HLASIWETZ AND BARTH-PIONEERS IN THE STRUCTURAL ASPECTS OF PLANT PRODUCTS VIRGINIA F. McCONNELL Newcomb College, Tulane University, New Orleans, Louisiana
Tm
contributions of Hlasiwetz and Barth to our knowledge of the chemistry of plant substances were in a sense the result of the activities of Justus Liebig. Although investigation into the nature of plant extracts had been carried on with great interest since the beginning of the nineteenth century, especially by the French chemists, i t was Liebig's interest in agricultural chemistry and his discoveries in the laboratory he had established a t Giessen in 18'24 which stimulated admiration in Austria. Students from Austria went to Giessen for study, and among these were Redtenbacher and Rochleder who in turn trained Hlasiwetz. It is interesting t o note that although Hlasiwetz did not study at Giessen, he nevertheless continued certain phases of chemistry that were systematically investigated by Liebig-glycosides and proteins. Barth studied under Liebig for a year at Munich. Moreover both Hlasiwetz and his student Barth followed the example set by Liebig, that of keeping up with advances in chemistry in all the great laboratories of Europe, and as early as 1861 both accepted the new atomic weights advocated by resolution at the Congress of Karlsruhe in 1860. The laboratory methods of these men pioneered in the exact analysis of plant extracts and of the compounds obtained from them. These investigations procured for their authors the name of clear, original thinkers and exact workers. HLASIWETZ
This the elder Hlasiwetz finally did with the stipulation that his son should first finish his study of pharmacy. We find him, therefore, from 1843 to 1846 as practicing apothecary in Briinn, Vienna, and Reichenberg. This done he devoted himself entirely to his professional studies under Redenbacher in Prague, where in 1848 he was awarded a diploma as master pharmacist. During these years he also carried on his scientific studies and on April 16, 1849, he was graduated as Doctor of Chemistry. Throughout his whole career he maintained his interest in music. As a young doctor, Hlasivetz' closest friend was Friedrich Rochleder, to whom he was assistant and who was Redtenbacher's successor a t Prague. Rochleder's chief interest was the study of the nature of plant substances, hut he was also inherested in theoretical speculation, publishing in 1853-54 articles on the radical theory.' Hlasimetz' first research was a study of asafetida oil, in which he set forth the formula. of this well-knoxvn substance, described its platinum and mercury compounds and investigated the action of chlorine, of hydrochloric acid, and of potash on During the next few years he worked with Rochleder on plant products, their characteristics, stability t o oxidation, and reaction t o acids and alkalies,3 as well as doing some independent work on a ~ e t o n e . ~ INNSBRUCK
In 1851 he was called to Innshruck as Professor Heinrich (Hermanm Christian) Hlasiwetz, eminent Extraordinary for the newly established Chair of Chemteacher and one of the most important Austrian chem- istry. Here he first exhibited his talent for organizaists of his time, was born on April 7, 1825, a t Reichen- tion, for no laboratory, no library, and no students berg in Northern Bohemia, the son of the town apoth- mere there when he arrived. In a remarkably short ecary. I n 1835 he went to the gymnasium at Prague time he built up an institution highly esteemed locally and while there, because of his outstanding talent, was and in foreign countries; the number of his students also a student a t the music school of Procksh. Four increased so that he required assistants, and a governyears later he returned home and worked with his fa- ment grant was made for the laboratory. Two years ther as an apprentice. During this time he acquired later he was appointed Ordinarius. An excellent practical chemical, botanical, and mineralogical knowl- teacher, he instructed his students a t their work edge. In 1842 he entered the University at Jena, tables, spurred them to activity, and discussed their attending the Pharmaceutical Institute with the idea problems with them so that they could work with underof taking charge of his father's pharmacy. Among his standing and independence. He was strict and conteachers were Dobereiner, Wackenroder, and Schleiden. scientious in his requirements, demanding full devotion The latter, an enthusiastic teacher, almost persuaded to the matter in hand; thus he gathered a group like Hlasiwetz to follow a career in botany, but his prefer' V . A d . , XI (1853); XI1 (1854). Ann., 87,196 (1853). ence for organic chemistry conquered. In 1843 he reAnn., 71,23 (1840). turned to Reichenberg in order t o persuade his father Ibid., 76,338 (1850); 82,197 (1851). to agree to his decision. to pursue a scientific career. Ibid., 76, 294 (1850).
