Heinrich Hlasiwetz (1825- 18%) MORITZ KOHN New York City
(Tamluted by Ralph E. Oesper,
University of Cincinnati, Cincinnati, Ohio)
I
N HIS biographical sketch of Baeyer, Willstatterl
tells how his revered teacher and predecessor was called to Munich. When Liebig died (1873), Kekul6 was offered the post. He refused to leave Bonn, and Hlasiwetz, of Vienna, was approached. He also declined; Baeyer, of Strassburg, was then called and he accepted. The man who was ranked by his contemporaries as of sufficient calibre to occupy Liebig's chair certainly should be included among the Austrian chemists whose achievements are being recorded in this series of biographical s k e t ~ h e s . ~ Heinrich Hlasiwetz was born on April 7, 1825, a t Reichenberg (Czechoslovakia). As the son of an apothecary, he was expected to follow his father's profession. He studied pharmacy a t Jena, and after he had also finished a course in the practical side, he obtained his Pharm.M. a t Prague in 1848. The next year he was awarded a doctorate in chemistry. His academic career began a t Prague where he was assistant to Rochleder (1819-74), a distinguished plant chemist. Two of the latter's triumphs will suffice to show his stature. In 1845, in collaboration with Wertheim, he isolated a volatile base, piperidine, by alkaline fission of piperine, the alkaloid of pepper. He was the first (1850) to prepare the pure glucoside of alizarin from madder root. He named this new substance mberythric acid. Hlasiwetz did such notable work during his assistantship a t Prague, that he was appointed to a professorship a t the University of Innsbruck in 1851. Henceforth, chemistry was to be treated there as an independent discipline. Hlasiwetz worked a t Innsbmck until 1867, when he was called to the Vienna Polytechnic as professor of chemical technology. When Schrotter, the discoverer of red phosphorusP assumed the mastership of the Mint a t Vienna, Hlasiwetz succeeded him (1869) as professor of general chemistry. He retained this chair until his untimely death on October 8, 1875. Hlasiwetz was only six years younger than Rochleder, but he was decisively influenced in his scientific learnings by his chief; he can thus be regarded as Rochleder's student' prominent chemist, Zd. H. Skraup4 was also Rochleder's student.
'
WILLSTXTPER,R., "Das Buch der grossen Chemiker," Bngge (ed.), Verlag Chemie. Berlin, 1929, Vol. 2, p. 328. 'See. for instance, the account of Hugo Weidel's career by M. Kom. THISJOURNAL 21,374 (1944). a KOHN.M.. THIS JOURNAL. 21,522 (1944). Kom. M.. THISJOURNAL, 20,471 (1943).
'
The latter, who later taught a t the University of Vienna from 1870 to 1874, deserves the credit for having induced Skraup to take up the study of cinchona alkaloids. At Innsbmck, Hlasiwetz could not begin his scientific labors until he had provided all the necessary equipment and materials; in fact he even had to install a laboratory. He accomplished big things with the modest facilities afforded by the little,university. The studies that were issued from the newly founded department aroused the respect of the chemical world. Phloridzin, the glucoside contained in the root bark of various fruit trees, is split by dilute acids into glucose and phloretin. When Hlasiwetz subjected phloretin to the action of alkalies (1855) he discovered a new compound, which he was to encounter in numerous other studies. Because of its sweet taste, he suggested the name phloroglucin (11). A second product is phloretic acid (111). which is now known to be 4hydroxyhydrocinnamic acid. The decomposition of phloretin (I), a polyhydroxy ketone, can be formulated:
COCH,CH~C)OH + KOH =
OOH+
HO I
I1
-
COOKCH~CH,~OH 111
phloroglucin was studied in more detail by Hlasiwetz and Pfaundler in 1861.~ 1, 1858, ~ l ~assisted i by ~ ~ Barth, ~ investi, gated beechwood creosote. hi^ is the alkali-soluble fraction(b. p. 2000 to 2200) obtained when beechwood tar is distilled, He found it to contain very con~ o he ~, siderable quantities of a compound, c ~ H ~which named creosol. ~ ~ constituent ~ which t he h found~ was guaiacol, that had long been known because Unverdorben had obtained i t in 1826 by dry distillal distilled~ tion of guaiacum resin. men~ this resin he found the distillate to containalso creosol.
