AUGUST WILHELM VON HOFMANN (8 April 1818 – 5 May 1892) was a German
chemist . After studying under
Justus von Liebig
He made considerable contributions to organic chemistry. His research
on aniline helped lay the basis of the aniline-dye industry. His
earliest research on coal tar laid the groundwork for his student
Charles Mansfield\'s practical methods for extracting benzene and
toluene and converting them into nitro compounds and amines . Hofmann
prepared three ethylamines and tetraethylammonium compounds and
established their structural relationship to ammonia . His discoveries
include formaldehyde , hydrazobenzene , the isonitriles , and allyl
alcohol . His name is associated with the
Hofmann received several significant awards in the field of
chemistry, including the
* 1 Early life and education
* 2 Career
* 3 Contributions
* 4 Publications * 5 Awards and honours * 6 Later life * 7 See also * 8 References * 9 Additional Sources
EARLY LIFE AND EDUCATION
August Wilhelm Hofmann was born at Giessen , Grand Duchy of Hesse , on 8 April 1818. He was the son of Johann Philipp Hofmann, privy councillor and provincial architect to the court at Darmstadt. As a young man, he travelled widely with his father. August Wilhelm matriculated at the University of Giessen in 1836.
He originally took up the study of law and philology at
Giessen . He
may have become interested in chemistry when his father enlarged
Giessen laboratories in 1839. August Wilhelm changed his
studies to chemistry , and studied under
Justus von Liebig
His association with Liebig eventually became personal as well as professional. Both his first wife, Helene Moldenhauer (m. 12 August 1846), and his third wife, Elise Moldenhauer (m. 19 May 1866), were nieces of Liebig's wife, Henriette Moldenhauer. Hofman reportedly courted Elise after Liebig's daughter Johanna refused him. :44, 318 In between, he married Rosamond Wilson (m. 13 December 1856), and later Bertha Tiemann (m. 11 August 1873) He had eleven children.
ROYAL COLLEGE OF CHEMISTRY IN LONDON
Hofmann at the Inauguration of the School of
As president of the
The financial position of the new institution was somewhat precarious. Hofmann accepted the position on the condition that he be appointed as extraordinary professor at Bonn, with leave of absence for two years, so that he could resume his career in Germany if the English appointment did not go well. The college opened in 1845 with 26 students at 16 Hanover Square, moving to cheaper premises at 299 Oxford Street in 1848. Hofmann himself relinquished his free personal accommodation in Hanover Square and gave up part of his salary. Despite this rocky start, the institution became successful for a time, and was an international leader in the development of aniline dyes. Many of the men who studied there made significant contributions to chemical history.
In 1853, the Royal College of Chemistry became part of the governmental Department of Science and Art, under the new School of Mines, putting it in a position to receive governmental funding on a somewhat more secure basis. However, with the death of Prince Albert in 1861, the institution lost one of its most significant supporters. Hofmann felt the loss deeply, writing in 1863, " early kindness exercised so powerful an influence upon the destinies of my existence. Year by year do I feel more deeply the debt of gratitude which I owe to him... it is to him, I feel, that I owe my opportunities through life." Without the Prince's encouragement, British government and industry lost interest in of science and technology. Hofmann's decision to return to Germany can be seen as a symptom of that decline, and with him gone, the Royal College of Chemistry lost its focus.
In 1864 Hofmann was offered a chair of chemistry at the University of
Bonn , and another at the University of
Hofmann's work covered a wide range of organic chemistry .
Hofmann was a major contributor to the development of techniques for organic synthesis, which originated at Liebig's laboratory in Giessen. Hofmann and John Blyth were the first to use the term "synthesis", in their paper "On Styrole, and Some of the Products of Its Decomposition," predating Kolbe's use of the term by some months. What Blyth and Hofmann called "synthesis" enabled them to make inferences about the constitution of styrole. A subsequent paper, Muspratt and Hofmann's "On Toluidine", described some of the first "synthetical experiments" (synthetische Versuche) in the field of organic chemistry. While the ultimate goal of such experiments was to artificially produce naturally occurring substances, such a goal was not practically attainable at the time. The immediate purpose of the technique was the application of known reactions to a variety of materials to discover what products could be formed. Understanding a substance's method of formation was an important step in placing it within a developing taxonomy of substances. This technique became the basis of Hofmann's research program. He used organic synthesis as a method of investigation, to increase chemical understanding of reaction products and the processes by which they were formed.
COAL TAR AND ANILINES
Hofmann's first research investigations, carried out in Liebig's
laboratory at Giessen, was an examination of the organic bases of coal
tar . Hofmann successfully isolated Kyanol and Leucol, bases
previously reported by
Friedlieb Ferdinand Runge
Hofmann drew an analogy between aniline and ammonia . He wanted to convince chemists that organic bases could be described in terms of derivatives of ammonia. Hofmann successfully converted ammonia into ethylamine and the compounds diethylamine , triethylamine , and tetraethylammonium . He was the first chemist to synthesize the quaternary amines. His method of converting an amide into an amine is known as the Hofmann rearrangement .
