DEHYDROFLUORINATION PROCESS TO MANUFACTURE HYDROFLUOROOLEFINS BACKGROUND INFORMATION

Field of the Disclosure

This disclosure relates in general to processes for the production of fluorinated olefins.

Description of the Related Art

The refrigeration industry has been working for the past few decades to find replacement refrigerants for the ozone depleting

chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) being phased out as a result of the Montreal Protocol. The solution for most refrigerant producers has been the commercialization of

hydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC- 134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase-out as a result of the Montreal Protocol.

In addition to ozone depleting concerns, global warming is another environmental concern. Thus, there is a need for heat transfer

compositions that have not only low ozone depletion potentials, but also low global warming potentials. Certain hydrofluoroolefins meet both goals. Thus there is a need for manufacturing processes that provide

halogenated hydrocarbons and fluoroolefins that contain no chlorine and also have lower global warming potential than current commercial refrigeration products.

SUMMARY

Disclosed is a process for the manufacture of hydrofluoroolefins of the structure CF ₃ CH=CHY, wherein Y can be Br, CI or F, through reacting at least one fluoropropane reactant of the structure CF ₃ CH ₂ CXYH, where X can be CI, Br or F and Y can be CI. Br or F, with a basic aqueous solution in the presence of a nonaqueous, nonalcoholic solvent.

DESCRIPTION OF THE INVENTION

The description below is exemplary and explanatory only and is not restrictive of the invention, as defined in the appended claims. Other features and benefits of any one or more of the embodiments will be apparent from the following detailed description, and from the claims.

Group numbers corresponding to columns within the Periodic Table of the elements use the "New Notation" convention as seen in the CRC Handbook of Chemistry and Physics, 81 ^st Edition (2000-2001 ).

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a particular passage is cited. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

Disclosed is a process for the manufacture of hydrofluoroolefins of the structure CF ₃ CH=CHY, wherein Y can be Br, CI or F, comprising at least one fluoropropane reactant of the structure CF ₃ CH ₂ CXYH, where X can be CI, Br or F and Y can be CI. Br or F, with a basic aqueous solution in the presence of a nonaqueous, nonalcoholic solvent, and in the absence of a phase transfer catalyst. While they can be effective, phase transfer catalysts are expensive, contribute to waste streams, and can be difficult to separate from solvents which may need to be recycled.

Commercially it is not desired to use phase transfer catalysts if other methods are available.

In certain embodiments, the hydrofluoroolefin produced by the disclosed embodiments are 1 ,3,3,3-tetrafluoro-1 -propene (HFC-1234ze)(E and Z isomers) and 1 -chloro-3,3,3-trifluoro-1 -propene (HCFO- 1233zd)(both E and Z isomers), each having zero or low ozone depletion potential and low global warming potential and having been identified as potential refrigerants, foam expansion agents, and or solvents.

As used herein, the basic aqueous solution is a liquid (whether a solution, dispersion, emulsion, or suspension and the like) that is primarily an aqueous liquid having a pH of over 7. In some embodiments the basic aqueous solution has a pH of over 8. In some embodiments, the basic aqueous solution has a pH of over 10. In some embodiments, the basic aqueous solution has a pH of 10-13. In some embodiments, the basic aqueous solution contains small amounts of organic liquids which may be miscible or immiscible with water. In some embodiments, the liquid medium in the basic aqueous solution is at least 90% water. In one embodiment the water is tap water; in other embodiments the water is deionized or distilled.

The base in the aqueous basic solution is selected from the group consisting of hydroxide, oxide, carbonate, or phosphate salts of alkali, alkaline earth metals and mixtures thereof. In one embodiment, bases which may be used include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, calcium oxide, sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, or mixtures thereof.

