Free radicals trifluoromethyl, structure

Styrene and 1,1-diphenylethene are frequently used as target molecules in investigations of the role of reagent structure on its reactivity toward organic compounds. Low-temperature fluorination with trifluoromethyl hypofluorite gives up to six products.32-33 The Hammett correlation value q was established to be — 2.48 and a mechanism suggested in which spin-paired free-radical pairs arc formed, which are then converted by electron transfer into an ion pair.33... 

ESR spectroscopy is perhaps the best method for the unequivocal detection and observation of free radicals, and ESR 13C hyperfine splitting (hfs) constants are considered to be a very useful indicator of a radical s geometry because non-planarity introduces s character into the orbital that contains the unpaired electron. The methyl radical s 13Ca value of 38 G is consistent with a planar structure. Fluoromethyl radicals exhibit increased 13Ca values, as shown in Table 1, thus indicating increasing non-planarity, with trifluoromethyl radical s value of 272 G lying close to that expected for its sp3 hybridization [4]. 

Free-radical initiation of the polymerization of pcrfluorobut-2-yne is difficult, and the solid polymer has previously been obtainable only by y-ray initiation or by a fluoride-initiated anionic pathway. - " A new technique now disclosed involves the use of trifluoromethyl hypofluorite, which at sub-ambient temperatures catalyses the conversion of the butyne to a polymer which is quite stable at 450 "C. Mass spectrometric analyses of the oligomers obtained by the anionic pathway, containing up to twelve butyne units, are consistent with an all-fra s conjugated polyolefin structure H—[CfCFs) C(CFa)]B—F. This result is wholly consistent with trapping experiments in which the incipient vinyl anions are intercepted by, for example, penta-fluoropyridine to give /ranj-olefins and /ranj,fra j-dienes. - ... 

Fluorinated poly(methacrylates) or poly(acrylates), rich in trifluoromethyl groups, exhibit superior performance of chemical inertness, excellent weatherability, low refractive index, lower dielectric constant, and special surface properties [14,61]. Poly(2,2,2-trifluoroethyl methacrylate), poly(MATRIF), is an important class of such materials. It has been extensively used in high performance coatings [17], photoelectric communications, and microelectronics [62]. Poly(MATRIF) is easily produced by free radical polymerization using bulk, solution, and emulsion polymerization methods [63]. Structural characterization of NMR of poly(MATRIF) prepared by radical and anionic polymerization has been studied. Syndiotactic structure was obtained by radical initiator in contrast to an isotactic structure achieved by anionic polymerization [64]. 

Radicals with very polar substituents e.g. trifluoromethyl radical 2), and radicals that arc part of strained ring systems (e.g. cydopropyl radical 3) arc ct-radicals. They have a pyramidal structure and are depicted with the free spin resident in an spJ hybrid orbital. nr-Radicals with appropriate substitution are potentially chiral, however, barriers to inversion are typically low with respect to the activation energy for reaction. 

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