Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1994-11-03
1996-10-08
Evans, Joseph E.
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
564497, 570178, C07C 1738, C07C 17395, C07C 1908, C07C 2336
Patent
active
055633064
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention pertains to a process for purification of perfluorocarbons or perfluorocarbon mixtures with impurities containing hydrogen and/or carbon-carbon double bonds.
Perfluorocarbons prepared in a known manner, e.g., via electrofluorination or by a CoF.sub.3 process or by direct fluorination, contain varying amounts of partially fluorinated substances depending on the preparation process, i.e., compounds that still contain hydrogen and/or carbon-carbon multiple bonds in the molecule. These by-products have increased chemical reactivity and toxicity compared to the perfluorinated compounds. For most areas of application, especially in the areas of medicine and microelectronics, it is indispensable to remove these compounds.
For this, the processes described to date utilize the higher, compared to perfluorocarbons, chemical reactivity regarding nucleophiles such as alkalis, amines, and oxidizing agents.
Thus, according to JP 60-112,724, treatment with a very highly concentrated solution is proposed. C. Fukaya et al. (10th Int. Symp. Fluorine Chem., Vancouver, August 1-6, 1982) do a combined treatment with isobutylamine and potassium hydroxide which is followed by an acid rinse. According to U.S. Pat. No. 4,328,376, ammonia or primary or secondary amines are used for purification of perfluorinated ethers.
In the above-indicated processes, the products to be purified are boiled with reflux for several days at normal pressure. Le Blanc et al. (Nouveau J. Chim. 8 (1984) 251) describe purification by shaking with 10% aqueous KOH and subsequent filtration over activated carbon and aluminum oxide. Weeks (U.S. Pat. No. 3,696,156) also does the purification with sodium hydroxide on Al.sub.2 O.sub.3.
Conte et al. (Chimicaoggi 11 (1988) 61) describe a purification process for perfluoro-N,N-diethylcyclohexylamine by means of diethylamine in an autoclave at 120.degree. C., rinsing of the reaction products with water, and subsequent autoclaving with 10% alcoholic KOH solution at 120.degree. C. and 5 atm.
A treatment with a mixture of CaO, NaOH, and water by Huang et al. (J. Fluorine Chem. 45 (1989) 239) is done not as a purification process but as a process for chemical decomposition of H-containing fluorine compounds. This reaction is based on a publication of Wallin et al. (Anesthesia and Analgesia 54 (1975) 758) on the stability of a fluorinated ether as anesthetic.
For analytical determination of the eliminatable HF and thus the fluorine ion from compounds with --CF.sub.2 CHF groups, Meinert et al. (Forschungsbericht, AdW [Akademie der Wissenschaften], Berlin 1986) use a reaction with hexamethylenediamine at 120.degree. C. This reaction was later done in a homogeneous phase by Gross et al. (Mittbl. Chem. Ges. 37 (1990) 1461) in the presence of nonane.
According to Radeck et al. (DD 287,478), the perfluorocarbons to be purified are treated with high-valance metal fluorides at temperatures of 350.degree.-500.degree. C. over a period of 0.5-6 h.
Meinert et al. (1989 Intern. Chem. Congr. Pacific Basin Soc., Honolulu, No. 174; Final report BMFT Project "PFC Emulsions" 1988; J. Fluorine Chem. 51 (1991) 53) used a pressure purification wherein the raw product is autoclaved with concentrated KOH, secondary amine, and CaO at 170.degree.-200.degree. C.
Some authors also propose extractive processes for purification of perfluorocarbons; thus, e.g., in U.S. Pat. No. 3,887,629, a liquid-liquid extraction with hydrocarbons, or in U.S. Pat. No. 3,449,218, an azeotropic distillation of perfluorocarbons with oxygen-containing hydrocarbons such as acetone. However, the degree of purity of the perfluorocarbons that can be attained with this is not yet adequate for biological and medicinal purposes so that it can only be considered a preliminary purification.
It is the object of the invention to make available a simple, highly effective process for elimination of compounds containing hydrogen and/or double bonds from perfluorocarbons or other mixtures.
This object is attained according to the invention by reacting the
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Evans Joseph E.
Pharmpur GmbH
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