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Staudinger, Hermann

STAUDINGER, HERMANN

(b. Worms, Germany, 23 March 1881; d. Freiburg im Breisgau, Germany, 8 September 1965), organic and macromolecular chemistry.

Staudinger studied at the Gymnasium in Worms. Then, after a brief period at the University of Halle, he transferred to the technical university at Darmstadt when his father, the neo-Kantian philosopher Franz Staudinger, was appointed to a teaching post in that town. Although Staudinger wished to study botany, his parents were advised to give him first a thorough training in chemistry to prepare him for a career in botany. This excellent advice was followed; and from Darmstadt, Staudinger went on to study in Munich and Halle. His dissertation, on the malonic esters of unsaturated compounds, was written under D. Vorländer and was completed in 1903. But it was in Strasbourg, under Johannes Thiele, that Staudinger made his first and unexpected discovery–the highly reactive ketenes. These formed the subject of his Habilitation in 1907, the year in which he was appointed associate professor at the Technische Hochschule in Karlsruhe.

Five years later Staudinger succeeded willstätter at the great Eidgenössische Technische Hochschule of Zurich, where he remained until his call to Freiburg im Breisgau in 1926. Three years after his retirement from the Freiburg chair he was awarded the Nobel Prize in chemistry. It was fitting, although unintentional, that this recognition of his wok on macromolecular chemistry should have come in 1953, at a time when the molecular biology that he had glimpsed more than two decades before was taking shape. Staudinger married the Latvian plant physiologist Magda Woit in 1927.

In Karlshruhe, Staudinger achieved a new and simple synthesis of isoprene, from which polyisoprene (synthetic rubber) had previously been formed; and with C. L. Lautenschläger, he synthesized polyoxymethylenes. These discoveries later served him in his studies of polymer chemistry in Zurich and Freiburg im Breisgau. Staudinger’s friends urged him to avoid so difficult a field as the chemistry of polymers, but he was not to be dissuaded. He realized that with polyisoprene he could devise a crucial experiment by which he might be able to confirm either the aggregate or long-chain-molecule theory of the structure of polymers. After synthetic rubber he turned to polyoxymethylene, which he saw as a model for the natural polymer cellulose.

In 1920 Staudinger first expressed his preference for the long-chain-molecule conception of polymers. Six years later he predicted the important role that such macromolecular compounds would be found to play in living organisms, especially in proteins. When he met his future wife, Staudinger’s attention was drawn to the role of macromolecules in structural substances like the plant cell-wall constituent, cellulose. Henceforth he sought to introduce the macromolecular concept into biological chemistry.

In the 1920’s there existed two conceptions of polymer structure. According to Samuel Pickles and K. Freudenberg, these substances consisted of long-chain molecules held together by “primary” or “Kekulé” bonds; but C. Harries and R. Pummerer believed the real molecules in polymers to be small. These and other authorities held that a polymer is formed by the binding action of the residual forces of unsaturated compounds. These “secondary” valency forces were responsible for the apparent nonstoichiometry and strange physical properties–the nonlinear relation between viscosity and concentration, the tendency to form colloidal solutions, and the failure to yield crystals. Supporters of this aggregate hypothesis argued that the true molecules of a substance like rubber were small and that in the free state they did obey the laws of physical chemistry; in particular, they could be crystallized. Destroy their aggregation and the molecules would be freed. Only thus could the organic chemist be confident that he had a pure compound.

Harries suggested that the secondary forces that held the butadiene molecules together in natural rubber owed their presence to the unsaturated state of these molecules. He stated that hydrogenation of rubber should yield a product with a low boiling point since it would involve saturation of the forces of affinity within the molecules, and this process would destroy the secondary or residual forces between them. In 1922 Staudinger and J. Fritschi produced hydrorubber. Its properties differed little from natural rubber; in particular, it could not be distilled and, like rubber, it gave a colloidal solution. In their paper of that year they used the term “macro-molecular association” for the first time. Two years later Staudinger defined the macromolecule: “For such colloidal particles in which the molecule is identical with the primary particles, in other words, where the single atoms of the colloidal molecule are bound together by normal valency activities, we suggest the term Makromolekül.1 He went on to point out that, since these colloidal particles are the true molecules, no attempts to produce typical, low-molecular solutions with other solvents would succeed.

