A Chapter of the History of Chemistry in Vienna Adolf Lieben, 1836-1914; Zdenko Hans Skraup, 1850-1910 MORITZ KOHN Formerly Professor of Organic Chemistry in the University of Vienna
H E DEVELOPMENT of chemistry in Vienna owes much to Lieben and Skraup. Even during their lifetimes they acquired reputations as outstanding organic chemists, and this judgment of their contemporaries has been verified with the passage of the years. Their careers were interrelated and consequently it seems advisable to consider both of them in this paper. Adolf Lieben was born in Vienna on December 3, 1836. His parents were well to do and provided their son with every educational advantage. When only 20, he took his doctorate a t Heidelberg under Bunsen. He then went to study with Wurtz at Paris, being attracted by the latter's successes, such as the discovery of methylamine (1849) and ethylene glycol (1856). On the recommendation of Wurtz, the young Austrian chemist, only 27, was called to Palermo as successor to Cannizzaro. In 1867 Lieben was appointed to the chair of chemistry a t Turin; in 1871 he received a call to the German University a t Prague. Four years later he made his last academic transfer; he was named successor to Rochleder at the University of Vienna. Austrian chemistry, up to that time, had been principally devoted to studies of compounds derived from vegetable sources. Rochleder, and particularly the more famous Hlasiwetz, had been very active in this line. The latter had made two discoveries of considerable conseauence: ~hloroelucinol(1855) and, in collaboration A t h ~ a r l hres&inol , (1'864).' The modern doctrine of the structure of aliphatic compounds was really introduced into Austria by Lieben. During his Italian years his excellent saentific capabilities and his very human qualities had brought him an excellent reputation. The municipality of Turin continued to have its drinking water tested in Lieben's Vienna laboratory. During his professorship in Turin he published (1870) his iodoform reaction, a delicate and reliable test for alcohol and acetone. It is still widely used by chemists and physiologists for
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In 1877, with Zeisel, Lieben started his extended studies of the condensation products of aldehydes and their derivatives, particularly the unsaturated aldehydes, such as notonaldehyde and its homologs. In continuation of these researches he and many coworkers studied the aldols. The first representative of this group, acetaldol (CH3CH20HCHz.CHO), had been discovered by Wurtz in 1872. Lieben described an improved method for preparing this compound and its homologs and successfully investigated the reduction of aldols to 1,3-diols (8-glycols) and the oxidation of aldols to @-hydroxyacids. The technical importance of acetaldol is now appreciated. Acetaldehyde is prepared on a commercial scale from acetylene, and is then transformed to aldol, which on reduction yields butylene glycol (CHaCHOHCHzOH). The latter can be used for the technical preparation of butadiene (CHF=CH.CH=CHZ) which is now so vital in the manufacture of synthetic rubber. Some of the findings of his work on chelidonic acid are worth special mention. He and Haitinger, 18841885, showed that chelidonic acid (C7H,0a) which occurs in chelidunium majus (celandine, a member of the poppy family), is decomposed by alkali into two mols of oxalic acid and one of acetone Complete reduction of chelidonic acid yields n-pimelic acid, COOH(CHz)sCOOH. With ammonia, chelidonic acid produces ammono-chelidonic acid (hydroxypyridinedicarboxylicacid), which, in turn, when heated with zinc dust, yields hydroxypyidine and eventually pyridine. 0
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detecting compounds that contain CHC- linked to hydrogen or carbon, or structures that are oxidized to this arrangement by treatment with iodine and potassium hydroxide. Also at Turin, and in collaboration with Rossi, Lieben made his valuable and systematic studies of the synthesis of aliphatic alcohols. These investigations were continued in Vienna, where, in collaboration with Janecek, he synthesized n-primary hexyl alcohol (CHa(CH2),CHzOH) and n-oeuauthylic acid (CHa(CH&COOH). 471
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On the basis of these findings, Lieben and Haitinger assigned to chelidonic acid the structure
been brought with him from Heidelberg. Though Lieben was primarily an organic chemist, he received Auer most kindly and lent him every possible aid in 0 the prosecution of his inorganic problems. When the II P results were published in 1884 and 1885, the young man expressed his sincere appreciation for the valuable aid given him by Lieben and Zeisel. The findings had il 1 1 COOH-C C-COOH led Auer to an invention that won him world-wide acclaim, namely, the incandescent gas maatle. .The '0" first patent was taken out in 1886, covering the use of namely, y-pyrone dicarboxylic acid. They introduced thoria. Later Auer made the important discovery that the name pyrone for the addition of a small proportion of ceria aided greatly in the emission of light. Ludwig Haitinger, whose R collahoration with Lieben on the chelidonic acid problem has been mentioned, became manager of Auer's factory at Atzgersdorf near Vienna. Auer always gave him a share of the credit for translating the laboratory work into successful technical practice. Lieben retired from his professorship in July, 1906. and this term has now been adopted officially, sup- The following autumn his seventieth birthday and planting the earlier name pyrokoman. Lerch, in golden doctorate jubilee were made the occasion of an Prague, was also working on chelidonic acid, but he impressive celebration. The ceremony was held in the did not succeed in elucidating its structure. The fore- great lecture hall of the chemical laboratory. Zeisel going structure was verified by Claisen in 1891.' He acted as spokesman and presented the revered chief condensed acetone with diethyl oxalate to produce with a "Festschrift." This large volumeZ contained the diethyl ester of xantho-chelidonic acid, whose tau- contributions by chemists, physicists, and physiologists. tomeric form loses water and is transformed into the Among the foreign contributors were Werner (Ziirich), Willstatter (Munich), Ciamician (Bologna), Moissan diethyl ester of chelidonic acid: (Paris), and Goldschmidt (Oslo). Skranp, who had been appointed successor to Lieben, made the principal address. He pointed out that although Lieben's publications were fewer in number than those of many other chemists, none the less their influence bad been COOCHI far greater. Although he often worked with small, sometimes minute quantities, all of his results are of the -H,O-.Ohighest reliability. Another characteristic was his \c=d refusal to publish results until one proof had been supH ported by another. Skraup continued and pointed LoocIHI out, with personal gratitude, that Lieben had invited Simon Zeisel, who was Lieben's coworker in the many young men to work with him, but he never prestudy of the condensation of aldehydes, appreciated vented those who had independent ideas from carrying the need for a method of determining methoxy groups, them out. Consequently Lieben thus contributed to since the constituents of plants are particularly rich in the development of fields which he personally did not methoxy compounds. He solved the ploblem in a till. simple and elegant way by boiling the substance with The great annual meeting of German natural scienhydriodic acid. The ether linkage is split: tists and physicians was held at Vienna in 1913. The high light was Emil Fischer's lecture on his investigaROCHI HI = ROH CHJ tions of depsides and tannins. In his hospitable and The resulting methyl iodide is swept from the reaction distinguished home Lieben gathered the more prominent flask into an alcoholic solution of silver nitrate. The foreign delegates, and entertained them and his Austrian precipitate is collected and weighed; one mol of AgI is chemical associates a t a great dinner. Lieben died on equivalent to one mol of CHsO. This "Zeisel" method, June 6,1914. which came from Lieben's laboratory in 1885, has Zdenko Hans Skraup was horn a t Prague on March proved to be a boon to many of the chemical frater- 3, 1850. After completing the course at the Technical nity. University there, he went to Vienna and secured a post Other extremely interesting publications of this labo- at the Mint. Later he became Rochleder's assistant ratory were those of the young Carl Auer von Wels- and continued in this capacity under Lieben. In 1887 bach, who, like Lieben, had done his doctorate work ' "Festschrift Adolf Lieben zur Feier des siebzigsten Geburtswith Bnnsen. The ideas which he wished to study had stages und des goldenen Doktorjubil5ums gewidmet van Frem-
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24, 119 (1891).
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den, Scbiileru, und Verehrern." Verlag von Winter in Heidelberg. 1906.
he was called to the chair of chemistry a t Graz, where he remained until October, 1906, when he succeeded Lieben a t the University of Vienna. Unfortunately this period lasted only four years. This life, so rich in scientific accomplishment, came to a sudden close on September 10,1910. Skraup's investigative activity had its origins in Rochleder. They collaborated on studies of the quinoline alkaloid, cinchonine. When Lieben came to Vienna he suggested the iron cyanide compounds as a promising field, but he did not hinder Skraup in his wish to elaborate the ideas he had nicked UD from Rochleder. This seed was to yield a bounteous & v e s t in the hands of the highly talented young chemist. Skraup published his first paper on cinchonine in 1878. These studies on the quinoline alkaloids were continued both in Vienna and a t Graz. The results, together with those obtained independently by Konigs in Munich, completely elucidated the structure of this class of compounds. The name Skraup is indissolubly linked with the svnthesis of auinoline. Prudhomme had described the dye alizarin hlue in 1877. It is obtained by heating nitro-alizarin with glycerol and sulfuric acid. Three years later, Graebe determined the structure of alizarin blue. He proved that glycerol forms a new pyridine nucleus, and consequently the reaction proceeds:
ZDENKO HANSSKRAUP. 1850-1910
thus assured, Skraup was free to elaborate this field a t a reasonable pace. The sphere of application of this synthesis has proved to be most extensive. It can be applied to starting materials such as substitution products of aromatic amines, including homologs of aniline, nitranilines, aminophenols, naphthylamines, diamino-benzenes, etc. Alizarin blue The structures of a good many compounds stemming from quinoline or pyridine have been unraveled with After read in^ Graebe's S k r a u ~concluded 11s am. -:> that quinoliie should b i produced when Gitrobenzene Lieben survived Skraup by almost four years. After reacts with glycerol and sulfuric acid. As early as 1842 Skraup's sudden and premature death, it was the older quinoline had been produced by Gerhardt, by the ac- man's sad duty to deliver the commemorative address tion of a caustic alkali on cinchonine, a mmpound that in honor of his successor and former assistant. It was intensely interested Skraup. a touching occasion. The closing statement, "By his Actual trials showed that Skraup's prognosis was achievements Skraup made i t impossible ever to be correct. Although not more than traces of quinoline forgotten," holds equally for Lieben. resulted when he heated a mixture of nitrobenzene, Monuments to these outstanding organic chemists glycerol, and sulfuric acid, success was achieved when were erected a t the University of Vienna. However, a aniline was included in the reaction mixture. Skraup better memorial is found in their publications and in the told the author that these experiments were carried out widespread influence they exerted through their stuin one night; he did not go to bed, but a t once wrote up dents and associates. Boltzmann, the great Austrian the report. On April 8, 1880, Liehen proudly presented physicist, once said, "Many scientific laborers are only from his laboratory to the Academy of Sciences the carrying bricks which disappear in the massive edimemorable preliminary communication: "A synthesis fice." But the achievements of Lieben and Skraup are of quinoline," by Zd. H. Skraup. With his priority proud corner pillars in the huge structure of modem organic chemistry; they can be-seen from afar a G R A E B E . A ~201,333 ~., (1880). !A.
