Skraup, Zdenko Hans
SKRAUP, ZDENKO HANS
(b. Prague, Czechoslovakia, 3 March 1850; d. Vienna, Austria, 10 September 1910)
Skraup came from a Czech family of musicians; his father composed church music and popular songs, and his uncle is remembered to this day for his composition of the Czech national anthem. Although musically gifted as well, Skraup turned to chemistry, which he studied at the German Technische Hochschule in Prague. He became a fervent German-Austrian patriot, abandoning the national allegiance of his Czech forebears. After completing his studies and briefly working in a porcelain factory near Karlovy Vary (Karlsbad) and in the mint in Vienna. Skraup became assistant under Friedrich Rochleder and then Adolf Lieben, who held professorships at the University of Vienna. In 1886 Skraup moved to Graz, where he was appointed professor of chemistry first at the Technische Hochschule and then a year later at the University of Graz. In 1906 he accepted the invitation to succeed Lieben at Vienna.
The development of science in Austria and Bohemia was closely linked during the years before 1918, as is clearly evident from an examination of the activities of the group of eminent chemists including Adolph Martin Pleischl, Jacob Redtenbacher, Rochleder, Heinrich Hlasiwetz, Lieben, and Skraup, in Prague and Vienna, (and other Austrian university towns). It was because of the influence of Rochleder, one of the founders of modern phytochemistry, that Skraup became interested in quinine alkaloids, an area of study important to medical and structural chemistry. In turn it was Skraup who guided young co-workers, among them Fritz Pregl, in the field of physiological chemistry.
Skraup’s most renowned scientific contribution was his synthesis of quinoline. The published account of his work resulted in the development of heterocyclid chemistry of the quinoline series. Although the relation of quinoline to various alkaloids was recognized at the time, there was no easy way to prepare the substance. From the investigations of Karl Graebe on alizarin blue and of Wilhelm Königs on quinoline. it became evident to Skraup that heating nitrobenzene and glycerol in the presence of sulfuric acid could produce the compound
C6H5NO2 + C3H8O3 = C9H7N + 3H2O + O2.
Skraup tried out the reaction and confirmed this conjecture but found that the yield of quinoline was rather low. He believed that this drawback was mainly the result of the evolution of oxygen, and in order to avoid it he proceeded to combine aniline with glycerol under the same conditions:
C6H7N + C3H8O3 = C9H7N + 3H2O + H2.
only finding that the amount of quinoline was again small. After combining the two methods, thus effectively oxidizing oxygen to water. Skraup obtained a satisfactory yield of quinoline:
2C6H5NH2 + C6H5NO2 + C3H8O3 = 3C9H7N + 11H2O.
Skraup’s synthesis became a general method for the preparation of quinolines, in which an aromatic primary amine is heated with glycerol and sulfuric acid in the presence of nitrobenzene or some other oxidizing agent.
The fundamental paper “Eine Synthese des Chinolins” appeared in the Sitzungsberichte der mathematischnaturwissenschaftlichen Classe der Kaiserlichen Akademie der Wissenschaften, 81 (1880), pt. II, I–V. Skraup’s works are listed in succeeding volumes of Poggendorff, III (1898), 1254; IV, pt. II (1904), 1402, and V. pt. II (1926), 1173. The obituary by H. Schrötter in Berichte der Deutschen chemischen Gesellschaft, 43 (1910), 3683–3702, is informative. See also the article by M. Kohn. “A Chapter of the History of Chemistry in Vienna,” in Journal of Chemical Education,20 (1943), 471–473.