AUGUST. 1953
h i in zeal, earnestness, and knowledge. Among these were Buckeisen, von Gim, Nachbar, Barth, Pfaundler, Mossmer, Graf Grabowski, Remhold, and Malin. Hlasiwetz remained at Innshrnck 16 years, during which time he traveled widely on the continent and to England, Scotland, Sweden, and Norway, where he studied the various establishments, collections, institutions of learning, and industrial plants. These years were fruitful in puhlications and discoveries of new organic compounds obtained from plant leaves, bark, roots, or resins by potash fusion. By this means he decomposed phloretin (dihydronaringenin, p-HOCs H4(CI-12)2COC&2(011)31,2,4,6) obtained from the glucoside phloridzin, and found two new substances, phloretinic acid5(p-hydroxycoumaric,p-HOCsHa(CHn)r COOH) and phloroglucino16 (1,3,5-trihydroxybenzene). This method was also applied to the glycosides ononin,l quinovin: quercitrin,g and carminic acid." He discovered that quercitrin was similar to rutin, found earlier in capers, and that quercetin and a sugar were obtained from it upon hydrolysis." With Pfaundler he isolated the sugar, found its formula to be CsHlo05 HZO and called it i~odulcit.'~It is a methyl pentose now known as rhamnose, and quercetin is knowu to he 3,5,7,3',4'-pentabydroxy flavone. He showed that quercetin was decomposed into protoeatechuic acid (3,4-dihydroxybenzoic) and phloroglucinol when heated with potassium hydroxide, but, that under certain circumstances intermediates conld be isolated. Two of these were quercetin acid, related to ellagic acid (later studied by Barth) and p-carthamin ((OH)p-CsHCOCH=CHC6H40H). He mentioned further that the irregular values found by analysis of different preparations of quercitrin justified the hypothesis that there were various quercitrins containing more or less sugar units or different sugar-like substances attached by ether linkages. This deduction proved correct: quercitrin is quercetin-3-rhamnoside; rntin is quercetin-3-rhamno-glucoside; and quercimeritrin is quercetin-7-glucoside. Later investigation of these compounds is due to Kostenekila and Robinson14 who worked out a large number of useful syntheses by which the flavones can be obtained relatively easily, and t o A. G. Perkin.15 The structure of quercitrin was worked out in 1936 during a study of diuretic drngs.I'' Since 1936 most of the work on these compounds has been done by members of the Indian Chemical Society and the Indian Academy of Science.
RESINS
Almost at the same time as his work on glycosides, Hlasiwetz began the investigation of resins. In the distillation products of guaiacum resin he detected guaiacol (o-methoxyphenol) and its homologue creosole" (3,1,4CH30CsHs(CH3)0H). Guaiacol had been
+
6
Ann., 96, 118 (1855); 102, 145 (1857).
Ibid., 112, 180 (1859); 119, 199 (1861). 7 J . Pmkt. Chem., 65, 419 (1856). 0
8
Ann., 111, 182 (1859).
* Ibzd.,
'0
"
96, 123 (1855); 122, 96 (1859). Ibid., 141, 329 (1867). J. Prakt. Chern., 67.97 (1856); Ann., 96,l
l4
Ann., 127, 362 (1863). Be?., 37,784, 1402,2819 (1904). J . Chern. Sac., 125,2192 (1924).
1s
Iba.,85,1459 (1904);
IP
105,2350 (1914).
