Title of Invention

"PROCESS FOR THE OBTENTION OF PURIFIED HEPTAFLUOROPROPANE"

Abstract A    process for    the obtention of 1,1,1,2,3,3,3-heptafluoropropane having a reduced content of organic impurities, which comprises (a) subjecting a crude 1,1,1,2,3,3,3-heptafluoropropane containing water and organic impurities to at least two distillations steps, consisting of a high pressure distillation step and a low pressure distillation step carried out at a pressure of at least 1 bar lower than the high pressure distillation step, drawing off in the high pressure distillation step a fraction containing water, which is thereby removed from the crude HFC-227ea, and low boiling organic impurities, and (b) recovering 1,1,1,2,3,3,3-heptafluoropropane having a reduced content of organic impurities, wherein the term "low boiling organic impurities" denotes impurities exhibiting, at the pressure of the distillation in the presence of 1,1,1,2,3,3,3-heptafluoropropane, a boiling point lower than the boiling point of the 1,1,1,2,3,3,3-heptafluoropropane.
Full Text Process for the obtention of purified heptafluoropropane
The present invention concerns a process for the obtention of purified l,l,l,2,3,3,3-hepta£luoropropaiie(EDPC-227ea).
HFC-227ea is useful in particular as environmeirtally-fnetidly fire-extinguishing agent and as propdlant, notably for pharmaceutical aerosols.
The industrial production of HFC-227ea frequently provides, however, a product which comprises saturated and unsaturated impurities. As such impurities are often toxic, strict standards &x the concentration of impurities, in particular unsaturated impurities are likely to be adopted fbi HFC-227ea for pharmaceutical applications.
In EP-05125Q2-A2 it was proposed to reduce or eliminate the olefin content in HFC-227ea by reaction with an alcohol in the presence of a base. While this process provides outstanding results for the elimination of ulcilns in HFC-227ea, it requires addition of further chemical compounds to the crude HFC-227ea.
Accordingly, it is a purpose of the invention to provide a process for the obtention of HFC-227ea having a reduced content of all kinds of organic impurities and in particular olefodc impurities which does not require addition of further chemical compounds to the crude HFC-227ea. In particular, it is a purpose of the invention to provide such a process allowing for the obtention of HFC-227ea having a purity suitable for use in pharmaceutical applications, especially as propellant for inhalation aerosols.
In consequence, the invention concerns a process for the obtention of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) having a reduced content of organic impurities, which comprises
(a) faihjftnrtnf a nrode HFCV227et containing organic impurities to at least twa
distillations steps, consisting of a high pressure distillation step ^x\6 a low
pressure distillation step carried out at a pressure of at least 1 bar lower than the
high pressure distillation step and
(b) recovering HFC 227-ea having a reduced content of organic impurities.
The process according to the invention makes it possible to achieve an efficient separation of organic impurities, in particular of the olefinic impurities from HFC-227ea by a physical method. The process can be carried out in an easy

manner and allows for use of steam-heating/water-cooling In a totally unexpected manner, the process is sufficiently efficient to allow for the use of the obtained HFC-227ea in pharmaceutical applications The process does not involve addition of further chemical compounds to the crude HFC-227ea. This is particularly advantageous in the manufacture of HFC-227ea for pharmaceutical applications, as all compounds used in manufacture of a pharmaceutical product must be examined as to their toxidty and notified in regulatory procedures
The purity of the HFC-227ea obtained in the process according to the invention is generally equal to or greater than 99,9% wt Often this purity is equal to or greater than 99,95% wt. Preferably, it is equal to or greater than 99,99% wt. The HFC-227ea obtained in the process preferably contains less than 5 ppm of any individual olefmic impurity.
The term "low-boiling impurity" is understood to denote an impurity exhibiting, at the pressure of the distillation in the presence of HFC-227ea, a boiling point lower than the boiling point of the HFC~227ea. The term "high-boiling impurity" is understood to denote an impurity exhibiting, at the pressure of the distillation in the presence of HFC-227ea, a boiling point greater than the boiling point of the HFC-227ea.
The pressure in the high pressure distillation is generally at most 30 bar. It is often at most 20 bar. Preferably, the pressure is at most 12 bar It is more preferably at most 11.5 bar The pressure ia the high pressure distillation is generally at least 6 bar. Often, this pressure is at least 7 5bar. It is preferably at least 9.5 bar Generally, a fraction comprising low boiling impurities is drawn off from the high pressure distillation step. The low boiling impurities are thereby removed from the HFC-227ea. Typical low-boiling organic impurities include saturated or insaturated fluorocarbons comprising 1, 2, 3 or 4 carbon atoms More particularly, low-boiling organic impurities include saturated or unsaturated (hydro)fluorocarbons xe. organic compounds consisting of carbon, fluorine and optionally hydrogen, comprising 1, 2 or 3 carbon atoms Hexafluoropropylene is a specific example of a Iow-boilmg organic impurity.
The pressure in the low pressure distillation is generally at least 1 bar It is often at least 4 bar. Ji is preferably at least 6 bar It is more preferably at least 7 bar. The pressure in the low pressure distillation is at generally at most 12 bar. Preferably this pressure is at most 20 bar. Generally, a fraction comprising high boiling impurities is drawn ofFfrom the low pressure distillation The high boiling impurities are thereby removed from the