-
Wnly two of his Innsbruck collaborators will be noted here. Leopold Pfaundler (1%79-1920) later turned to physical chemis try and then to physics. He became well known as an experimental physicist and taught with success at Innsbruck and Graz. Ludwig von Barth (1839-90) studied under Hlasiwetz, and eventually succeeded him at Innsbruck. He was professor of cbemistry at the University of Vienna at the time of his death. Among the coworkers at the Vienna Polytechnic was Josef Habamann (1841-1914). From 1875 to 1911 he was professor at the Polytechnic in Bn3nn. the city made famous in scientific cirdes b y Gregor Mendel.
55
~ i
Hugo Miiller (1864) showed this compound to be the methyl ether of homopyrocatechol (IV), i. e., i t is 4hydroxy-3-methoxy-l-methyl-benzene (V) : CHs
CHs
In 1859 Hlasiwetz reported on the action of potassium cyanide on picric acid. He obtained the potassium salt of an acid, which he called isopurpuric acid because of its resemblance to purpuric acid. A number of salts of the new acid were prepared and analyzed. The intense red solution of the potasslum salt is a familiar test in the detection of picric acid.6 Baeyer was working on this substance a t about this same time, hut Hlasiwetz unquestionably earned priority. Kekul6, then professor a t Ghent, discussed this matter in his letter of June 16, 18.59, to Erlenmeyer:' "Before he left, Baeyer gave me the results of his two last researches for publication in the Brussels Academy. You know: cyanic a& and the picric acid product. The very day he left we meived tlie June iswe df the Annalen. Hlasiwetz' impurpuric acid is identical with Baeyer's compound. So once again Baeyer has missed the boat. . . . The poor devil of course doesn't know i t yet." Not until 1904 did Borsche elucidate the complicated strrrdure of isopurpuric acid. The bark of the American oak, that is used for dyeing silk and wool, contains the glucoeide quercitrin. Rochleder and Hlasiwetz had studied this material in 1852. It is split into a sugar and querceth by the action of dilute mineral acids. Hlasiwetz and Pfaundler isolated the quercitrin sngar in 1863. This materid had been in the hands of various investigators, but had never before been obtained pure. They found that its empirical formula is C ~ H M O and ~ showed that isodulcite, as they called it, easily loses a molecde of water to give an anhydride, C6HI2O6. In 1887 and 1S3, Emil Fischer and Tafel, and later others, showed that isodulcite is a methyl aldopentose containing one molecule of water, namely, rhamnose, CH,(CHOH)&HO.H,O. It has now been shown that rhamnose can be isolated from quite a variety of plant juices. Hlasiwetz and Pfaundler, in 1864, showed that phloroglucin and protocatechuic acid are produced when quercetin is fused with caustic alkalies. In 1867 he and Malin found quercetin in tea leaves. The synthesis of quercetin, one of the most widely distributed vegetable dyes, was accomplished in 1904 by Kostanecki, Lampe, and Tambor. The outstanding studies of resins by Hlasiwetz and Barth were published from 1864 to 1807. They introduced in this area of research the important method 6 F ~ ~F.. o "Qualitative ~ , Analysis by Spot Tests." Elsevier
'Publishing Co., New York. 1939, p. 270. A~sc~itirz, R., "August Kekule," Verlag Chemie. Berlin, 1929, Vol. 1, p. 152.
'
of oxidative fission by fused alkali. When galbanum was subjected to this treatment, they obtained a material which these keen observers a t once recognized as quite similar to orcin. This compound bad been discovered in 1829 by Robiquet, who was investigating a lichen. Hlasiwetz and Barth stated: "We propose for the new compound that we have discovered, that can also be obtained from gum ammoniac, the name resorcin, since this indicates its production from resins and its relation to orcin." Resorcin eventualIy became of great importance in the dye industry. They found that only those resins that are formed from dried latexes, presumably with participation of atmospheric oxygen, or that are extractive in nature, are attacked by fused caustic alkali and give wellcharacterized fission products. Phlorogluciu, resorcin, protocatechnic acid, p-bydroxybenzoic acid are especially frequent products. These studies also led to observations on the preparation of artificial resins. Hlasiwetz and Grabowski found that henzaldehyde when treated with phosphorus pentoxide produces a resin, which in turn gives benzoic acid and p-hydroxybenzoic acid when fused with caustic alkali. Hlasiwetz and Barth also found that asafetida resin ~(ferularesin) contains an acid which they named fernlic acid. Many years later, it was found to be 4-hydroxyPmethoxy-cinnamic acid (VI). Caffeic acid is closely related to fernlic acid. Rochleder as early as 1847 had worked on cdetannic acid, which can be extractedfrom coffee beans. Hlasiwetz discovered c d e i c a d d when he treated caffetannic acid with caustic potash (1867). It was later shown to be 3,4-dihydroxycinnamic acid (VII).