'OJ. Pkarrn. Soc.. Japan. 56, 68 (1936);
ohtained in 1826 by the dry distillation of guaiacum by Unverdorben. With the help of Barth, his assistant, he studied a series of gums aud resins by means of the follo\\.ing procedure: The crude substance vas purified by treatment with alcohol or alkali to separate it from mechanical impurities. It was then melted with ahout three times its amount of potash until the usual strong. froth slackened; the mixture was acidified, filtered, and extracted with ether. The ethereal solntion vas dried by evaporation and the various components separated by crystallisatinn, etc. The resins explorcd were: guaiacum,18 gum benzoin, drachenblut. aloes.'g asafetida, aamboee,w acaroid resin.
382
JOURNAL OF CHEMICAL EDUCATION
sagepenum, o p ~ p a n a x and , ~ ~ g a l h a n ~ m . ~The ~ vari- it with moderately strong potassium hydroxide, and ~ Malin he studied ous decomposition products obtained were acetic acid, showed it to he a g l y c o ~ i d e . ~With benzoic acid, p-hydroxybenzoic acid, pyrotartaric the constitution of teaa1and found in it tannic, gallic acid (methyl succinic), protocatechuic acid, catechol, (3,4,5-trihydroxybenzoic), and oxalic acids. Upon phloroglucinol, orcinol (5-methyl resorcinol), resorcinol, boiling with dilute sulfuric acid, the tannic acid, a and homophthalic acid. They succeeded in isolating glucoside, was hydrolyzed into quercetin and glucose. for the first time p-coumaric acidz3(p-hydroxy-cinnamic, He regarded the tannic acids as intermediates in the p-HOCsH4CH=CHCOOH) from aloes and ferulic formation of complex glycosides. Tannic acids are acid (3,4,1-methoxy-hydroxy-cinnamic) from asafetida, are now known to be polymeric glycoside derivatives both of which are intermediates, as the former of gallic acid containing a number of acidic groups, may he broken down into acetic acid and p-hydroxy- some bound as antimony1groups. These investigations benzoic and the latter into acetic acid and protocate- led him to classify glycosides according to their decomposition ~roducts,as follows: chuic acid. Homophthalic acid (0-carboxy-phenyl acetic) was (1) True glucosides which yield glucose and an aromatic obtained by Hlasiwetz and Barth from gamboge, and compound. named isuvitic acid because of its similarity to uvitic (2) Phloroglucides which yield phloroglucinol and a sugar (ploretin, quercetin, catechin). acid (5-methyl-isophthalic). It received its present (3) Phloroglucosides which yield a phloroglucide and a sugar name from J. SchrederZ4who showed that it is iden(auercitrin vields aueroetin and 8-rhamnase). .. tical with the phenyl-aceto-carhoxy acid obtained by (4) Gummides which yield a sugar and a gum (csrminic acid). Wilicenus from potassium cyanide and ~ h t h a l i d e . ~ ~ (5) Mannides which yield mannitol (caffetannie acid and quinovin). Resorcinol (mdi-hydroxybenzene) obtained from (6) Nitrogen-bearing glucosides. galbanum was the subject of much research. I t was recognized as an isomer of catechol (discovered in At that time the term glucoside wasused to designate 1839 by Reinach) and hydroquinone (discovered 1844 compounds composed of a sugar and a hydroxy comby Wohler) and a homologue of orcinol, and its use as pound (or other residue containing an active hydrogen). a dye intermediate and in medicinals soon followed. It is still loosely used in this sense, although glycosides It was later obtained by the dry distillation of umbel- are now classified as to the kind of sugar they contain liferone2e (p-hydroxy-coumarin) which comes from the and the term glucoside should be reserved for glucoseresins of a number of umbelliferae. bearing compounds. The glycosides are analogous to Hlasiwetz and Barth carried out experiments on the acetals and like them are stable toward alkaline synthetic resin b~ilding.~'A resin was produced by hydrolysis but are hydrolyzed easily in acid media. the reaction of phosphoric acid on benzaldehyde that Potash fusion results in a more complete breakdovn was very like natural gum benzoin. At another time than does simple hydrolysis. they obtained resinous substances with properties l i e that of natural turpentine resin. Like theseit was IN VIENNA with difficulty attacked by caustic alkali. The years 1860-65, in which Hlasiwetz was most active in the laboratory, also were the years of his greatTANNINS est musical activity. He composed an opera, various Researches on glycosides, resins, and related com- songs, and sonatas, some of which enjoyed the approval pounds led Hlasiwetz to the so-called tannic acids of skilled professionals and critics. He also played the (tannins). The latter substances have