ALEXANDER MIKHAILOVICH BUTLEROV HENRY M. LEICESTER ~ o l < e of p Physicians and Surgeons, San Francisco, California
A
MONG the leaders of chemistry in the midnineteenth century was Alexander Butlerov, who contributed much of both theoretical and experimental nature to the fundamentals of organic chemistry. However, his important work has been largely forgotten, and, although he ranks with Kolbe and Kekule as one of the founders of structural theory. even his name is unfamiliar to most modem chemists. In order to understand Butlerov and his achievements, it is necessary to know something of the conditions under which he lived and worked. In about the year 1840, the center of chemical research in Russia was to be found a t the small provincial University of Kazan, founded only thiity-six years before, in the east central part of the country. That this was true was due to the presence of two men on the faculty, Karl Karlovich Klaus and Nikolal Nikolaevich Zinin. Klaus, the professor of chemistry, was both a botanist and a chemist, but he was chiefly known for his work on the platinum metals and for the discovery of ruthenium.' He was an ardent follower of Berzelius and held to the latter's dualistic theory long after i t had been abandoned by almost the entire chemical world. Klaus was a tireless and enthusiastic worker, but his outlook was somewhat limited. He was practically self-educated and though he visited many parts of Russia in the course of his botanical researches, he did not travel abroad until nearly the end of his life. Zinin, the professor of technolob, was avery different type of man, and a far broader one. He had begun his career as a mathematician, but he was soon attracted to organic chemistry, and he devoted his life to this subject. He travelled extensively in westem Europe and worked for some time in the laboratory of Liebig, where he absorbed to the full the spirit of research. His most famous work,= published in 1843, was the discovery of the reduction of aromatic nitro compounds to amines, which led to the first synthesis of aniline and naphthylamine. His broad experience and active scientific work kept Zinin abreast of the latest developments in chemistry and, as a result, he did not always see eye to eye with the more conservative Klaus.
In spite of the excellent work of these two men, and of the high reputation which they held, the physical equipment of the Kazan laboratory was very poor. Before Klaus came to the university there was no
laboratory at all. He converted as much room as possible into working space, but even in 1857, when V, v ~ ~ ~ was ka student ~ at~ Kazan, ~ condii tiom were far from satisfactory. Markovnikov described the laboratory as consisting of one room con. taining Dutch tile a large stove, a sand bath, and several sorts of furnaces. Behind a low parti203
'According to Markovnikov (6), Klaus had the habit of stirring the solutions of the platinum metals in aqua regia with his fingers and determining the strength of the remaining acid by taste. A sketch of his life is given by Weeks (8). Of this work, Hofmann later said. "If Zinin had done nothing more than to convert nitrobenzene into aniline, even then his name should be inscribed in golden letters in the history of chemistry" (5).
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tion the old laboratory servant washed the apparatus. No gas was available. All the lecture experiments were prepared in the room, which was so crowded that the students carrying on research were forced to work in the embrasures of the windows. In addition to these physical difficulties, the intellectual atmosphere was not of the best. The Russians of this period lived more or less apart from the currents
he was only eleven days old, he spent his early years in the home of his maternal grandfather. He received most of his lower education in the Kazan Gymnasium, and proceeded directly from that institution to the University of Kazan. He was interested in the natural sciences, and enrolled in this division of the university, but almost from the first he devoted himself largely to chemistry. I n this way he came almost a t once under the influence of Klaus. Zinin was not directly connected with the purely chemical courses, but a student with the great interest and activity which Butlerov displayed could not long remain unaware of the excellent work which was going on in Zinin's laboratory. Klaus and Zinin, in their turn, were attracted by the brilliancy of the young student. Butlerov began to work with Klaus on the preparation of antimony, but Zinin's activities soon drew his interest. He himself later said, "A sixteen-year-old student, a novice, I was naturally attracted by the external side of chemistry, and I was especially interested in the beautiful red plates of azobenzene, the yellow needles of azoxybenzene, and the glittering scales of benzidine. Zinin returned my interest and quickly acquainted me with the progress of his work and the different beuzoins and naphthalene compounds with which he afterwards worked. Little by little I began to work by preference under the guidance of Zinin, which was not limited to his own studies. He also felt an interest in the repetition of outside experiments. Although he entrusted these to his students, he himself also carried out most of them. Thus, along with him, we performed a, niimber of known experiments, prep&ng uric acid and indigo, undertaking the dry distillation of