Nonfluorinated

Fluorochemicals repel both water and oU because they produce an extremely low energy surface (18—26). The effectiveness of the fluorochemicals depends upon uniform surface coverage and orientation of the molecules on the fiber surface so that the perfluoroalkyl chains are directed away from the surface. The result is a GST as low as 5—10 mN /m (dyne/cm). Fluorochemical finishes are often formulated with nonfluorinated resin-based water-repeUent extenders. These water repeUents not only reduce the cost of the finish but may also improve durabUity (27,28). 

Nonfluorinated a- and P diketoms give the corresponding tetrafluoroalkanes as the major products together with considerable amounts of alkenes, ethers, and sulfites Formation of side products is reduced, and yields of tetrafluoroalkanes are greatly improved by conducting the lluori nation reactions in an excess of anhydrous hydrogen fluoride [176, 177]... 

Generally, additions of halogens to fluoroalkenes are less stereoselective than the analogous reactions with nonfluorinated systems. The stereochemical mode of addition can be either anti or syn Partitioning between these paths is determined... 

Fluoroolefins may he prepared by the reaction of Wittig reagents and other pho sphorus-containtng y tides with fluorinated carbonyl compounds. (A discussion of the fluorinated Wittig reagents or other fluonnated phosphorus reagents with nonfluorinated carbonyl compounds is on page 581.) Tnphenylphosphoranes, derived from alkyltriphenyl phosphonium salts, react with 1,1,1-trifluoroacetone [3/] or other trifluoromethyl ketones [32, iJ] (equation 26) (Table 10). 

This new reaction type should be transferable to nonfluorinated hetero-1,3-di-enes that are capable of stepwise cycloaddition reactions... 

The elimination of water from a fluorinated compound generally follows a reaction path similar to that of its nonfluorinated counterpart, although the presence of the highly electronegative fluorine atoms may have unexpected effects Various monofluoro alcohols can be dehydrated via their tosyl esters at 75 C by using potassium rert-butoxide [80] (equation 50)... 

Certain fluorine compounds may be used to dehydrate nonfluorinated alcohols through their complexes or derivatives With aleohols, 1,1,1-trichlorotri-fluoroacetone forms intermediate hemiketals that easily decompose to olefins in the presence of a catalytic amount of p toluenesulfomc acid [S5] Similarly, the... 

Table 3. Bailing Points of Perfluonnated and Nonfluorinated Isomers...

The Dewar benzene of hexafluorobenzene formed an adduct with pheny-lazide that gave a polyfluoro-l//-azepine on pyrolysis. R=C02Et (47) was obtained when ethylazidoformate was decomposed in C6F6 [82JCS(P1)2101]. Photolysis of (47) yielded a 2-aza-bicyclo(3.2.0.)hepta-3,6-diene, which, in contrast to its nonfluorinated analogue, showed excellent thermal stability (3 h, 200°C, 88% recovered) [82JCS(P1 )2105]. 

FIGURE 23.14 Explosive decompression (ED) damage in a fluoroelastomer O-ring seal section left and miscellaneous samples of a nonfluorinated oil-field elastomer right obtained using pressure vessels such as those shown in Eigure 23.15. 

H and 13C NMR Data. The examples in Scheme 3.23 provide characteristic proton and carbon chemical shift and coupling constant data for fluorinated alcohols, ethers, thioethers, sulfoxides, and sul-fones. An ether substituent serves to deshield the carbon of a CH2F by about 20 ppm. This can be compared to the 40-ppm deshielding generally observed in a nonfluorinated ether system. Thus, the fluorine substituent seems to have a damping effect on the usual effects of other substituents. 

The heterobimetallic asymmetric catalyst, Sm-Li-(/ )-BINOL, catalyzes the nitro-aldol reaction of ot,ot-difluoroaldehydes with nitromethane in a good enantioselective manner, as shown in Eq. 3.78. In general, catalytic asymmetric syntheses of fluorine containing compounds have been rather difficult. The S configuration of the nitro-aldol adduct of Eq. 3.78 shows that the nitronate reacts preferentially on the Si face of aldehydes in the presence of (R)-LLB. In general, (R)-LLB causes attack on the Re face. Thus, enantiotopic face selection for a,a-difluoroaldehydes is opposite to that for nonfluorinated aldehydes. The stereoselectivity for a,a-difluoroaldehydes is identical to that of (3-alkoxyaldehydes, as shown in Scheme 3.19, suggesting that the fluorine atoms at the a-position have a great influence on enantioface selection. 

Some of the disadvantages of the Stille reaction, e. g. the low reactivity of some substrates, separation difficulties in chromatography, and the toxicity of tin compounds, have been ameliorated by recent efforts to improve the procedure. Curran has, in a series of papers, reported the development of the concept of fluorous chemistry, in which the special solubility properties of perfluorinated or partly fluorinated reagents and solvents are put to good use [45]. In short, fluorinated solvents are well known for their insolubility in standard organic solvents or water. If a compound contains a sufficient number of fluorine atoms it will partition to the fluorous phase, if such a phase is present. An extraction procedure would thus give rise to a three-phase solution enabling ready separation of fluorinated from nonfluorinated compounds. 

Since the reaction is shown to be a one-electron oxidation process, the reaction may proceed via a perfluoro carbocation intermediate as is seen with nonfluorinated iodides (Eq. 15). 

The reaction proceeds via electrogenerated cationic species as its seen with the nonfluorinated amines, carbamates, and amides (Scheme 6.14). However, the regiochemistry of this anodic methoxylation is not governed by the stability of the cationic intermediates B and B (thermodynamic control) since the main products are formed via the less stable intermediates B. Indeed, this remarkable promotion effect and unique regioselectivity can be explained mainly in terms of a-CH kinetic acidities of the cation radicals formed by one-electron oxidation of the amines since the stronger the acidity of the methylene hydrogen, the easier the deprotonation. 

As part of an effort to develop high-performance, high-temperature-resistant polymers for microelectronics applications, we also recently described a series of both partially fluorinated and nonfluorinated poly(aryl ether ketone)s containing amide, amide-imide, cyano oxadizole, or pyridazine groups and characterized their thermal and electrical properties.11... 

In Figure 15.2 Pictures 1.1 and 2.1 are SEM images of nonfluorinated (reference) material and fluorinated samples (Batch 15A20PR7), and Pictures 1.2 and 2.2 are the corresponding X-ray spectra. The EDS spectrum shows that Batch 15A20PR is fluorinated, since a fluorine peak can be seen in the left part of the spectrum (Picture 1.2). 

Change in charge density for the indicated carbon atom in the nonfluorinated compound (qC,. . . -... 

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