since been divided piano with considerable virtuosity. His creative power into twogroups by Freudenberg? (1)the hydrolyzable must have been at its height in this period and, as altype (such as the tea tannnis) which are glycosides or ready pointed out he was thoroughly alive to the changes depside esters of sugars and (2) condensed tannins in in chemistry which followed the Conference of Karlswhich the nuclei are held together by carbon linkages mhe which he undersigned and attended.3z Austria (such as the catechins and kinotannic acid). Consti- began to pay him honor in 1861 when he mas named a tutionally the latter have been proved by Russell to corresponding member by the Vienna Academy of resemble anthocyanins" and flavone derivatives, with Science, and two years later a full member. I n 1864 he which Hlasiwetz was familiar. He began with a study was honored by the University by being chosen Rector, of caffetannic acid, obtained a new acid, caffeic acid and in 1865 His Majesty bestowed on him, in recogni(3,4dihydroxycinnamic), and a sugar, upon boiling tion of his work in science and teaching, the order of Franz Josef. Five years later he mas elected to the Ann., 139, 77 (1866). Vienna Society of Chemistry and Physics and the 19 Zbid., 130, 354 (1864). Imperial Bavarian Academy of Science. '3 Zbid, 136, 31 (1865). 24 Monatsh. Chem., 6, 168 (1885). A new chair of chemical technology was established 16Ber., 18, 172 (1885). at the Vienna Polytechnic, and on June 5, 1867, a Ann., 139, 99 (1866); Ber., 4, 550 (1871).
.
7
Zbid., 139, 83 (1866).
F ~ E ~ E N B EK.. R G"Chemie . der natiirlichen Gerbstoffe." 2nd ed., Berlin, 1932. ' U J . Chem. Soe., 139, 218 (1934); 142, 421 (1937).
a Ann., 142, 219 (1867).
J . Prakl. Chem., 101, 109 (1867),
" J. CHEM.E ~ a c .28,421 , (1951).
AUGUST, 1953
Hlasiwetz was named professor of this department. During the holidays, in order to prepare for his new teaching activity, he made trips to various factories, smelting works and mines. At the end of Augnst he went t o the salt mines near Hall in the Tyrol. Through an accident he lost his footing by the entrance to a deep shaft and suffered a broken leg in the fall. Not entirely recovered, he left on the 19th of October for his new post. One year passed before his lahoratory was organized and research could begin again. He had hardly begun work on the behavior of turpentine oil on heatinga3when Schrotter was called to he Master of the Mint and Hlasiwetz was named his successor (January 25, 1869) as Professor of Chemistry, at the same institution. He remained in this position until his death although other opportunities were offered him, such as one in 1870 from the University of Vienna and also a request to become Liebig's successor a t Munich. Here he again succeeded in training a succession of skillful workers such as Weselsky, his later successor, Sommaruga, Habermann, Kachler, Weidel, J. Schreder, and Benedict. In 1871 he begau work on potassium hexacarbonyl. Through a fearful explosion he mas badly burned on his face and hands, and many weeks elapsed before he could take up his work again. In this same year he was chosen t o the Board of Directors of the Vienna Musical Society, and Rector of the Polytechnic. In the latter capacity he took a prominent part in the preparation of w w regulations for this institution. He was active on behalf of the German Chemical Society on the statute revision commission, having already (1870) functioned as a member of the foreign committee. He mas named Councillor (Hofrath) in the Government Teaching Ministry and was entrusted with conducting the Department of Technical Universities, commercial schools, nautical and other technical institutions. In March, 1875, he became acquainted with a highly educated young woman, Marie Freiin von Ankershofen, who shared his love of music. They were married in July and he took her on a wedding trip to Italy and Switzerland. On the evening of the seventh of October he went mith his wife to visit a group of close friends. The next morning as he was leaving his house t o go to the laboratory a cardiac paralysis brought his life to a sudden end. PROTEINS
The most important work of this later epoch was unquestionably that with Habermann on splitting proteins.a4 They chose as reagents bromine and water, followed by silver oxide. They found a parallel between this degradation and the decomposition of the carbohydrates. They found further that all proteins gave the same decomposition products qualitatively but that the relative amounts varied. I n a second work, they attempted t o find the primary decompo3a
J . P d l . Chem., 103, 316 (1868).
