Fukui, Kenichi

Kenichi Fukui was born in Nara , Japan on October 4, 1918. ^[1] He was the eldest of the three sons of Ryokiti's father and Chie's mother, who before marriage bore the name of Sughisawa. Ryokichi Fukui graduated from the Tokyo Institute of Commerce (later Hitotsubashi University ), was a member of the National Geographic Society. The magazine of this society Kenichi often read in childhood. Chie graduated from Nara Women's College. She bought the children full of the works of the famous Japanese novelist Natsume Soseki , very beloved Kenichi.

Shortly after the birth of Kenichi, the family moved to a new home in Kishinato, Osaka, Kenichi lived until the 18th anniversary. As a child he loved to play outdoors and spent almost every vacation in his mother’s home in Osikum. Kenichi collected stamps, matchboxes, leaves, plant buds, and stones. Interest in nature was always with him: when he went to lecture at international symposia many years later, he caught butterflies and cicadas there.

Kenichi enrolled in the Tamada Deni Elementary School in 1925. He was poorly developed physically, although he liked to work in the field at a summer school on the south coast of Osaka. Imamiya Ken-ichi High School enrolled in 1931. There he became a member of the biological circle, whose members often traveled to nearby mountains on the outskirts of Osaka for insects. At this time Kenichi became acquainted with the works of Jean-Henri Fabre - the series of Entomological Memories (Souvenirs Entomologiques). The observations described in the book fully corresponded to his own, which was very surprising to Kenichi, because he was so far from Provence, where Jean Fabre lived.

The chemistry course began at Kenichi in the third year of secondary school, but he didn’t like it because there was much to memorize and teach, and partly because Fabre was not lucky as a chemist.

Kenichi wrote ^{[ where? ]} at the age of 65, that children's experience was very important in his development as a natural scientist. Then at school, he did not think about the career of a scientist, rather about working in literature, his favorite subjects were history and literature. The reason for this was his place of birth, the city of Osikuma, which was located between Nara and Kyoto, in which there are many historical monuments. Kenichi entered the Faculty of Science and studied German as a second language. At that time, students had to go in for sports, and Kenichi chose Japanese kendo fencing.

In the spring of 1938, on the last year of study, his father visited Gen'itsu Kit ( Japanese 喜 多 源 逸 whale Genitsy ) , his relative, a professor of chemistry at Kyoto University , who lives in the same area of ​​Nara. He consulted with him about further studies Kenichi and explained that his son loves German and mathematics. Kita replied that mathematics and German are important to chemistry, and offered work in a laboratory in Kyoto. This was a bit unexpected, since in those days mathematical methods were not used in chemistry. When Kenichi found out about this proposal, he agreed to study there: Professor Kita graduated from the Faculty of Applied Chemistry of the Imperial University of Tokyo in 1906, where he became a professor at the Faculty of Industrial Chemistry of the Imperial University of Kyoto in 1921. Kita was not only an outstanding chemist who published more than 1000 articles, but also an excellent teacher who trained a large number of leading Japanese chemists such as Junko Sakurada, Sachiko Kodama, Masaaki Horio and Jun Furukawa. After his retirement from Kyoto University in 1944, he became president of Naniwa University (later Osaka University ) and a member of the Japanese Academy of Sciences.

University years

Kenichi entered the department of industrial chemistry, the department of engineering at Kyoto University in 1937. He often visited Professor Keith at home. The Faculty of Industrial Chemistry focused on applied fields such as ceramic chemistry, electrochemistry , enzymatic chemistry, and chemistry of synthetic dyes , fibers, rubber and plastics. Lectures were strictly oriented on applied chemistry. Kenichi, who wanted to study basic science, listened to lectures at the department of natural science located nearby. Kenichi also wanted to study the recently appeared quantum mechanics , but since there were no lectures on this discipline, he went to the library to the physics department and took books there. Kenichi wondered why there was no "mathematical chemistry" and believed that the empirical nature of chemistry should decrease after the advent of mathematical methods in chemistry. "Reducing the empirical nature of chemistry" was Professor Fukui's favorite phrase .

In the third year, he began to study in graduate school under the guidance of a junior professor Haruo Singu (Professor Kita was going to retire). In addition to the main field of research - studies of hydrocarbon reactions with antimony pentachloride, Fukui was also interested in the different reactivity of aromatic compounds such as naphthalene and anthracene . This was the subject of a new electronic theory, the first rudiments of which were just beginning to appear; for Kenichi it was fortunate that the results of his experiments were not explained by existing theories.

