Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
2001-01-11
2002-05-07
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S161000, C570S164000, C570S185000
Reexamination Certificate
active
06384289
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production of a novel 1,4-bis(difluoroalkyl)benzene derivative. More particularly, this invention relates to a process which, through a simple and inexpensive procedure relying on the reaction of a compound (A) of the formula (1) with fluorine at a low temperature under a normal pressure, accomplishes the production of a 1,4-bis(difluoroalkyl)benzene derivative which is of the formula (2) and is useful as a raw material for a resin excellent in heat-resistance, chemical-resistance, water-repellency, low dielectric property, and low refractivity.
2. Description of the Related Art
1,4-Bis(difluoromethyl)benzene is used as a raw material for the synthesis of 1,4-bis(bromodifluoromethyl)benzene, which is further used for derivation of per-&agr;-fluoro[2,2]paracyclophane therefrom. This product of derivation allows synthesis of fluorine-substituted Parylene resin (PA-F) which excels in heat-resistance, chemical-resistance, and water-repellency. As methods for producing 1,4-bis(difluoromethyl)benzene, a method which relies on the reaction of terephthal aldehyde with sulfur tetrafluoride (SF
4
) [J. Am. Chem. Soc., 82, pp. 543-551 (1960)], a method which resorts to the reaction of &agr;,&agr;,&agr;′,&agr;′-tetrabromo-p-xylene with antimony trifluoride [RU 2032654, Zn, Org. Khim., 29, pp. 1999-2001 (1993)], and etc. have been known to the art to date.
Of these methods, the former method which uses sulfur tetrafluoride is at a disadvantage in needing such facilities as special reaction vessels made of Hastelloy, a (Ni-Mo type) stainless alloy excellent in corrosion-resistance and, as a consequence, incurring an increase in the cost of production because the sulfur tetrafluoride shows strong toxicity and corrosiveness, costs dearly, and entails such harsh reaction conditions as 150° C. and 8 MPa.
Then, the latter method which uses antimony trifluoride is likewise at a disadvantage in needing special facilities and, as a result, incurring an increase in the cost of production because the reaction involved therein proceeds at such elevated reaction temperatures as 100° to 150° C.
Therefore, a demand for a method which permits 1,4-bis(difluoromethyl)benzene and the derivatives thereof to be produced inexpensively by a simple procedure without requiring any special facility has been still strong.
SUMMARY OF THE INVENTION
This invention, originated in the light of the present situation of prior art mentioned above, has an object to provide a process for the production of a novel 1,4-bis(difluoroalkyl)benzene derivative.
Another object of this invention is to provide a process for producing a 1,4-bis(difluoroalkyl)benzene derivative inexpensively by a simple procedure without requiring any special facility.
The objects mentioned above can be accomplished by a process for the production of a 1,4-bis(difluoroalkyl)benzene derivative of the formula (2):
wherein k is an integer in the range of 0 to 4, G stands for a halogen group, an alkyl group, a perfluoroalkyl group, or an alkoxy group, and m is an integer in the range of 0 to 4, which process comprises causing a compound (A) of the formula (1):
wherein k, G, and m are as defined above, X
1
, X
2
, X
3
, and X
4
independently stand for an oxygen or sulfur atom, and Y
1
and Y
2
independently stand for a group of the formula: —C
n
H
2n
—, in which n is 2 or 3 (hereinafter occasionally referred to simply as “compound (A)”), to react with a fluorine-containing species, the molar ratio of the fluorine-containing species to compound (A) being in the range of 20 -40. The process is carried out in the presence of a bromine-containing compound, which is in an amount of 2 to 3 equivalences to the amount of compound (A), in an organic solvent at −80° C. to 30° C., the final concentration of compound (A) being in the range of 3 to 30% by weight.
The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments.
The process of the present invention permits the omission of such special facilities as have been heretofore needed and also allows 1,4-bis(difluoroalkyl)benzene derivative of the formula (2) to be produced inexpensively as aimed at because the reaction of the compound (A) of the formula (1) with fluorine can be carried out at a low temperature under a normal pressure and also because the fluorine source can be supplied at a relatively low cost.
REFERENCES:
Grechkina et al., “Synthesis of 1,1,2,2,9,9,10,10-Octafluoro[2,2]-para-cyclophane”, Zhurnal organicheskoi khimii, 1993, 29(10):1999-2001 (English translation attached).
Hasek et al., “The Chemistry of Sulfur Tetrafluoride. II. The Fluorination of Organic Carbonyl Compounds”, J.Amer.Chem.Soc., 1960, 82:543-551.
Sondej et al, Journal of Organic Chemistry, vol. 51, #18, pp. 3508-3513 (1986).
Asako Yoshinobu
Teshima Seiichi
Fish & Richardson P.C.
Nippon Shokubai Co. , Ltd.
Padmanabhan Sreeni
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