Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1995-11-16
1997-11-04
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568683, C07C 4100
Patent
active
056842112
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. In more detail, it relates to a method of suppressing decomposition of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether at the time of distillation and thus obtaining fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether of high purity.
BACKGROUND TECHNOLOGY
Hitherto, fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether has been widely used as a safe inhalation anesthetic.
This fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether can be obtained, for example, by reacting together fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl alcohol, formaldehyde, and hydrogen fluoride. The thus produced crude fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether contains various by-products. A means is selected to remove these by-products by passing the reaction product through usual treatment steps, that is, steps such as washing with acid, washing with alkali, washing with water, distillation, and the like.
However, in the distillation step of this fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, it was found that crude fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether decomposes or disproportionates and thus can not be distilled and that impurities thus increase. In other words, it was found that defluorohydrogenation of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether occurs during distillation and that fluoromethyl-1,1,3,3,3-pentafluoroisopropenyl ether is gradually formed as a new impurity. This fluoromethyl-1,1,3,3,3-pentafluoroisopropenyl ether which is a decomposition product of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether is a volatile analogous compound of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, and can not be separated because their boiling points are nearly the same. It is needless to say that the contamination of the product thereby is extremely unfavorable in use as an inhalation anesthetic, and thus an immediate solution has been desired.
DISCLOSURE OF THE INVENTION
In view of such problem in the past, the present inventors have eagerly examined a method of distilling fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, in which method the decomposition of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether is suppressed and fluoromethyl-1,1,3,3,3-pentafluoroisopropenyl ether is not formed. As a result, we have found that the decomposition of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether can be suppressed and thus fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether of high purity essentially not containing fluoromethyl-1,1,3,3,3-pentafluoroisopropenyl ether can be obtained by adding a compound selected from hydroxides of, hydrogenphosphates of, phosphates of, hydrogencarbonates of, borates of or sulfites of alkali metals, or alkali metal salts of acetic acid or of phthalic acid, or boric acid, in the form of solid as it is or of aqueous solution, to fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, and then by conducting distillation. 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-hexafluoroisopropyl ether, characterized in that a compound selected from hydroxides of, hydrogenphosphates of, phosphates of, hydrogencarbonates of, borates of or sulfites of alkali metals, or alkali metal salts of acetic acid or of phthalic acid, or boric acid is added to fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, followed by distillation.
Additives for suppressing decomposition of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether used in the present invention are hydroxides of, hydrogenphosphates of, phosphates of, hydrogencarbonates of, borates of or sulfites of alkali metals, or alkali metal salts of acetic acid or of phthalic acid, or boric acid. Hydroxides of alkali metals are NaOH, KOH, and the like. Hydrogenphosphates of alkali metals are hydrogenphosphates of or dihydrogenphosphates
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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