HFC-227ea. Typical high-boiling organic impurities include saturated or unsaturated (bydro)fluorocarbons comprising at least 5 carbon atoms and (hydro)cMorofluorocarbons comprising preferably at least two carbon atoms More particularly, high-boiling organic impurities include saturated or unsaturated (hydro)fluorocarbons i.e. organic compounds consisting of carbon, fluorine and optionally hydrogen, comprising at least 6 carbon atoms Hexafluoropropylene dimers of general formula C6F12 are specific examples of high-boiling organic impurities.
Another type of high-boiling organic impurities includes organic compounds comprising at least one heteroatom, which is preferably selected from oxygen and nitrogen. Generally, these compounds also contain at least one fluorine atom. Mention may be made, for example of fluorinated ethers comprising from 2 to 10 carbon atoms.
In the present description, any reference to the pressure corresponds to the absolute pressure, measured at the top of the distillation column
The pressure difference between the high pressure distillation step and the low pressure distillation step is at least 1 bar. Preferably, this difference is at least 2 bar A pressure difference of about 2.5 bar is particularly preferred Generally, the pressure difference between the high pressure distillation step and the low pressure distillation step is at most 29 bar. Preferably, this difference is at most 10 bar. A pressure difference of at most 5 bar is particularly preferred
The temperature at which the high or fte low pressure distillation is carried out corresponds approximately to the boiling point of the HFC-227ea at the pressure chosen for the respective distillation.
In a first embodiment of the process according to the invention the low pressure distillation step is carried out before the high pressure distillation step.
In a second embodiment of the process according to the invention, which is preferred, the low pressure distillation step is carried out after the high pressure distillation step In the second embodiment it is possible to recover the HFC-227ea having a reduced contrail uf ui-ganic impurities from the top of the low pressure distillation. This mode of recovery is particularly advantageous, as rt allows to minimise and even completely eHminate the nsk of contamination of the HFC-227ea by optionally present conofion products nf finlnmn material
Each of the two distillation steps can be carried out in one or more distillation columns. Use will preferably be made of a single column per distillation step

