Lithium triflate

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). 

The reaction between epoxides and ammonia is a general and useful method for the preparation of P-hydroxyamines. " Ammonia gives largely the primary amine, but also some secondary and tertiary amines. The useful solvents, the ethanolamines, are prepared by this reaction. For another way of accomplishing this conversion, see 10-54. The reaction can be catalyzed with Yb(OTf)3 and in the presence of a-BINOL is l,l -bi-2-naphthol derivative gives amino alcohols with high asymmetric induction. A variation used Yb(OTf)3 at lOkbar or at ambient pressure. Lithium triflate can also be used. Primary and secondary amines give, respectively, secondary and tertiary amines, for example. 

Other examples of nucleophilic attack on the oxirane ring include the formation of (3-halohydrins with silica-gel supported lithium halides <96TL1845>, the addition of amines catalyzed by lithium triflate, an ersatz for lithium perchlorate <96TL7715>, and the addition of pyrroles, indoles and imidazoles under high pressure i.e., 91 —> 93) <96JOC984>. 

Lithium triflate was the most used salt and the temperature dependence of the electrical conductivity of a series of (LiS03CF3)x/MEEP complexes with a ratio metal cation/MEEP repeat unit 0.125[Pg.203]

NP(ORi)(OR2)] /lithium triflate systems R,=(CH2CH20)2CH3 R2=(CH2)xCH3... 

Gel electrolytes were also prepared by Allcock [605] from co-substituted polyphosphazenes with various ratios of methoxyethoxyethoxy and trifluo-roethoxy side groups, lithium triflate and propylene carbonate. These gel electrolyte systems have a better mechanical stability than MEEP. The highest ionic conductivity obtained was 7.7x10" S cm" at 25 °C for a gel containing 37.5% of polymer with 80% and 20% of methoxyethoxyethoxy and trifluoro ethoxy... 

The sol-gel technique was also used to prepare solid electrolytes containing MEEP, triethoxysilane (TEOS) and lithium triflate. Homogeneous, transparent and mechanicaUy stable materials have been obtained by Gughelmi [611] from a partially hydroxylated MEEP and TEOS, which after doping with LiSOjCFj exhibited a conductivity in the range 3x10 S cm at 60 °C. 

Table 18 Maximum conductivity of the polymers Xlll-XV/lithium triflate systems at 25 °C...

The variations of the conductivity of the corresponding complexes with salt concentration with lithium triflate were similar to those of MEEP, with a passage through a maximum when this concentration increased. The maximum conductivities of these complexes are reported Table 18. 

Lithium perchlorate and lithium triflate in acetonitrile catalyze intramolecular cycloaddition reactions of nitrones of allyloxybenzaldehydes and unsaturated aldehydes.154... 

On the other hand, sulfonate (—SOsLi) became the anion of choice because it is highly resistant to oxidation, thermally stable, nontoxic, and insensitive to ambient moisture as compared with LiPFe or LiBp4. As the simplest member of this category (Rp = CFs), lithium triflate (LiTf) received extensive research as a candidate for lithium/lithium ion cells. Other similar salts studied include perfluoroethyl sulfonate (Rp = C2F5), perfluorobutylsulfonate (Rp = and the oligomeric versions that are based on polyether linkages. 

Flow fluorination of the 4,4 -bipyridine —boron trifluoride complex gives only mono-fluorinated l-fluoro-4-(4-pyridyl)pyridinium boron trifluoride tetrafluoroborate (31), while fluorination of l-methyl-4-(4-pyridyl)pyridinium triflate in the presence of lithium triflate provides l-fluoro-l -methyl-4,4 -bipyridinium ditriflatc (32) 67... 

The bridgehead-amine-derived electrophilic fluorinating reagents l-alkyl-4-fluoro-l,4-di-azoniabicyclo[2.2.2]octane ditriflate 5 a or bis(tetrafluoroborates) 5b and 6 can be prepared from l-alkyl-4-aza-l-azoniabicyclo[2.2.2]octane salts and elemental fluorine. For example, treatment of l-methyl-4-aza-l-azoniabicyclo[2.2.2]octane triflate (4a) and lithium triflate in acetonitrile at — 35CC with neat fluorine over three hours gives l-fluoro-4-methyl-l,4-dia-zoniabicyclo[2.2.2]octane ditriflate (5a).81 The reagents 5b, 6, 7, and 8 can be synthesized in a similar manner.76 83... 

Figure 3.16 Ionic electrical conductivity for solutions of lithium triflate in solid poly[fc (methoxyethoxyethoxy)phosphazene] ( MEEP ) is believed to occur following coordination of the etheric side groups to Li+ ions, cation-anion separation, ion transfer from one polymer to another as the polymer and side groups undergo extensive thermal motions. From Shriver and Farrington, Chem. Eng. News, 1985, 42-57 (May 20). Reprinted by permission of the American Chemical Society.

Figure 3.17 Cross-sectional diagram of a thin film rechargeable lithium battery based on the conductivity of lithium triflate in solid pol y W.v(mcthoxyethoxyethoxy )phosphazene].

An opposite type of behavior, positive ionochromism, is shown by the polymer [C2H50CH2CH20(CH2)5]2Si n52- In this case, as shown in Figure 9, addition of lithium triflate to a thin film of the polymer promotes a bathochromic shift, increasing the midpoint temperature of the thermochromic transition from —45 to +50 °C Probably in this example the lithium ions, complexed to the ethylene oxide units, lock the polymer... 

As mentioned previously, it is also important that the corrosiveness of the conductivity salt in the solvent system is also assessed as corrosion in organic solvents is hard to predict theoretically. Typical conductivity salts used as additives within CIJ ink formulations include lithium nitrate, potassium thiocyanate, lithium triflate etc. 

Zhu Z, Einset A G, Yang Ch-Y et al. (1994) Synthesis of PolysUoxanes Bearing Cyclic Carbonate Side Chains. Dielectric Properties and Ionic Conductivities of Lithium Triflate Complexes. Macromolecules 27 4076-4079. 

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