Addition of fluorine atoms

Since metal ions play key roles in cellular physiological processes many specific reporter molecules have been developed, mostly as fluorescent indicators incorporating extended aromatic and conjugated structures, where the wavelength of fluorescence depends upon specific binding of a metal ion. Several F NMR reporters have been created by addition of fluorine atoms (Table 5). 

Investigation of the reaction of xenon difluoride and difluoroiodobenzene with aliphatic 1,3-dienes in the presence of boron trifluoride-diethyl ether complex has shown that under mild conditions this reaction proceeds with kinetic control, to form mainly the products of 1,2-addition of fluorine atoms. The ratio of product is reported in Table 5. 

There is yet another phenomenon that points to a 1,4-addition of fluorine atoms occurring at least partially The products obtained from the reaction of single-walled carbon nanotubes with fluorine are definite nonconductors (resistance >20 MQ), while the nanotubes employed feature a resistance of 10-15 2 only. Considering the structures that result from a consecutive 1,2- or 1,4-addition of fluorine, respectively, reveals that an electric current via conjugated it-bonds would still be possible in the 1,2-adduct (Figure 3.70). In the 1,4-adduct, on the other... 

ADDITION OF FLUORINE ATOMS TO DOUBLE AND TRIPLE BONDS... 

The addition of fluorine atoms to butene has been investigated as an extension of the ejq)eriments outlined above. Isobutylene was also studied with the N2F4 technique and behaved very similarly to propylene (3 ). The ratio of terminal to central addition was 3.1/1.0, again with no correction for decomposition of (CHs)2CFCH2 formed at relatively low pressures. Standard F experiments with isobutylene and HI are not possible because they react with each other thermally. Tracer F studies with 1-butene have shown that it resembles F-... 

The addition of fluorine atoms to olefins carries the possibility of significant isotope effects at several stages of reaction. The most extensive study of these possibilities has been carried... 

Bettinger, H. F. (2004). Effects of finite carbon nanotube length on sidewall addition of fluorine atom and methylene. Organic Letters, 6,731-734. 

The fluorination reaction is best described as a radical-chain process involving fluorine atoms (19) and hydrogen abstraction as the initiation step. If the molecule contains unsaturation, addition of fluorine also takes place (17). Gomplete fluorination of complex molecules can be conducted using this method (see Fluorine compounds, organic-direct fluorination). 

The solubility is generally improved by the introduction of fluorine atoms into aromatic condensation polymers. Poly(carbonate)s containing hexafluoroisopropylidene units are much more soluble than Bisphenol A poly(carbonate) (3). All of the hexafluoroisopropylidene-unit-containing poly(carbonate)s become soluble in acetone, ethyl acetate, chloroform, and dimethyl sulfoxide (DMSO) in addition to the solvents of Bisphenol A poly(carbonate) (3). Colorless, transparent, and flexible films are prepared from hexafluoroisopropylidene-unit-containing poly(carbonate)s by casting or pressing. 

The exceptional thermal and chemical stability of PTFE originate in the strength of its primary chemical bonds. The carbon-fluorine bond energy is the highest currently known among organic compounds [3, 4]. In addition, the fluorine atoms... 

The sulfur tetrafluoride fluorination of most nonhalogenated quinones and hydroxyquinones is erratic in behavior and generally occurs with isomerization, substitution of a hydrogen atom by fluorine, and addition of fluorine to the carbon atom / to the carbonyl group. Thus, the fluorination of benzo-l,4-quinone results in aromatization to give 1,2,4-trifluorobenzene (8) as the sole product.41... 

Highly halogenated alkenes, e.g. 6, react with sulfur tetrafluoride at elevated temperatures in the presence of Lewis acid type fluorides to afford halofluoroalkanes, which result from both addition of fluorine to the C = C bond and substitution of halogen atoms.191... 

The fluorination of polyfluorocyclohexenes with antimony(V) fluoride proceeds under much more severe temperature conditions ( 150 C) than with vanadium(V) fluoride (see Section 12.4.2). In these reactions antimony(V) fluoride effects both the oxidative addition of fluorine and the substitution of vinyl chlorine atoms by fluorine.48... 

In the case of addition of fluorine to double bonds (Table II), note that the corresponding initiation step (lb) is probably exothermic by 5-36 kcal and thus plays an important role. A second important possibility is the concerted reaction mechanism 2, which is exothermic by 50-68.4 kcal per carbon atom. 

A laser beam was used for graft polymerization of AAc onto a tetrafluo-roethylene-perfluoroalkyl vinyl ether copolymer film [81]. The film placed in contact with AAc solution was irradiated with KrF laser through the film to excite the film/solution interface. Surface composition of the grafted film determined by XPS revealed an extensive loss of fluorine atom and an increase of oxygen atom in addition to the presence of a Cls line shape, similar to that of AAc monomer. Mirzadeh et al. [82] used pulsed laser beam for the graft polymerization of AAm on a rubber surface in the presence of a photosensitizer, ben-zophenone, or AIBN. 

In order to determine whether the enhanced reactivities of perfluoroalkyl radicals could be attributed to some linear combination of the individual contributions of fluorine atoms on the a-carbon (the radical center), the /1-carbon and the y-carbon atom, the absolute rates of addition of a number of parfza/Zy-fluorinated alkyl radicals to a-methylstyrene, styrene, and pentafluorostyrene were determined by LFP [70]. The data in Table 9 clearly indicated that this is not the case, that y- and /1-fluorinated-n-alkyl radicals exhibit little enhancement, while a-difluoroalkyl radicals, although more reactive, remain very much less-reactive than analogous perfluoro species. 

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