"'Am, 159, 304 (1871).
383
sition products of proteins and chose hydrochloric acid in the presence of stannous chloride on casehas They obtained aspartic acid, glutamic acid, leucine, tyrosine, and ammonia, hut no carbohydrates as end products. They concluded that carbohydrates are not concerned in the constitution of proteins and stated, "The differences in the properties of the various proteins lies in the different ratios of the primary groups constituting them."36 Hlasiwetz wrote the following articles: "On photography," "On the chemistry of earthenware," "On mortar and cement," and "On the composition of animal fluids." He also wrote a book, "Instruction in Qualitative Chemical Analysis" with Weselsky, proof of his command of many subjects. BARTH
Ludwig Barth von Barthenau was horn on the 17th of January, 1839, in Roveredo in the Tyrol (near the Italian border of Austria), the son of the chief civil officer of the district, Franz von Barth. Here he lived until his father was transferred in swift succession to Schwas, Imst, and Bregenz. In 1850 his father was sent to Innsbruck and he went to the gymnasium there after a year with a private tutor. He was the youngest as well as the largest boy in his class. (Indeed, as professor a t Innsbruck one of his first regulations was to have straightened the heavy iron lever which he had bent as a boy.) His progress was excellent, and in July, 1856, he passed the entrance examinations for the university and without hesitation entered on the study of chemistry. His incomparable teacher, Hlasiwetz, he had known earlier. In the laboratory his activity was characterized by skill, zeal, and industry, and in the year 1858 he published a note on camphol acid.37 He was a gymnast, swimmer, rider, dancer, and fencer, but his preference lay in hunting and long walks. He was great in body and soul and kindliness was one of his outstanding characteristics. In the year 1859 he was among the first to apply for service in a volunteer academic rifle company. In the following semester we find him in Munich attracted there by Liehig and Pettenkofer. At the same time he enlisted in the Corps Franconia. In the summer semester of 1860 he returned to Innsbruck and when only 21 years of age he was awarded the Ph.D. degree. In another two years he was Privatdocent. At this time he worked on poisonous compounds, the picrotoxins, work which he resumed 20 years later mith Michael Kretschy." In 1864 he was appointed assistant to Hlasiwetz. In the summer of 1866we find him again on the southern border of the Tyrol, this time as Lieutenant of a voluntary defense company. Soon after the campaign, Barth was named Ordinarius for general chemistry at the University of Innsbruck as successor to Hlasiwetz (August 4, 1867). During the Easter holi"Ann., 169, 150 (1873). a Ber., 9, 1982 (1876). * Ann., 107,249 (1858). Monalsh. Chem., 2,796 (1881); 5,65 (1884)
384
JOURNAL OF CHEMICAL EDUCATION
it prepared a new isomer of pn,tocatechoic a~,id(which he called u-rrsonyl acid) and isophrhulir acid, verifying its stmcture.46 Thus by making one of these compounds from another he arrived a t a clear idea of their relationships, their constitution, and the positions of the substituent groups. From the fusion of phenol and potash, Barth obtained a new class of componnds, the d i p h e n o l ~ ~ ((C&OH)s). He was also interested in condensation products. From dihydroxyhenzoic acid in the presence of sulfuric acid he obtained tetrahydroxyanthraqninone,4' which he called anthrachryson, and from w h y droxy benzoic acid, anthraflavone" (diiydroxyanthraquinone) an isomer of alizarin, both of which are similar t o rufigallic acid (1,2,3,5,6,7-hexahydroxyanthraquinone), and neither of which gives phthalic acid upon oxidation. It isnow wellknown that hydroxybenzoic acids in which the hydroxyl group is meta to the carhoxyl group form on heating the corresponding hydroxyanthraquinones. IN VIENNA
