Group, replacement fluonne

Boron tribromide replaces fluonne with bromine on tertiary or secondary carbons however, trifluoromethyl groups are inert in this reaction [70] (equation 57). 

Perfluoropmacol reacts with sulfur tetrafluonde in an unconventional way instead of replacement of the hydroxyl groups by fluorine, the substitution of four fluonne atoms in the sulfur tetrafluonde molecule with oxygen occurs to give the corresponding spirosulfurane [J6J] (equation 79)... 

The reaction of diethyl tartrate with sulfur tetrafluonde at 25 °C results in replacement of one hydroxyl group, whereas at 100 °C, both hydroxyl groups are replaced by fluonne to form a,a -difluorosuccinate [762] The stereochemical outcome of the fluonnation of tartrate esters is retention of configuration at one of the chiral carbon atoms and inversion of configuration at the second chiral center [163,164, 165] Thus, treatment ofdimethyl(+)-L-tartrate with sulfur tetrafluonde gives dimethyl meso-a,a difluorosuccinate as the final product [163, 164], whereas dimethyl meso tartrate is converted into a racemic mixture of D- and L-a,a -difluorosuccmates [765] (equation 80)... 

Functionalized hydrazine groups can be replaced by fluonne. The first example is the replacement ot tnalkylhydrazine groups in bis(l,2,2-trimethylhydrazmo)meth-ane, a hydrazine acetal, by tnchloroacetyl fluonde to fotm 1,1,2- trimethyl-2-fluoromethylhydrazine in 87% yield [5J]... 

A nitro group in the artho or para position to fluonne is known to enhance its replacement by hydroxyl [II, 12] Bromine and iodine are much less prone to hydrolysis under similar conditions The effect is much less pronounced with the meta nitro derivative (equation 11) With o-nitro-p-fluoroaniline, it is the amino group ortho to the nitro group, rather than meia fluorine, that is replaced by hydroxyl (equation 12)... 

The replacement of a substituent on an aromauc nng by a nucleophile is termed arylaUon. This chapter considers the replacement by nucleophihc oxygen, sulfur, nitrogen, and carbon of aromatic fluonne atoms, which are often activated by electron-withdrawing groups. 

The fluonne atom of monofluoroaromatk systems activated toward the S Ar reaction by electron-withdrawmg groups is readily replaced by alkoxide ion [7, 2, 3, 4, 5] (equations 1 and 2),... 

When position 4 of perfluoropyridine is blocked with a poor leaving group, ammonia replaces the fluonne in position 2 in good yield. Oxidation of the products obtained with hypochlorite, followed by lodme-catalyzed rearrangement, yields interesting fluorodienes [78] (equation 41) Ultraviolet irradiation can be used to assist reactions m which substitution is difficult [79]... 

The mfluoromethyl group activates the fluorine in position 4 ofperfluorotolu ene toward reaction with carbon nucleophiles Examples on che use of perfluoro-toluene as an arylation agent abound, and in all cases, the 4-fluonne atom is replaced predommantly or exclusively [% 87,88,89, 90 (equation 48) In perjluoromesity-lene, the aromatic fluorine atoms are activated toward Ar reaction, and a reaction... 

Reactions of fluorinated dipolarophiles. Electron-deficient unsaturated species generally make better dipolarophiles, therefore, fluonnated alkenes become better dipolarophiles when vinylic fluonnes are replaced by perfluoroalkyl groups For example, perfluoro-2-butene is unreactive with diazomethane, but more highly substituted perfluoroalkenes, such as perfluoro-2-methyl-2-pentene, undergo cycloadditions in high yields [5] (equation 2) Note the regiospecificity that IS observed in this reaction... 

One of the most useful ways of introducing fluonne into organic compounds is the replacement of the hydroxyl group in alcohols hydroxy compounds, and carboxylic acuis Methyl alcohol reacts with anhydrous hydrogen fluoride at 100 500 C in the presence of aluminum fluoride [60, 6J], zinc fluoride [62] chromium fluonde [63], or a mixture of aluminum and chromium fluondes [64] to give a 20-78% yield of fluoromethane Attempted fluorinations of higher alcohols by this method failed [60]... 

---