Kenichi graduated from the Kyoto University Engineering Department in March 1941 and enrolled in the graduate school of the Faculty of Fuel Chemistry at the Department of Engineering. His supervisor was Professor Shinjiro Kodama, who also studied under Professor Kita. Kodama studied in Germany from the age of 24 and also had many books on quantum chemistry and electromagnetism. Kenichi had the opportunity to study fundamental physics in a free atmosphere at the Kodama laboratory.

Writing doctoral theses

In August 1941 Kenichi moved to the Fuel Institute of the Japanese Army in Tokyo. In 1943, he lectured at the Faculty of Fuel Chemistry, at Kyoto University, and in 1944 became an assistant professor there. Kenichi spent a lot of time studying quantum mechanics, especially interesting for him were the books of R.H. Fowler “Statistical Mechanics” (1936) and “Introduction to Quantum Mechanics” (1947) “Introduction to Particle Physics” (1948) Hideki Yukawa . Fuel Institute was engaged in the synthesis of hydrocarbons, which could improve the properties of gasoline. In the US, 2,2,4-trimethylpentane was used, and Kenichi had to synthesize similar compounds from butanol, which was obtained by fermentation of sugar. In September 1944, his team succeeded in the synthesis of isooctane and received a grant from the Japanese army. After the 2nd World War, Kenichi returned to Kyoto University and became involved in molecular design under the guidance of Professor Kodama. He worked on the synthesis of high-pressure polyethylene. This research consisted of a part of his doctoral dissertation, which was called “Theoretical study of the temperature distribution in the reactors of the chemical industry”. This was a 200-page study. When he showed it to Professor Kit, who had already retired by then, he said only that it was very thick. Kenichi completed his research in the summer of 1948.

The theory of chemical reactions, orbital theory

After completing his thesis, Kenichi decided to study the theory of chemical reactions. In those days, chemical reactions were the main subject of study at the Faculty of Natural Sciences of the Department of Chemistry, Kyoto University. In particular, at this time Horiba, T. Li and S. Sasaki worked in this area. The research differed from what Fukui was used to at the Faculty of Natural Sciences at the University of Tokyo, where he studied the molecular structure. In such an atmosphere Keniti was convenient to do the theory of chemical reactions.

An experimental study of the reactions of hydrocarbons, which he conducted in his student years and later at the Fuel Institute in Tokyo, formed the basis for his theoretical studies. In 1951, Fukui became a professor in the department of fuel chemistry. In February of that year, there was a fire at the faculty and he had to share his laboratory with Professor Singh and others. It was in this room that the theory of boundary orbitals was born. He believed that the electron in the outer orbital plays a very important role in the process of chemical reaction, it is in the outer parts of the molecules that the chemical reaction occurs. The orbital participating in the chemical reaction was called the "frontier orbital". Fukui was the first to calculate the density of naphthalene boundary electrons and found that the density was maximum in the place where the chemical reaction took place. He succeeded, with the help of Tedziro Enezawa, his graduate student, in studying more complex hydrocarbons, such as anthracene, pyrene and perylene. The theory of border orbitals accurately showed the positions of chemical attacks with electrophiles like NO2 +, thus confirming itself in the experiment. The collection of many experimental results was interpreted with the help of Professor Singu, an organics with a deep knowledge of the electronic theory of organic reactions. Scientists decided to name the new theory in honor of Professor Singh, who proposed the "boundary" electronic theory. One of his most important articles is his first theory of chemical reactions ^[2] . He found a correlation between the reactivity of aromatic hydrocarbons to electrophilic reagents and the squares of the coefficients of atomic orbitals in a linear combination of upper occupied molecular orbitals (HOMO).

The spatial distribution of electron density in HOMO was parallel to the order of the reactivity of the molecule. Later, a similar correlation was found in reactions with nucleophilic reagents between reactivity and the distribution of lower free molecular orbitals (LUMO). The reactivity of free radicals was determined by the total density of the LUMO and HOMO ^[3] . Fukui regarded this result as a general pattern of chemical reactions, as a general orientational behavior. He tried to expand the range of compounds to which it was possible to apply a similar rule, for example, to expand it to organic and inorganic substances, aromatic and aliphatic, saturated and unsaturated. He found that the spectrum of chemical reactions can be extended to substitution, addition, separation, bond breaking, elimination, and formation of molecular complexes.