The years 1875-76 brought important changes for Rnrth. Throunh the sudden death of Hlasiwetz and retirement of von Schneider from the University, two important positions were vacant in Vienna and Barth was sent for. While in Vienna considering this prohlem, he was informed of his wife's illness. She died before he could reach Innsbmck and, with mixed feelings, he accepted the appointment as Professor of Chemistry at the University of Vienna on August 9, 1876. days of 1869 he married Maria Kammerlander. They With characteristic energy he undertook a thorough were a very devoted couple hut had no children. Dur- change in the organization of his department. A ing the next eight years Barth did extensive research on number of students were attracted to work under him hydroxy aromatic acids. I n the "History of t y r o ~ i n e " ~and ~ from the time of Barth's appointment until his he showed the falsity of the prevalent view that tyro- death, not less than 170 papers were produced. With sine was a derivative of salicylic acid, since he had ob- Goldschmidt he began the study of ellagic acid40 (a tained p-hydroxybenzoic acid as a result of potash dilactone of hexahydroxydiphenyl-2,2'-dicarboxylic fusion. He studied the constitution of tyrosine and acid), a constituent of many tannins, and noted its relaproposed its correct formula." He studied proto- tion to gallic and mfigallic acids. It is now synthesized catechnic acid,41 in detail, noting its basicity, its iso- by regulated oxidation of gallic acid with arsenic acid. mers, its similarity t o benzoic, p-hydroxy benzoic, and I n the fall of 1875 he took up with Schreder the difgallic acids, and its synthesis from m-hydroxy benzoic ference in the reaction of potassium and sodium hydroxacid, which he had previously inve~tigated.4~Proto- ide on aromatic componnds. Three years before, they catechnic acid had been obtained by Hlasiwetz from had noted that the course of reaction of benzoic acid the potash fusion of guaiaretic acid from g u a i a ~ u m ~was ~ d i e r e n t when sodium hydroxide was substituted resin (the method now used). Barth noted that from for potassium hydr0xide.6~ A continuation of the bromoprotocatechuic acid a substance resembling gallic work showed that sodium hydroxide promoted loss of acid mas obtained. Gallic acid, used in inks and dye- carbon dioxide by acids,s1 and that the sodium hystuffs, is now made by fusion of the two isomeric di- droxide fusion of phenol produced very little diphenol hydroxybenzoic acids with alkali. He converted o- but that phloroglucinol was produced in fair yield. This and p-toluenesulfonic acids and p-cresolsulfonic acid was the first synthesis of phloroglucinol. Using beninto the corresponding hydroxy acids, thus elucidating zene trisulfonic acid, they replaced the three sulfonic their s t r u c t ~ r e . ~ This ' led to a study of cresols. He acid groups with hydroxyl groups and again synthemade disulfonicbenzoic acid for the first time and from * Ibid., 154,356 (1870); 159,217 (1871).
-
-
JB
Ann., 136, 110 (1865).
* Ibid., 42
Ibid., Ibid., Ibid., Ibid.,
152, 96 (1869). 142,246 (1867); 159,230 (1871). 148, 30 (1868). 119, 266 (1861). 152,91 (18fi9); 174,235 (1874).
45 4'
Ibid., 156,93 (1870); J. Pmkt. Chem., 19.22 (1879). Ibib.. 164. 109 (1872). -.
50
"
.
.
~ n n : , l & ,138 (162). ' Be?., 12,1255 (1879); M m t s h . Chem., 3,799 (1882).
AUGUST, 1953
sized phloroglucinol." With von Schmidt he subjected dihydroxybenzene monosulfonic acid to potash fusion and obtained protocatechuic acid, thus replacing a sulfonic acid group by a carboxyl group for the first They later discovered that sodium hydroxide and hydroquinone gave hydroxyhydroquinone, the third trihvdroxy benzene, and very little pyrogallol and phlor~gluc&o~.54 STRUCTURE OF BENZENE
385
and preparation of an author and subject index, had a prominent part in the writing of a new edition of the Austrian Pharmacopeia, and was a member of the highest Sanitary Council of the Reich. Both he and Hlasiwetz published their work in the Journal of the Vienna Academy of Science and gave papers before this body. During the last few years of his life he suffered from a severe heart ailment and only his will power enabled him to follow his career. On August 3, 1890, he died.
