2. Partly Fluorinated Alcohols as Effective O-nucleophilic reagents, their application for creation of fluorine containing semi-products and materials on their base.
On the basis of alcohols interaction with tetrafluoroethylene and hexafluoropropylene in the liquid phase in the presence of radical sources universal complex obtaining technology of semi-products (poly-fluorinated alcohols, the most important components of fluoroorganic materials production) was developed and is functioning successfully. They can be parent materials for production of many fluorocontaining materials, used in engineering industry and medicine. In connection with this the functionalization of telomeric alcohols like H(CF2CF2)nCH2OH, n = 1-5 widens the production fields of new perspective fluorine materials. Below you will find some directions of its realization.
Thus on their basis new materials with important chemical and physical characteristics are created. These researches opened excellent features of a number of new emulsions regarding their ability to storage, sterilization and rheology. As time goes by they will become a basis of alternative replacement of industrial liquids and they will find a wide range of application.
Poly-fluorinated alcohols are more acidic compare to hydrocarbons
analogues,
that results in reduction of their nucleophilic properties (table 2) [56].
Table 2. Constants of some fluoroalchols acidity at 25 oC [56].
| ROH | pKa | ROH | pKa a |
| ((CHF2)2C(OH)2 | 9,11 | CF3CF2CH2OH | 12,39 |
| (CF3)2CHOH | 9,39 | CF3CH2OH | 12,40 |
| (CF3)2(CH3)COH | 9,93 | (CF3)(CH3)CHOH | 12,70 |
| (CF3)(CH3)C(OH)2 | 10,57 | (CF3)(CH3)2COH | 13,13 |
| C3F7CH2OH | 11,4 | ||
a [57].
The peculiarity of telomeric alcohols chemical behavior is their higher acidity and reduced reaction ability as nucleophilic reagents. Nevertheless, they were used in nucleophilic replacement and addition reactions. For example , 2,2,3,3-tetrafluoropropanol reacts in autoclave with tetrafluoroethylene in the presence of NaOH in dioxane at 60 oC during two hours, producing CHF2CF2CH2OCF=CF2 with the yield of 42 % [58].2.1. The interaction of trimethylsilyl ethers of partly fluorinated alcohols and unsaturated compounds - the way of wide application field dialkyl ethers synthesis.
One of the approaches of partly fluorinated alcohols activation as O-nucleophiles was their trimethylsilyl ethers use in the process carrying out conditions in the presence of fluoride-ion source. Cesium fluoride is rather effective source. Thus, this method is used for forming of C-O and C-N bonds in highly fluorinated systems [48,49]. This method is successfully used instead of olefins reactions with alcoholates of alkali elements.
The alcohols' reaction H(CF2CF2)nCH2OH (n = 1-3) with hexafluorobenzene and octafluorotoluene in the presence of CsF, Et3N or pyridine results in formation of replacement products of fluorine atoms in benzene ring [61]. In case of trimethylsilyl ethers of telomeric alcohols reaction with mixture of isomeric trimers of hexafluoropropylene two butadiene derivatives are formed.
For reactions with pentafluoropyridine, pentafluorosubstituted benzenes like C6F5X (X = CN, CF3, Cl, F) , 1,4-diiodotetrafluorobenzene in the conditions of catalysis using fluoride-ion the following trimethylsilyl ethers of fluorocontaining alcohols are used: (CF3)2CHOSiMe3, (CF3)3COSiMe3 , CH3C(CF3)2OSiMe3, PhC(CF3)2OSiMe3, C7F17CH2CH2SiMe3, CF3CH2OSiMe3, CF3C(CH3)2OSiMe3, (CF2CH2OSiMe3)2, CF2(CF2CH2OSiMe3)2 [62]. Likewise such ethers are introduced into reaction with tribromomethane.
Reactions with fluorocontaining ketones were put into practice, resulting in formation of perfluorinated alcohols, which are transferred into corresponding perfluorinated ethers [62].
The reactions of bifunctional trimethylsilyl ethers of telomeric alcohols with polyfluorinated benzenes and pentafluorobenzylbromide in diglyme produce replacement products of fluorine atoms in benzene ring and bromine of CH2Br group [63].
These compounds are liquids with freezing points -20 oC and boiling points 330-350 oC and they can be used as dielectric heat transfers with wide application field.
Compounds, possessing movable halogen atoms, also react in such reaction with formation of halogen atoms replacement products, besides this the formation of heterocyclic compounds exists [64].
In the case of perfluorocyclic olefins the replacement of both fluorine atoms takes place at multiply bond with formation of polycyclic compound. It should be noted, that cycles like these can act as complex formers like crown ethers, for example with fluorine anion [65].
This method doesn't have any limits for practical purposes. Thus compounds, having movable fluorine atoms at phosphorus atom, are introduced into the reaction [66].
Polyfluoroalkoxytrimethylsilanes react with compounds of quinquivalent phosphorus with formation of polyfluoroalkyliodids [67]. This is an interesting variant of transfer from telomeric alcohols to polyfluoroalkyliodids. The key moment of this reaction is the formation of stable triphenylphosphine oxide.