dragon's blood, and obtaining malic, gallic, formic, oxalic, and other acids. From these different experiments his students obtained almost automatically an acquaintance with the different branches of organic chemistry, and this acquaintance came of itself and was clothed, so to speak, in flesh and blood because the substances from the various branches of nature passed before our eyes, and one could not be lazy when one worked along with the professor" (3). .. Butlerov was soon inspired by this work to independent studies. He goes on to say, "How active an of scientific thought which were arousing the rest of interest in facts was thus aroused is clear from this, Europe. A man like Zinin was the exception; for that, not satisfied with experiments a t the university, most Russians the situation was that described by I made preparations at home. Solemnly I would bring Markovnikov when he said, "Between Russia and to the laboratory the objects which I had prepared a t Europe there existed a strong, high wall, and only a few home, caffeine, isatin, alloxanthine, and others. I fresucceeded in breaking through it. We remained as if quently drew on myself the reproaches of those who in quarantine, strongly protected from the infecting lived in the house with me, since the nitric or sulfuric vapors drifting through the place did not please those breath of Europe" (6). Such were the conditions and the atmosphere into who were not accustomed to a laboratory atmosphere" which, in 1844, came the young student, -~lexander (3). The activity and the stimulation which he found in Mikhailovich Butlerov. He was born on August 25, 1828 in the small town of Chistopol, not far from these surroundings undoubtedly gave Butlerov a firm Kazan. His father was a retired lieutenant-colonel. and lasting foundation in the field of o r ~ a n i cchemistry. a landlord of the district. As his mother died when and one which underlay his later work. ~
ow ever,
unfortunately for him, in 1847 Zinin was called to the Medico-Surgical Institute in St. Petersburg, and Butlerov was left entirely under the guidance of Klaus. As a result, he was cut off from the new developments which were then occurring so rapidly in the west. For the next ten years he was left in an atmosphere of scientific conservatism, a backwater of progress. In 1849 Butlerov completed his work for the Candidate's degree with a thesis on the buttedies of the Ural-Volga region. The young man's abilities had so strongly impressed the Kazan faculty that they wished to keep him in the university. The only position available a t the time was that of lecturer in physics and physical geography, and to this Butlerov was accordingly appointed. At the same time he was working on his Master's degree. He completed his thesis in 1851, a t which time he received the degree. This thesis was entitled "The Oxidation of Organic Compounds," and was a critical review and coordination of all the available literature on the subject. In his conclusion, Butlerov wrote the following prophetic words, "When we look back, we cannot avoid astonishment a t the great steps made by organic chemistry in the short period of its existence. Its future, however, appears to be incomparably greater, and the time will finally come when the products of organic changes will be studied not only qualitatively, but quantitati.i.ely, and, little by little, we will expose and determine the true and exact laws of its compounds and understand their natural place in the chemical system. Then, chemists, knowing the properties and general conditions for the preparation of any compound, will be able to determine not only its composition, but also its other properties. This time can and must come for our science, and then, along with the work already available, what a field it will be for enthusiastic development" (9). At the time Butlerov received his Master's degree, he was ao~ointedadiunct in chemistrv to assist Klaus. Shortly iiterwards, 'in 1852, appeared his first published chemical paper, which concerned the action of osmic acid on a rather heterogeneous assortment of organic compounds. The results were not very conclusive, but they showed that the research instinct was awake in him. In 1852 Klaus was called to Dorpat, and Butlerov was left to carry on much of the chemical work. At the same time he was engaged in research for his doctoral dissertation, which he completed in 1853. This thesis concerned the ethereal oil of a Russian plant and the isolation from it of a camphor-like substance. The thesis was approved by the professors of chemistry and mineralogy, but Savel'ev, the professor of physics, did not consider it satisfactory for the Doctor's degree. The Senate of Kazan University wished, therefore, to submit the thesis to some other university for a final decision, but there was no method by which this could properly be done. The matter was finally settled by permitting Butlerov to submit his dissertation to the
University of Moscow, where it was approved. He was granted the degree of Doctor of Chemistry and Physics by that university in 1854. Following the receipt of his degree, Butlerov made a short trip to St. Petersburg, where he visited Zinin, who was actively continuing his researches and had attracted an enthusiastic group about him. This visit was an important step in arousing Butlerov from the sleepy and conservative atmosphere which prevailed in Kazan. Zinin had become an ardent convert to the unitary theory of Gerhardt and Laurent. He was the first Russian chemist to appreciate the significance of their work, arid he explained it in detail to Butlerov,
