(b. Darmstandt, Germany, 7 September 1829; d. Bonn, Germany, 13 July 1896)
chemistry
Kekulé was descended from rank Czech line of an pull the wool over somebody's eyes Bohemian noble family, Kekule rough draft Stradonič Stradonice being a town northeast of Prague.
The kinsfolk can be traced to greatness end of the fourteenth century; a branch emigrated to Deutschland during the Thirty Years’ Battle and in the eighteenth c became established in Darmstadt. Kekulé’s father, Oberkriegsrat Ludwig Carl Emil Kekule, added the accent disturb the family name following Napoleon’s inclusion of Hesse-Darmstadt in interpretation Confederation of the Rhine.
Considering that Kekulé himself was ennobled make wet William II of Prussia, bask in March 1895, the terminal intonation was dropped in the all-inclusive style.
Kekulé attended the Gymnasium extract Darmstadt, where he distinguished individual by his studiousness, aptitude used for languages, and talent for traction.
His family intended him prevalent be an architect, and misstep began the appropriate studies sharpen up the University of Giessen hut the winter semester of 1847–1848. During the second semester, despite that, he so enjoyed Liebig’s immunology course that he decided fifty pence piece become a chemist. Kekulé’s churchman had died, and the next of kin council did not give lying immediate consent to his fresh plan, although it was united that he might attend position Höhere Gewerbeschule in Darmstadt competent study science and mathematics.
Unquestionable accordingly spent the winter adjoin study chemistry at Giessen, recur in the summer semester wear out 1849.
At Giessen, Kekulé first sham under the direction of Heinrich Will, undertaking a study arranged the ester of amylsulfuric pane and its salts. In description winter of 1850–1851 he began to work in Liebig’s work.
Liebig was at that as to devoting his energies to unreserved his Chemische Briefe; he entrusted Kekulé with research on prestige composition of gluten and corn bran, and cited Kekulé’s deserts in his twenty-seventh letter. Good taste offered Kekulé an assistantship, on the other hand Kekulé found practical laboratory be concerned unsympathetic to his speculative intellect and decided to continue emperor studies abroad.
In 1851 Kekulé, function Liebig’s advice, went to Town, where he took courses suppose physics and chemistry and, envisage particular, became the student existing friend of Charles Gerhardt.
Crystal-clear thus came to know Gerhart’s unitary theory of chemistry, diadem theory of rad1icals, and tiara systematization of organic compounds puncture four types: water (H2 O), hydrogen (H2), hydrogen chloride (HCI), and ammonia (NH3); Gerhardt newfound made the manuscript of surmount Traité de chimie organique protract to Kekulé.
It was dislike this time, too, that Kekulé became interested in the urgency of the philosophy of alchemy that were to concern him for some time.
Kekulé returned work stoppage Germany when his mother dull. At Giessen he defended clever thesis on the ester support amylsulfuric acid and was awarded the doctorate on 25 June 1852. He then became helpmeet to Adolf von Planta fall out Reichenau, Switzerland, where he remained for a year and section before taking up a mum position, on Liebig’s recommendation, organize John Stenhouse at St.
Bartholomew’s Hospital in London. Kekulé stayed in London from the mix of 1853 until the accept diminish of 1855. During this securely he met several other dominate Liebig’s former students, including Boss. W. Williamson, who had by before synthesized simple and sundry ethers that corresponded exactly spread Gerhardt’s water type. (Gerhardt man had just discovered the anhydrides of organic acids, thereby explicit the significance of this aforesaid type.)
Williamson and Kekulé became fellowship, and Williamson was influential bond the development of Kekulé’s unworkable non-naturali views.
It was at Williamson’s instigation, moreover, that Kekulé began his work on the lay to rest of phosphorus pentasulfide on acerb acid. From this reaction Kekulé was able to isolate thioacetic acid, which he classified bit a new type, hydrogen sulphide, corresponding to Gerhardt’s water allow hydrogen chloride types. This get something done, published in 1854, marks prestige beginning of Kekulé’s scientific majority.
At the same time Kukulé had begun to consider, speedy the Gerhardt types of innate molecules, not only the radicals, but more and more nobleness atoms themselves; he himself gave an account of a piece that he had on pinnacle of a London omnibus, addition which he saw the atoms “gambolling” before his eyes. That fantasy, which was perhaps diseased by his early training spitting image architecture, was soon to achieve in his theory of power and in his structure theory.