The Fukui article of 1952 ^[2] was published the same year when Mulliken ’s important article on charge transfer in donor – acceptor complexes appeared (Mulliken, 1952). With the work of Mulliken, Fukui received a theoretical substantiation of his results. The main idea was to electronically delocalize between LUMO and HOMO reactants. These orbitals were called boundary.

The theory of boundary orbitals was developed in many directions, not only by the Fukui scientific group, but also by other scientists. Useful indicators of reactivity, for example, “super-delocalization” ^[4] , came from this theory and were used in various special topics, for example, comparing reactivity, polymerization kinetics and copolymer structure ^[5] , antioxidants ^[6] , and other biochemical substances ^[7],. However, the Fukui theory began to attract enormous attention from scientists only after the discovery of the relationship between LUMO, HOMO and phenomena of stereoselectivity. In 1961, in the study of silver complexes of aromatic compounds, the importance of the main part of the boundary theory was shown. In 1964, Fukui compared the symmetry of LUMO and HOMO of reacting molecules with the case of cycloaddition reactions ^[8] . This was the result of a simple application of the theory of boundary orbitals to the so-called “consistent” two-center reactions. Fukui received a more vivid light from Woodward and Hoffman (Woodward & Hoffmann, 1965), who used LUMO and HOMO to explain the formation of stereospecific products in thermal cyclization and photocyclization of conjugated polyenes. This discovery was the first step towards establishing the rule of stereoselectivity in various coordinated responses. They interpreted the occurrence of these reactions as the fulfillment of the rule of “conservation of orbital symmetry” (Woodward & Hoffmann, 1969).

All the results, explained by the Woodward-Hoffman rule, were interpreted by Fukui using the boundary orbitals theory approximation ^[9] . However, there is no doubt that the work of Fukui became widespread precisely because of the work of Woodward and Hoffman.

Studies of the interactions of VZMO-LUMO in the work on cyclic addition of Fukui in 1964 were applied by his group and other scientists (Hawk, 1973) to various chemical reactions: cyclic and acyclic addition, elimination, rehybridization, multicyclization, various intramolecular rearrangements, reactions with a benzene ring, opening and closing cycles, etc., including even thermally induced and photo-induced reactions ^[10] . The theory turned out to be particularly effective in relation to the explanation of complex regioselectivity and the different types of secondary stereochemical effects in coordinated cycloadditions. Everything was explained in terms of boundary orbitals. The charge transfer and spin change could be explained from this point of view ^[11] . Fukui and his colleagues expanded the orbital interaction to participate from two to three orbitals. Orbital mixing, polarization, and three-orbital interaction were used to explain further more complex experiments.

The theory of three-component interaction was introduced to explain the role of catalysts in terms of LUMO-HOMO analysis. The concept of “pseudo-excitation” was revealed and applied to the interpretation of several chemical phenomena ^[12] .

In addition to these fundamental advances, Fukui, with his scientific group, tried to give his theory a quantitative character. In 1968, a general theory of intermolecular reactions was proposed to unify general principles on reaction paths, noting the increasing influence of the HOMO – LUMO interaction in the process of studying chemical reactions. The mechanism for changing bonds in the course of the reaction and the stabilization of the reaction system along the reaction path ^[13] were clarified.

Global recognition, awards

In 1962, Fukui received the prize of the Japanese Academy for the study of the electronic structure and reactivity of conjugated compounds. Yoshio Tanaka, Professor Emeritus of the University of Tokyo, who fervently supported Kenichi, once said: "This theory could get the Nobel Prize." ^[one]

Nobel Prize

In 1964, Fukui attended the Sanibel Symposium, where he first met Roald Hoffman . Hoffman was 19 years younger than Fukui and is already known for the advanced Hückel method, which he studied in his PhD thesis. They became friends and remained good friends for the rest of their lives. After Sanibel, he traveled for almost two months in America and Europe with his wife Tomo. It was his first trip abroad, and he celebrated his 19th anniversary of living together with Tomo at a restaurant in Paris.

