Perfluoroalkylorthocarbonates and perfluoropolyalkoxypropanes are disclosed. The perfluoro compounds are synthesized by direct fluorination procedures. The perfluoro compounds are useful lubricants, heat exchangers, vapor phase soldering fluids, solvents, and oxygen carriers.

BACKGROUND 
The difficulty with the synthesis of perfluoro esters lies in instability 
of the ester linkage toward hydrogen fluoride and the facile dissociation 
of perfluoro esters by nucleophilic attack. The electrolytic fluorination 
of esters is precluded because they are spontaneously decomposed in the 
acidic solution. The direct fluorination of ethyl acetate (See Adcock, J. 
L. et al., J. Org. Chem. 40, 3271 (1975)) represents the first successful 
fluorination of an ester, giving CF.sub.3 COOCF.sub.2 CF.sub.3 and 
CF.sub.3 COOCHFCF.sub.3 in 5% and 20% yield respectively. Extension of 
this direct fluorination technique has previously led to the conversion of 
hydrocarbon polyesters to highly fluorinated polyesters, which are 
important precursors to perfluoropolyethers. Persico, D. F. et al., J. Am. 
Chem. Soc. 107, 1197 (1985). 
There were few reports of the preparation of perfluoroesters by indirect 
methods. The first reported reactions were the dimerization and 
trimerization of COF.sub.2 to yield FCO.sub.2 CF.sub.3 and (CF.sub.3 
O).sub.2 CO respectively. Photolysis reaction of CF.sub.3 OF and CF.sub.3 
OOCF.sub.3 in the presence of CO resulted in the same products as above 
reactions. Aymonino, P. J., Chem. Commun. 241 (1965); Varetti, E. L. and 
Aymonino, P. J., Chem. Commun. 680 (1967). A more general synthesis is the 
low temperature reaction of perfluoroacyl fluorides with perfluoro 
alkoxide salts. 
With the execption of the reaction of fluoroesters R.sub.f COOCH.sub.3 with 
dimethyl sulfone to yield ortho esters R.sub.f C(OCH.sub.3).sub.3 (Holm, 
T., U.S. Pat. No. 2,611,787 (1952)) and the isolation of CHFClC(OC.sub.2 
H.sub.5).sub.3 by Tarrant and Brown (Tarrant, P. and Brown, H. A., J. Am. 
Chem. Soc. 73, 1781 (1951)) little synthetic information on fluorinated 
ortho esters has appeared in the literature. 
SUMMARY OF THE INVENTION 
This invention pertains to perfluoroalkyl orthocarbonates and 
perfluoropolyalkoxypropanes and to methods of producing these 
perfluorinated compounds. 
The perfluoroalkyoorthocarbonates are represented by the formula: 
##STR1## 
wherein R.sub.f1, R.sub.f2, R.sub.f3 and R.sub.f4 are the same or 
different short, straight or branched chain perfluoroalkyl radicals. In 
preferred embodiments, R.sub.f1, R.sub.f2, R.sub.f3 and R.sub.f4 are the 
same or different and are selected from --CF.sub.3, --CF.sub.2 CF.sub.3, 
--CF.sub.2 CF.sub.2 CF.sub.3, --CF(CF.sub.3).sub.2, --CF.sub.2 CF.sub.2 
CF.sub.2 CF.sub.3, --CF(CF.sub.3)CF.sub.2 CF.sub.3, --CF.sub.2 
CF(CF.sub.3).sub.2, and --C(CF.sub.3).sub.3. 
The perfluoroalkoxypropanes are represented by the formula: 
##STR2## 
wherein R.sub.f1, R.sub.f2, R.sub.f3 and R.sub.f4 are short, straight or 
branched chain perfluoroalkyl radicals. In preferred embodiments, 
R.sub.f1, R.sub.f2, R.sub.f3 and R.sub.f4 are the same or different and 
are selected from --CF.sub.3, --CF.sub.2 CF.sub.3, --CF.sub.2 CF.sub.2 
CF.sub.3, --CF(CF.sub.3).sub.2, --CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.3, 
--CF(CF.sub.3)CF.sub.2 CF.sub.3, --CF.sub.2 CF(CF.sub.3).sub.2, and 
--C(CF.sub.3).sub.3. 
The perfluoroalkylorthocarbonates and perfluoroalkoxypropanes of this 
invention are produced by direct fluorination with elemental fluorine. The 
perfluoro compounds are more volatile than perfluoropolyethers of the same 
molecular weight. They are unaffected by concentrated sulfuric acid and 
nitric acid, but decompose in hydrogen fluoride solution and concentrated 
hydrochloric acid. They are stable at 150.degree. C. and above. The 
perfluoro compounds of this invention are useful as lubricants, heat 
exchangers, solvents, vapor phase soldering fluids and oxygen carriers.