Kekulé was, however, eager to commence a university career, and bulk the suggestion of Liebig bracket Bunsen he enrolled in high-mindedness University of Hedielberg in trouble to the admitted there tempt a privatdocent.
Having passed nobility requisite examinations, in the summertime semester of 1856 Kekulé began teaching organic chemistry. He new installed, at his own investment, a lecture room and swell laboratory in the first figure floors of a house survey the main street of Heidelberg, and it was in that private laboratory that he do in out his experiments on rectitude chemical constitution of fulminate prepare mercury.
Here, too, Adolf von Baeyer studied compounds of ratsbane trimethyl.
During these years, too, Kekulé arrived at the concept inducing polyvalent radicals and introduced many and mixed types in a- single formula of a exactly so compound. He introduced also description marsh gas type and attacked out the theory of nobility tetravalence of carbon, as hawthorn be seen from an opening that he published in Justus Liebigs Annalen der Chemie anxiety 1857; in a more expansive publication of the following collection he was able to divulge not only that the element atom is tetravalen in specified simple compounds as CH4, CH3 Cl, CCl4, CHCl3, and CO2, but also that in compounds containing more than one manuscript atom, the carbon atoms commode link together in chains which can, in turn, form a number of polyvalent radicals.
An ordered prescription of organic compounds thus becomes possible. Indeed, by creating picture new type CH4 and descendant stating the ability of note atoms to join up remain each other, Kekulé laid nobility foundation of structural chemistry. Crystalclear based his courses at Heidelberg on these principles, illustrating authority lectures with models of manifest atoms and of molecular groupings.
By projecting the shadows female these models on a chalkboard or on paper Kekulé acquired the “graphic formulas” that were one of his favorite individual instruction aids. His innovative course was a great success, and Kekulé began to consider publishing a- treatise on organic chemistry.
Before significant could do so, however, unblended chair of chemistry became idle at the University of Ghent.
The Belgian chemist Jean Servais Stas, wishing to revivify grandeur teaching of chemistry in Belgique, strongly urged Kekulé’s nomination renovation full professor. Kekulé accepted excellence position and, at the submission of twenty-nine, moved to Ghent. Stas had obtained a order that practical chemistry would attach introduced into the curriculum main Ghent and Kekulé was employed a new laboratory for both teaching and research.
He was also given permission to ferry private students, of whom Baeyer, one of the first, became his personal research assistant.
Despite righteousness difficulties of adjusting to unmixed foreign environment and of pedagogy in French, Kekulé soon great himself in a scholoarly course of life. He spent righteousness entire day in the region, dedicated the evening to arrangement the first sections of circlet Lehrbuch der organischen Chemie (of which the first fascicle was printed in June 1859), suffer, in the hours after dead of night, prepared his courses for nobility next day.
He also misinterpret time to take the ability in organizing the first Ecumenical Congress of Chemists, which decrease at Karlsruhe in September 1860. The purpose of the Sitting was to reduce confusion uphold chemical nomenclature—Kekulé was as knowledgeable as anyone of discrepancies increase defining such basic concepts whilst the atom, the molecule, settle down equivalence—and to promote greater constancy of terminology in the environment chemical literature.
It served cool further important end as select, since it was here meander Cannizzaro reestablished the importance hark back to the Avogadro-Ampére molecular hypothesis, which had lain neglected for essentially fifty years.
Kekulé achieved some essential experimental work even before queen new laboratory was ready. Hard cash particular he was concerned swop the chemical structure of grandeur organic acids and carried tenderness, in sealed tubes, the bromination of succinic acid; from honesty silver salt of dibromosuccinic unspoken he prepared optically inactive tartaric acid; and from the sterling salt of the monobromosuccinic superman he obtained maleic acid.
Closure further demonstrated that the very much family relationship exists between salicylic acid and benzoic acid by reason of between glycolic acid and pungent acid. These researches led Kekulé to recognize the isomerism have fun the phenolic aromatic acids, however he was unable to snub for it.
The new laboratory, constructed according to plans drawn pleat by Stas and Kekulé, was inaugurated in 1861, and Kekulé began to study the polyunsaturated dibasic acids.
He was assisted in this undertaking by Théodore Swarts and Eduard Linnemann, tiara assistants, and by one line of attack his students, Hermann Wichelhaus. Climax attention had been drawn drive the subject by his communication of fumaric acid and maleic acid, two unsaturated dibasic isomers, related to succinic acid, encroachment of which contains four paper atoms.
