Sulfonyl fluorides

Yields of sulfonyl fluorides prepared by ECF vary depending on the particular stmcture. Chain degradation becomes more important as the chain length kicreases (6). Yields can vary from 96% for perfluoromethanesulfonyl fluoride (7) to 43—50% for perfluorooctanesulfonyl fluoride (8). Trifluoromethanesulfonic acid can be prepared via trifluoromethanesulfenyl chloride as shown ki equations 5—7 (9). 

Other preparations of trifluoromethanesulfonic acid kiclude oxidation of methyltrifluoromethyl sulfide under a variety of conditions (10,11). Perfluorosulfonyl fluorides have also been prepared by reaction of fluoroolefkis with sulfuryl fluoride (12,13). Chinese chemists have pubflshed numerous papers on the conversion of telomer-based alkyl iodides to sulfonyl fluorides (14,15) (eqs. 8 and 9) ... 

The metallic salts of trifluoromethanesulfonic acid can be prepared by reaction of the acid with the corresponding hydroxide or carbonate or by reaction of sulfonyl fluoride with the corresponding hydroxide. The salts are hydroscopic but can be dehydrated at 100°C under vacuum. The sodium salt has a melting point of 248°C and decomposes at 425°C. The lithium salt of trifluoromethanesulfonic acid [33454-82-9] CF SO Li, commonly called lithium triflate, is used as a battery electrolyte in primary lithium batteries because solutions of it exhibit high electrical conductivity, and because of the compound s low toxicity and excellent chemical stabiUty. It melts at 423°C and decomposes at 430°C. It is quite soluble in polar organic solvents and water. Table 2 shows the electrical conductivities of lithium triflate in comparison with other lithium electrolytes which are much more toxic (24). 

Carbonyl sulfonyl fluorides of the formula FC0(CF2) S02F have been prepared by electrochemical fluorination of hydrocarbon sultones (41,42). More commonly in a technology pioneered by Du Pont, perfluoroalkanecarbonyl sulfonyl fluorides are prepared by addition of SO to tetrafluoroethylene followed by isomerization with a tertiary amine such as triethylamine (43). 

The vinyl ether in the latter part of the equation is copolymetized with tetrafluoroethylene, and then the sulfonyl fluoride group is hydrolyzed under basic conditions in order to produce the ion-exchange membrane (44—46). 

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may be used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, aHenes, and ketenes, as shown in Figure 1 (10). Sulfonic acids may be converted to sulfonamides via reaction with an amine in the presence of phosphoms oxychloride [10025-87-3] POCl (H)- Because sulfonic acids are generally not converted directiy to sulfonamides, the reaction most likely involves a sulfonyl chloride intermediate. Phosphoms pentachlotide [10026-13-8] and phosphoms pentabromide [7789-69-7] can be used to convert sulfonic acids to the corresponding sulfonyl haUdes (12,13). The conversion may also be accompHshed by continuous electrolysis of thiols or disulfides in the presence of aqueous HCl [7647-01-0] (14) or by direct sulfonation with chlorosulfuric acid. Sulfonyl fluorides are typically prepared by direct sulfonation with fluorosulfutic acid [7789-21-17, or by reaction of the sulfonic acid or sulfonate with fluorosulfutic acid. Halogenation of sulfonic acids, which avoids production of a sulfonyl haUde, can be achieved under oxidative halogenation conditions (15). 

Amino groups bound to sulfur can be replaced by fluorine via diazotization. In contrast to carboxylic acid amides, fluorodediazoniation of aromatic sulfonamides IS readily accomplished to give sulfonyl fluorides in high yields [52, 7S (equation 16) Tetrazotization-fluorination of sulfanilamide can also be effected to give a 38% yield of p-fluorobenzenesulfonyl fluoride [52],... 

Inhibitors which interact only with peptidases of one catalytic type include pepstatin (aspartic peptidases) E64 (cysteine peptidases from clan CA) diisopropyl fluorophosphates (DFP) and phenylmethane sulfonyl-fluoride (PMSF) (serine peptidases). Bestatin is a useful inhibitor of aminopeptidases. 

Besides radical additions to unsaturated C—C bonds (Section III.B.l) and sulfene reactions (see above), sulfonyl halides are able to furnish sulfones by nucleophilic substitution of halide by appropriate C-nucleophiles. Undesired radical reactions are suppressed by avoiding heat, irradiation, radical initiators, transition-element ion catalysis, and unsuitable halogens. However, a second type of undesired reaction can occur by transfer of halogen instead of sulfonyl groups283-286 (which becomes the main reaction, e.g. with sulfuryl chloride). Normally, both types of undesired side-reaction can be avoided by utilizing sulfonyl fluorides. 

