Trifluoromethylsulfonation

The most useful pseudo-halides are aryl triflates (trifluoromethylsulfonates) of phenols and enol triflates derived from carbonyl compounds[4,5,6]. 

Cupric trifluoromethylsulfonate (copper II triflate) [34946-82-2] M 361.7, pK <-3.0 (for triflic acid). Dissolve in MeCN, add dry Et20 until cloudy and cool at -20° in a freezer. The light blue ppte is collected and dried in a vacuum oven at 130°/20mm for 8h. It has Xmax 737nm (e 22.4M cm ) in AcOH. [J Am Chem Soc 95 330 1973], It has also been dried in a vessel at O.lTorr by heating with a Fischer burner [J Org Chem 43 3422 1978], It has been dried at 110-120°/5mm for Ih before use and forms a benzene complex which should be handled in a dry box because it is air sensitive [Chem Pharm Bull Jpn 28 262 I980-, J Am Chem Soc 95 330 1973]. 

Acetals can be prepared under very mild conditions by reaction of the carbonyl compound with a trimethylsilyl ether, using trimethylsilyl trifluoromethylsulfonate as the catalyst.248... 

As an example of esters of aliphatic sulfonic acids trifluoromethylsulfonic imidazo-lide has been treated with various phenols to give phenyl sulfonic esters [U1... 

Phenols can be converted with trifluoromethylsulfonic imidazolide in the presence of sodium hydride into the corresponding trifluoromethylsulfonates, which react with potassium amide/ammonia to give aromatic amines. 15]... 

Many of these complications can be avoided when monosulfoxides are converted to the dications using triflic anhydride instead of concentrated sulfuric acid. This method was suggested by Furukawa et al.71 in 1987. Reaction of triflic anhydride with a monosulfoxide72 transforms it into trifluoromethanesulfonyloxysulfonium salt 47, which undergoes clean intramolecular nucleophilic substitution of trifluoromethylsulfonate anion by the other sulfur atom with formation of the disulfonium dication 34 in a high yield (Scheme 16).73... 

N Fujii, A Otaka, O Ikemura, K Akiji, S Funakoshi, Y Hayashi, Y Kuroda, H Yajima. Trimethylsilyl trifluoromethylsulfonate as a useful deprotecting reagent in both solution and solid phase peptide syntheses. J Chem Soc Chem Commun 274, 1987. 

A reaction which is related to hydroxy-de-diazoniations is the formation of aryl trifluoromethylsulfonic esters (aryl triflates, ArOSC CFs) which became widely used reagents because of their leaving-group properties. The classical method of synthesis by esterification of phenols with trifluoromethane-sulfonic anhydride or -sulfonyl halide is, however, not applicable for the preparation of aryl triflates bearing a (free)... 

The evaluation of catalysts typically uses two techniques. The first is evaluation as a thin layer on a bulk electrode (e.g., glassy carbon) in dilute liquid electrolyte (e.g., H2 4) either as a static electrode or an RDE. In the study of oxygen reduction, there has been much discussion as to the most appropriate electrolyte to use. In general, dilute perchloric acid (HCIOJ is preferred because of its noncoordinating nature, it is thus closest to the environment foxmd within a FEM catalyst layer with perfluorosulfonic acid ionomer. A possible alternative is trifluoromethylsulfonic acid (CF3SO3H), which mimics perfluorosulfonic acids closely, but there are relatively few studies with this acid. Rotating... 

Treatment of the alcohol ( ) with trifluoromethylsulfonic anhydride (triflic anhydride) at -78 C afforded the ester (1 ) which could be isolated and characterized. We knew from previous experience (2J that sulfonyl esters vicinal to an isopropylidene acetal are relatively stable. The triflate T,) reacted cleanly with potassium azide and 18-crown-6 in dichloromethane at room temperature. The crystalline product [68% overall from (1 )] was not the azide ( ) but the isomeric A -triazoline ( )- Clearly the initially formed azide (18) had undergone intramolecular 1,3-cyclo-addition to the double bond of the unsaturated ester (21- ). The stereochemistry of the triazoline (1 ), determined by proton nmr spectroscopy, showed that the reaction was stereospecific. There are several known examples of this reaction ( ), including one in the carbohydrate series ( ). When the triazoline was treated with sodium ethoxide ( ) the diazoester ( ) was rapidly formed by ring-opening and was isolated in 85% yield, Hydrogenolysis of the diazo group of (M) gave the required pyrrolidine ester ( ) (90%). 

