The Action of Elementary Fluorine upon Organic Compounds.

Bigelow, Lucius A.

doi:10.1021/cr60125a004

Cited by 40 publications

(13 citation statements)

References 25 publications

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“…One of the many drawbacks of the classic Balz-Schiemann synthesis is the generation of large quantities of undesired waste products such as NaBF 4 The thermodynamic force driving this process is the formation of water as the only stoichiometric byproduct. The intermediately formed CuF 2 acts as the fluorinating agent at temperatures around 500 • C. The resulting copper is subsequently recycled by reaction with hydrofluoric acid and oxygen at 400 • C. The reaction-regeneration cycles can be repeated without loss of activity of the copper reagent.…”

Section: Transition Metal-catalyzed Aromatic Fluorinationmentioning

confidence: 99%

“…Sulfur tetrafluoride first converts the alcohol into a covalent intermediate with a nucleofugic group, which is subsequently replaced by a liberated fluoride ion, with inversion (S N 2 mechanism). In order to overcome these difficulties, less volatile analogs of SF 4 have been synthesized by replacing one fluorine atom with a dialkylamino group (Scheme 2.65). Despite its versatility, SF 4 has some major disadvantages.…”

Section: Sulfur Tetrafluoride Dast and Related Reagentsmentioning

confidence: 99%

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Introduction of Fluorine

Kirsch

2013

Modern Fluoroorganic Chemistry

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Shortly after their first isolation of elemental fluorine in 1886, Moissan and his co-workers treated several organic substrates with this highly reactive gas. All these experiments, either at room temperature or at liquid nitrogen temperature, resulted in sometimes violent explosions. No major defined reaction products could be isolated.A plausible, first explanation for these discouraging results was proposed by W. Bockemüller in the 1930s, on the basis of thermochemical considerations. The energy released by formation of the highly stable carbon-fluorine bonds (∼116 kcal mol −1 ) is considerably greater than the energy needed for dissociation of carbon-carbon (∼83 kcal mol −1 ) or carbon-hydrogen bonds (∼99 kcal mol −1 ) [1]. A second problem is the extremely low homolytic dissociation energy of elemental fluorine (only 37 kcal mol −1 ), which allows the ready initiation of uncontrollable radical chain reactions, even at low temperatures and in the absence of light [2].The first defined fluoroaliphatic compounds obtained by direct fluorination of organic substrates in liquid reaction media were characterized by Bockemüller [3] in the early 1930s and published with his thermochemical analysis. To control the immense reaction enthalpy, the fluorine gas was diluted with nitrogen or carbon dioxide. The organic substrate was dissolved in a cooled inert solvent, for example, CCl 4 or CF 2 Cl 2 . A similar line of work was pursued in the United States by L. A. Bigelow [4], who studied the reaction of arenes with fluorine gas.In an alternative approach, volatile organic substrates were fluorinated in the gas phase on contact with a copper mesh. This work was pioneered by K. Fredenhagen and G. Cadenbach in the early 1930s [5] and then continued by N. Fukuhara and L. A. Bigelow [6] as part of the Manhattan Project (Figure 2.1). Vapor-phase fluorination finally permitted the preparation of (relatively) defined polyfluorination products from aliphatic hydrocarbons, benzene, or acetone.A modern, improved version of this general method, the LaMar (Lagow-Margrave) process, uses a nickel reactor with different temperature zones and Modern Fluoroorganic Chemistry: Synthesis, Reactivity, Applications, Second Edition. Peer Kirsch.

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Section: Transition Metal-catalyzed Aromatic Fluorinationmentioning

confidence: 99%

Section: Sulfur Tetrafluoride Dast and Related Reagentsmentioning

confidence: 99%

Introduction of Fluorine

Kirsch

2013

Modern Fluoroorganic Chemistry

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“…The first methods to produce fluorocarbons were cumbersome and yields were poor. Thus the direct reaction of fluorine with a hydrocarbon or with a chlorinated hydrocarbon or with a hydrocarbon partially fluorinated by less vigorous methods, completes the replacement of hydrogen by fluorine, but the energy evolved in the replacement is sufficient to damage the basic carbon skeleton (63). The method of direct ffuorination, however, is still being studied and advances are being made (64).…”

Section: Fluorocarbon Chemistrymentioning

confidence: 99%

Recent Advances in Fluorine Chemistry and Technology

Gall¹

1959

ARS Journal

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“…Suas reações eram baseadas em metátese, usando SbF 3 Br 2 ou HgF. 3 Porém, foi durante a Segunda Guerra Mundial que houve grande desenvolvimento na pesquisa de organofluorados, devido ao uso dos fluorocarbonos como gaxetas e válvulas em plantas de enriquecimento de U 235 . 4 Desde então, substâncias organofluoradas são de grande interesse comercial.…”

Section: Introductionunclassified

Importance and highlights in difluorination of organic compounds

Ferreira¹

2009

Revista Virtual De Química

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This mini-review aims to present the importance of replacement one or more fluorine atoms at C-O or C-H centers especially in the medicinal chemistry area. This bioisosteric change produces marked results and unexpected biological activity. In particular, the group difluoromethylene has been described as a bioisoster of the carbonyl function and has increased the biological activity of many compounds. The insertion of CF 2 group in organic molecules can be achieved through direct or indirect fluorination. In this paper will be described some positive examples of the introduction of the CF 2 group in medicinal chemistry and some methods used to insert it. Keywords: difluoromethylene; bioisoster; difluorination ResumoEste artigo descreve a importância da substituição de um ou mais átomos de flúor em ligações C-O ou C-H especialmente na área de química medicinal. Esta modificação bioisostérica produz resultados marcantes e inesperados na atividade biológica. Em especial, o grupo difluorometileno tem sido descrito como um bioisóstero da função carbonila e tem aumentado a atividade biológica de muitas substâncias. A inserção do grupamento CF 2 em moléculas orgânicas pode ser realizada através da fluoração direta ou indireta. Nesta minirrevisão serão abordados alguns exemplos da introdução do grupo CF 2 e alguns métodos utilizados para a sua inserção em moléculas orgânicas.

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The Action of Elementary Fluorine upon Organic Compounds.

Cited by 40 publications

References 25 publications

Introduction of Fluorine

Introduction of Fluorine

Recent Advances in Fluorine Chemistry and Technology

Importance and highlights in difluorination of organic compounds

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