Molecular orbital theory of reactivity in radical polymerization. Part II

The Many Chemists Who Could Have Proposed the Woodward-Hoffmann Rules But Didn't: The Organic Chemists Who Knew of the Smoking Guns

It is a reasonable question to ask, why, as of 1965 when the five Woodward-Hoffmann communications appeared, did no other organic chemist discover the orbital symmetry rules for pericyclic reactions? The previous two papers in this 27-paper series on the history of the Woodward-Hoffmann rules discussed the physical chemists, chemical physicists, and theoretical chemists who could have solved the pericyclic no-mechanism problem; and the organic chemists in whose laboratory many of the key hints to this problem were found but still did not solve the problem. The stories of 16 other chemists who knew of (at least portions of) the pericyclic no-mechanism problem are presented in this paper. Social, political, and scientific explanations are presented as partial rationalizations as to why none of these individuals - except Woodward with Hoffmann - solved the pericyclic no-mechanism problem.

The Many Chemists Who Could Have Proposed the Woodward-Hoffmann Rules (Including Roald Hoffmann) But Didn't: The Theoretical and Physical Chemists†

It is a reasonable question to ask, why, as of 1965 when the five Woodward-Hoffmann communication appeared, did no other physical chemist or chemical physicist or theoretical chemist discover the orbital symmetry rules for all pericyclic reactions? Two theoretical chemists - Luitzen Oosterhoff (in 1961) and Kenichi Fukui (in 1964) had discovered portions of the orbital symmetry rules; their stories appear in the papers immediately preceding this paper which is Paper 5 in a 27-paper series on the history of Woodward-Hoffmann rules. Concise yet telling stories of 19 other chemists who could have, might have, perhaps even should have discovered the Woodward-Hoffmann rules are presented with explanations as to why they did not do so. Social, political, and scientific explanations will summarize the analyses.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part II. A Sleeping Beauty in Chemistry†

In 1964, Kenichi Fukui published a chapter in a book honoring the career of Robert S. Mulliken. While most of that chapter is a review of Fukui's previously published research dealing with frontier molecular orbital theory and organic reactions, one section provided a frontier molecular orbital explanation of the mechanism of the Diels-Alder reaction. Fukui concluded that the "symmetry relation of wave functions of both dienes and dienophiles" control the course of this reaction. Thus, Fukui's paper was a precursor to Woodward and Hoffmann's 1965 papers that proposed orbital symmetry control of what would later be termed "pericyclic reactions." Fukui published numerous papers in the 1950s and 1960s, many of which were expositions of his research in theoretical chemistry. Eight of those Fukui papers were direct precursors to his breakthrough 1964 publication. This paper presents the intellectual and scientific path that Fukui took from the early 1950s to 1964 to his award-winning publication.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part III. Fukui's Science and Technology, 1918-1965†

In 1981, Kenichi Fukui shared the Nobel Prize in Chemistry with Roald Hoffmann "for their theories, developed independently, concerning the course of chemical reactions." In 1964, Fukui used his frontier molecular orbital theory to reveal the mechanism of the Diels-Alder reaction, a prototypical pericyclic cycloaddition reaction. Fukui revealed this molecular orbital symmetry explanation a year before Woodward and Hoffmann's first publication on "the conservation of orbital symmetry." As detailed in this paper, during the 1960s and early 1960s, Fukui was involved in several major programs in synthesis and polymer chemistry as well as aspects of theoretical chemistry quite distant from his contributions to the orbital symmetry research that preceded Woodward and Hoffmann. In this paper, a detailed examination of Fukui's pre-1965 research is discussed. This is Paper 4 - Part III of a trilogy that deals with Fukui's Nobel Prize research and is part of a 27-paper series on the history of the development of the Woodward-Hoffmann rules.

Free Radical Copolymerization of Acrylamide and Linalool with Functional Group as a Pendant

Linalool (LIN) and acrylamide (AM) have been copolymerized by benzoyl peroxide (BPO) in xylene at 75°C for 40 min. The system follows the ideal kinetics with bimolecular termination and results in the formation of nearly alternating copolymer as evidenced from the reactivity ratios, r1(AM) = 0.3 and r2(LIN) = 0.05, which have been calculated by the Kelen-Tudos method. The overall activation energy of copolymerization is 40 kJ mol−1. The Fourier transform infrared spectrum of the copolymer shows the presence of the band at 3395 cm−1 due to the alcoholic group of LIN and at 1453 cm−1 due to the amide group of AM. The 1HNMR spectrum shows peaks at 7.0-7.7δ due to the alcoholic group of LIN and at 6.3-7.0δ due to the amide group of AM. The Alfrey-Price Q- e parameters for LIN have been calculated as Q2 = 0:274 and e2 = −0.749. The mechanism of copolymerization has been elucidated. In this paper we also report on the measurement of Mark-Houwink constants in tetrahydrofuran (THF) at 25°C by means of gel permeation chromatography (GPC) as α = 0.50 and K = 7.5 × 10−4 dl g−1. The thermal decompositions of the copolymer are established with the help of the thermal gravimetric analysis technique.