In 1879, Max Gmber, then Barth's assistant, found that, by the reaction of nitric acid on protocatechuic CONCLUSION acid, a new acid was formed which gave up carbon diHlasiwetz and Barth are representative of that great oxide easily, yielding tartronic acid (hydroxymalonic group of scientists who laid the groundwork for others. CHOH(COOH)3. He and Barth believed this acid They discovered and identified many important comto be tribasic and called it carboxytartronic, H-&Cpounds, and while reaching no brilliant theoretical con(COOH)s. Barth thought it improbable that the car- clusions themselves, their meticulous, intelligent invesboxy group had heen cleaved in the process and there- tigations of plant pigments, roots, barks, and the subfore that the acid must have come from the benzene stances obtained therefrom, gave an insight into the nucleus." This meant that in the benzene nucleus structure of these compounds which could be made use one carbon atom was hound to three others. Conse- of by later workers. It is of interest to note that many quently, from chemical evidence they came to the same classes of compounds investigated by Hlasiwetz were conclusion as Julius T h o m ~ e nhad ~ ~ by thermochem- later taken up by Emil Fischer. The lives of Hlasiical research, namely that KekulB's ring formula for wetz and Barth were as well-ordered as their work and benzene must be abandoned and replaced by the prism it is evident that the high regard in which they were formula of Ladenburg or another of similar linkage. held by their colleagues, and the number of students Keknl6 answered by upholding his ideas and later inspired by them, were the result of the example they proved that the formula for the new acid must be set, as well as-or even more than-the ideas they proHOOC(C(OH)2)zCOOH (2,3-tetrahydroxytar- pounded. Today, as always, chemistry needs men of taric), as it could he prepared from tartaric acid, and their caliber--accurate, reliable workers with a deeptherefore that the carbon atoms had normal l i n k a ~ e . ~ 'seated interest in the laboratorv. It should be noted that these two formulas differ by H20, Barth's formula being C A O 7 and KelculB's ACKNOWLEDGMENT ClH6O8. At this time the Kekul6 stmcture of benzene study of the lives and work of these important was a matter of/ great argument. Many organic ohem- chemists of the middle nineteenth century was underists advocated the prism formula and Beilstein in the talrerl at the suggestion of D ~clara . de ~ i l t . first edition of his handbook [page 1, Vol. I1 (1888)l mentions three equally probable structures of benzene. LITERATURE In the year 1879 Barth was elected a of the LADENRURG, A,, Life of Hlasiwetz in "Allgemeine Deutsche Vienna Academy of Science, having been since 1876 a Biographie," Leipzig, 1880, Vol. 12, p. 513. corres~ondine member. He assisted the editor of H~aslwrTz,H. IT., "Necrology of Rochleder," Ber., 8 [I], 1702 (1875). ~onaisheftefiirChemie in the organization of material "Ber., 12,417, 503 (1879). Ibid., 12, 1260 (1879). s4 Monatsh. Chem., 4,176 (1883); 5,589 (1884). s5 Ibid., 1, 869 (1880). Ann., 205,133 (1880); Ber., 13,1808 (1880).
mIbid., 221, 230 (1883).
BARTH, I,., "Necrology of Hlasiwetz,"ibid., 9 [2], 1961 (1876). SENHOIEB AND GOLDSCAMIDT, "Necrology of Barth," ibid., 24 [3], 1089 (1891).
GIULEBE, CARL,"Geschichte der organischen Chemie," SpringerVerlag, Berlin, 1920, Vol. I. WALDEN,PAUL, "Geschichte' der organischen Chemie eeit 1880," Springer-Verlag, Berlin, 1941, Vol. 11 (of Gmebe).