presenting him also with copies of the "M6thode de Chimie" and the "Trait6 de Chimie Organique." Bntlerov was excited by these works, and the shackling influence of Klaus began to fall away. Not for three more years, however, was he to become entirely free from the older ideas. Butlerov now returned to Kazan as extraordinary professor of chemistry. For the next few years he devoted himself to a series of tentative and rather inconclusive researches. He studied reactions between weak mercuric chloride solutions and lime water, the action of phosphorus triiodide on mannitol, and the
(Councsy of E d w r Pohs Smirk M m m i o l Colkclion, Univnsily of Pennryloonin)
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behavior of turpentine under various conditions. During this time he also published several papers of a horticultural and zoological nature. In 1858 he was raised to the rank of ordinary professor. At this time he had the reputation of being one of the best professors in the university. Markovnikov, who entered Kazan in 1857, was led to study chemistry by the reputation of Butlerov. He described his in-
structor as follows, "Besides the internal content of Bufferov's lectures and his ability of expression, he fully had the appearance of a professor. Before us stood a young and lively lecturer with manners as animated and polished as his words. That natural reserve which we noticed in him in the auditorium vanished entirely when he was in the laboratory. Here he was not only a good and kind teacher, always ready to Iisten to a
question and give an answer to each of his students, but he was also a comrade to each of the workers. He not only listened to and told anecdotes, but his sincere and ringing laugh usually included all those around him. When we worked in the laboratory, we felt it a home, perfectly free. However, this did not prevent each from doing his work properly" (6). Nevertheless, Butlerov himself realized to the full the results of his ten years of scientific isolation. In his own words, he "remained no more than a good student, possessing a rather full collection of facts, but still completely limited in scientific outlook and in critical reaction to affairs." The time had now come when he was able to take the step which turned him, as he said, "from a student to a scholar" (3). In June, 1857, Butlerov set out on a trip through western Europe which lasted until August, 1858. He had a perfect command of French and German, and had long been developing his abilities upon the fundamental training which he had received from Zinin. Thus, he was perhaps better equipped to take advantage of the new ideas which he encountered than those who lived where these were developing, and in whom familiarity bred indifference. Butlerov went &st to Berlin and the laboratory of Mitscberlich. Here, for the first time in his experience, he saw the use of gas in a chemical laboratory. All the experiments a t Kazan had been carried out with the aid of spirit lamps or coal furnaces, and the difficulties of running an organic analysis under these conditions were formidable. During the rest of his journey, Butlerov was constantly on the watch for novelties and improvements which he could take back to Kazan with him. From Berlin be travelled through Germany, visiting most of the chemical centers. He spent some time in Heidelberg, where Kekuld was a privat dozent. Kekuld was on the point of publishing his famous paper on "The Chemical Nature of Carbon" (April, 1858), in which the idea of valence was fir$ expressed, and Butlerov was greatly interested and impressed by this theory. The friendship which then began between the two men had a great influence on the later work of Butlerov. After leaving Heidelberg, Butlerov travelled through Switzerland and Italy, and in December, 1857, he reached Paris, where he remained until May, 1858, with the exception of a ten-day visit to London to see the laboratories of Hofmann and Wiiiamson. At this time, Paris was full of outstanding chemists, not the least of whom was Adolph Wurtz a t the Ecole de M&icine. Butlerov worked in his laboratory during most of his stay in Paris. He studied the preparation of methylene iodide from sodium ethylate and iodine, and its reaction with silver acetate to form the acetate of methylene glycol. This was the first connected and successful piece of work in the chemical field which Butlerov had camed out, and his enthusiasm was greatly aroused by it. While in Paris, Butlerov met Durn&, ~erthelot;St. Claire Deville, Balard, and Chev-
