NATTA, GIULIO

(b. Porto Maurizio ‘now Imperia’, Italy, 26 February 1903; d. Milan, Italy, 2 May 1979)

chemistry.

Natta was the son of Francesco Natta, a judge, and of Elena Crespi Natta. The traditional profession in the Natta family was that of law, but after completing secondary school at the age of sixteen, Natta enrolled in the two-year engineering preparatory course at the University of Genoa, and in 1921 he entered the Milan Polytechnic Institute, from which he graduated with a degree in chemical engineering in 1924. As a student he worked in the first Italian center for X-ray crystallography, directed by Giuseppe Bruni and Giorgio Renato Levi.

Natta became libero docénte at twenty-four. He taught analytical chemistry from 1925 until 1933 at the Milan Polytechnic and physical chemistry from 1931 until 1933 at Milan University. In 1932 he went to Freiburg, where he studied the techniques of electron interference in the laboratory of the physicist H. Seemann. At Freiburg he also became acquainted with Hermann Staudinger and his important work on macromolecules. In 1933 Natta was appointed to the chair of general chemistry at the University of Pavia; in the academic years 1935–1936 and 1936–1937 he was professor of physical chemistry at Rome University; in the years 1937 to 1938 and 1938 to 1939 he worked at the Turin Polytechnic Institute as professor of industrial chemistry. In 1939 he returned to Milan Polytechnic, where he was professor of industrial chemistry until his retirement in 1973.

In 1935 Natta married Rosita Beati; they had two sons. His wife died in 1968. Natta was a nature lover, fond of outdoor activites; in his youth he was a mountain climber. During long walks he collected fossils and mushrooms. These activities ceased with the onset of Parkinson’s disease in 1959.

Natta was elected a member of the Accademia dei Lincei in 1955 and belonged to many Italian and foreign academies and chemical societies. In 1942 he received the Royal Award of the Reale Accademia d’Italia for his achievements in X-ray crystallography and industrial catalysis. In 1963 he and Karl Ziegler shared the Nobel Prize for chemistry, Natta for his studies on stereospecific polymerization and macromolecular chemistry.

Natta’s scientific activity may be divided into three periods: roughly until he went to Pavia University (1933); the two decades until the discovery of stereospecific polymerization (1954); and from 1954 until his retirement (1973). In the first period Natta published many X-ray studies on alloys and other inorganic substances (fifty-six papers in seven years), including important studies on spinels, ionic radii, and solid hydride structures. The use of fast electron diffraction was crowned in 1936 with a study on cellulose. At the same time Natta applied the most advanced structural knowledge of the crystalline texture of catalysts to the formidable task of selecting a catalyst for the synthesis of methanol.

Thus he succeeded in breaking the monopoly of Badische Anilin und Soda Fabrik of the synthetic production of methanol, and from the end of the 1920’s his work was increasingly directed toward the solution of key problems of the chemical industry. Most of these were solved in connection with leading Italian chemical firms: coal gasification, the synthesis of formaldehyde, and the polymerization of formaldehyde with Montecatini SpA. (later Montedison) in 1932; the preparation of butadiene and its separation from butenes with Società per Azioni Pirelli in 1942; and oxosynthesis (reaction of carbon monoxide and hydrogen with olefins) with Bombrini Parodi Delfino in 1945.

After World War II, Natta developed close ties with the top management of Montecatini, and he was able to provide Milan Polytechnic with advanced instrumentation and brilliant young scientists. From the beginning of the 1950’s, Natta became fascinated with the problems of the polymer solid state. In 1952 he attended K. Ziegler’s lecture at Frankfurt on his recently discovered Aufbau reaction and was greatly impressed. The Aufbau (literally “buildup”) reaction employs aluminum triethyl to link ethylene molecules end to end to form higher alkyls. At the time, Ziegler had obtained only molecules of low molecular weight, but with a very important feature: the chains were unbranched, a fundamental step toward the synthesis of ordered polymers that are crystallizable into high-strength solids. That feature did not elude Natta and was instrumental in bringing him into contact with the German scientists working for Montecatini. The discovery of linear polyethylene in Ziegler’s laboratory with a titanium/aluminum aklyl system as catalyst (fall of 1953) was quickly followed in Natta’s laboratory by the synthesis of linear polypropylene in March 1954.