Potentiometric non-aqueous titration (using bismuth oxyacetate and perchloric acid or trifluoromethylsulfonic acid) was used by Zakhari et al. (90) for the determination of procaine and other drugs (halides and nitrogen bases) [90], Procaine hydrochloride was dissolved in 5 1 acetic... 

Similarly, treatment of 2-phenylindan-l,3-dione with (V-fluorobis(trifluoromethylsulfon-yl)amine (Id) in chloroform at 20°C results in fluorination at position 2 to give 2-fluoro-2-phenylindan-l,3-dione (23).148... 

The impure metal dissolves easily in mineral acids and in fluoroboric, sulfamic am trifluoromethylsulfonic acids to give Cr2+ solutions, but oxidation of Cr2+ by hydrogen ion (equation 6), °(Cr3+, Cr2+) = —0.41 V) even in an inert atmosphere is catalyzed by thi impurities and various ions.71 Indefinitely stable chromium(II) solutions can be obtained fron the pure (electrolytic) metal (99.5% or better), although the reaction with acid may need to b< initiated by heat and the inclusion of some metal previously attacked by acid. The use of ai excess of metal, which can be filtered off, ensures that little acid remains. In near neutra solution the hydrogen potential is lowered and the Cr2+ ion is stable. In alkaline condition brown Cr(OH)2, which slowly reduces water, precipitates.73,73... 

The lanthanide trifluoromethylsulfonates M(CF3S03)3 have been prepared and their complexes with pyo and bpyo have been prepared in ethanol or ethanol/triethylformate and examined. Complexes [M(pyo)g](CF3S03)3 and [M(bpyo)4](CF3S03)3 (M = La, Nd, Eu or Ho in each case) were obtained and results indicated that the anions were not coordinated.304,305 A number of complexes of pyo, bpyo and 2,2, 6, 2"-terpyridyl-JV,lV, iV"-trioxide (tpyo) with... 

When 3PN solution containing Ni[P(0-p-tolyl)3]4 is treated with trifluoromethylsulfonic acid (1 eq/Ni) at 50°C, rapid isomerization occurs for less than 30 sec before catalyst degrades. During this short burst of isomerization, 4PN and 2PN are produced in a ratio of 70 1. Similar results are obtained at 40°C and 25°C (61). 

When a different phosphite ligand is used, the ratio of 4PN to 2PN initially produced is altered significantly isomerizations with Ni[P(OEt)3]4 and trifluoromethylsulfonic acid at 50°C produce a 4PN 2PN ratio of 17.5 1. In contrast, when 2-hexene is treated with this same catalyst system, the initial ratio of 1-hexene to 3-hexene produced is less than 2 1. 

Vinyl cations are less stable than their aliphatic counterparts. Therefore solvolysis of l-methyl-2,2-diphenylethenyl triflate (trifluoromethylsulfonate)... 

E. P. Barrette and L. Goodman, Convenient and stereospecific synthesis of deoxy sugars. Reductive displacement of trifluoromethylsulfonates, J. Org. Chem., 49 (1984) 176-178. 

The electrodeposition of silver from chloroaluminate ionic liquids has been studied by several authors [45-47], Katayama et al. [48] reported that the room-temperature ionic liquid l-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4) is applicable as an alternative electroplating bath for silver. The ionic liquid [EMIM]BF4 is superior to the chloroaluminate systems since the electrodeposition of silver can be performed without contamination of aluminum. Electrodeposition of silver in the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) and l-butyl-3-methylimidazoliumhexafluorophosphate was also reported [49], Recently we showed that isolated silver nanoparticles can be deposited on the surface of the ionic liquid Tbutyl-3-methylimidazolium trifluoromethylsulfonate ([BMIMJTfO) by electrochemical reduction with free electrons from low-temperature plasma [50] (see Chapter 10). This unusual reaction represents a novel electrochemical process, leading to the reproducible growth of nanoscale materials. In our experience silver is quite easy to deposit in many air- and water-stable ionic liquids. 

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