Bis-(polyfluoroalkyl)-acetylenes. I. Synthesis of Bis-(polyfluoroalkyl)-acetylenes

Krespan, Carl G.; Harder, Robert J.; Drysdale, J. J.

doi:10.1021/ja01477a017

Cited by 21 publications

(4 citation statements)

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“…Many CTAs, or telogens, have been employed, and 1iodoperfluoroalkanes (such as CF 3 I, 173,174 C 2 F 5 I, and IC 2 F 4 I) were the primary telogens for TFE telomerization. Other halogenated telogens include HBr, CH 2 Cl 2 , 175 CHCl 3 , 176,177 CCl 4 , 178 and CF 2 Cl-CFClI. 179 In the last case, the reaction was initiated by 60 Co γ rays, while when CF 3 CCl 2 I 180 was employed, thermal activation was preferred.…”

Section: Telomerization Of Tfementioning

confidence: 99%

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

2019

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This Review aims to be a comprehensive, authoritative, and critical review of general interest to the chemistry community (both academia and industry) as it contains an extensive overview of all published data on the homopolymerization of tetrafluoroethylene (TFE), detailing the TFE homopolymerization process and the resulting chemical and physical properties. Several reviews and encyclopedia chapters on the properties and applications of fluoropolymers in general have been published, including various reviews that extensively report copolymers of TFE (listed below). Despite this, a thorough review of the specific methods of synthesis of the homopolymer, and the relationships between synthesis conditions and the physicochemical properties of the material prepared, has not been available. This Review intends to fill that gap. As known, PTFE and its marginally modified derivatives comprise some 60−65% of the total international fluoropolymer market with a global increase of ca. 7% per annum of its production. Numerous companies, such as Asahi Glass, Solvay Specialty Polymers, Daikin, DuPont/Chemours, Juhua, 3F, 3M/ Dyneon, etc., produce TFE homopolymers. Such polymers, both high-molecular-mass materials and waxes, are chemically inert and hydrophobic and exhibit an excellent thermal stability as well as an exceptionally low coefficient of friction. These polymers find use in applications ranging from coatings and lubrication to pyrotechnics, and an extensive industry (electronic, aerospace, wires and cables, and textiles) has been built around them. South Africa, being the third largest producer of fluorspar (CaF 2 ), the precursor to hydrogen fluoride and fluorine, has embarked on an industrial initiative to locally beneficiate its fluorspar reserves, with the local production of fluoropolymers being one projected outcome. As our manuscript focuses specifically on the homopolymerization of TFE (the starting point for all fluoropolymer industries), it will be of considerable use to start-up companies and other commercial entities looking to enter the fluoropolymer market, as well as to end-user companies. The manuscript commences with a short discussion on the synthesis and production of TFE (both at industrial and laboratory scales), including the safety aspects surrounding handling (because that monomer is regarded as explosive if brought into contact with oxygen due to the formation of peroxides), transport, and storage, and then expands into detailed discussions dealing with aspects such as the various additives used (buffers, chain transfer agents, surfactants, etc.), the solvent environment, and the reaction conditions. A further section reports the properties of PTFE with respect to the polymerization conditions as well as an overview on the specialized techniques used to characterize PTFE. Finally, the applications of PTFE in various fields, ranging from electrical insulation to tribological to medical applications, as well as chemically resistant coatings and pyrotechnics, are discussed.

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Section: Telomerization Of Tfementioning

confidence: 99%

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

2019

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“…Elimination reactions, processes that remove two substituents (atoms or groups) from a molecule, play a fundamental role in organic synthesis since Hanhart and Ingold first studied this process in 1927 . It has been widely applied in the formation of alkenes − and alkynes , via dehalogenation. The two prominent elimination types are the α- and β-elimination (Scheme ), generating carbenes/nitrenes and alkenes/alkynes, respectively .…”

Section: Introductionmentioning

confidence: 99%

Bottom-Up Synthesis of Metalated Carbyne Ribbons via Elimination Reactions

et al. 2023

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Elimination reactions are one of the most important reactions in organic synthesis, especially in the formation of alkenes and alkynes. Herein, based on scanning tunneling microscopy, we report the bottom-up synthesis of one-dimensional carbyne-like nanostructures, metalated carbyne ribbons with the incorporation of Cu or Ag atoms, through αand β-elimination reactions of tetrabromomethane and hexabromoethane on surfaces. Density functional theory calculations demonstrate a width-dependent band gap modulation within these ribbon structures, which is affected by interchain interactions. Moreover, mechanistic insights into the onsurface elimination reactions have also been provided in this study.