The distillation columns which can be used in the process according to the invention are known per se. Use may be made, for example, of conventional pkte columns or plate columns of dual-flow type or alternatively of columns with bulk or structured packing.
Thfi TWirnhftr nf rhpnrptir^l rilatM m rhp higti jtHSsiuv* distillatinn it generally at least 10. ft is often at least 20. A number of at least 35 gives good results.
The number of theoretical plates m flit low pressure, riisf iitotinn is gwvmiiy at least 5. It is often at least 15. A muab& of at least 30 gives good results.
The mass reboiling ratio in the high pressure distillation is generally at least 1. Frequently, the mass reboiling ratio is at least 3. More frequently, the mass reboiling ratio is at least 8. A iiiiis icboiling ratio of at least 10 is preferred. The mass reboiling ratio in the high pressure distillation is generally at most 100. Frequently, the mass reboiling ratio is at most 50. More frequently, the mass reboiling ratio is at most 30. A mass reboiling ratio of at most 25 is preferred.
The miss reflux ratio in the low pressure distillation is generally at least 2. Frequently, the mass reflux ratio is at least 4. A mass reflux ratio of at least 5 is preferred. The mass reflux ratio in the low pressure column is generally at most 50. Frequently, the mass reflux ratio is at most 30. A mass reflux ratio of at most 20 is preferred.
In. a particular embodiment, the mass ratio in the high pressure distillation of the feed of crude HFO227ea to the fraction comprising said low-boiling organic impurities withdrawn from said high presswe distillation is kept in a range from 1 to 100. Preferably this mass ratio is kept in a range from 3 to 60. In a particularly preferred embodiment the mass ratio is controlled so as to display a deviation from the desired mass ratio of at most 10%. Preferably this deviation is at most 5%. Most preferably the deviation is at most 3%.
The high and low pressure distillations can be operated in continuous or discontinuous mode. In a preferred embodiment, the fraction comprising low-boiling organic impwities. is continuously withdrawn frnm tk* high preisure distillation. The latter embodiment is used in a particularly advantageous manner, when the crude HFC-227ea contains a tow amount of low-boiling organic impurities.
Typical examples of crude HFC-227ea which can be used in the process according to the invention, have a content of low-boiling organic impurities of

1% by weight or less. Often this content is 0,5% by weight or less. Preferably, this content is 0,3 % by weight or less.
Typical examples of crude HFC-227ea which can be used in the process according to tho invaatio» have % parity al"at least 95 % by wel^U. OILeu die , purity is greater than, or equal U> 99% by weight Preferably, the punty is greater than or equal to 99,5 % by weight.
The crude HFC-227ea can-be obtatmd for example, through hydrofmorination of hexafhioropcopyleae, through hydrofluorination of suitable halofluoropropanes or through hydrogenation of 2-chloroheptafluoropropane. Advantageously, the crude HFC-227ea has been obtained by a reaction comprising use of hexaJIuoropropylene as a starting material. Preferably, the crude HFC-227ea has been obtained by reaction of hexafluoropropylene with hydrogen fluoride, preferably in the presence of a hydrofluorination catalyst.
If necessary, the crude HFC-227ea product obtained in reactions such as mentioned hcrebefore, may be worked-up by operations such as washing and rough-distillation to achieve the preferred purities for the crude HFC-227ea which is introduced into the process according to the invention
In a still fiirther embodiment, the crude EDFC-227ea also comprises water. In this embodiment of the process accordiag to the invention, the fraction comprising low-boiling organic impurities, which can be withdrawn from the high pressure distillation step, also comprises water which is thereby removed from the crude HFC-227ea. It should be understood that the specific preferences and general descriptions of the process according to the invention specifically apply to the present further embodiment. 1 has been surprisingly found that water, which normally should be expected to be a high boiler with regard to HFC-227ea at all distillation pressures, foims an azeotrope with low boiling organic impurities and HFC-227ea, thus enabling for efficient water removal from HFC-227ea. Water removal is especially advantageous when a HFO-227ea suitable for pharmaceutical aerosols is desired, as the presence of water might influence in an undesirable way, the solubility and crystal growth of medicaments to be dissolved or suspended in the HFC-227ea-comprising propellant.
Basically, the thermodynamic state of a fluid is defined by four interdependent variables, the presajre (P), the temperature (T), the composition of the liquid phase (X) and the composition of the gas phase (Y). A true azeotrope is a specific system of 2 or more components for which, at a givftn

