Perkin |
August Wilhelm von Hofmann (8 April 1818 – 5 May 1892) was a German chemist.
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Contents
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Biography
Hofmann was born at Gießen, Grand Duchy of Hesse. Not intending originally to devote himself to physical science, he first took up the study of law and philology at Göttingen. But he then turned to chemistry, and studied under Justus von Liebig at University of Giessen. When, in 1845, a school of practical chemistry was started in London, under the style of the Royal College of Chemistry, Hofmann, largely through the influence of the Prince Consort, was appointed its first director. It was with some hesitation that he, then a Privatdozent at Bonn, accepted the position, which may well have seemed rather a precarious one; but the difficulty was removed by his appointment as extraordinary professor at Bonn, with leave of absence for two years, so that he could resume his career in Germany if his English proved unsatisfactory. Fortunately the college was more or less successful, owing largely to his enthusiasm and energy, and many of the men who were trained there subsequently made their mark in chemical history. In 1864 he returned to Bonn, and in the succeeding year he was selected to succeed Eilhard Mitscherlich as professor of chemistry and director of the laboratory in Berlin University.
Hofmann's work covered a wide range of organic chemistry. His first research, carried out in Liebig's laboratory at Giessen, was on coal-tar and his investigation of the organic bases in naphtha established the nature of aniline. This substance he referred to as his first love, and it was a love to which he remained faithful throughout his life. His perception of the analogy between it and ammonia led to his famous work on the amines and ammonium bases and the allied organic phosphorus compounds, while his researches on rosaniline, which he first prepared, formed the first of a series of investigations on coloring matter which only ended with quinoline red in 1887.
The Hofmann rearrangement and Hofmann elimination reaction bear his namesake. Hoffmann isolated sorbic acid from rowanberries' oil in 1859, a chemical compound that is widely used as a food preservative.
Hofmann also was the first to introduce molecular models into public lectures, around 1860 following the earlier (1855) suggestion by his colleague William Odling that carbon is tetravalent. Hofmann's colour scheme is still in use by some scientists: carbon = black, hydrogen = white, nitrogen = blue, oxygen = red, chlorine = green, and sulfur = yellow.[1] His models look rather odd nowadays, primarily because Hofmann had them built so that they were, in essence, two-dimensional representations of molecules, and with the carbon atom smaller in size than the hydrogen. (It was Loschmidt in 1861 who probably first appreciated the variations in atomic sizes). After 1874, when van't Hoff and Le Bel independently suggested organic molecules can be three dimensional, molecular models began to assume their modern appearance.
William Henry Perkin was a student of Hofmann at the Royal College of Chemistry in London, when he discovered the first aniline dye, mauveine.
Hoffman died in 1892 and was buried in Berlin's Friedhof der Dorotheenstädtischen und Friedrichswerderschen Gemeinden.[2][3]
Awards
He was elected a fellow of the Royal Society in 1851. He was awarded the society's Royal Medal in 1854 and their Copley Medal in 1875. [4]
Hofmann voltameter
The Hofmann voltameter is an apparatus for electrolyzing water, invented by August Wilhelm von Hofmann.[5] It consists of three joined upright cylinders, usually glass. The inner cylinder is open at the top to allow addition of water and an ionic compound to improve conductivity, such as a small amount of sulphuric acid. A platinum electrode is placed inside the bottom of each of the two side cylinders, connected to the positive and negative terminals of a source of electricity. When current is run through Hofmann's Voltameter, gaseous oxygen forms at the anode and gaseous hydrogen at the cathode. Each gas displaces water and collects at the top of the two outer tubes.
See also
References
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Wikisource has original works written by or about: August Wilhelm von Hofmann |
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- ^ Ollis, W. D. (1972). "Models and Molecules". Proceedings of the Royal Institution of Great Britain 45: 1–31.
- ^ "Friedhof der Dorotheenstädtischen und Friedrichswerderschen Gemeinden". http://de.wikipedia.org/wiki/Friedhof_der_Dorotheenst%C3%A4dtischen_und_Friedrichswerderschen_Gemeinden. Retrieved 2009-06-20.
- ^ Oesper, Ralph E. (1968). "The burial place of August Wilhelm Hofmann (1818-1892)". Journal of Chemical Education 45 (3): 153. doi:10.1021/ed045p153.
- ^ "Library and Archive Catalogue". Royal Society. http://www2.royalsociety.org/DServe/dserve.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Persons&dsqPos=0&dsqSearch=%28Surname%3D%27hofmann%27%29. Retrieved 2012-03-10.
- ^ von Hofmann, A. W. Introduction to Modern Chemistry: Experimental and Theoretic; Embodying Twelve Lectures Delivered in the Royal College of Chemistry, London. Walton and Maberly, London, 1866. [1]
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Hofmann, August Wilhelm von". Encyclopædia Britannica (11th ed.). Cambridge University Press.
Further reading
- Theodore A. Alston (2003). "The Contributions of A. W. Hofmann". Anesthesia Analgesia 96 (2): 622–625. doi:10.1097/00000539-200302000-00058. PMID 12538223. http://www.anesthesia-analgesia.org/cgi/content/abstract/96/2/622.
- John J. Beer (1960). "A. W. Hofmann and the Founding of the Royal College of Chemistry". Journal of Chemical Education 37 (5): 248–251. doi:10.1021/ed037p248.
- Christoph Meinel (1992). "August Wilhelm Hofmann - Reigning Chemist-in-Chief". Angewandte Chemie International Edition in English 31 (10): 1265–1282. doi:10.1002/anie.199212653.
- William Henry Perkin (1896). "The origin of the coal-tar colour industry, and the contributions of Hofmann and his pupils". Journal Chemical Society Transaction 69: 596. doi:10.1039/CT8966900596.
- Anthony S. Travis (1992). "August Wilhelm Hofmann (1818–1892)". Endeavour 16 (2): 59–65. doi:10.1016/0160-9327(92)90003-8.
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