Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1996-06-20
1998-08-04
Rotman, Alan L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
570177, C07C 1738, C07C 17383
Patent
active
057896321
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process of concentrating or purifying 1,1,1,3,3-pentafluoro-2,3-dichloropropane (hereinafter, referred to as R-225da) by separating hydrogen fluoride (hereinafter, referred to as HF) from a mixture which mainly contains HF and R-225da, and a process of concentrating or purifying HF by separating R-225da from such a mixture.
BACKGROUND ART
R-225da is usually produced by reacting a chlorinated hydrocarbon such as hexachloropropene with HF under the presence of for example antimony halide as catalyst. As a separation manner of R-225da from a reaction mixture from the reaction step, a process is employed in which the reaction mixture is subjected to simple distillation so that the catalyst is removed and a resulted mixture comprising HF and R-225da is washed with water so as to isolate R-225da. However, such a separation manner forms a large amount of an aqueous solution of diluted hydrofluoric acid, and an apparatus is therefore required which treats the solution. Further, a large amount of an alkali is required which neutralizes the solution. Thus, the above described separation manner is not necessarily effective.
DISCLOSURE OF INVENTION
The present inventors have made extensive studies on a process which separates HF from a mixture comprising HF (of which boiling point is 20.degree. C. at 1 atm.) and R-225da (of which boiling point is 50.4.degree. C. at 1 atm.) as main components, and found that HF and R-225da form a minimum azeotropic composition having a molar ratio of about 90/10 (its boiling point is 18.degree. C. under a pressure of 1 Kg/cm.sup.2 -abs).
It has been further found that such an azeotropic composition is separated into an upper liquid phase (liquid layer) which is rich in HF and a lower liquid phase which is rich in R-225da (liquid layer) (namely, liquid separation) at a temperature which is generally used in industries, for example in a range of 80.degree. to -60.degree. C., which have resulted in the present invention.
Especially, the present invention provides an azeotropic composition (or an azeotropic mixture) which consists substantially of HF and R-225da, and in particular an azeotropic composition which contains 85 to 95 mol % of HF and 15 to 5 mol % of R-225da (boiling point in a range of 18.degree. to 50.degree. C.) under a pressure in a range of 1 to 5 Kg/cm.sup.2 (abs).
In addition, the present invention provides a process of separating HF or R-225da from a mixture which comprises HF and R-225da characterized in that the mixture is subjected to distillation using the formation of the azeotropic composition so that HF and R-225da is distilled off as the azeotropic composition, and the balance are obtained as a bottom product. The balance is rich in one of the components, and preferably consists substantially of one component.
That is, the present invention provides a process of concentrating (or purifying) R-225da or HF by separating HF or R-225da from a mixture comprising HF and R-225da as a feed in which process the mixture is subjected to an azeotropic distillation step so as to distill off an azeotropic composition from an enriching zone of the distillation step, for example from a top of a distillation column, and obtain, from a recovery zone of the distillation step, for example a bottom of the distillation column, R-225da of which HF content is reduced relative to that of the feed and which is preferably substantially free of HF, or HF of which R-225da content is reduced relative to that of the feed and which is preferably substantially free of R-225da, depending on a composition of the mixture.
Further, the present invention provides a process of concentrating R-225da by separating HF which process is characterized in that an azeotropic mixture resulted from azeotropic distillation which consists substantially of HF and R-225da is phase separated into an upper liquid phase which is rich in HF and a lower liquid phase which is rich in R-225da, and the lower liquid phase is supplied to another distillation column s
Aoyama Hirokazu
Nakada Tatsuo
Daikin Industries Ltd.
Rotman Alan L.
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