In certain embodiments, the non-aqueous non-alcoholic solvent is selected from the group consisting of alkyl and aryl nitriles, alkyl and aryl ethers, amides, ketones, sulfoxides, phosphate esters and mixtures thereof. Said alkyl groups may be cyclic or acyclic and straight-chain or branched alkyl groups. In another embodiment, the solvent is selected from the group consisting of acetonitrile, propionitrile, butyronitrile, methyl glutaronitrile, adiponitrile, benzonitrile, ethylene carbonate, propylene carbonate, methyl ethyl ketone, methyl isoamyl ketone, diisobutyl ketone, anisole, 2-methyltetrahydrofuran, tetrahydrofuran, dioxane, diglyme, triglyme, tetraglyme, Ν,Ν-dimethyl formamide, Ν,Ν-dimethyl acetamide, N- methyl pyrrolidinone, sulfolane, dimethyl sulfoxide, peril uoro-N-methyl morpholine, perfluorotetrahydrofuran, trialkylamines, dialkylamines, benzene, toluene, xylene, naphthalene, methylnapthalene, other aromatic solvents, and mixtures thereof. In one embodiment, the solvent is triethylamine, toluene, or morpholine.

In one embodiment, the process is for the manufacture of 1 ,3,3,3- tetrafluoro-1 -propene (HFO-1234ze) by dehydrofluorination of 1 ,1 ,1 ,3,3- pentafluoropropane (HFC-245fa). HFO-1234ze may exist as two configurational isomers, E, or Z. HFO-1234ze as used herein refers to the isomers, E-HFO-1234ze (CAS RN 291 18-24-9) or Z-HFO-1234ze (CAS RN 291 18-25-0), as well as any combinations or mixtures of such isomers. In another embodiment, the process is for the manufacture of 1 ,3,3,3- tetrafluoro-1 -propene (HCF-1234ze) by dehydrochlorination of 1 -chloro- 1 ,3,3,3-tetrafluoropropane (HCFC-244fb). In another embodiment, the process is for the manufacture of 1 -chloro-3,3,3-trifluoro-1 -propene

(HCFO-1233zd) by dehydrofluorination of 1 -chloro-1 ,3,3,3- tetrafluoropropane (HCFC-244fb). In another embodiment, the process is for the manufacture of 1 -chloro-3,3,3-trifluoro-1 -propene (HCFO-1233zd) by dehydrochlorination of 1 ,1 -dichloro-3,3,3-trifluoropropane (HCFC- 243fa).HCFO-1233zd may exist as two configurational isomers, E, or Z. HCFO-1233zd as used herein refers to the isomers, E-HCFO-1233zd (CAS RN 102687-65-0) or Z-HCFO-1233zd (CAS RN 2730-43-0), as well as any combinations or mixtures of such isomers.

In one embodiment, the fluoropropane is 1 ,1 ,1 ,3,3- pentafluoropropane (HFC-245fa) which can be produced by many known methods in the art. For example, HFC-245fa can be prepared by reaction of 1 ,1 ,1 ,3,3-pentachloropropane with HF in the presence of an antimony catalyst. In another embodiment, the fluoropropane is 1 -chloro-1 ,3,3,3- tetrafluoropropane (HCFC-244fa) which can be produced by many known methods in the art. For example, HCFC-244fa can be prepared by reaction of 1 ,1 ,1 ,3,3-pentachloropropane with HF in the presence of an antimony catalyst under conditions where complete fluorination to the pentafluoropropane does not occur and one chlorine remains. In yet another embodiment, the fluoropropane is 1 ,1 -dichloro-3,3,3- trifluoropropane (HCFC-243fa) which can be produced by many know methods in the art. For example, HCFC-243fa can be prepared by reaction of 1 ,1 ,1 ,3,3-pentachloropropane with HF in the presence of an antimony catalyst under conditions where complete fluorination to the pentafluoropropane does not occur and two chlorine substituents remain.

In one embodiment, the dehydrofluorination of fluoropropane is accomplished using a basic aqueous solution in the presence of a nonaqueous, non-alcoholic solvent in which the fluoropropane is at least partially miscible. In one embodiment, the base in the basic aqueous solution includes alkali metal or alkaline earth metal hydroxides and oxides, or mixtures thereof, which can include without limitation lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, calcium oxide, sodium carbonate, potassium

carbonate, sodium phosphate, potassium phosphate, or mixtures thereof.

