Perfluoroalkenes addition reactions

Heats of hj drogenation have been measured for a wide variety of unsaturated organic compounds, to give information about strain and stabilization (resonance) energies. However, this is only one type of addition reaction for which thermochemical data have been accumulated. Lacher and his co-workers have measured heats of halogenation of ethylenic compounds, for example the chlorination of the homologous series of perfluoroalkenes, viz.,... 

The uncatalyzed hydroboration-oxidation of an alkene usually affords the //-Markovnikov product while the catalyzed version can be induced to produce either Markovnikov or /z/z-Markovnikov products. The regioselectivity obtained with a catalyst has been shown to depend on the ligands attached to the metal and also on the steric and electronic properties of the reacting alkene.69 In the case of monosubstituted alkenes (except for vinylarenes), the anti-Markovnikov alcohol is obtained as the major product in either the presence or absence of a metal catalyst. However, the difference is that the metal-catalyzed reaction with catecholborane proceeds to completion within minutes at room temperature, while extended heating at 90 °C is required for the uncatalyzed transformation.60 It should be noted that there is a reversal of regioselectivity from Markovnikov B-H addition in unfunctionalized terminal olefins to the anti-Markovnikov manner in monosubstituted perfluoroalkenes, both in the achiral and chiral versions.70,71... 

Under similar experimental conditions (SIFT at room temperature), however, F adds to the C—C double bond of perfluoroalkenes such as tetrafluoroethylene and hexafluo-ropropene, which are industrially important monomers290. In the case of hexafluoro-propene a second addition step is also observed (Scheme 43). These reactions are believed to involve covalent addition rather than cluster formation for a number of reasons. First, ab initio calculations show that QF5 and C3Ff are stable ions and that the chemically bonded species 132 is more stable than the 7r-complex structure 133291. Second, these reactions... 

Acetylene is one of the simplest hydrocarbons and a fundamentally important chemical in organic chemistry. The electronic structure of acetylene and its related compounds have been extensively studied both experimentally and theoretically, and a number of interesting observations have been reported. For example, a trans-bent structure has been reported for acetylene in an excited state [42, 43] and also in a radical anion form [34, 44]. The interaction between acetylene and metal atoms such as A1 and Li has been studied by inert gas matrix isolation (MI) ESR and IR methods [45-48]. Here we present our ESR study on the structural distortion in acetylene radical anion in the glassy 2-MTHE matrix, which is another example showing a mixing of the k and higher-lying a orbitals at the C=C carbons similar to that at the C=C carbons for the perfluoroalkene radical anions. In addition photo-induced isomerization reaction of the acetylene radical anion in the matrix is briefly presented. 

Silver fluoride adds to electron deficient alkenes. The reaction of l,l-dichloro-2,2-dicyanoethylene with AgF, for example, does not produce the expected 1,1-difluoro derivative. Instead, this reaction yields the silver salt of trifluoromethylmalononitrile, presumably through the 1,1-difluoro derivative by subsequent addition of AgF to the strongly electrophilic double bond. Perfluo-roalkylsilver compounds can be prepared by the addition of AgF to perfluoroalkenes. The fluorination of tetrabromo-2,3-diaza-1,3-butadiene affords the tetrafluoro derivative. 

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