Finally, the reaction of 19b with potassium fluoride in the presence of a crown-ether phase-transfer agent118 to yield the sulfonyl fluoride 67 and diphenylacetylene119 belongs to the same category in which a nucleophile (F in this case) attacks the electrophilic sulfur of the sulfone group (equation 19). 

This reaction, parallel with 10-77, is the standard method for the preparation of sulfonyl halides. Also used are PCI3 and SOCI2, and sulfonic acid salts can also serve as substrates. Sulfonyl bromides and iodides have been prepared from sulfonyl hydrazides (ArS02NHNH2, themselves prepared by 10-126) by treatment with bromine or iodine.Sulfonyl fluorides are generally prepared from the chlorides, by halogen exchange. 

The reaction can be extended to the preparation of alkyl aryl sulfones by the use of a sulfonyl fluoride. 

Whereas aryl Grignard compounds afford good yields of sulfones with sulfonyl fluorides , phenyllithium is mainly chlorinated by a-toluene-sulfonyl chloride on the other hand, the corresponding fluoride yields only a trace of the expected mono-sulfonylation product, while the main product is 26 obtained by twofold sulfonylation °° (equation 61). 

The formation of halogenation products from Grignard reagents and sulfonic acid anhydrides is the result of an oxidative reaction pathway . This side-reaction can be reduced by using sulfonic acid esters, however, in these cases alkylations as well as twofold sulfonylations (cf. corresponding results with sulfonyl fluorides ) are competing (equations 64 and 65). 

Deutsch DG, Lin S, Hill WAG, Morse KL, Salehani D, Arreaza G, Omeir RL, Makriyannis A. Fatty acid sulfonyl fluorides inhibit anandamide metabolism and bind to the cannabinoid receptor. Biochem Biophys Res Com-mun 1997 231 217-221. 

Although the chemical shifts of most commonly encountered orga-nofluorine compounds are upheld of CFC13 and thus have negative values, there are a number of structural situations for fluorine that lead to positive chemical shifts (downfield from CFC13). These include acyl and sulfonyl fluorides as well as the fluorines of SF5 substituents. 

As indicated in Chapter 2, the single fluorine substituent has an extremely broad range of observed chemical shifts, which include sulfonyl fluorides and acyl fluorides absorbing downfield in the region of +40 and +25 ppm, respectively, all the way up to fluoromethyltrimethylsilane, with its signal far upheld at -277 ppm. 

Two other functional groups that contain a single fluorine substituent are acyl fluorides and sulfonyl fluorides. Such fluorines are among the rare few that absorb in the highly deshielded region downfield of CFC13. 

Chapter 6 will provide a more thorough coverage of compounds with fluorine bound directly to sulfur, but typical examples of sulfinyl and sulfonyl fluorides are given in Scheme 3.75. 

Typical examples of fluorine chemical shifts of sulfinyl and sulfonyl fluorides are give in Scheme 7.21. 

An efficient method has been developed for the conversion of pyrimidine-2-thiol into the sulfonyl chloride 75, which was reacted in situ with amines. A modified method gave the rather more stable (and storable) sulfonyl fluoride 74 <06JOC1081>. 

Sulfonyl Chloride Sulfonyl Dichloride Sulfonyl Difluoride Sulfonyl Fluoride... 

Thaw roots for 2 min by dipping into 50% dimethyl sulfoxide containing 0.1 MNa-cacodylate, pH 7.4,2 mM CaCl2,5 mMMgCl2, and 1 mM phenylmethyl-sulfonyl fluoride (PMSF). 

Since PTFE was first synthesized more than 50 years ago, fluoropolymers have been produced by radical polymerization and copolymerizaton processes, but without any functional groups, for several reasons. First, the synthesis of functional vinyl compounds suitable for radical polymerization is much more complicated and expensive in comparison with common fluoroolefins. In radical polymerization of one of the simplest possible candidates—perfluorovinyl sulfonic acid (or sulfonyl fluoride—there was not enough reactivity to provide high-molecular-weight polymers or even perfluorinated copolymers with considerable functional comonomer content. Several methods for the synthesis of the other simplest monomer—trifluoroacrylic acid or its esters—were reported,1 but convenient improved synthesis of these compounds as well as radical copolymerization with TFE induced by y-irradiation were not described until 1980.2... 

As the initial sulfonyl fluoride groups can be easily modified by the reaction with corresponding amino derivatives, e.g., those of crown ethers, the composites obtained can be used as polymeric reagents for a wide range of organic reactions. 

---