SYNTHETIC AND MECHANISTIC STUDIES IN ORGANIC FLUORINE CHEMISTRY.

摘要

The synthesis and reactions of some electrophilic halogen sources were investigated. Most of these materials were fluorinated compounds containing oxygen-halogen bond, where the halogen bonded to oxygen is the halogen electrophile.;Some new chemistry of Cl (I) and Br (I) trifluoromethane sulfonates was investigated. It was shown that these hypihalites are equally effective in undergoing substitutive electrophilic dehalogenation with inorganic substrates as with organic substrates. Several trifluoromethane sulfonate esters of non-metals were synthesized. These hypohalites also readily undergo addition to unsaturated molecules like CO, SO(,2) and SF(,4). For comparison some reactions of the related compound, FSO(,2)OBr, were also studied. The isolation of F(,2)P(O)OSO(,2)F and F(,2)P(O)OSO(,2)CF(,3) allowed a comparison of the group electronegativities of FSO(,3) and CF(,3)SO(,3) which are identical.;Two new hypohalites, perfluoro-n-butanesulfonyl hypochlorite and hypobromite are also reported. The synthesis of these hypohalites was undertaken to compare the effects of the larger perfluoroalkyl groups on stability and reactivity of this class of compounds. The new hypohalites exhibit reactions similar to the analogous trifluoromethanesulfonates, CF(,3)SO(,3)X (X = Cl, Br), which are source of very electrophilic halogens.;The reactions of CS(,2) with ClF, CF(,3)OCl and CF(,3)OF were also examined in an attempt to prepare some novel dithietanes. However the reactions were very complex and no new compounds could be unambiguously identified.;The addition of fluoroxytrifluoromethane to alkenes were investigated. The hypofluorite was added to simple olefins and the results were compared to the addition of trifluoromethanehypochlorite to the same alkenes. The additions of CF(,3)OCl to the double bonds are consistent with an electrophilic mechanism. With certain olefins it was possible to observe the stereochemistry of the addition and in every case reactions of CF(,3)OCl were, stereospecific. With CF(,3)OF, however, no stereospecific was observed. The addition products are readily explained on the basis of a free-radical mechanism, where the CF(,3)O attacks the least sterically hindered carbon of the olefin.