Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
1999-12-13
2001-08-07
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S412000, C510S415000
Reexamination Certificate
active
06271189
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel azeotropic mixture of hydrogen fluoride and 1,1,1,2,2-pentafluoroethyl iodide and a method for isolating and purifying 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride.
BACKGROUND ART
1,1,1,2,2-Pentafluoroethyl iodide is a compound useful as an intermediate for a repellent, an etchant, a surface modifier, a pharmaceutical, an agricultural substance or the like and is used for various applications.
In these applications, for example, when 1,1,1,2,2-pentafluoroethyl iodide as the raw material is reacted with hydrogen fluoride, or when hydrogen fluoride is produced as a by-product in producing 1,1,1,2,2-pentafluoroethyl iodide, or when 1,1,1,2,2-pentafluoroethyl iodide is produced using hydrogen fluoride, there is formed a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride in a variable ratio.
To purify 1,1,1,2,2-pentafluoroethyl iodide by separating hydrogen fluoride from such mixture, generally hydrogen fluoride is eliminated as an aqueous solution of hydrofluoric acid, e.g. by washing with water or with alkaline solution. However, in the method of removing hydrogen fluoride by washing, unavoidably hydrogen fluoride is discarded entirely as an aqueous solution. Thus the method raises problems that hydrogen fluoride is uselessly thrown away and the method incurs costs for washing and dumping.
DISCLOUSURE OF THE INVENTION
It is a principal object of the present invention to provide a method for efficiently isolating and purifying perfluoroalkyl iodide or hydrogen fluoride from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride without washing.
The present inventors carried out extensive research in view of the foregoing problems and newly found that a mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride forms a minimum azeotropic mixture and that 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride have a low mutual solubility. It was also discovered that utilizing such properties, 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride can be efficiently isolated and purified from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride by distilling off said azeotropic mixture either directly when the mixture is homogeneous or after liquid-liquid separation when the mixture is heterogeneous. Based on these findings, the present invention was completed.
That is, the present invention provides the following azeotropic mixtures and isolating and purifying methods.
(1) An azeotropic mixture consisting of hydrogen fluoride and 1,1,1,2,2-pentafluoroethyl iodide.
(2) The azeotropic mixture as defined above in item (1) which comprises 86 to 88% by weight of 1,1,1,2,2-pentafluoroethyl iodide and 12 to 14% by weight of hydrogen fluoride under an atmospheric pressure.
(3) A method for isolating and purifying 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride, characterized by conducting liquid-liquid separation of a heterogeneous mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride and distilling a layer of 1,1,1,2,2-pentafluoroethyl iodide or a layer of hydrogen fluoride so that an azeotropic mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is removed through the top of a distillation column while 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride is obtained from the bottom of the distillation column.
(4) A method for isolating and purifying 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride, characterized by distilling a homogeneous mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride so that an azeotropic mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is removed through the top of a distillation column while 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride is obtained from the bottom of the distillation column.
(5) A method for isolating and purifying 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride from a mixture containing 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride, characterized by conducting a liquid-liquid separation of the distillate obtained through the top of the distillation column by the method as defined above in item (3) or (4), and distilling a layer of 1,1,1,2,2-pentafluoroethyl iodide or a layer of hydrogen fluoride so that an azeotropic mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is removed through the top of a distillation column while 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride is obtained from the bottom of the distillation column.
1,1,1,2,2-Pentafluoroethyl iodide and hydrogen fluoride form a minimum azeotropic mixture in proportions of 86 to 88% by weight of the former and 12 to 14% by weight of the latter under an atmospheric pressure. It is unknown, i.e. a novel finding that these two compounds give a minimum azeotropic mixture.
1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride have a limited mutual solubility and are easily separable into two layers. Each of the separated layers contains only a small amount of other component.
The methods of the present invention are based on the newly discovered properties of a mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride. When the mixture is homogeneous, it is used as such. Alternatively, when the mixture is heterogeneous, a liquid-liquid separated product is used. In either case, distillation is carried out to remove an azeotropic mixture thereof, whereby 1,1,1,2,2-pentafluoroethyl iodide or hydrogen fluoride can be efficiently isolated and purified from the mixture thereof.
Separation methods differ depending on whether a mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is heterogeneous or homogeneous and are separately described below.
First, when the mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is heterogeneous, the mixture is subjected to liquid-liquid separation, and a layer of 1,1,1,2,2-pentafluoroethyl iodide is distilled to remove an azeotropic mixture through the top of a distillation column, whereby 1,1,1,2,2-pentafluoroethyl iodide substantially free of hydrogen fluoride can be efficiently obtained from the bottom of the distillation column. In this case, when a layer of hydrogen fluoride obtained by liquid-liquid separation is distilled to remove an azeotropic mixture through the top of the distillation column, hydrogen fluoride substantially free of 1,1,1,2,2-pentafluoroethyl iodide can be efficiently obtained from the bottom of the distillation column.
Further, when the distillate obtained through the top of the distillation column is subjected to the same procedure as above after liquid-liquid separation, hydrogen fluoride substantially free of 1,1,1,2,2-pentafluoroethyl iodide or 1,1,1,2,2-pentafluoroethyl iodide substantially free of hydrogen fluoride can be obtained.
When a mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is homogeneous and contains a small amount of 1,1,1,2,2-pentafluoroethyl iodide, the mixture is distilled as such to remove an azeotropic mixture from the top of the distillation column, whereby hydrogen fluoride substantially free of 1,1,1,2,2-pentafluoroethyl iodide can be efficiently obtained from the bottom of the distillation column. On the other hand, when a mixture of 1,1,1,2,2-pentafluoroethyl iodide and hydrogen fluoride is homogeneous and contains a small amount of hydrogen fluoride, the mixture is distilled as such to remove an azeotropic mixture from the top of the distillation column, whereby 1,1,1,2,2-pentafluoroethyl iodide substantially free of hydrogen fluoride can be efficiently obtained from the bottom of the distillation column.
Further, in either case of the mixture containing a small amount of 1,1,1,2,2-pentafluoroethyl iodide or containi
Aoyama Hirokazu
Hirata Tatsuya
Otsuka Tatsuya
Seki Eiji
Tanaka Yoshinori
Boyer Charles
Daikin Industries Ltd.
Gupta Yogendra N.
Larson & Taylor PLC
LandOfFree
Azeotropic mixture of perfluoroalkyl iodide and hydrogen... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Azeotropic mixture of perfluoroalkyl iodide and hydrogen..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Azeotropic mixture of perfluoroalkyl iodide and hydrogen... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509237