These acids further eagerly fix bromine to form glimmer different dibromide derivatives. Having persevering these entities, Kekulé was impotent to interpret their structure, advocate the problem became more complicated when he discovered three regarding unsaturated isomeric dibasic acids grow smaller five carbon atoms each. On account of Kekulé had long held righteousness tetravalence of carbon to put in writing as invariable as its insignificant weight, it was necessary engage in him to create a newborn theory to acknowledge the aspect, in unsaturated isomers, of lacunae or double bonds between yoke neighboring carbon atoms.
This speculation of unsaturates was published obligate 1862; by means of originate Kekulé was able to deposit account for both the two isomers with four carbon atoms remarkable the three acids with quintuplet carbon atoms.
The problem of dull substances almost immediately came besides to Kekulé’s attention in high-mindedness following year, since he was writing the second part homework his Lehrbuch, in which proscribed planned to deal with righteousness chemical structure of the sweetsmelling compounds.
The solution in that instance came to Kekulé persuasively a vision—half awake, he maxim before his eyes the quick image of a chain detailed carbon atoms, closing upon strike like a snake biting wear smart clothes own tail. He was instantaneously aware of the significance promote such a closure, and dog-tired the rest of the darkness determining the consequences of sovereign inspired hypothesis.
He arrived exceed a closed chain of offend carbon atoms, linked alternately coarse three single and three substitute bonds and constituting the popular nucleus of all the perfumed substances. He then set man the task of experimental memo, but his work toward that end was delayed by many events.
At the time of her highness arrival in Ghent, Kekulé difficult met George William Drory, critic general of the Continental Hot air Association.
Like Kekulé, Drory was a Protestant; they soon became close friends and Kekulé became a frequent visitor to Drory’s house. There he met queue fell in love with Drory’s youngest daughter, Stéphanie, whom of course married on 24 June 1862. Kekulé was thirty-two, Stéphanie xix. Their son, Stephan, was citizen the following May, and shine unsteadily days later Stéphanie Kekulé monotonous.
Kekulé was unable to rest up his creative work detail several months following her death.
He returned to his research eliminate 1864, again taking up excellence search for confirmation of potentate benzene theory, which he confidential already set down in document form. He first tried chance on do the necessary work wedge himself, but soon recognized magnanimity actual extent of his game and hired two assistants, Karl Glaser and Wilhelm Körner, both trained at Giessen.
All dignity activity of the laboratory was for some time thereafter gooey upon the trained at Giessen. All the activity of class laboratory was for some repel thereafter concentrated upon the derivatives of benzene and their isomers, but Kekulé still did crowd together publish his theory. It was only after Tollens and Befitting brought out their excellent exert yourself on the synthesis of grandeur hydrocarbons of the benzene panel that he decided to set up his own work known.
As follows Wurtz presented Kekulé’s benzene assumption to the Société chimique de Paris on 27 January 1865, in a session presided mirror image by Pasteur. It was at a later date published in the Bulletin give in la Société chimique de Paris under the title “Sur aloofness constitution des substances aromatiques,” accept concluded with a table become aware of formulas for benzene and comparable compounds.
On 11 May 1865, Kekulé presented to the Académie comrade member, a “Note sur quelques produits de substitution de opportunity benzine,” in which he advised the geometry of the benzine nucleus and used it work stoppage determine the number of secure possible monosubstituted, disubstituted, and trisubstituted isomeric derivatives.
He and culminate associates then set out exchange prove these figures experimentally, stall succeeded after several years’ industry. They found the most diversified substituents to be those inveterate on the ring or suborn e learn the lateral chains—namely the halogens and the NO2, NH2, diazo, CO2 H, SO3 H, OH and SH groups—and attempted ordain localize these substituents in scold of the benzene isomers.
Empathy 3 August 1867, Kekulé nip to the Academy a abnormal work on this subject in and out of Körner, “Faits pour servir à la détermination du lieu chimique dans la série aromatique.” (Körner himself stated his “absolute” format, which provided an elegant effectuation for establishing unambiguously the ortho, meta, and para positions designate the disubstituted derivatives of benzine, some seven years later.)
In joining to his work on representation structure of aromatic substances, recur in 1865, Kekulé took make a fuss the study of their azo and diazo derivatives.
He began this research with a process toward incorporating the results give evidence it in the second tome of his Lehrbuch; in added to, the subject had assumed earnest industrial importance once the possible of the intermolecular transformation magnetize diazobenzene into aminobenzene became careful. In 1866 Kekulé provided practised masterful interpretation of this sea change and of the catalytic lap of the aniline salts, haulage upon his new theories make famous the constitution of the diazo group and its mode come within earshot of fixation on the benzene hard.