In 1964, P.-O. Lyovdin and B. Pullman offered Fukui to make a contribution to the chapter of the book devoted to Robert Mulliken on his 60th birthday. He agreed, writing an article entitled “A simple quantum theoretical explanation of the reactivity of chemical compounds” ^[8] . In this article, he studied the Diels-Alder reaction , and for the first time carried the types of symmetries of the highest occupied molecular orbitals (HOMO) and the lowest free molecular orbitals (LUMO) to the selectivity of the reaction. This circumstance was also noted by Woodward and Hofman in the presentation of the theory of conservation of orbital symmetry, the so-called Woodward-Hoffman rule. This theory, presented in 1965, asserted that the reactivity of substances directly depends on the nature of HOMO and LUMO molecules. The theory was warmly accepted by chemists and immediately opened up a new field in organic chemistry. As a result, the frontier orbital theory as an application to the Woodward-Hoffman rule quickly spread and received the Nobel Prize in Chemistry in 1981. At about 10 am on October 19, 1981, Kenichi received a call from the Tokyo newspaper asking for an interview with the Nobel Prize winner. He was stunned, and only when he saw his name next to Roald Hofman on the news on TV did he finally believe in what had happened. That night, a lot of people came to him: television and newspaper reporters, friends, acquaintances and students. Kenichi and Tomo were surrounded by journalists until midnight.

December 10, 1981 Kenichi Fukui received a diploma and a medal of Alfred Nobel in chemistry from the King of Sweden Gustav. He shared the prize with Roald Hofman. At that moment, he received thanks and guidance from professors Genitsy Kit and Yoshio Tanaka. He was struck by the number of events after the awards ceremony, which were held under the auspices of the Student Union of Sweden.

After receiving the Nobel Prize in Fukui, a whole bunch of cases came over, and the attention of the Japanese press to it increased. This made his life less “mobile”, but he still loved to walk in the morning in nature, in the fresh air. He became president of the Kyoto Institute of Technology. Since his position was not scientific, but administrative, he could not have a laboratory at the University. Three years later, he became president of the Institute of Fundamental Chemistry, which was built for him in Kyoto, with money from the Japanese chemical industry. He also became chairman of many organizations and committees, leaving a minimum of time for science.

Fukui was often asked to give lectures, not of a specific, but of a general nature, in which he liked to say that in the future chemistry will become one of the most popular sciences in the world. Although environmental problems have darkened the face of chemistry, they nevertheless gave impetus to the chemical industry to change. It became clear that without chemistry it is impossible to solve the problems of resources, food and energy. Modern students, he believed, should study more fundamental theoretical chemistry, and less experimental. Achievements of computer science will help theoretical chemistry to develop rapidly. He even proposed the term "molecular engineering" for an area that is looking for the necessary properties of molecules. He inspired young scientists to be more creative in the new science and engineering.

Signed " Prevention of scientists to mankind " (1992) ^[14] .

In the winter of 1997, Kenichi was diagnosed with stomach cancer . He immediately underwent surgery, but in the summer he again had to return to the hospital. January 9, 1998, he died at the age of 79. His grave is located on the slope of Mount Higashiyama, where his favorite teacher Genitsu Keith was also buried ^[1] .

Tomo (before marriage - Tomo Horie) and Kenichi married in the summer of 1946. She dreamed of becoming a scientist after reading the biography of Marie Curie , she graduated from the Faculty of Physical Chemistry of the Imperial Women's University of Science in Tokyo. Before marriage, Kenichi had once driven her to a concert where they played Beethoven’s Ninth Symphony. After the concert, he proudly noted that the concert did not play some of the original parts of the symphony, declared in the poster. She thought then how can he spoil the impression of the concert. These were difficult days for Japan, but Tomo did everything to concentrate Kenichi on science. Their son Tetsuya was born on January 8, 1948, and their daughter Miyako on May 19, 1954.

• K., Fukui. Theor. Chem. Accts. - Cornell University Press, 1999.
• RB, Woodward. The conservation of orbital symmetry. - New York: Academic Press., 1969.
• H., Yukawa. Introduction to particle physics .. - Tokyo: Iwanami, 1948.
• H., Yukawa. Introduction to quantum mechanics .. - Tokyo: Khobundo., 1946.
• RS, Mulliken. J. Am. Chem. Soc. , 74. - 1952.
• RG, Parr. J. Am. Chem. Soc. , 106. - 1984.
• I., Fleming. Frontier orbitals and organic chemical reactions. - Chichester: Wiley, 1976.
• RH, Fowler. Statistical mechanics .. - Cambridge University Press., 1936.
• LP, Hammlet. Physical organic chemistry. - New-York: McGraw-Hill., 1940.
• KN, Houk. J. Am. Chem. Soc., 95. - 1973.

• Fukui Kenichi autobiography . - The Official Web Site of the Nobel Prize.