If Ziegler opened the path. Natta realized where it led. The staff of his institute was put to work in research, and in December 1954 a letter titled “Crystalline High Polymers of α-Olefins” was sent to the editor of the Journal of the American Chemical Society. In this seminal paper, signed by Natta and his principal co-workers, a threefold (three monomeric units) helical structure of polypropylene was proposed, and the isotactic concepts of poly (α-olefin) structures were defined. The authors wrote in a footnote: “We propose to designate as ‘isotactical chains,’ from the Greek words ισοσ equal, and ταττω = to set up, the polymer chains having such exceptionally regular structure, containing series of asymmetric carbon atoms with the same steric configuration (‘isotactical’ asymmetric carbon atoms).” The impact of Natta’s proposal on the scientific community was strengthened by a continous flow of discoveries from Milan. Several classes of monomers, from styrenes to cycloolefins, were studied. For every monomer the best stereospecific catalyst was found, and the properties of both the polymer and the catalyst were fully investigated if the reaction appeared to have industrial and economic uses.

On the purely scientific side, Natta’s interpretation of the structure of the stereospecific polymers had a major consequence in the search for a way to produce an optically active polymer from a nonchiral (that is, that can be superimposed upon its mirror image) monomer. Such a process had (and has) important theoretical implications because of the light it can throw on the ubiquitous presence of optically active biopolymers in living organisms. The first definite results were obtained by the Milan school in 1960, and Natta showed his intense interest in the field by recalling the problem in his Nobel Prize lecture. “Macromolecular Chemistry: From the Stereospecifc Polymerization to the Asymmetric Autocatalytic Synthesis of Macromolecules.”

Under Natta’s leadership the Milan school published over 1,200 papers; he himself signed 540 papers and nearly 500 patents. Since Stanislau Cannizzaro’s time the Italian school of chemistry had nourished the ideal of a German-style relationship between advanced academic science and the chemical industry; a scientist in the German mold, Natta converted the ideal into fact.

BIBLIOGRAPHY

I. Original Works. Natta’s important papers in the field of X-ray and fast-electron structure determinations are those on spinels, “Spinelli del cobalto bivalente: Alluminato, cromito, ferrito e cobaltito cobaltosi,” in Gazzetta chimica italianu, 59 (1929), 280–288, with Luigi Passeroni; on ionic radii, “Dimensioni degli atomi e degliioni monovalenti nei reticoli dei cristalli,” in Memorie della Classe di scienze fisiche, matematiche e naturali della R. Accademia d’Italia, 2 no. 2 (1931), 365-379; and on cellulose, “Esame della cellulosa coi raggi di elettroni,” in Atti dell’ Accademia nazionale dei Lincei, 23 (1936), 444–447, with Mario Baccaredda. Natta discusses his research on the catalytic synthesis of methanol in Paul H. Emmett, ed., Catalysis (New York, 1955), III, 349–411.

Natta’s seminal paper on the crystalline high polymers of a-olefins. Cited in the text of this article, is “Crystalline High Polymers of α-Olefins,” in Journal of the American Chemical Society, 77 (1955), 1708–1710, with Piero Pino as coauthor and five of Natta’s colleagues supplying special discussions on X-ray structure determinations, infrared spectra, physical determinations, and the polymerization of α-olefins. A more complete treatment, with an extensive list of co-workers, is “Une nouvelle classe de polyméres d’α-olefines ayant une régularité de structure exceptionnelle,” in Journal of Polymer Science, 16 (1955), 143–154, with a brief English synopsis. The English text of Natta’s Nobel Prize lecture, “Macromolecular Chemistry,” is in Science, 147 (1965), 261–272.

Natta’s major works on polymer chemistry were collected by Natta in Stereoregular Polymers and Stereospecific Polymerizations, edited with Ferdinando Danusso, Luisa M. Vaccaroni, trans. 2 vols. (Oxford, 1967).

Natta’s constant interest in “the grand organic synthesis” is demonstrated in “Le nuove grandi sintesi organiche,” in La chemica e l’industria (Rome), 20 (1938), 187–198; and “Orientamenti nel campo delle grandi sintesi organiche negli Stati Uniti,” ibid., 30 (1948), 63–72.

II. Secondary Literature. An excellent comparative study of Natta and Ziegler is F. M. McMillan, The Chain Straighteners (London, 1979). Important studies on Natta’s life and work are in Sergio Carrà, Federico Parisi, Italo Pasquon, and Piero Pino, eds., Glulio Natta. Present significance of His Scientific Contribution (Milan, 1982). Papers having to do with Natta’s contributions that were given at a symposium on the history of polyolefins (held at Miami Beach in 1985) are in Raymond B. Seymour and Tai Cheng, eds., History of Polyolefins (Dordrecht and Boston, 1986).

Luigi Cerruti