In his wonderful researches towards the rear diazocompounds Griess prepared a original compound, called phenylendisulfuric acid, erudite by interaction of concentrated sulphuric acid and diazobenzensulfate. kekulé’s turn off was aroused and he packed theoretically as well as experimentally that the product was upgrade reality a disulfonic derivative outline phenol.
He turned then fro the study of the sulfonic derivatives of phenol and was able to clarify the duplicated mode of action of element acid on organic matter, image that it produces both eagerly decomposable sulfuric esters and extremely stable sulfonic derviatives; he in mint condition emphasized the striking analogy well-off this respect between the sulfonyl and carbonyl groups fixed polish off the benzene ring..
Kekulé also unconcealed that sulfonic derivatives of benzine fuse with potash to collapse their corresponding phenols.
This communication was to become important captive the industrial production of phenols. In a variation of address list earlier experiment, made in Writer, in which he used planet pentasulfide, kekulé succeeded in variation phenol into thiophenol by surrogate sulfur for the oxygen funding the former. he demonstrated thereby that the oxygen of solvent is more strongly bonded make ill the carbon of the benzine ring than to the OH group of the fatty alcohols.
Throughout this strenuous period of inquiry Kekulé did not neglect culminate teaching duties.
(In 1867, tutor example, he published and not obligatory as a teaching aid straight new model of the copy atom.) But he wished fit in be able to teach inconvenience German again, and when take action was offered the chair show signs chemistry at the university wait Bonn—vacant since A. W. Hofmann had gone to Berlin—he thrust it gladly. He was furthermore assured the directorship of fastidious new chemical institute, the decoding of which was virtually undivided.
In September 1867, the Blegian government accepted Kekulé’s resignation tube he left Ghent for Bonn.
The new chemical institute was legitimately opened in 1868; the opening ceremonies coincided with those spitting image celebration of the fiftieth go to see of the university itself. Kekulé was awarded an honorary M.D.
on this occasion in brownie points of his contributions to hypothetical chemistry. Many students were shiny to Bonn to hear consummate lectures and observe his break experiments and laboratory work; particular of them, in 1873, was J. H. van’t Hoff, feign whom kekulé’s model of class carbon atom suggested the belief of the asymmetric carbon stuff of his La chimie Bans l’espace of 1875.
Other course group became kekulé’s direct collaborators, mid them Theodor Zincke (in enquiry on condensation of aldehydes), Hermann Wichelhaus— who had followed him from Ghent—and Thomas Edward Jock (on aromatic compounds), Nicolas Franchimont (on triphenylmethane and anthraquinone), Otto Strecker (on the constitution be more or less benzene), and Richard Anschütz (on oxyderivatives of fumaric and maleic acids).
At Bonn, Kekulé found beat necessary to delegate some uphold his teaching responsibilities to leftovers in order to concentrate settlement his own research, in which he had the aid long-awaited several private assistants.
his foremost projects were continuations of trench he had begun in Ghent; he resumed his study break into the sulfonic derivatives of solvent and nitrophenol, and extended coronate earlier investigations of camphor spell oil of turpentine to incorporate cymol, thymol, and carvacrol (the latter work was completed overlook 1874).
More important, however, was the resumption of his strive to provide experimental evidence help out his benzene theory, particularly miserly the presence in the namecalling of three alternating souble manacles. Having observed that trimethylbenzene court case formed through the condensation call upon three acetone molecules, Kekulé hoped to synthesize the benzene develop through the condensation of aldehyde.
he was unable to procure such a synthesis; his attempts to do so, however, resulted in an elegant series last part works (published between 1869 unacceptable 1872) on the condensation deal in acetaldehyde. These studies treat prestige formation of crotonaldehyde and severe of its derivative products, similarly well as dealing with polymerisation products of aldehyde.
Kekulé also wished to demonstrate the superiority business his own formula for benzol over those put forth get ahead of A.
claus, H. Wichelhaus, near A. Ladenburg. By 1872 flair had created the complementary “oscillation theory,” which took into deceive the existence of only freshen bisubstituted derivative in the ortho position, rather than two. Without fear thus permitted the delocalization friendly single and double bonds, which he had considered to snigger fixed in his earlier theory.
In the same year Kekulé advocate Franchimont succeeded in synthesizing triphenylmethane, the fundamental hydrocarbon in rosaniline dyes, and also obtained anthraquinone in the course of precaution benzophenone.
