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4. New in application of perfluoralkanesulfo-acides derivatives 4.1. Electrolytes and ionic liquids on the basis of bis-(perfluoroalkylsulfonyl) imide. The search for new electrolytes for lithium batteries and new organic materials with high electroconductivity had stimulated the interest for synthesis of salts on the basis of bis-(trifluoromethanesulfonyl)amide. It was important that such salts should have had not only high electoconductivity but they also should have been stable at room temperature and well soluble in organic solvents and should have had low melting points and they should not have decayed in aqueous medium Besides this it was important to get quantity data regarding anion influence (CF3SO2)2N- on salt elecroconductivity. Lithium salt of bis-(trifluoromethanesulfonyl)imide may be used as solid electrolytes for batteries [167-179]. Moreover the other salts of bis-(trifluoromethanesulfonyl)imide ( for example, aluminium salt [180-182], salts of Mg, Ca, Sr, Ba [183,184]) can be used for these purposes. It was proposed the method of cyclic perfluoroalkane-bis-(sulfonyl)imides or it's salts producing via cyclization corresponding perfluoroalkane-bis-sulfonylfluorides during reaction with liquid ammonia [185]. Cyclo-difluoromethane-bis-(sulfonyl)imides of lithium use as conductive salts in non-aqueous solutions of electrolytes.
Lithium salts with different perfluoralkyl groups are also used as solid electrolytes in the material containing other elements, for example Liy(Mn2-xMx)O4 [ M = Li, Ca, Fe, Ni, Cr, Co, In, Mg; x = 0-1] [186]. It can be supposed that the base for production of new electrolytes for lithium batteries and new complexing agent for rare-earth elements used as laser mediums will be created.
The following fields of application of perfluoralkanesulfo-acids derivatives can be supposed:
Along with lithium salts of perfluoralkanesulfo-acids the salts, which cations contained different nitrogen-containing heterocycles and quaternary alkylamines, were obtained .
The structure of salts is confirmed by data of X-ray analysis [163,164]. In the work [162,163] was described the producing of salts with such anion, at that the cation was heterocyclic compound. The synthesis of salts was carried out according to the scheme :
It was found, that electroconductivity of methylbutyl derivatives of these salts is 2*10-3 S/cm at 20 oC, and the one of methylpropyl derivatives is 1*10-6 S/cm at 0 oC. It should be noted that at comparing to electroconductivity of sample system, containing imidozonium ion (EMI) [165] (8*10-3 S/cm at 20 oC),
they are comparable. However, this sample salt can't be applied in realty at room temperature, because it decays at cathode voltage of a few hundred mv. Also other salts, containing imidozonium are obtained [166].
In the work [187] the similar salts are studied using aliphatic quaternary ammonium cations, which are stable in the open air and in water:
It was found that these salts are electrochemically stable and small sizes of trimethylalkylammonium cations create the conditions of high electroconductivity. It can be seen if you look at Fig. 1 and table 3.
Fig.. 1. Electroconductivity of salts on the base of anion (CF3SO2)2- . Salt electroconductivity is not so great as the sample salt (EMI), nevertheless the opportunity of working at high temperature makes this salts more attractive from practical point of view, because it is not required to use cycle system for generation of cationoid part and use more available trimethylalkylammonium cations. The salts
which are ionic liquids are used as medium of some chemical processes. It was stated [188], that 1-ethyl-3-methyldiazolium bis-(trifluoromethylmethanesulfonyl)imide and 1-butyl-3-methyldiazolium bis-(trifluoromethylmethanesulfonyl)imide are active bicatalysts and ionic liquids for conducting of butyl-butyrate synthesis under the action of candida Antarctica lipase B exime. The process passes with high synthetic activity, selectively and stably in the medium of supercritical carbon dioxide. The authors of the work [189] used this medium for the synthesis of asymmetric cyclopropanes by ethyl diazoacetate acting on styrene in presence of bis-(oxozoline)-copper complex.
Iodonium salt (CF3SO2)2NI(Ph)CH2CF3 appeared to be excellent alkylating reagent (introducing of CH2CF3 group) into different amino acids [190]. The structure of reaction product is confirmed by X-ray analysis [190].
Table 3. Salts characteristics of the basis of anion (CF3SO2)2N- at 25 oC [187].
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