In the 1920’s Staudinger extended these studies to polystyrene and polyoxymethylene, showing that a whole range of products can be produced that, like the members of a homologous series, show a serial order in the viscosity of their solutions. This work was described on three important occasions–in 1924 at the Innsbruck meeting of the Deutsche Naturgorscher und Aerzte, in 1925 at a meeting of the Zurich Chemical Society, and in 1926 at the Düsseldorf, Staudinger encountered vigorous opposition from the exponents of the aggregate theory. Viscosity measurements, it was argued, did not give direct evidence of molecular weights but, rather, reflected the state of colloidal aggregates in solution. No reliable data on such compounds would be forthcoming until genuine solutions and crystals had been formed. Moreover, the unit cells derived from fiber diagrams of these polymers were far too small to accommodate a macromolecule; and the mineralogist Paul Niggli assured Staudinger that molecules larger than the unit cell did not exist.

It was at this juncture that Theodor Svedberg and Robin Fåhraeus made their first successful measurements of the equilibrium sedimentation of oxy- and carbonylhemoglobin in the ultracentrifuge. The result indicated a molecular weight between 3.73 and 4.25 times the minimum value of 16,700 obtained from elementary analysis.2 This work laid the basis for the recognition of high-molecular compounds in protein chemistry. Meanwhile, Staudinger battled on against the upholders of the aggregate and micellar theories for synthetic polymers, cellulose, and rubber.

So long as there existed no theoretical relationship between molecular weight and viscosity for nonspherical particles (exhibiting non-Newtonian flow), Staudinger’s viscosimetric data were thought to be unsatisfactory as evidence for the existence of macromolecules. But in 1929–1930 R. Nodzu and E. Ochiai, working under Staudinger, showed that for low molecular compounds with linear-shaped molecules the viscosity of their solutions is proportional to the number of residues in the chain.

Staudinger hoped to achieve independent evidence for the macromolecular structure of synthetic and natural polymers by installing an ultracentrifuge in Freiburg, but in 1929 the Notgemeinschaft der Deutsche Wissenschaft refused him the necessary funds. In desperation he returned to viscosimetry and succeeded in deriving a relationship known as the Staudinger law, between specific viscosity ηsp and molecular weight, where ηsp represents the increase in viscosity of a solvent caused by the addition of solute. The solvent constant Km in the equation was evaluated by using solutes of unknown molecualr weight and was then used for polymers of unknown molecular weight. He took the precaution of extrapolating to infinite dilution.

Here was a simple and quick method for obtaining molecular weights, which, unlike the ultracentrifuge, did not require costly and elaborate apparatus. Although further objections were voiced against it, viscosimetry–as based on Staudinger’s law–was widely used in industry wherever polymer research was in progress.

To establish the conception of long–chain molecules by independent lines of evidence, Staudinger asked R. Singer to examine the shape of macro-molecules in solution. Singer accomplished this task by using the technique of flow birefringence. He devised a simple apparatus for the rapid measurement of the approximate length:breadth ratio of long-chain molecules.

Meanwhile, Staudinger’s conception of macromolecules received further support: X-ray crystallographers realized that the symmetry of crystals could be achieved on the basis of rope–like bundles of chains that stretched in the direction of the fiber axis far beyond a single–unit cell, even beyond a crystallite. Furthermore, in America, W. H. Carothers was achieving polymerization by a condensation reaction in which the eliminated water could be measured and the number of residues in the product estimated.

As early as 1926, Staudinger had appreciated the importance of macromolecular compounds in living organisms. He had seen how the traditional methods of isolation and identification of organic compounds inhibited the study of these sensitive and awkward compounds. Consequently, chemists were only “standing on the threshold of the chemistry of organic compounds.”3 Life processes, he argued, were bound up with high polymers in the shape of proteins and enzymes. In a lecture delivered in Munich in 1936 he returned to this theme. “Every gene macromolecule,” he declared, “possesses a quite definite structural plan, which determines its function in life.”4 Such giant protein molecules had innumerable possible structures which chemical techniques were then too crude to reveal.

