Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2003-02-26
2004-10-12
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S604000, C568S347000, C568S348000, C568S354000, C568S364000, C568S391000, C568S393000, C562S849000, C562S852000, C549S372000, C549S375000, C549S453000, C549S454000
Reexamination Certificate
active
06803488
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an industrially useful process for producing a fluorinated ketone.
BACKGROUND ART
Heretofore, as a method for fluorinating all of C—H portions in a C—H containing compound to C—F, a method of employing cobalt trifluoride, a method for direct fluorination by means of fluorine gas, or a method of carrying out a fluorination reaction by using, as a fluorine source, hydrogen fluoride formed by electrolysis in an electritic cell (electrochemical fluorination, hereinafter referred to as ECF method), has been known. The method of employing cobalt trifluoride is one wherein the reaction is carried out by a gas-solid reaction at a high temperature, whereby there is a problem such that isomerization or bond breakage is likely to take place, to form various types of by-products. While, the fluorination reaction by ECF method has had a problem such that an isomerization reaction takes place, or a problem such that breakage of the main chain or a rebonding reaction is likely to take place, and thus has had a problem that the desired compound can not be obtained with good purity.
In a case where a fluorination reaction is carried out by means of fluorine gas, a method of carrying out the reaction in a gas phase and a method of carrying out the reaction in a liquid phase, are known. However, the gas phase reaction has a problem such that breakage of C—C single bonds takes place during the fluorination reaction to form various types of by-products. In recent years, a method of carrying out the reaction in a liquid phase has been reported. For example, a method of carrying out fluorination in a liquid phase by reacting fluorine gas to a non-fluorinated compound in a liquid phase (U.S. Pat. No. 5,093,432), has been reported. Further, a method for obtaining an acid fluoride compound by pyrolyzing a perfluorinated ester compound, is also known, and it is disclosed that such a compound can be obtained by directly fluorinating a hydrocarbon type ester compound having the corresponding structure by means of fluorine gas in a liquid phase (J. Am. Chem. Soc., 120, 7117 (1998)).
In a case where a fluorination reaction is carried out by means of fluorine gas in a liquid phase, it is common to employ a solvent capable of dissolving fluorine gas, as the solvent of the reaction. However, a hydrocarbon compound as the starting material in the conventional method usually has a low solubility to a solvent which is commonly used for the fluorination reaction. Accordingly, the reaction is carried out at a very low concentration, whereby there has been a problem that the production efficiency is poor, or the reaction will be a reaction in a suspension system which is rather disadvantageous. Further, if it is attempted to directly fluorinate a low molecular weight hydrocarbon compound like one having a molecular weight of less than 200, in a liquid phase, there has been a problem that the yield in the reaction tends to be remarkably low.
On the other hand, as a method for producing a fluorinated ketone, a method is known wherein a partially fluorinated ester is perfluorinated by ECF method, followed by a dissociation reaction to obtain a fluorinated ketone (U.S. Pat. No. 3,900,372). However, the method employing ECF method has the above-mentioned drawbacks and a problem that the yield is low. Especially when an etheric oxygen atom is present in the structure of the compound, there has been a drawback that due to the cleavage of the C—O bond, the yield in the fluorination reaction tends to be extremely low.
Further, a method for obtaining a ketone by dissociating a perfluoroester, is known (U.S. Pat. No. 5,466,877). However, if a fluorination reaction is employed for the step of producing a perfluoroester in the method, there has been a problem that supply of the ester tends to fail, or the reaction system tends to be non-uniform.
It is an object of the present invention to provide an industrial process, whereby a fluorinated ketone can be produced efficiently and at a low cost.
DISCLOSURE OF THE INVENTION
In the present invention, as a result of various studies on causes of the problems of the conventional methods, attention has been drawn to the drawbacks in a fluorination reaction in a liquid phase such that if a conventional hydrocarbon compound is used as a substrate for the fluorination reaction, the solubility in the liquid phase used for the fluorination reaction is low, and if the substrate for the fluorination reaction is of a low molecular weight, the boiling point of the substrate tends to be low, so that the reaction of fluorine with the substrate is likely to take place in a gas phase, and a decomposition reaction will take place.
Accordingly, from a compound which is available at a low cost, an ester compound (3) having a specific structure, which has a high molecular weight to such an extent that a gas phase reaction hardly takes place and which has fluorine atoms introduced so that it will be soluble in a solvent for the fluorination reaction, has been obtained, and this has been employed as a substrate for the fluorination reaction. And, the present invention has been accomplished wherein such a substrate is fluorinated in a liquid phase, and then the ester bond is splitted to obtain the desired fluorinated ketone (5). Further, it has been found that a process of recycling an acylfluoride compound (6) which is formed together with the fluorinated ketone (5) by this dissociation reaction, is an industrially useful process for producing a fluorinated ketone (5).
Namely, the present invention provides a process for producing a fluorinated ketone of the following formula (5), which comprises reacting a compound of the following formula (3) having a fluorine content of at least 30 mass %, with fluorine in a liquid phase to obtain a compound of the following formula (4), and then, subjecting the ester linkage of the compound of the formula (4) to a dissociation reaction:
R
C
COOCHR
A
R
B
(3)
R
CF
COOCFR
AF
R
BF
(4)
R
AF
R
BF
C═O (5)
wherein each of R
A
and R
AF
which may be the same or different, is a monovalent organic group, provided that when R
A
and R
AF
are different, R
AF
is a monovalent organic group formed by fluorination of R
A
, and each of R
B
and R
BF
which may be the same or different, is a monovalent organic group, provided that when R
B
and R
BF
are different, R
BF
is a monovalent organic group formed by fluorination of R
B
, and at least one of R
AF
and R
BF
is a fluorinated monovalent organic group; or
R
A
and R
B
may be bonded to each other to form a bivalent organic group, and in such a case, R
AF
and R
BF
are bonded to each other to form a bivalent organic group, the bivalent organic group formed by R
AF
and R
BF
is a fluorinated bivalent organic group, the bivalent organic group formed by R
A
and R
B
and the bivalent organic group formed by R
AF
and R
BF
may be the same or different, provided that when they are different, the bivalent organic group formed by R
AF
and R
BF
is a group formed by fluorination; and
each of R
C
and R
CF
which may be the same or different, is a monovalent organic group, provided that when R
C
and R
CF
are different, R
CF
is a monovalent organic group formed by fluorination of R
C
, and provided that at least one of R
A
, R
B
and R
C
is a group having an atom or an atomic group which can be substituted by a fluorine atom, and at least one of R
A
, R
B
and R
C
is a group having a fluorine atom.
Further, the present invention provides the above process wherein the compound of the formula (3) is a compound obtained by reacting a compound of the formula (1) and a compound of the formula (2):
HOCHR
A
R
B
(1)
R
C
COX (2)
R
C
COOCHR
A
R
B
(3)
wherein R
A
, R
B
and R
C
are as defined above, and X is a halogen atom.
Further, the present invention provides the above process wherein a compound of the following formula (6) is obtained together with the fluorinated ketone of the formula (5) from the reaction pro
Ito Masahiro
Okazoe Takashi
Shirakawa Daisuke
Takagi Hirokazu
Tatematsu Shin
Asahi Glass Company Limited
Richter Johann
Witherspoon Sikarl A.
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