OH
OH VI
VII
Consequently, ferulic acid is the 3-methyl ether of caffeic acid. Hlasiwetz also introduced a new method into sugar chemistry, namely, oxidation by halogens (Clz or Br2). I n 1862, he and Barth subjected lactose to the action of bromine. They obtained the hexonic acid, CsH1207, that is now known as d-galactonic acid. When he and Habermann (1870) treated sucrose, as well as glucose with chlorine, hoth these sugars yielded d-gluconic acid, CBH~~OI. The value of oxidation by means of halogens was by no means exhausted by these instances, in which it led to the discovery of these two hexonic acids that have played such prominent roles in sngar chemistry. Many years later, Emil Fischer, as well as other students of the field of polyhydroxy compounds, used this procedure advantageously hoth for preparative ends and in the solution of problems relating to the structure of these materials. (Continued on page 73)
HEINRICH HLASIWETZ (Codinwed from page 56) Hlasiwetz and Habermann studied (1871) the action of bromine on albuminous materials. In 1873 they reported their results on the hydrolysis of proteins. They used hydrochloric acid as the hydrolyzing agent, and successfully avoided the formation of dark hurnous materials by adding stannous chloride. They obtained a number of amino acids and ammonia, but no carbohydrate-like products. Special importance attaches to their proof that d-glutaminic acid, which hitherto had been obtained from vegetable proteins only, can be produced in considerable amounts also from animal albumen. Kekule reported in 1866 that benzene yields iodobenzene when heated in a sealed tube with iodine and iodic acid, which act as an oxidant. Three years later, Hlasiwetz and Weselsky reported that mercuric oxide can be used as the oxidizing agent. Thus, phenol yields mono-iodophenol and 2,-diiodophenol, and furthermore, the reaction can be accomplished in an open vessel. This Hlasiwetz-Weselsky procedure is still being used advantageously in the preparation of the most varied iodinated products. In the course of his studies of glucosides, Hlasiwetz studied arbutin, a glucoside found in the bearbeny. He and Habermann found (1875) that dilute acids hydrolyze arbutin and yield glucose, hydroquinone, and a new compound, C,H802, that was found to be the mono methyl ether of hydroquinone. This interesting result was beautifully substantiated when i t was found that this ether could be produced by the action of potassium methyl sulfate on hydroquinone. (The dimethyl ether was formed concurrently.) Later workers showed that arbutin occurs in the plant along with methylarbutin, and consequently the material used by Hlasiwetz and Habermann must also have contained methylarbutin.
Genuine sorrow, in all quarters, was occasioned by the unexpected and untimely death of Hlasiwetz in October, 1875. His teacher and friend, Rochleder, had passed on the previous year. At the 1875 general assembly of the German Chemical Society, the President, A. W. Hofmann, stated that the forthcoming issue of the Berichte would contain an obituary of Rochleder composed by Hlasiwetz, and that the members would read this biographical sketch with particular emotion because i t was his sad duty to inform them that the hand that had penned this tribute was now cold in death. The Rector of the Vienna Polytechnikum in his inaugural address a t the opening of the new session on October 11, 1875, announced the heavy loss that the school had suffered. Only the day before, Professor Hlasiwetz had been borne to his last resting place; a man possessing the noblest human qualities, distinguished equally as investigator and teacher. Hlasiwetz had dealt chiefly with natural materials or products derived from them: glucosides, vegetable dyes, resins, sugars, proteins, tanning agents, their hydrolysis and degradation products. The originality of the methods and the brilliant experimental technique characterize his approach and handling of the chosen problems. Seventy years have passed since his death. It is a great satisfaction to note that the splendid progress of structural chemistry and synthesis have brought the answers to most of the problems he left open, and for whose solution his times were not yet prepared. A. W. Hofmann wrote: "We will not tire of peering into the mirror of the past, or we shall lose the image of the men on whose shoulders we stand, those who because of their love of science have wrought so much that is excellent and laudable in all branches of chemistry and physics."
