Fluorine abstraction

It is believed that polymer surface fluorination proceeds via a free radical mechanism, where fluorine abstracts hydrogen atoms from the hydrocarbon, and fluorine atoms are substituted.11 Of course, the precise conditions depend on the nature of the polymer in question and the surface properties required. 

The pentacarbonyltungstenhydrogen sulfide anion has been reacted with excess HFA in acetone at ambient temperature. Equation (155) is one of the rare examples where fluorine abstraction, rather than insertion, occurs 13). 

In our studies (6) attempting fluorine abstraction, O2F2 was reacted with GIF. If the reaction is carried out without special precautions, the two substances readily react following the stoichiometric equation ... 

Table II Calculated formation enthalpy (AH) and activation energy (AEa) in a fluorine-abstraction of fluorocarbons using MOPAC (PM3) [unit kcal mol l]...

The results of radiolysis ( "Co y-rays and neutrons) experiments on CF -CgF mixtures encapsulated in aluminium [the predominant products were CjFg, i-CiFu, i-CsFu, and (CF3)2CF-CF(CFs)2 oxygenated products, e.g. (CjFslaO, presumably arose through attack on aluminium oxide) have been quoted in support of the contribution of fluorine-abstraction reactions to the mechanisms of radiation-induced fluorocarbon transformations [for example CF CFj + F 2 CFj- C,F -b F- CFj -I- C2F ... 

The highly rigid, close packed structure and the great strength of the C—F bond (507 kJ/mol) imply that no fluorine abstraction or internal chain rearrangements of... 

Inasmuch as the F2 molecule is only bound by about 155 kj/ mole, fluorine abstraction by F atoms requires a reagent with a very weeikly bound fluorine. One possibility is the reaction... 

The experimental results which we will describe are primarily those obtained in this laboratory but a few experimental data exist which have been collected elsewhere. Our experimental program in fluorine atom chemistry has been motivated primarily by two facts which have also been important to studies performed by other methods (1) atomic fluorine abstraction of hydrogen atoms from appropriate molecules has been demonstrated to be an important class of reactions for chemical lasers W. In particular, the reactions of F + H2 HF + H and F + D DF + D have been investigated in great detail by various theoretical and experimental approaches (3-11) the latter reaction provides us with an example from the general class of reactions of fluorine atoms with diatomic molecules. (2) Substitution reactions of fluorine atoms with unsaturated hydrocarbons Involving the formation of C-F bonds frequently are observed to proceed through a "complex" which... 

On the basis of a density functional theory study, it was found that the C-F bond dissociation energy required for fluorine abstraction is lowest for tertiary carbon and highest for primary carbon (Mitov et al. 2005). The C-F bond on the side chain a-ether carbon is thus potentially more activated, which creates a weak site for radical attack and chain scission. Even with the less stable C-F bonds, direct HO attack is unlikely, as discussed above. 

We attempted to expand the scope of this reaction by investigating substrates from which fluorine abstraction would be much more difficult. First, we... 

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