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“…The choice is limited of the existing methods for extending the carbon chain of polyfl uorinated compounds in order to prepare olefi ns containing chlorine atoms at the multiple bond and suitable for the application to the above described processes. A reductive dimerization of fl uorochlorocarbons in the presence of copper was reported [3]. The cross-dimerization in the simultaneous reduction of the mixture of both these compounds is also possible with the formation of the olefi ns C 4 -C 6 .…”

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confidence: 95%

“…The currently known procedures of the synthesis of fl uoroolefi ns based on chemical transformations of polyfl uorochlorocarbons in the medium of organic solvents are not attractive for processing due to the necessity of wastes utilization [1][2][3]. This disadvantage is absent from the described catalytic processes for fl uoroolefi ns synthesis in the gas phase.…”

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confidence: 99%

Catalytic synthesis of polyfluoroolefins

2010

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A catalytic synthesis of polyfl uoroolefi ns was developed proceeding from polyfl uorochlorocarbons with the use of industrially produced nickel-chromium catalyst. Three ways of the catalytic synthesis of fl uoroolefi ns were implemented: the cleavage of vicinal chlorine atoms from polyfl uorochlorocarbons, the replacement of vinyl chlorine atoms by hydrogen in fl uorochloroolrfi ns, and the reductive dimerization of polyfl uorochlorocarbons containing a trichloromethyl group. The condition of a prolonged operation of the nickel-chromium catalyst was found consisting in the application of quartz for absorption of the hydrogen fl uoride formed as a side product.Fluoroolefi ns are the most important raw materials for preparation versatile widely used polyfl uorinated compounds. The currently known procedures of the synthesis of fl uoroolefi ns based on chemical transformations of polyfl uorochlorocarbons in the medium of organic solvents are not attractive for processing due to the necessity of wastes utilization [1][2][3]. This disadvantage is absent from the described catalytic processes for fl uoroolefi ns synthesis in the gas phase. The dechlorination of polyfl uorochlorocarbons was studied in the presence of various catalysts: copper, cobalt [4], lead [5]. The application of this process is hampered by the high temperature (400-600°C) close to the pyrolysis that adversely affects the yield and the purity of the target compounds. Another considerable disadvantage is the fast deactivation of the catalyst. It was shown [6] that the catalyst based on nickel and chromium operated for 5 h at 350-450°C. The described in a patent [7] catalytic replacement of chlorine by hydrogen in fl uoroolefi ns and the reductive dimerization of polyfl uorochlorocarbons were performed under the catalysis of platinum group metals, e.g., ruthenium.The goal of this study was the development of a catalytic synthesis of polyfl uoroolefi ns proceeding from polyfl uorochlorocarbons. To this end we studied the industrially produced nickel-chromium catalyst applied to the fi ne purifi cation of hydrogen from oxygen and traces of CO and CO 2 in the processes of hydrogenation of benzene, phenol, aniline, dehydrolysate, and also in the process of isotope exchange. We developed three ways of the catalytic synthesis of fl uoroolefi ns: the elimination of vicinal chlorine atoms from the fl uorochlorocarbons, the substitution of vinyl chlorine atoms in fl uorochloroolefi ns by hydrogen, and the reductive dimerization of polyfl uorochlorocarbons containing a trichloromethyl group.Production of fl uoroolefi ns by eliminating vicinal chlorine atoms from fl uorochlorocarbons. Polyfl uorochlorocarbons of various structures containing vicinal chlorine atoms were converted into the corresponding olefi ns with the use of the nickel-chromium catalyst at the temperature from 150 to 270°C, essentially lower than used with the previously described catalysts (400-600°C). The 1,1-difl uorotetrachloroethane dechlorinated the most readily giving 1,1-difl uorodich...

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Bis-(polyfluoroalkyl)-acetylenes. I. Synthesis of Bis-(polyfluoroalkyl)-acetylenes

Cited by 21 publications

References 1 publication

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

Bottom-Up Synthesis of Metalated Carbyne Ribbons via Elimination Reactions

Catalytic synthesis of polyfluoroolefins

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