temperature and a given pressure, the composition of the liquid phase X is exactly equal to the composition of the gas phase Y A pseudo-azeotrope is a system of 2 or more components for which, at a given temperature and a given pressure, X is substantially equal to Y. In practice, this means that the constituents of such azeotropic and pseudo-azeotropic systems cannot be readily separated by distillation.
For the purposes of the present invention, the expression 'pseudo-azeotropic mixture" means a nrixtore of two constituents whose boiling point (at a given pressure) differs from the boiling point of the true azeotrope by a maximum of 0.5°C. Mixtures whose boiling point differs from the boiling point of the true azeotrope by a maximum of 0.2#C are preferred. Mixtures whose boiling point differs from the boiling point of the true azeotrope by a maximum of 0 1°C are particularly preferred.
The invention concerns also an azeotropic or pseudo-azeotropic mixture comprising HFC-227ea and water. The azeotropic or pseudo-azeotropic mixture according to the invention consists generally, at a pressure of 10 5 bar essentially of HFC-227ea and at most 500 mg/kg of water. Preferably the water content in the azeotropic or pseudo-azeotropic mixture at 10.5 bar is at most 300 mg/kg. A water content in the azeotropic or pseudo-aieotropic mixture at 10 5 bar of at most 200 mg/kg is particularly preferred The azeotropic or pseudo-azeotropic mixture according to the invention consists generally, at a pressure of 10.5 bar essentially of HFC-227ea and at least 20 mg/kg of water Preferably the water content in the azeotropic or pseudo-azeotropic mixture at 10.5 bar is at least 50 mg/kg. A water content in the azeotropic or pseudo-azeotropic mixture at 10.5 bar of at least 100 mg/kg is particularly preferred
The azeotropic or pseudo-azeotropic mixture according to the invention consists generally, at a pressure of 1 bar essentially of HFC~227ea and at most 50 mg/kg of water. Preferably the water content in the azeotropic or pseudo-azeotropic mixture at 1 bar is at most 30 mg/kg. The azeotropic or pseudo-azeotropic mixture according to the invention consists generally, at a pressure of 1 bar essentially of HFO227ea and at least 5 mg/kg of water. Preferably the water content in the azeotropic or pseudo-azeotropic mixture at 10.5 bar is at least 10 mg/kg.
In a particular embodiment the azeotropic or pseudo-azeotropic mixture according to the invention comprises in addition organic impurities which are

low-boiling with respect to HFC-227ea at the pressures of the high pressure distillation step such as described above.
The azeotropic or pseudo-azeotropic mixture according to the invention can be used to remove water and optionally low boiling organic impurities from HFC-227ea.
The example given below is intended to illustrate, without implied limitation, the process according to the invention.
Example
A crude HFC-227ea obtained by hydrofluorination of hexafluoropropene having a purity of about 99,8% wt and containing 0,1% wt. low-boiling organic impurities including hexafluoropropylene, 0,05 %wt. high-boiling organic impurities including CgFu and water has been purified according to the process according to the invention. The erode HFC-227ea was introduced into the high pressure distillation step. The light-boilers were continuously drawn off from the top of the high pressure distillation AnHFC-227ea fraction containing high-boilers was withdrawn from the bottom of the high pressure distillation and introduced into the low pressure distillation. Purified HFC-227ea was withdrawn from the top of the low pressure distillation. The table hereafter indicates the process conditions which were used in the first and low pressure distillation respectively.
High pressure distillation Low pressure distillation
Pressure (bar) 10_5 J5
Temperature (°C) 55 45
Recoiling ratio (mass) 17.5 -
Reflux ratio (mass) _ 14
Theoretical plates _40 33
Mass ratio (feed crude 30
HFC-227ea/low boiler
fraction drawn off)
The obtained purified HFC~227ea had a purity of greater than 99.99% vol determined by gas chromatography. The content of any olefinic impurities was less than 5ppm. The HFC-227ea contained less than 10 ppm of water determined by Karl-Fischer method.



