Migration fluorine

In Figure 6.22, the product ion scan of (M—H) mIz 352, C17H10N1O2F3CI, showed three major product ions at miz 286 (loss of F2CO) with the fluorine migrating to the indole ring, miz 283 (loss of CF3 radical) and m z 266 (loss of CF3OH). Using the (M—H) ion at miz 352 as the reference mass the measured exact masses were all within 5.8 ppm of the theoretical value for the proposed formula. 

It is presumed that the barrier-to-1,2-fluorine migration in the singlet nitrene substantially exceeds the analogous barrier-to-hydrogen shift. This difference allows a portion of the nascent singlet nitrene to relax to the lower energy triplet in the matrix. 

The mass spectra of various /3-diketonates have been extensively studied.762,763 The availability of ionization energies, measured by mass spectra, has led to a fairly detailed debate as to the nature of the orbital from which the first electron ionizes.764 Gas phase rearrangements,765 often involving fluorine migration to the metal, have been observed. The SIMS spectrum of [Cr(acac)3] is particularly simple,766 yielding the base peak [Cr(acac)2]+. 

Fluorine migrates around a benzene ring in the presence of aluminum trichloride and water.2-3 Thus, starting with any of the three positional isomers of ethylfluorobenzene (1), an equilibrium mixture of the ortho-, meta-, and /wa-isomers is obtained in a ratio of roughly 3.5 5 1.5. 

Fluorine coordination degenerate fluorine migration in a Merry-Go-Round type mechanism... 

The appearance of SnF+ ions is also observed in the mass spectra of (p- or m-CF3C6FLt)4Sn and it becomes the major ion in the spectra of the perfluorinated (CgFs Sn species. This fluorine migration has been rationalized in terms of hard/soft acid base theory (HSAB) by considering Sn2+ as a hard acid that favors fluoride transfer55. 

Another reaction in which the dimerization of a mononuclear silylene complex is suggested to play an important role is shown in Scheme ll.58 After the oxidative addition of disilacyclobutene to each iron center, fluorine migration accompanied by the cleavage of the Fe-Fe bond leads to a silyl(silylene) complex as one of the intermediates, which then dimerizes in head-to-tail fashion to form the product. 

Group Migration Reactions.—1,3-Fluorine migrations have been reported following the mercury-sensitized irradiation (7 days) of the perfluoroalkenes (17a) and (17b).The products from the reaction are the skeletally rearranged compounds (18). Direct irradiation of the natural product Mortonin C (19) in methanol yielded two photoproducts identified as (20a) and (20b). These... 

There is also a report of fluorophosphine formation via fluorine migration from carbon to phosphorus in the thermal decomposition of bistrifluoromethyldiphosphoxane 119). 

The enzymatic migration of chloro and bromo groups, but not of fluoro substituents, by a cationoid mechanism is supported by observations on aluminum chloride-catalyzed isomerizations of halo arenes (22), where all halogens except fluorine migrate by a mechanism involving cationoid intermediates. For the enzymes, however, fluorine appears to be removed reductively, so that it is lost as fluoride ion rather than as positive fluorine. 

Fluorine migration from the CF3 group to the metal occurs with Cr", Fe ", Co ", Pt" and Zn" but not with Ru ", Rh" , Ni" and Pd". The reaction pathway for the zinc complexes is shown in Scheme 3. The molecular ion (48) loses a CFj radical from one monothio-)8-diketone moiety to give the ion (49), which then loses carbon monoxide to yield the fragment (50). Sulfur is ejected from (50) with the concomitant formation of a zinc-carbon bond in the species (51), which can subsequently lose the alkyne RC=CH to give the mono-ligand ion [ZnL] (52). The second ligand moiety loses Cp2 with the formation of a zinc-fluorine bond in the ion (53). 

Pomes V, Fernandez A, Costarramone N, Grano B, Houi D. (1999). Fluorine migration in a soil bed submitted to an electric field Influence of electric potential on fluorine removal. Colloids and Surfaces A Physicochemical and Engineering Aspects 159 481-490. 

Many other systems have subsequently been found to display anion conductivity. The electrical conductivity of lead fluoroborate and fluorogermanate glasses is similar to that of the lead fluorosilicate glasses. Calcium fluoroaluminate glasses also conduct by fluorine migration. Fluorophosphate glasses have also proven to be good anionic conductors. All of these systems are free of alkali ions. 

Allylpentafluorobenzene photoisomerizes to the Dewar-benzene (123), but pentailuorostyrenes yield benzocyclobutenes, e.g. (124), by fluorine migration. ... 

Although the high volatility of fluorinated hydrocarbons is of potential advantage in GC work, they capture electrons poorly. However, the presence of a number of fluorine atoms can produce derivatives that exhibit favourable detection limits. The flophemesyl derivatives discussed above are excellent examples of the use of multiple fluorination to enhance detectability. Fluoroalkylsilanes with fluorine atoms alpha or beta to the silicon are thermally unstable at GC elution temperatures above 200 °C because of fluorine migration. 

In then article on intramolecular fluorine migration via four-member cychc transition states Nguyen et al analysed p values at BCPs in transition states of fluorinated aldehydes and acychc ketones reactants at the B3LYP/6-31G // B3LYP/6-31G level. 

Arsenault G, McAlees A, McCrindle R et al (2007) Analysis of perfluoroalkyl anion fragmentation pathways for perfluoroalkyl carboxylates and sulfonates during liquid chromatog-raphy/tandem mass spectrometry evidence for fluorine migration prior to secondary and tertiary fragmentation. Rapid Commun Mass Spec 21 3803-3814... 

Perfluoromethacryloyl fluoride forms both [2 + 2] and, with fluorine migration, [2 + 4] adducts with isocyanates adducts are also formed with olefins, probably via dipolar intermediates, e.g. (65) with propene, which may cyclize or undergo proton or fluoride ion migration. [2 + 4] Adducts are formed with ketens and nitriles. Perfluoroacryoyl fluoride adds neither... 

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