Ernst Beckmann, 1853-1923 RALPH E. OESPER University of Cincinnati, Cincinnati, Ohio
B
ECKMANN" as applied to a thermometer or to the rearrangement of an oxime is a household word in many laboratories. Nonetheless, few chemists know anything about the life of the gifted man whose name is so glibly used. To him we also owe the sodium press; an excellent atomizer for producing colored flames; the chromic acid mixture for the stepwise oxidation of hydroxylated compounds; reliable methods of determining molecular weights by means of boiling and freezing points. His papers numbered 170; no less than 130 doctorate dissertations came from his laboratory. He was one of the outstanding teachers of his time, and his administrative abilities led to his appointment as the first director of the great Kaiser Wilhelm Institut fiir Chemie a t Berlin-Dahlem. Emst Otto Beckmann was born on July 4, 1853, at Solingen, a city long famous for its cutlery and other steel wares. His father, a progressive manufacturer of dyes, pigments, and emery powder, was constantly experimenting in the hope of improving his methods and discovering new profitable products. The boy was thus brought up in a chemical environment and early decided to fit himself for a career in industrial chemistry. However, his elders thought pharmacy offered more financial security and a t 17 Ernst was apprenticed to an apothecary. Rolling pills, rubbingup ointments, and the similar tasks that filled the day, could not satisfy his longing to do something more scientific. He returned home, but his plea to be released was met by the taunt that his urge for chemical things certainly could not amount to much if even the post of apprentice apothecary was beyond his powers of endurance. "I'll show you that I can do it"; and he went back to his master and finished his term. Feeling his weakness in chemical theory, he enrolled (1874) a t the Fresenius school in Wiesbaden and soon was promoted to the post of assistant. After a year he entered the University of Leipsic to complete his pharmaceutical studies. Here he came in contact with Hermann Kolbe, whose invention of the salicylic acid synthesis had aroused the interest of the pharmaceutical world. Kolhe was then a t the height of his powers, and his personality and sympathetic helpfulness were dominant factors in strengthening Beckmann's resolve to become a scientific chemist. The state examination in pharmacy was passed in 1877 "with distinction." Throughout his life Beckmann kept in close touch with pharmacy; he appreciated that it gave him a wider view of chemistry, and he also knew that his pharmaceutical studies had been an excellent preparation for his chemical career. However, he did not practice his profession, hut instead "
prepared himself to become a teacher of chemistry. Under the guidance of Kolbe and Ernst von Meyer he received his Ph.D. in 1878. The dissertation was a study of the oxidation products of di-alkyl sulfides. His method of using permanganate with these evilsmelling compounds later became technically important in the preparation of the widely adopted soporifics, sulfonal and trional. After completing his required military service, Beckmann in 1879 took an assistantship a t the Technical University a t Brunswick. He was assigned to the analytical division. His habilitation essay, "Aluminates and basic halides of barium,'' and his probationary lecture on "Ethereal oils" gained him the right to give independent courses in chemistry and pharmacy. The four years a t Brunswick were primarily a period of ripening. Prepared for better things, he returned to his alma mater. However, his docentship was not valid in the University of Leipsic, .and he was obliged to meet the local requirements. These included a certification of maturity from a humanistic gymnasium. Undaunted, Beckmann, 30 years old and an experienced instructor, took a seat in a secondary school and applied himself to the intricacies of Latin and Greek. Wishing to obtain the necessary quiet and solitude without stealing time from his chemistry, he took his hooks a t dawn and at dusk into the remoter parts of a park, reading with the aid of a bull's-eye lantern when necessary. The result was almost inevitable; the police took this suspicious character into custody. A permanent, and less humorous reminder of this bdated schooling, pursued in unconventional surroundings, was a severe neuralgic affliction that plagued him even in his last years. His diligence and matured mental abilities made it possible for him to secure the necessary certificate in about six months. Kolbe died suddenly in 1884; his successor, Wislicenus took over about a year later. By this time Beckmann had qualified as docent1 and he was offering a course in toxicology. The new chief, who had been bitterly attacked by Kolhe, was expected to make a clean sweep of the ancia regime2 but he was so impressed by Beckmann that he urged him t'o stay on as his assistant. Kolhe and Wislicenus differed radically in their views on organic chemistry. Beckmann with his characteristically open mind was, of course, eager to learn the newer concepts that now prevailed. Frankly and without embarrassment he took a seat among the students, many of whom he was instructing,
~I a
The probationary lecture was on "Ptomaines." See OEspen, THISJOURNAL, 21,107 (1944).
because Wislicenus had given him supervision of the organic l a b o r a t ~ r y . ~ Beckmann's previous interests were now joined with the organic field. Well acquainted with the essential oil industry, he began to study the constituents of peppermint and camphor oils. The oximes of menthone proved particularly interesting. Under the guidance of Wislicenus he investigated the spatial arrangements of these compounds. This study led to the discovery of the reaction which, a t Victor Meyer's recommendation, has ever since been known as the Beckmann rearrangement. I t was first observed in 1886, when he found that benzophenone oxime is converted to benzanilide when treated with pbosphorus pentachloride followed by alcohol and alkali:
This striking migration of the radical from carbon to nitrogen created a justified stir; Beckmann's name was on the lips of most of the organic chemists. From then on, he intermittently published accounts of various phases of this reaction that has contributed so much to the elucidation of the stereochemical relationships of carbon-nitrogen compounds. Another remarkable development grew out of this notable discovery. In 1887 Beckmann found that cold sulfuric acid converted benzaldoxime into a new material of the same empirical composition. Though the product was later proved to be a stereo-isomer, at the time i t seemed likely that it was a polymer. Conszquently, it was imperative to determine the molecular weights of the two oximes. This brought Beckmann face to face with a situation that had balked organic and physical chemists. In short, there was no satisfactory means of determining, with any degree of exactness, the molecular weights of the constantly lengthening list of organic compounds. The Victor Meyer vapor density method obviously was limited, in its application to organic compounds, to the relatively few materials that could be vaporized without decomposition. Molecular weight measurements based on osmotic phenomena foundered on the complications of the procedure. The use of effects based on Raault's Law offered more promise, but Raoult's apparatus, despite modifications by Victor Meyer, Auwers, and Ostwald, remained impractical for general laboratory use. In an astonishingly short time Beckmann succeeded in improving Raoult's primitive apparatus enough so that fairly accurate results obtained by the cryoscopic method were published in 1888. The chair of physical chemistry at Leipsic was, a t that time, the only professorship of its kind in the world. Wiedemann, the incumbent since 1871, wished to return to his real field, physics. Lothar Meyer and Landolt refused tlfe post, and likewise, after long M a n y found \Visliccnas cold and uoapproaehablc but his friendship with Beckmann grew stradily. Hc invited him, his junior by I R y a r s , to adrln..;