reul. He also attended the meetings of a group of young and active chemists which later developed into the French Chemical Society. When he had completed his work in Paris, Butlerov returned to Heidelberg, where he attended the lectures of Bunsen and Kekul6. The latter interested him, as he said, "by the clearness and precision of presentation, and by the originality and novelty of some of the ideas introduced by the lecturer in the theoretical part of organic chemistry" (9). Following this visit, Butlerov continued his trip throngh Germany, and a t Munich he inspected the gas plant which Pettenkoffer had installed there. In July he returned to St. Petersburg, and then a t last to Kazan. Here hc immediately began to introduce the imnrovements he had observed abroad. 1Ie installed a small plant to manufacture gas, and, for reasons of economy of space, he located the storage tank under the floor of the laboratory. This made the work of the students much easier, but gave a t least some of them the feeling that they were working above the crater of a volcano. In his theoretical ideas a t this time Butlerov was a supporter of the unitary and type theories of Gerhardt and Laurent, but he was familiar with the work of both Kekul6 and Couper, which had appeared a t about the same time, and he recognized the need for modifying the current theories as new facts appeared. Thus, a t the end of 1858, he said, "Although type formulas can explain only double decompositions, and not the internal construction of a substance, yet it does not follow from this that the constitution can never be known, and I think even Gerhardt himself;althougb he shows the impossibility .of explaining the molecular structure by the present formulas, does not think the resolution of this structure will forever remain impossible. New discoveries will permit us to go farther in our theoretical Experimental study will give us the ideas. . . . basis for chemical theory for' . ~ molecular e forces which we call chemical af6nity. However, since afEmity serves as a reason not only for chemical changes, but also for determining the grouping of elementary atoms in complex molecules, then this affinity should be studied not only a t the time of molecular movement, but also in a state of equilibrium" (6). Here we see that Butlerov was already well on the way to an expression of the structural theory. With his theoretical ideas already so firmly based, Butlerov began the activity in the laboratory which lasted the rest of his life. Naturally enough, he began his work by continuing the studies on which he had been busy in Paris. His attempts to isolate methylene glycol itself failed, but he showed the impossibility of the existence of free methylene, and the formation of higher hydrocarbons where i t might have been expected to occur. In the course of this work he obtained the polymer of formaldehyde which he called dioxymethylene. His study of the reaction of this compound with ammonia led to the first isolation of hexamethylene tetramine. He also treated the polymer with-lime
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water and obtained a sugar-like substance, the first example of the synthesis of a carbohydrate from relatively simple substances. In 1861, Butlerov again travelled in western Europe, visiting a number of German and French laboratories and renewing his acquaintance with Keknl6, who was now a t Ghent. He then attended a scientific congress a t Speyer. Here he was struck by the lack of agreement among the various scientists present on any uniform theory to explain the facts of organic chemistry. However, for the three preceding years, he had been developing his own ideas during the lectures a t Kazan. He was convinced that there was an underlying basis for all the apparently contradictory theories of the German chemists, and he felt that this basis was to be found in the actual constitution of the compounds themselves. The results of his thinking were embodied in a paper which he read to the congress. It was entitled "The Chemical Structure of Compounds." This was the first use in organic chemistry of the term "chemical structure," and so it is to Butlerov that we owe this expressive phrase (1). In this paper he showed the difficulties which arose from the application of the unitary theory alone and advocated a partial return to the older electrochemical ideas. The truth lay somewhere between the ideas of Gerhardt and Laurent and those of Berzelius. In this point of view it is possible to recognize the result of his early training under both Klaus and Zinin. He expressed his ideas clearly when he said, "A new opinion usually widens what went before; it is to be preferred because it considers the facts from a new angle and shows those analogies which had previously remained unnoticed, but this does not exclude the correctness of the older ideas when they have gone to the limit of the facts which lay before them. Unfortunately, this is often forgotten by the proponents of a new theory or belief" (6). This paper was the first clear and outspoken statement of the new structural theory and the ideas expressed in it required practically no revision later. 0' When Butlerov returned to Kazan, he made a report to the University Senate in which he summed up his experiences and gave a remarkably keen and penetrating analysis of the character and work of the leading European chemists whom he had met on his travels. Indicating the state of his own ideas, he wrote in this report, "None of the ideas which I found in western Europe seemed especially new to me. Laying aside here misplaced false modesty, I can say that these ideas and conclnsions have been quite familiar in recent years in the Kazan laboratory, and they have not been considered especially original. They were developed in the general course of the work and were introduced in part into the lectures" (7). Shortly before his second western journey, Butlerov had been appointed Rector of Kazan University, but he did not want a position which interfered with his chemical activities, and he therefore asked to be relieved of these duties. However, the University Senate, convinced of his ability, elected him Rector ggain in 1862.
