L. S. German

Synthesis of fluorinated pyrimidines by the reaction of perfluoro-2-methylpent-2-ene with amidines

Abstract4-Fluoro-6-pentafluoroethyl-5-trifluoromethylpyrimidines have been synthesized by the reaction of perfluoro-2-methylpent-2-ene with aceto- and trifluoroacetoamidines. The high activity of the fluorine atom at position 4 of these compounds in reactions with nucleophilic reagents was found.

Synthesis of the perfluoroacetyldiisopropylmethyl radical

A stable trifluoroacetylperfluorodiisopropylmethyl radical has been prepared by interaction of the (α-fluorosulfonyloxytetrafluoroethyl)perfluorodiisopropylmethyl radical with anhydrous CsF. This reaction is the first example of a chemical transformation of a C-centered radical which is not resonance-stabilized with retention of the radical center.

ISOMERIZATION OF MONOHYDROPERFLUOROALKENES

Isomerization of monohydroperfluoro-1-alkenes HC(CF2)nCF=CF2 (n = 2 to 8) catalyzed by Lewis bases or acids (CsF, KHF2, and SbF5) under conditions of thermodynamic control affords equilibrium mixtures of all of the possible isomers resulting from migration of the double bond along the carbon chain. Under conditions of kinetic control, isomerization through the action of SbF5 gives ω-H-perfluoro-2-alkenes. The substantially higher proportion ofcis-isomers in the resulting monohydroperfluoroalkenes than in their perfluorinated analogs has been attributed to the effect of an intramolecular hydrogen bond.

Perfluoro- and polyfluorochloroketones in the haloform cleavage reaction

Conclusions1.Unsymmetrical perfluoro- and ω-hydroperfluoro-2-ketones are cleaved by the action of aqueous NaOH with the formation of the polyfluoroalkane corresponding to the longest ketone substituent.2.The product composition in the haloform cleaveage of α-chlorofluoroketones is determined by the stability of the chlorine-containing carbanions under the reaction conditions.

Isomeric transformations of polyfluorobutenes caused by SbF5

ConclusionsThe 4-H- and 4-Cl-perfluoro-1-butenes when treated with SbF5 rearrange to terminal polyfluorobutenes that contain either H or Cl at the multiple bond.

Polyfluorinated enol acetates

The synthesis of polyfluorinated enol acetates has been performed by reductive dechlorination of chloropolyfluoroketones with zinc in Ac2O. Under these conditions, hexafluoroacetone is preferably reduced at the carbonyl group.

Monoamination of internal fluoroolefins

Perfluoro-2-methyl-2-pentene and perfluoro-1-methylcyclopentene react with ammonia or aniline under controlled conditions to give monoamination products.

Mass spectrometry study of the pyrolysis of perfluoroolefin oxides

The pyrolysis of perfluoroolefin oxides has been studied by gas chromatography/mass spectrometry at 400–700°C, in a current of He (1∶10 dilution, contact time 1 sec). For oxides containing a terminal CF2 group, the sole degradation route is through the elimination of difluorocarbene. Pyrolysis of symmetrical disubstituted oxides results in the elimination of a perfluoroalkylfluorocarbene, which subsequently isomerizes to the corresponding perfluoroolefin. In the pyrolysis of unsymmetric disubstituted oxides the elimination of perfluoroalkylfluorocarbenes occurs by both of the possible routes. Trisubstituted oxides eliminate bis-perfluoroalkylcarbenes. The decomposition of tetrasubstituted oxides proceeds along several directions concurrently.

Synthesis and properties of 2-chloroperfluorobutene oxides

Conclusions1.Nucleophilic epoxidation of heptafluorobutenes containing a chlorine atom in position 2 was carried out.2.Chemical transformations of 2-chloroheptafluorobutene oxides in the presence of acids and Lewis bases were studied. 2-Chloro-2,3-epoxyheptafluorobutane isomerizes easily to 3-chloroheptafluoro-2-butanone under the action of catalytic amounts of SbF5 and MF (M = Cs, K)e but it is resistant to the action of Et3N. Catalytic action of F and Et3N on 2-chloro-1,2-epoxyheptafluorobutane leads to 2-chlorohexafluorobutanoyl fluoride and SbF5 and SbCl5 give l-chloroheptafluoro-2-butanone. Under the action of an equimolar amount of SbF5 on 2-chloro-1,2-epoxy- and 2-chloro-2,3-epoxyheptafluorobutane, octafluoro-2-butanone is formed.

Synthesis of polyfluorochloro ketones

ConclusionsFluoroolefin oxides when reacted with AlCl3 undergo mainly opening of the ring with conversion to polyfluorochloro ketones RFCOCF2Cl and RFCOCCl3.