Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1997-09-16
1998-06-09
Geist, Gary
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568683, C07C 4100
Patent
active
057636842
DESCRIPTION:
BRIEF SUMMARY
This is the U.S. National Stage Application of PCT/JP97/00128 filed Jan. 22, 1997 now WO97/27165 published Jul. 31, 1997.
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 widely been used as a safe inhalation anesthetic. In use of such inhalation anesthetic, it is demanded that impurity is essentially not contained therein. 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, formaldehyde, and concentrated sulfuric acid or another dehydrating agent, in accordance with the description of U.S. Pat. No. 4,250,334, it was found that fluorinated ethers, except fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, and high-boiling-point polyethers are inevitably produced, as well as the by-products, such as formal and acetal, which are described in the above-mentioned patent specification, and that, of these, particularly the fluorinated ethers as by-products suppress the improvement of the purity 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 and the like, which is usually used against such reaction products. There has been found an unexpected property troublesome in the purification treatment, in which, although among the fluorinated ethers as by-products, 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 the above-cited usual recovery treatment method. Thus, when the purification was tried by distilling fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether containing bisfluoromethyl ether, contrary to the expectation, it was confirmed that bisfluoromethyl ether and fluoromethyl1,1,1,3,3,3-hexafluoroisopropyl ether do not easily separate from each other and show an azeotropic behavior.
Thus, the present inventors have already proposed in JP-A-7-258138 a method of purifying fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether by treating a fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether containing at least bisfluoromethyl ether with one or at least two of a Broensted acid, a Lewis acid, or an acid fixed to a resin or the like. This method is effective in decreasing the bisfluoromethyl ether content. It is, however, necessary to treat newly produced by-products, due to the use of a chemical change caused by the reaction. Therefore, the position of the above step may be limited in the production process, or the cost may increase due to the complication of the process.
Therefore, the present invention's task is the provision of a method of removing bisfluoromethyl ether contained in fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, in an easy, effective manner.
DISCLOSURE OF THE INVENTION
In view of the above-mentioned prior art problems, the present inventors have eagerly examined a purification method for obtaining a fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether essentially not containing bisfluoromethyl ether, without having an adverse effect on fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether. As a result, we have found that, if the fluorinated ether formed as a by-product in the synthesis of fluoromethyl1,1,1,3,3,3-hexafluoroisopropyl ether is contacted with zeolite, it is efficiently removed. Thus, we have achieved the present invention.
In other words, the present invention provides a method of purifying fluoromethyl-1,1,1,3,3,3-hexafluo
REFERENCES:
patent: 4250334 (1981-02-01), Coon et al.
patent: 5684210 (1997-11-01), Kawai et al.
Kawai Toshikazu
Kobayashi Manami
Watanabe Mineo
Central Glass Co. Ltd.
Geist Gary
Padmanabhan Sreeni
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