The amount of base (in the basic aqueous solution) required to convert a fluoropropane to a hydrofluoroolefin is approximately the stoichiometric quantity or about 1 mole of base to one mole of

fluoropropane. In one embodiment, it may desirable (e.g., to increase reaction rate) to employ a ratio of base to fluoropropane of greater than one. In some embodiments, large excesses of base (in the basic aqueous solution) are to be avoided as further reaction of the desired

hydrofluoroolefin may occur. Thus, in some embodiments, it may be necessary to employ an amount of base (in the basic aqueous solution) that is slightly below the stoichiometric so as to minimize secondary reactions. Thus, in one embodiment, the molar ratio of base (in the basic aqueous solution) to fluoropropane is from about 0.75:1 to about 10:1 . In another embodiment, the molar ratio of base (in the basic aqueous solution) to fluoropropane is from about 0.9:1 to about 5:1 . In yet another embodiment, the molar ratio of base to fluoropropane is from about 1 :1 to about 4:1 .

In one embodiment, the dehydrofluorination may occur by reverse addition whereby the reactor is filled with fluoroalkane and solvent and a solution of base is added so that the stoichiometry remains less than one and the lower boiling fluoroolefin leaves the reactor so it does not further react. The dehydrofluorination can occur in this manner from 10°C to about 150°C or from about 5 degrees above the freezing point of the solvent whichever is higher.

In one embodiment, the dehydrofluorination is conducted within a temperature range at which the fluoropropane will dehydrofluorinate. In one embodiment, such temperatures can be from about 10 °C to about 150 °C. In another embodiment, the reaction is conducted in the range of from about 30 °C to about 1 10 °C. In yet another embodiment, the reaction is carried out in the range of from about 40 °C to about 90 °C. The reaction pressure is not critical. The reaction can be conducted at atmospheric pressure, super-atmospheric pressure, or under reduced pressure. In one embodiment, the reaction is carried out at atmospheric pressure.

In one embodiment, the reaction is carried out with agitation. When reactants are in the same phase, as in solution, thermal motion brings them into contact. However, when they are in different phases, such as immiscible liquids, the reaction is limited to the interface between the reactants. Reaction can occur only at their area of contact; in the case of a liquid and a gas, at the surface of the liquid. In the case of a liquid and a solid, reaction can occur at the surface of the solid. In the case of a liquid and a liquid, at the interface of the two liquids. Vigorous shaking, agitation, and/or stirring may be needed to bring the reaction to

completion. The extent of agitation depends on the desired reaction rate which is dependent on the reactor geometry, residence time, agitator and baffling design, and solubility or miscibility of the reactants.

In one embodiment, a solid base (e.g., KOH, NaOH, LiOH or mixtures thereof) is dissolved in water, or alternatively, a concentrated solution of a base (e.g., 50% by weight aqueous potassium hydroxide) is diluted to the desired concentration with water. The non-aqueous, nonalcoholic solvent for the method is then added with agitation under otherwise ambient conditions. In one embodiment, a solvent for the reaction can be a nitrile, ether, amide, ketone, sulfoxide, phosphate ester, or mixtures thereof. In another embodiment, the solvent is selected from the group consisting of acetonitrile, adiponitrile, 2-methyltetrahydrofuran, tetrahydrofuran, dioxane, diglyme, tetraglyme, perfluorotetrahydrofuran, and mixtures thereof.

In some embodiments, the dehydrofluorination process is carried out in batch techniques and in other embodiments the

dehydrofluorination process can be carried out in a continuous mode of operation. In one embodiment, in the batch mode, the above described components are combined in a suitable vessel for a time sufficient to convert at least a portion of the fluoropropane to hydrofluoroolefin and then the hydrofluoroolefin is recovered from the reaction mixture. In one embodiment, in the batch mode, the above described components are combined in a suitable vessel for a time sufficient to convert at least a portion of the hydrochlorofluoropropane to hydrochlorofluoroolefin and then the hydrochlorofluoroolefin is recovered from the reaction mixture.

In another embodiment, in a continuous mode of operation, the reaction vessel is charged with the basic aqueous solution and

nonaqueous, nonalcoholic solvent, and the fluoropropane is fed to the reactor. The reaction vessel is fitted with a condenser cooled to a temperature sufficient to reflux the fluoropropane, but the hydrofluoro olefin is permitted to exit the reaction vessel and collect in an appropriate vessel such as cold trap.