He served for only five months, and in April, 1863, he again resigned the position and devoted himself to the research which was already producing important results. Nevertheless, he continued to have great influence in the university, and his advice and experience were frequently sought. After he had left Kazan, it was a common remark among the faculty when trouble arose, "If Butlerov had been here, this would not have happened." His first publications after his return to Kazan were of a theoretical nature. He pointed out that the apparently conflicting theories of Kekul6 and Kolbe had in reality much in common, and he went on in several papers to develop and popularize the structural theory. Very soon he began to support his theoretical ideas by a series of brilliant laboratory studies. In 1864 he published the results of a study of the action of zinc dimethyl on phosgene and described the mixture of alcohols which was obtained. He then studied the reaction in which acetyl chloride replaced phosgene and obtained a new alcohol which he showed to be tert.-butyl alcohol. This was the first representative of the class of tertiary alcohols to be prepared. Kolbe had predicted that such compounds should exist, but it remained for Butlerov to discover them and explain them in far simpler terms than had Kolbe. Butlerov continued to work on the tertiary alcohols for some time, improving the methods of preparation, studying their oxidation, and isolating many derivatives. In the course of this work he discovered the isomeric butanes and hutenes. While he was carrying out these major investigations, Butlerov also conducted a number of less spectacular, but by no means unimportant studies. During this .period Butlerov also wrote his "Introduction to the Full Study of Organic Chemistry" which first appeared in its Russian edition in 1864. This was one of the first texts to be based entirely on the structural theory, for even Kekule's textbook had been based on the ideas of Gerhardt and so was not a strictly modern text. Butlerov's book appeared in its German translation in 1867, and Markovnikov, who was then studying with Kolbe, tells of the great impression which it made. KekulC's benzene theory appeared shortly before the German edition of Butlerov's hook, and some questio~sof priority arose. The situation was summed up by Markovnikov as follows, "Kekul6, and especially Couper, actually gave the first explanation of the atomicity of carbon and its accumulation in complex compounds, but this was still far from the theory which related not only t o carbon compounds, but to all chemical substances in general, and we actually saw that Kekul6 himself gave only second-rate value to his original communication. The services of Butlerov are that he gave full value to this hypothesis and developed it into the whole structural system" (6). In Aumst. - . 1867. Butlerov made a third t r i ~abroad which lasted until june, 1868. While on this'jonrney, he received word that he had been appointed ordinary professor of chemistry a t the ~ n i v e r %of~ St. peters-
burg. His selection for this important position was largely due to Mendeleeff, who had been greatly impressed by his work on chemical structure. Butlerov returned first to Kazan and settled his affairs there. When he left, he was elected an honorary member of the University of Kazan. He gave his first lecture a t St. Petersburg on January 23, 1869. His abilities were quickly recognized, and he soon attained the front rank in the scientific circles of the capital, where he remained until his death. He became the acknowledged leader of a school of chemists from which came almost all of the chief Russian organic chemists of the next generation (4). In this connection he impressed all his associates by his kindliness, sincerity, perseverance, and open frankness. He was a member, and for a time, president, of the St. Petersburg Academy of Sciences, and he was elected an honorary member of the Russian and most of the foreign chemical societies. In 