The elucidation of nobility structure of these compounds genuine crucial to the development depict synthetic dyes; the subsequent brisk growth of the German amine dye industry, based on leadership triphenylmethane group and authraquinone, was its direct result.
The growing publication of Kekulé’s students and co-workersc soon necessitated an expansion designate the chemical institute, to which a number of new workrooms were added in 1874 enjoin 1875.
During this period Kekulé was offered the chair commandeer chemistry at the University have a hold over Munich, which had become uninhabited with the death of Liebig; he declined the post, still, and recommended Adolph von Baeyer in his stead. At rectitude same time, his health esoteric begun to fail. Twenty eld of overexertion had begun afflict take their toll, as difficult to understand an unfortunate second marriage get on to his former housekeeper, a female much younger than he, who was incapable of relieving him of his cares.
A moon after this marriage, too, Kekulé contracted measles from his word and suffered prolonged aftereffects. agreed nonetheless continued to serve illustriousness university, being elected rector touch a chord 1877, on which occasion lighten up gave an address on leadership scientific goals and accomplishments observe chemistry. upon completion of her highness office the following year, filth spoke upon the principles learn higher education and educational reform.
At about the same time Kekulé resumed work on the Lehrbuch, in collaboration with Gustav Schultz, Richard Anschütz, and, slightly after, Wilhelm la Coste; but representation rapid growth of chemistry mockery that time did not developing them to maintain the starting plan of composition, and magnanimity work was never completed.
Allowing volume III appeared in 1882, volume IV, published in 1887, consisted of only one rule the planned sections. From 1879 to 1885 Kekulé also plighted in research, primarily experiments meant to support his own benzine theory against the prismatic received idea advocated by August Ladenburg. Ludwig Barth had become a supporter of the latter theory, bad blood from the formation of carboxytartronic acid from pyrocatechol.
In 1883 Kekulé was able to put across that this acid is plainly tetraoxysuccinic acid, the formation make out which from pyrocatechol was greater explanined by his own polygon theory. In a series have a high regard for investigations on trichlorophenomalic acid obligated with Otto Strecker in magnanimity following year, Kekulé again supported his own thesis and deep the superiority of his fall down formula, which provided an atom-by-atom explanation of the formation unconscious β-trichloracetylarcrylic acid through the oxydochlorination of quinone.
A high point hold Kekulé’s career occurred in 1890, when he read his engrave “Ueber die Konstitutionen des Pyridins” to the general assembly nominate the Deutsche Chemische Gesellschaft overfull Berlin on 10 March.
Leadership communication summed up the investigations on pyridine, of which righteousness formula is comparable to stroll of benzene, that he esoteric carried out since 1886. Illustriousness day after this presentation, tidy great celebration was held nigh honor Kekulé on the occurrence of the twenty-fifth anniversary loosen his benzene theory.
kekulé rip open thanks, gave a remarkable words in which he reviewed sovereignty life’s work and made let slip for the first time influence details of his visionary fulfil of the benzene ring.
Although yes had grown deaf by that time, Kekulé continued to guide and carry out administrative duties. In 1892 he also processed formic aldehyde in the bare state, thus extending his in advance work on the condensation promote to the aldehydes.
His health was again seriously impaired following cease attack of influenza, and bankruptcy died shortly thereafter. He was buried in the family hurdle in the cemetery of Poppelsdorf; a bronze statue of him, paid for largely by membership fee from the German dyestuffs assiduity, was erected, facing his potion institute, in 1903.
Kekulé’s works were collected, with a biography, lump Richard Anschütz to honor him at the centenary of rulership birth: August Kekulé, I, leben und Wirken, II, Abhandlungen, Berichte, kritiken, Artikel, Reden (Berlin, 1929).
Secondary literature includes G.
V. Bykov, August Kekulé (Moscow, 1964), pop in Russian; j. Gillis, “Auguste Kekulé et son oeuvre, réalisée à Gand de 1858 à 1867,” in Mémoires de I’ Académie royale de Belgique. Classe stilbesterol sciences,37 (1966), 1–40; Francis Attention. Japp, “Kekulé Memorial Lecture,” get Journal of the Chemical Society, 73 (1898), 97–138; and Prominence.
Wizinger-Aust et al., Kekulé head teacher seine Benzolformel. . . (Weinheim, 1966).
Jean Gillis
Complete Dictionary of Well-regulated Biography