WE CLAIM:
1. A process for the obtention of 1,l,2,3,3,3-heptafluoropropane having a reduced content of organic impurities, which comprises
(a) subjecting a crude 1,1,1,2,33,3-heptafluoropropane containing water and organic impurities to at least two distillations steps, consisting of a high pressure distillation step and a low pressure distillation step carried out at a pressure of at least 1 bar lower than the high pressure distillation step, drawing off in the high pressure distillation step a fraction containing water, which is thereby removed from the crude HFC-227ea, and low boiling organic impurities, and
(b) recovering 1,1,1,2,3,3,3-heptafluoropropane having a reduced content of organic impurities,
wherein the term "low boiling organic impurities" denotes impurities exhibiting, at the pressure of the distillation in the presence of 1,1,1,2,3,3,3-heptafluoropropane, a boiling point lower than the boiling point of the 1,1,1,2,3,3,3-heptafluoropirpane.
2. Process as claimed in claim ] wherein the pressure difference between the high pressure distillation step and the low pressure distillation step is from 2 to 5 bar.
3. Process as claimed in claim 1 or 2 wherein the pressure in the low pressure distillation step is from 1 to 12 bar and the pressure in the high pressure distillation step is from 6 to
30 bar.
4. Process as claimed in anyone of claims 1 to 3 wherein the low pressure distillation step is carried out before the high pressure distillation step,
5. Process as claimed in anyone of claims 1 to 3 wherein the low pressure distillation step is carried out after the high pressure distillation step.
6. Process as claimed in claim 5 wherein 1,1,1,2,3,3,3-heptafluoropropane having a reduced content of organic impurities is recovered from the top of the low pressure distillation.
7. Process as claimed in claim 6, wherein the fraction comprising said low-boiling organic impurities is continuously drawn off from the high pressure distillation step.
8. Process as claimed in claim 7, wherein in the high pressure distillation the mass tatio of the feed of crude 1,1,l,2,3,3,3-heptafluoropropaiie to the fraction comprising said low-boiling organic impurities withdrawn from said high pressure distillation is kept in a range from 1 to 100.
9. Process as claimed in anyone of claims 1 to 8, wherein the crude 1,1,1,2,3,3,3-heptafluoropropane has a purity of at least 95%.
10. Process as claimed in anyone of claims 1 to 9, wherein the crude 1,1,1,2,3,3,3-heptafluoropropane has been obtained by a reaction comprising use of hexafluoropropylene as a starting material.





Documents:

571-DELNP-2004-Abstract-(31-12-2010).pdf

571-delnp-2004-abstract.pdf

571-delnp-2004-claims (08-07-2011).pdf

571-DELNP-2004-Claims-(08-07-2011).pdf

571-DELNP-2004-Claims-(31-12-2010).pdf

571-delnp-2004-claims.pdf

571-DELNP-2004-Correspodence Others-(08-07-2011).pdf

571-delnp-2004-correspondence-others (08-07-2011).pdf

571-delnp-2004-correspondence-others (15-06-2011).pdf

571-DELNP-2004-Correspondence-Others (21-08-2006).pdf

571-delnp-2004-Correspondence-Others(16-05-2011).pdf

571-DELNP-2004-Correspondence-Others-(20-01-2011).pdf

571-DELNP-2004-Correspondence-Others-(31-12-2010).pdf

571-delnp-2004-correspondence-others.pdf

571-delnp-2004-description (complete).pdf

571-delnp-2004-form-1 (15-06-2011).pdf

571-delnp-2004-form-1.pdf

571-delnp-2004-form-18.pdf

571-delnp-2004-form-2.pdf

571-delnp-2004-form-26.pdf

571-DELNP-2004-Form-3-(20-01-2011).pdf

571-DELNP-2004-Form-3-(31-12-2010).pdf

571-delnp-2004-form-3.pdf

571-delnp-2004-gpa (15-06-2011).pdf

571-DELNP-2004-Petition 137-(31-12-2010).pdf


Patent Number 248382
Indian Patent Application Number 571/DELNP/2004
PG Journal Number 28/2011
Publication Date 15-Jul-2011
Grant Date 08-Jul-2011
Date of Filing 08-Mar-2004
Name of Patentee SOLVAY (SOCIETE ANONYME)
Applicant Address RUE DU PRINCE ALBERT 33, B-1050 BRUXELLES, BELGIUM
Inventors:
# Inventor's Name Inventor's Address
1 THOMAS MULLER CARL-ULRICH-STRASSE 18, 74206 BAD WIMPFEN, GERMANY
2 DOMINIQUE BALTHASART RUE DU CHATEAU BEYAERD 150, B-1120 BRUXELLES, BELGIUM
3 BERND KUTZNER JOHANN-STRAUSS-STRASSE 25, 65779 KELKHEIM, GERMANY
PCT International Classification Number C07C 17/383
PCT International Application Number PCT/EP02/10381
PCT International Filing date 2002-09-05
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 01203374.2 2001-09-07 Germany