While primary, secondary, and tertiary amines were stable when distilled at high temperatures under alkaline conditions, the quaternary amine was not. Heating quaternary tetraethylammonium hydroxide yielded tertiary triethylamine vapour. This became the basis of what is now known as the Hofmann elimination , a method for converting quaternary amines into tertiary amines. Hofman successfully applied the method to coniine , the cholinergic poison of hemlock , to derive the first structure of an alkaloid. His method became extremely significant as a tool for examining the molecular structures of alkaloids, and was eventually applied to morphine, coca amine, atropine, and tubocurarine, among others. Coniine eventually became the first of the alkaloids to be artificially synthesised.
In 1848, Hofmann's student Charles Blachford Mansfield developed a method of fractional distillation of coal tar and separated out benzene , xylene , and toluene , an essential step towards the development of products from coal tar.
In 1856, Hofmann's student William Henry Perkin was attempting to synthesize quinine at the Royal College of Chemistry in London, when he discovered the first aniline dye , mauveine . The discovery led to the creation of a wide range of artificially created colourful textile dyes, revolutionising the fashion world. Hofmann's researches on rosaniline , which he first prepared in 1858, were the beginning of a series of investigations on colouring matter. In 1863, Hofmann showed that aniline blue is a triphenyl derivative of rosaniline and discovered that different alkyl groups could be introduced into the rosaniline molecule to produce dyes of various purple or violet colours, which became known as 'Hofmann's violets'. In 1864, Hofmann confirmed that magenta can only be made by oxidation of commercial aniline in which isomeric orthotoluidine and paratoluidine are present as impurities, not from pure aniline. Other students of Hofmann's who became involved in the British dyestuffs industry include Edward Chambers Nicholson , George Maule , and George Simpson . After his return to Germany, Hofmann continued to experiment with dyestuffs, finally creating quinoline red in 1887.
Hofmann studied nitrogen bases, including the development of methods for separating mixtures of amines and the preparation of large numbers of "polyammonias" (diamines and triamines such as ethylenediamine and diethylenediamine). He worked with Auguste Cahours on phosphorus bases between 1855 and 1857. With him, in 1857, Hofmann prepared the first aliphatic unsaturated alcohol , allyl alcohol , C3 H5OH. He also examined its derivative, allyl isothiocyanate (mustard oil), in 1868, and studied various other isocyanates and isonitriles (isocyanides, or carbylamines).
Hofmann also developed a method for determining the molecular weights of liquids from vapour densities . Hofmann isolated sorbic acid from rowanberries' oil in 1859, a chemical compound that is widely used as a food preservative .
In 1865, inspired by Auguste Laurent , Hofmann suggested a systematic nomenclature for hydrocarbons and their derivatives. It was adopted internationally by the Geneva Congress, with some modifications, in 1892.
Hofmann's methane model
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 sulphur = yellow. 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.
Library resources about AUGUST WILHELM VON HOFMANN -------------------------
* Resources in your library * Resources in other libraries
BY AUGUST WILHELM VON HOFMANN
* Online books * Resources in your library * Resources in other libraries
Hofmann was multilingual and published extensively, particularly about his work on coal tar and its derivatives. In 1865 Hofmann published An Introduction to Modern Chemistry, summarising type theory and emerging ideas about chemical structure. Type theory modelled four inorganic molecules, hydrogen, hydrogen chloride, water, and ammonia, and used them as a basis for systematising and categorising both organic and inorganic compounds by exploring the substitution of one or more atoms of hydrogen for an equivalent atom or group. Hofmann himself had focused on researching ammonia, but discussed all four models in his book. In it, he also first introduced the term valence , under its longer variant quantivalence, to describe the combining capacity of an atom. His textbook strongly influenced introductory textbooks in both Europe and the United States.
In addition to his scientific works, Hofmann wrote biographical notices and essays on the history of chemistry, including a study of Liebig.
AWARDS AND HONOURS
Monument to Hofmann at Berlin, destroyed in 1944 by British air raid
He was elected a fellow of the
In 1900, the
German Chemical Society built the "Hofmann-Haus" at
Hofmann died in 1892 and was buried in Berlin's Friedhof der Dorotheenstädtischen und Friedrichswerderschen Gemeinden.
* ^ A B Volhard, Jacob; Fischer, Emil (1902). August Wilhelm von
Hofmann: Ein Lebensbild. Berlin.
* ^ A B C D E F G
August Wilhelm von Hofmann
* ^ Griffith, Bill. "
Wikimedia Commons has media related to AUGUST WILHELM VON HOFMANN .
* 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.
* Bericht über die Entwickelung der chemischen Industrie während
des letzten Jahrzehends : im Verein mit Freunden und Fachgenossen
erstattet . Volume 1–3.1, Vieweg, Braunschweig 1875 – 1877 Digital
edition by the
University and State Library Düsseldorf
* v * t * e
Copley Medallists of 1851–1900
* WorldCat Identities * VIAF : 56726163 * LCCN