Michael James Steuart Dewar (24 September 1918 – 10 October 1997) was an American

theoretical chemist Theoretical chemistry is the branch of chemistry which develops theoretical generalizations that are part of the theoretical arsenal of modern chemistry: for example, the concepts of chemical bonding, chemical reaction, valence, the surface ...

.Michael Dewar IAQMS page
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Education and early life

Dewar was the son of Scottish parents, Annie Balfour (Keith) and Francis Dewar. He received the degrees of Bachelor of Arts, Master of Arts, and DPhil from

Balliol College, Oxford Balliol College () is one of the constituent colleges of the University of Oxford in England. One of Oxford's oldest colleges, it was founded around 1263 by John I de Balliol, a landowner from Barnard Castle in County Durham, who provided the f ...

Career and research

Dewar was appointed to the Chair in Chemistry at Queen Mary College of the University of London in 1951. He moved to the University of Chicago in 1959 and then to the first Robert A. Welch research chair at the University of Texas at Austin in 1963. After a long and productive period there, he moved to the University of Florida in 1989. He retired in 1994 as Professor Emeritus at the University of Florida. He died in 1997.List of IAQMS members
/ref> Dewar's reputation for providing original solutions to vexing puzzles first developed when he was still a postdoctoral fellow at the University of Oxford. In 1945, he deduced the correct structure for

stipitatic acid Stipitatic acid is a tropolone derivative isolated from ''Talaromyces stipitatus ''Talaromyces'' is a genus of fungi in the family Trichocomaceae. Described in 1955 by American mycologist Chester Ray Benjamin, species in the genus form soft, c ...

, a mould product whose structure had baffled the leading chemists of the day. It involved a new kind of aromatic structure with a seven-membered ring for which Dewar coined the term '' tropolone''. The discovery of the tropolone structure launched the field of non-benzenoid aromaticity, which witnessed feverish activity for several decades and greatly expanded the chemists' understanding of cyclic π-electron systems. Also in 1945, Dewar devised the then novel notion of a π complex, which he proposed as an intermediate in the

benzidine Benzidine (trivial name), also called 1,1'-biphenyl-4,4'-diamine (systematic name), is an organic compound with the formula (C6H4NH2)2. It is an aromatic amine. It is a component of a test for cyanide. Related derivatives are used in the produc ...

rearrangement. This offered the first correct rationalisation of the electronic structure of complexes of transition metals with alkenes, later known as the Dewar–Chatt–Duncanson model. In the early 1950s, Dewar wrote a famous series of six articles on a general Molecular orbital Theory of Organic Chemistry, which extended and generalised

Erich Hückel Erich Armand Arthur Joseph Hückel (August 9, 1896, Berlin – February 16, 1980, Marburg) was a German physicist and physical chemist. He is known for two major contributions: *The Debye–Hückel theory of electrolytic solutions *The Hückel m ...

's original quantum mechanical treatments by using perturbation theory and resonance theory, and which in many ways originated the modern era of theoretical and computational organic chemistry. Following

Woodward A woodward is a warden of a wood. Woodward may also refer to: Places ;United States * Woodward, Iowa * Woodward, Oklahoma * Woodward, Pennsylvania, a census-designated place * Woodward Avenue, a street in Tallahassee, Florida, which bisects the ca ...

and Hoffmann's suggestion of selection rules for pericyclic reactions, Dewar championed (concurrently with Howard Zimmerman) an alternative approach (which he erroneously felt had been pioneered by M. G. Evans) to understanding pericyclic reactivity based on aromatic and antiaromatic transition states. He did not however believe in the utility of

Möbius aromaticity In organic chemistry, Möbius aromaticity is a special type of aromaticity believed to exist in a number of organic molecules. In terms of molecular orbital theory these compounds have in common a monocyclic array of molecular orbitals in which th ...

, introduced by

Edgar Heilbronner Edgar Heilbronner (13 May 1921 – 28 August 2006) was a Swiss German chemist. In 1964 he published the concept of Möbius cyclic annulenes, but the first Möbius aromatic was not synthesized until 2003.On Molecular Orbital Correlation Dia ...

in 1964, and now a flourishing area of chemistry. He is known most famously for the development in the 1970s and 1980s of the Semi-empirical quantum chemistry methods, MINDO, MNDO, AM1 and PM3 that are in the MOPAC computer program, and which for the first time enabled the quantitative study of the structure and mechanism of reaction ( transition state) of many ''real'' (i.e. large) systems. This was illustrated in 1974 by computing (using the technique of energy minimisation) the structure of a molecule as large as LSD (with 49 atoms) at a quantum mechanical level (the calculation taking several days of the then state-of-the-art

supercomputer A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructions ...

time, a CDC 6600). It is worth noting that in 2006, the equivalent calculation takes less than 1 minute on a personal computer. In 2006, the same structure computation can now be completed using high-level ab initio or density functional procedures in less than two days, and semiempirical programs can be used to optimise the structures of molecules with perhaps 10,000 atoms. He was a member of the International Academy of Quantum Molecular Science.

Awards and honours

His accolades include: Fellow of the American Academy of Arts and Sciences (1966); Member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

(1983); Honorary Fellow, Balliol College, Oxford (1974); Tilden Medal of the Chemical Society (1954); Harrison Howe Award of the American Chemical Society (1961); Robert Robinson Medal, Chemical Society (1974); G.W. Wheland Medal of the University of Chicago (1976); Evans Award, The Ohio State University (1977); Southwest Regional Award of the American Chemical Society (1978); Davy Medal (1982); James Flack Norris Award of the American Chemical Society (1984); William H. Nichols Award of the American Chemical Society (1986); Auburn-G. M. Kosolapoff Award of the American Chemical Society (1988); Tetrahedron Prize for Creativity in Organic Chemistry (1989); WATOC Medal (World Association of Theoretical Organic Chemists Meda), (1990).

Personal life

He is the father of

Robert Dewar Robert Berriedale Keith Dewar (21 June 1945 – 30 June 2015) was an American computer scientist and educator. He helped to develop programming languages and compilers and was an outspoken advocate of freely licensed open-source software. He wa ...

and C.E. Steuart Dewar.''DEWAR'' https://www.cesdewar.com/

References

{{DEFAULTSORT:Dewar, Michael James Steuart 1918 births 1997 deaths University of Florida faculty Fellows of the Royal Society British chemists Alumni of Balliol College, Oxford Academics of Queen Mary University of London Members of the International Academy of Quantum Molecular Science Theoretical chemists Computational chemists