1876 he was one of the group of distinguished chemists chosen for honorary membership in the newly formed American Chemical Society, and the letter in which he accepted this distinction is still extant. His outside interests were many and varied. He was much interested in the education of women, and for many years lectured for them in the higher chemical courses. He was an enthusiastic beekeeper, and became one of the leading Russian apiarists. In the later years of his life he became greatly interested in spiritualism, and a firm believer in it. On this ground he was the subject of rather widespread ridicule in Russia, but he did not permit this to sway him from his belief. During the first few years after his arrival in St. Petersburg, Butlerov continued the work he had been carrvinp on a t Kazan. In 1872 be turned to a new --~---field, the synthesis and properties of trimethyl acetic acid, which he prepared by treating tert.-butyl iodide with mercurous cyanide and hydrolyzing the tertiary nitrile thus formed. These studies led him to investigate the structure of pinacolone, which he correctly in2---0
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terpreted. At the same time he continued his studies on unsaturated hydrocarbons and on the synthetic possibilities of the zinc alkyls. In 1876 Butlerov presented a paper a t Warsaw on diisobutylenes. This was published in the next year, and besides its excellent study of the reactions and polymerization mechanisms, it is noteworthy in that it contains the first clear statement of the theory of tautomerism (2). From tert.-butyl alcohol, Butlerov obtained by the action of sulfuric acid two isomeric diisobutylenes. He explained their formation by assuming an equilibrium between the two hydrocarbons, water, and the corresponding alcohols. He then went on to discuss the possible existence of an equilibrium between isomers, even in the absence of any reagent. He stated his idea thus, "In this case, in every study of the chemical structure of a substance, the molecule will always behave in two or more isomeric forms. I t is clear that the chemical reactions of such a substance must occur in accordance with sometimes one, sometimes the other structure, depending on the reagent and on the experimental conditions." As a possible example, he suggested hydrocyanic acid. This work did not receive the consideration it deserved a t the time, and it was not until the work of Laar in 1885 that the fact of tautomerism was generally recognized. During the next few years, Butlerov continued his studies on isobutylene and began work on several naturally occurring compounds. At the same time, he began to consider the possibility that the molecular weight of a compound might not be constant. He spent his last years attempting-to prove this, although he did not pblish any espeGmental work on the subject. In the spring of 1886, Butlerov's health began to fail. Although he was not considered seriously ill, he discontinued his work for the time and withdrew he died suddenly from the city. On August 5; 1886, ' at the early age of fifty-eight.
BIBLIOGRAPHY
Ktkt&." \'rrbg Chernie, C . M . B. H., krlin. 1929. Vol I, p. 217. ('2) . and Son. Ltd . . B A K E R .'Tautom~"sm." C ~ O Routlnlge London, 1934, pp. 1 4 . (3) Banoo~NAND B~TLEROV, "Nikolai Nikolaevich Zinin," 3. Russ. Phys. Chen. Soc., 12, 215-52 (1880); Ber., 14, 2087 (I)
.\NSCII~TZ, August
.
(1881).
(4) Gusr~vso~, "A. M. Butlerov as the leader of a schaol." ihid., 19, Butlerov Memorial Number, 58-68 (1887). (5) HOFMANN, Ber., 13, 449 (1880).
(C,)
hl~rr~ovsr~ov. "Kwollertions and traits from
(8)
WEEKS, "The discovery of the elements," 2nd ed., Mack
rhe life and acrinrirr of .4. \ I Ilutlerov." J Kssr P h y s C h m S,c.. 19, 13urlerov hlemorial Sumhw,(i9-96 (1837). (7) MENSHUTKIN. ''Recollections of A. M. Butlerov," ibid., 19,
2-12 (1887).
Printing Co., Easton, Pa., 1934, pp. 110-15. (9) Z A ~ E V "A. , M. Butlerov." J. Rurr. Phyr. Chem. Soc., 19, Butlerov Memorial Number. 13-57 (1887).