In 1947, in his book Makromolekulare Chemie und Biologie, Staudinger again visualized the molecular biology of the future. He reported the first attempts by Linderstrøm-Lang to arrive at amino acid sequences. This was the kind of problem that Staudinger wished to tackle in his later days, but he found no methods suited to the task. In this book Staudinger computed the molecular weight of a bacterium, from which we may conclude that he did allow his enthusiasm for macromolecules to carry him too far. Long before this time C. F. Robinow had demonstrated an organization in bacteria, including a nuclear structure revealed by differential staining.5 Such an organism could hardly represent a single macromolecule.

Although Staudinger surely comprehended the conception of chemical individuality, it is understandable that he lacked any appreciation of the nature of information transfer from nucleic acids to proteins or, indeed, of the storage of such information in the nucleic acids rather than in the proteins. Nonetheless, his pioneer work in macromolecular chemistry constituted a major foundation for the molecular biology that was to be built upon it. The debates that took place between Staudinger and the champions of the aggregate theory furnished an interesting conflict of paradigms that only the further development of several sciences could resolve. As a result Staudinger achieved recognition for his work belatedly, receiving the Nobel Prize at the age of seventy–three.

Staudinger tried to produce visual evidence of the existence and form of macromolecules. The ultraviolet phase-contrast microscope and the electron microscope were used to this end in Freiburg. Magda Staudinger began such work in 1937. She and G. A. Kausche described spherical molecules of glycogen two years later. In 1942 Staudinger’s colleagues E. Husemann and H. Ruska obtained electron micrographs of glycogen particles with a diameter of 10mμ. From the osmotic pressure of the corresponding glycogen in solution, they concluded that these were the molecules of glycogen with a molecular weight of one and a half million. This is work was brought to an abrupt end when the greater part of the chemistry institute was destroyed during the bombing of Freiburg in 1944. By the time normal working conditions were restored, Staudinger’s vigorous powers had been spent; but it was due to him that in 1947 a new journal, Makromolekulare Chemie, was published by the firm of Karl Alber in Freiburg; the earlier Journal für makromolekulare Chemie appeared only from 1943 to 1945. Both journals were edited by Staudinger. On his retirement in 1951, Staudinger’s department became the State Research Institute for Macromolecular Chemistry; five years later an associate professorship in macromolecular chemistry was established for the director of this institute.

NOTES

1. H. Staudinger, “Ueber die Konstitution des Kautschuks,” in Berichte der Deutschen chemischen Gesellschaft, 57 (1924), 1206.

2. T. Svedberg and R. Fåhraeus, “A New Method for the Determination of the Molecular Weight of the Proteins,” in Journal of the American Chemical Society, 48 (1926), 430–438.

3. H. Staudinger, “Die Chemie der hochmolekularen organischen Stoffe im Sinne der Kekuléschen Strukturlehre,” in Berichte der Deutschen chemischen Gesellschaft, 59 (1926), 3019–3043.

4. H. Staudinger, “Ueber die makromolekulare Chemie,” in Angewandte Chemie, 49 (1936), 801.

5. C. F. Robinow, “A Study of the Nuclear Apparatus of Bacteria,” in Proceedings of the Royal Society, 130 B (1942), 299.

BIBLIOGRAPHY

For a comprehensive bibliography of 644 works of Staudinger, see H. Staudinger, Arbeitserinnerungen (Heidelberg, 1961), trans. as From Organic Chemistry to Macromolecules (New York, 1970).

Staudinger’s work on macromolecular chemistry is discussed in several papers: J. T. Edsal, “Proteins as Macromolecules: An Essay on the Development of the Macromolecule Concept and Some of Its Vicissitudes,” in Archives of Biochemistry and Biophysics, supp. 1, pp. 12–20; H. Mark, “Polymers–Past, Present and Future,” in an unpublished symposium of the Welch Foundation on polymer science (1965); and R. C. Olby, “The Macromolecule Concept and the Origins of Molecular Biology,” in Journal of Chemical Education, 47 (1970), 168–174; and The Path to the Double Helix, chs. 1, 2 (London, 1974).

Robert Olby

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Staudinger, Hermann

Staudinger, Hermann


GERMAN CHEMIST
18811965

Hermann Staudinger was one of the most influential organic chemists of the twentieth century. His wide-ranging research interests included the investigation of many kinds of molecules, ranging from small organic compounds to large polymers. He is generally considered to be the father of macromolecular (polymer) chemistry and won the 1953 Nobel Prize in chemistry for his discoveries in that field.

