Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1995-11-10
1997-11-04
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568683, C07C 4100
Patent
active
056842104
DESCRIPTION:
BRIEF SUMMARY
TECHNOLOGICAL FIELD
The present invention relates to a method of purifying fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, which is widely used as a pharmaceutical and particularly as an inhalation anesthetic.
BACKGROUND TECHNOLOGY
Hitherto, fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether has been widely used as an inhalation anesthetic which is safe for use. For example, the production method is described in detail in U.S. Pat. No. 4,250,334, while the purifying method for obtaining a purity suitable for medical use is described in U.S. Pat. No. 4,328,376. To be concrete, according to the production method described in U.S. Pat. No. 4,250,334, when concentrated sulfuric acid and hydrogen fluoride are added to paraformaldehyde, and then when a gas generated by a method in which 1,1,1,3,3,3-hexafluoroisopropyl alcohol is added dropwise to this heated reaction mixture is collected, the non-reacted alcohol and organic by-products such as formal, acetal and the like, which have been formed as by-products, are recovered along with the aimed product. However, according to the description of U.S. Pat. No. 4,328,376, it has been found that fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether synthesized by such method contains a small amount of an olefin compound in addition to the above-mentioned by-products. In view of that this compound shows an azeotropic behavior in distillation and thus the purification does not succeed by a distillation means, it has succeeded in obtaining fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, which has a high purity, by chemically treating the obtained crude fluoromethylhexafluoroisopropyl ether with an amine or the like, and then by subjecting it to a distillation process. Fluoromethylhexafluoroisopropyl ether obtained by using the purification method, in which the amine or the like is used, is satisfactory in increasing the purity, but a small amount of the amine or the like remains instead in fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, resulting in a fault accompanied by a secondary effect of the recognizable smell of the amine, which is extremely undesirable as an inhalation anesthetic.
In use of the aimed inhalation anesthetic in the present invention, there is no doubt but that it is demanded that an undesirable impurity is essentially not contained. In order to achieve this aim, a method of improving the purity of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether was eagerly continuously examined. As a result, when fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether is produced from 1,1,1,3,3,3-hexafluoroisopropyl alcohol, hydrogen fluoride, concentrated sulfuric acid and formaldehyde, in accordance with the method described in U.S. Pat. No. 4,250,334, it was found that a fluorinated ether(s) except fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether (referred to as "fluorinated ether as a by-product" in the present specification) or the like and a high-boiling-point polyether(s) or the like are inevitably produced, as well as the by-products such as formal, acetal and the like, which are described in the above-mentioned patent specification, and that, of these, particularly the fluorinated ether as a by-product or the like suppresses the purity increase of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether. With regard to most of these by-products, it is usual that they receive the chemical or physical action and thus essentially do not remain in the product, by conducting the recovery treatment method, i.e. water washing, alkali washing, drying, distillation or the like, which is usually used against such reaction product. There has been found an unexpected property troublesome in the purification treatment, in which, although among the fluorinated ethers as by-products or the like, bisfluoromethyl ether alone is an extremely unstable compound, when it coexists with fluoromethyl-1,1,1,3,3,3-hexafluoro-isopropyl ether, it is not separated by a usual recovery treatment method, i.e. water washing, alkali washing, drying or the like. Thus, when the purifi
REFERENCES:
patent: 4250334 (1981-02-01), Coon et al.
patent: 4328376 (1982-05-01), Berger et al.
Kawai Toshikazu
Kumakura Manami
Watanabe Mineo
Yoshimura Takaaki
Central Glass Company Limited
Dees Jos,e G.
Puttlitz, Jr. Karl J.
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