- Squaric acid difluoride
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Hitherto unknown squaric acid difluoride (3,4-difluoro-3-cyclobutene-1,2-dione) (1a) has been synthesized in 71% yield by gas phase fluorination of squaric acid dichloride (1c) with KF at 250°C. (1a) has been characterized by multinuclear NMR, mass, IR and Raman spectra. The IR spectrum is in excellent agreement with its ab initio prediction (MP2, 6-311 + G(2d, p)). The vacuum thermolysis of (1a) at 700°C does not yield the expected decarbonylation product FCCF (2a) although the precursor of the latter, F2CCCO, and three C3F4 isomers (propyne, allene, cyclopropene) which are also found as decomposition products of (2a) have been identified.
- Senzlober, Michael,Buerger, Hans,Eujen, Reint,Gelessus, Achim,Thiel, Walter
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- Oxidation of difluorovinylidene
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Difluorovinylidene is a highly reactive and extremely electrophilic singlet carbene that thermally abstracts an oxygen atom from CO2 at temperatures as low as 30 K. The resulting difluoroketene is characterized for the first time using IR spectroscopy in combination with isotopic labeling and density functional theory (DFT) calculations. The three observed IR absorptions of the ketene at 1274, 1427, and 2162 cm-1 are assigned to the asymmetrical FCF stretching vibration and the asymmetrical and symmetrical CCO stretching vibrations, respectively. The oxidation of difluorovinylidene with 3O2 results in a complex product mixture with CF2, C2F4, CO2, COF2, and CO as the major products. A mechanism consistent with all observed products is proposed.
- Koetting, Carsten,Sander, Wolfram,Senzlober, Michael,Buerger, Hans
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p. 1611 - 1615
(2007/10/03)
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- Isolation, Characterization and Some Properties of Free Difluoroethyne, FCCF
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Difluoroethyne, FCCF 1, has been prepared by vacuum pyrolysis of perfluoro-1,2,3-triazine, isolated in pure form and characterized by 19F NMR and gas phase IR spectroscopy; its decomposition, with a half-life-time at 300 K and ca. 2.5 mbar of ca. 15 min, yields in the first step a polymer and :CF2, the latter either oligomerizing or reacting with 1 to form three different C3F4 isomers.
- Buerger, Hans,Sommer, Silvia
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p. 456 - 458
(2007/10/02)
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- Infrared Multiphoton-Induced Isomerization of Tetrafluorocyclopropene
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Infrared multiphoton excitation of tetrafluorocyclopropene (TFCP) leads to the unexpected formation of tetrafluoroallene (TFA) and tetrafluoropropyne (TFP).The ratio of TFP to TFA formed in the reaction is independent of fluence and pressure, and no other products are formed.The conversion per pulse increases as the pressure of TFCP increases but decreases as the pressure of a buffer gas or the products increases.The apparent intramolecular 1,2-fluorine migration required to form the products is discussed in terms of both unimolecular and bimolecular processes.
- Friedrich, H. Bruce,Burton, Donald J.,Tardy, D. C.
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p. 6334 - 6336
(2007/10/02)
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