Staudinger was born in Worms, Germany, on March 23, 1881. He at first planned to study botany at the University of Halle, but he subsequently followed his father's advice and switched to chemistry. After graduating from

Halle with a degree in chemistry in 1903, Staudinger moved to the University of Strasbourg and became an academic lecturer there in 1907. Subsequent academic appointments took him to Karlsruhe, Zurich, and, finally, Freiburg.

Although Staudinger's work on ketenes, diazo compounds, oxalyl chloride, and pentavalent phosphorus compounds is still relevant, he is more recognized for his seminal contributions to macromolecular chemistry. Staudinger started working on macromolecules in the early 1920s. Following his move to Freiburg in 1926, he discontinued his investigations of small organic compounds and concentrated exclusively on the chemistry of what he believed were high molecular weight compounds.

It was a risky career move for Staudinger, and one that put him at odds with many of the leading organic chemists of the time. He proposed (without much proof to back up his proposal) that macromolecules were long-chain molecules of identical or nearly identical units that were linked by covalent bonds . Today it is known that many of Staudinger's ideas were essentially correct, but in the 1920s most chemists disagreed with him. They viewed macromolecules as colloidal aggregates of small molecules and did not believe that covalent bonding was involved.

Staudinger's colleague, Dr. Heinrich Wieland, told him to drop his idea of large molecule organic compounds and assured him that a sample of purified rubber would be shown eventually to be composed of low molecular weight compounds. During a lecture in Zurich in 1925, Staudinger was verbally attacked for advocating the idea of covalent bonding in macromolecules.

Despite the attacks, Staudinger was determined to convince his detractors that his ideas on the structures of macromolecules were sound. To prove his point he carried out a series of experiments designed to yield more understanding of the chemical and physical properties of polymers. He began with natural rubber. He and J. Fritschi hydrogenated the double bonds present in natural rubber polymer molecules in an autoclave and found that the isolated product had properties similar to those of the starting rubber. From this Staudinger concluded that natural rubber was not a colloidal substance, but a long-chain macromolecular substance.

He gathered more evidence by synthesizing polymers from formaldehyde and from styrene. The homologous formaldehyde-derived polymers spanned the molecular size range, from small molecules to large macro-molecules. From the results Staudinger concluded that polymers were molecules whose repeating units were linked by covalent bonds, and that they had characteristic functional groups at their ends. The polystyrene polymers were prepared under varying reaction conditions and had a range of molecular weights and physical properties. These data were also consistent with covalent bonding, but not with colloidal association.

Staudinger's ideas were gaining popularity, but it was a 1928 paper by Herman Mark and Kurt Meyer that finally convinced chemists that Staudinger had been right. Mark and Meyer used x-ray crystallography to probe the structure of a crystallized polymer and found that polymers were indeed long-chain molecules in which repeating units were linked by covalent bonds.

Staudinger spent the next twenty or so years building up macromolecular chemistry and helping to lay the foundation for today's multibillion-dollar polymer industry. He retired in 1951 and received the 1953 Nobel Prize in chemistry for his work on polymers. He died on September 8, 1965.

see also Polymers, Natural; Polymers, Synthetic.

Thomas M. Zydowsky

Bibliography

James, Laylin K., ed. (1993). Nobel Laureates in Chemistry 19011992. Washington, DC: American Chemical Society; Chemical Heritage Foundation.

Internet Resources

"Science Explains Polymers." National Academy of Sciences. Available from <http://www.beyonddiscovery.org>.

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Zydowsky, Thomas M.. "Staudinger, Hermann." Chemistry: Foundations and Applications. 2004. Encyclopedia.com. 27 Sep. 2016 <http://www.encyclopedia.com>.

Zydowsky, Thomas M.. "Staudinger, Hermann." Chemistry: Foundations and Applications. 2004. Encyclopedia.com. (September 27, 2016). http://www.encyclopedia.com/doc/1G2-3400900479.html

Zydowsky, Thomas M.. "Staudinger, Hermann." Chemistry: Foundations and Applications. 2004. Retrieved September 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3400900479.html

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