In another embodiment, in the batch mode, the above described components are combined in a suitable vessel for a time sufficient to convert at least a portion of the fluoropropane to hydrofluoroolefin and then the hydrofluoroolefin is recovered from the reaction mixture.

EXAMPLES

The concepts described herein will be further described in the following examples, which do not limit the scope of the invention described in the claims.

Example 1 , Dehydrofluorination of 245fa by aqueous KOH and triethylamine.

180g 30% KOH solution and 14 ml triethylamine were added into a 500 ml three-neck round bottomed flask equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as a gas at 30sccm with agitation and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 1 which shows triethylamine greatly promoted 245fa dehydrofluorination reaction in the absence of any phase transfer catalyst. The product does not contain any trifluoropropyne byproduct.

Table 1

ND = not determined

Example 2, Dehydrofluorination of 245fa by aqueous KOH and morpholine

180g 30% KOH solution and 14 ml morpholine were added to a 500 ml three-neck round bottomed flask equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as a gas at 30sccm with agitation and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 2 which shows morpholine could promote 245fa dehydrofluonnation reaction without the need a phase transfer catalyst.

Table 2

ND = not determined.

Example 3, Dehydrofluorination of 245fa by aqueous KOH and toluene without presence of a phase transfer catalyst

180g 30% KOH solution and 14 ml toluene were added into a 500 ml three-neck round bottomed flask which was equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as a gas at 30 seem with agitation, and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 3.

Table 3

ND = not determined. Example 4, Dehydrofluorination of 245fa by aqueous KOH and hexane.

180g 30% KOH solution and 14 ml toluene were added into a 500 ml three-neck round bottomed flask which was equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as a gas at 30 seem with agitation and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 4 which shows 245fa dehydrfluorination reaction did not proceed appreciably in hexane without a phase transfer catalyst.

Table 4

Example 5, Dehydrofluorination of 245fa by aqueous KOH without presence of a solvent or a phase transfer catalyst

180g 30% KOH solution were added into a 500 ml three-neck round bottomed flask which was equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as a gas at 30 seem with agitation, and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 5. Table 5

ND = not determined.

Examples 1 -5 show that the desired product may be manufactured without the use of a phase transfer catalyst. Comparing Examples 1 and 6 below demonstrates that some solvents actually perform better than phase transfer catalysts.

Comparative Example 6, Dehydrofluorination of 245fa by aqueous KOH with presence of phase transfer catalyst Aliquat 336

180g 30% KOH solution and 3.6g Aliquat 336 were added into a 500 ml three-neck round bottomed flask which was equipped with an overhead mechanical stirrer and a 245fa feed line. The tip of 245fa feed line was located in the liquid phase. 245fa was fed into the reactor as gas at 30 seem with agitation and the product was vented to a bubbler. The gas sample from the outlet of reactor was analyzed by GCMS during the run and results are listed in Table 6 which shows 245fa dehydrofluorination reaction to the desired product.

Table 6

ND = not determined. Prophetic Example 7. Dehydrochlorination of 243fa by aqueous NaOH and triethylamine without presence of a phase transfer catalyst. 10 g triethylamine, 30 g 243fa and 7.2g 30% NaOH solution are added into a 250 ml three-neck round bottomed flask which is equipped with an overhead magnetic stirrer. The mixture is stirred for 2 hours and a little less than 0.1 ml of organic samples are taken and analyzed by GC-MS during the run. The expected results of analysis are listed in Table 7, which shows triethylamine greatly promotes 243fa dehydrochlorination reaction without the need of a phase transfer catalyst. Also the product does not contain any trifluoropropyne.

Table 7

Comparative Example 8. Dehydrochlorination of 243fa by aqueous NaOH without presence of a solvent.

30g 243fa and 7.2g 30% NaOH solution are added into a 250 ml three- neck round bottom flask which is equipped with an overhead magnetic stirrer. The mixture is stirred for 2 hours and a little less than 0.1 ml of organic samples are taken and analyzed by GCMS during the run. The expected results of analysis are listed in Table 8, which shows 243fa dehydrochlorination reaction does not proceed well without triethylamine solvent. Table 8

5