Fluorierungen organischer Substanzen mit freiem Fluor

Fredenhagen, Karl; Cadenbach, Gustav

doi:10.1002/cber.19340670603

Cited by 22 publications

(8 citation statements)

References 5 publications

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“…his values for A and B are approximately 107 and 103 when X = F, while they are only 33 and 23, respectively, when X = Cl. These heats of reaction are to be compared with the heat of formation (or disruption) of a C-C bond, which is about 71 kg.-cal.…”

Section: B Contributions Of Bockemullermentioning

confidence: 93%

“…On this basis, Miller, Calfee, and Bigelow (61) carried out the vapor-phase fluorination of hexachloroethane (CsCh) over a copper-gauze catalyst, by a modification of the procedure originally described by Fredenhagen and Cadenbach (33) moderate the reaction by reducing local overheating, and that the presence of a surface layer of cupric fluoride might promote the change. The simple apparatus consisted of a glass tube heated by sliding air baths.…”

Section: F Ishikawa Murookamentioning

confidence: 99%

See 1 more Smart Citation

The Action of Elementary Fluorine upon Organic Compounds.

Bigelow¹

1947

Chem. Rev.

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Section: B Contributions Of Bockemullermentioning

confidence: 93%

Section: F Ishikawa Murookamentioning

confidence: 99%

The Action of Elementary Fluorine upon Organic Compounds.

Bigelow¹

1947

Chem. Rev.

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“…The sulfur compound is then treated with a thiophilic, ''soft'' electrophilic oxidant, for example, electrophilic halogenation agents such as NBS, NIS, 1,3-dibromo-5,5-dimethylhydantoin (DBH), Br 2 , SO 2 Cl 2 [157], F 2 [163], IF 5 [164], BrF 3 [165], 4-MePhIF 2 [166], nitrosyl cations (NO + BF 4 − ) [160], or F-TEDA [167] in the presence of a fluoride source (50 or 70% HF-pyridine [157], HF-melamine [158], and NEt 3 ·3HF [161]). The sulfur compound is then treated with a thiophilic, ''soft'' electrophilic oxidant, for example, electrophilic halogenation agents such as NBS, NIS, 1,3-dibromo-5,5-dimethylhydantoin (DBH), Br 2 , SO 2 Cl 2 [157], F 2 [163], IF 5 [164], BrF 3 [165], 4-MePhIF 2 [166], nitrosyl cations (NO + BF 4 − ) [160], or F-TEDA [167] in the presence of a fluoride source (50 or 70% HF-pyridine [157], HF-melamine [158], and NEt 3 ·3HF [161]).…”

Section: Oxidative Fluorodesulfurationmentioning

confidence: 99%

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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“…Miller, Calfee, and Bigelow-(3) have suggested that a film of cupric fluoride coating the metal may behave as a fluorinating agent and be responsible for the beneficial action of copper gauze, originally introduced by Fredenhagen and Cadenbach (1).…”

Section: Nature Of Catalytic Reactionmentioning

confidence: 99%

“…It seemed possible then that these compounds might react with hydrocarbons to replace hydrogen by fluorine as does elementary fluorine, and that the reaction would be less drastic. The replacement of hydrogen with fluorine in hydrocarbons would therefore essentially be accomplished by the use of elementary fluorine, but the process would be in two steps: first, the fluorination of the lower metallic fluoride to the higher: MeFz, + (%~^•) F2 -> MeF/, (1) and, second, the replacement of hydrogen with fluorine in the hydrocarbon by the higher fluoride:…”

Section: Acknowledgmentmentioning

confidence: 99%

Preparation of Fluorocarbons by Catalytic Fluorination of Hydrocarbons

Cady¹,

Grosse²,

Barber³

et al. 1947

Ind. Eng. Chem.

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THE technique for catalytic fluorination has been iniproved to such an extent that a desired saturated fluorocarbon may be produced in moderate to high yield b v the reaction of the corresponding hydrocarbon with elementary fluorine. The hydrocarbon vapor and the fluorine are each diluted by nitrogen and are gradually mixed iu the presence of fine copper turnings or ribbon coated with a thin layer of silver fluorides. This procedure has been used to produce straight or branchedchain fluorocarbons ranging from perfluorobutane to perfluorohexadecane and naphthenic fluorocarbons from C6Flz to Cl8F30. Volatile hydrocarbon lubricating oils have also been fluorinated. It appears probable that the fluorocarbons are produced by the action of the fluorinating agent, AgFz, upon the hydrocarbon vapor and that the supply of the silver difluoride in maintained by the reaction: 2AgFz f Fz ---.f 2AgF2.

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Fluorierungen organischer Substanzen mit freiem Fluor

Cited by 22 publications

References 5 publications

The Action of Elementary Fluorine upon Organic Compounds.

The Action of Elementary Fluorine upon Organic Compounds.

Introduction of Fluorine

Preparation of Fluorocarbons by Catalytic Fluorination of Hydrocarbons

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