WO2013086262A1

WO2013086262A1 - Process for the production of chlorinated propanes

Info

Publication number: WO2013086262A1
Application number: PCT/US2012/068353
Authority: WO
Inventors: William J. Kruper; Edward M. Calverley; Max Markus Tirtowidjojo
Original assignee: Dow Global Technologies, Llc
Priority date: 2011-12-09
Filing date: 2012-12-07
Publication date: 2013-06-13

Abstract

Processes for the production of pentachlorinated propanes are provided. The present processes make use of methylacetylene, a by-product in the production of ethylene and/or propylene, as a low cost starting material, alone or in combination with propadiene, propene and/or propane. The feedstream is chlorinated in a single step to provide pentachloropropanes with a high regioselectivity.

Description

PROCESS FOR THE PRODUCTION OF CHLORINATED PROPANES

FIELD

[0001] The present invention relates to processes for the production of chlorinated propanes, and in particular, for the production of pentachlorinated propanes.

BACKGROUND

[0002] Hydrofluorocarbon (HFC) products are widely utilized in many applications, including refrigeration, air conditioning, foam expansion, and as propellants for aerosol products including medical aerosol devices. Although HFC's have proven to be more climate friendly than the chlorofluorocarbon and hydrochlorofluorocarbon products that they replaced, it has now been discovered that they exhibit an appreciable global warming potential (GWP).

[0003] The search for more acceptable alternatives to current fluorocarbon products has led to the emergence of hydrofluoroolefin (HFO) products. Relative to their predecessors, HFOs are expected to exert less impact on the atmosphere in the form of a much lower GWP. Advantageously, HFO's also exhibit low flammability and low toxicity.

[0004] As the environmental, and thus, economic importance of HFO's has developed, so has the demand for precursors utilized in their production. Many desirable HFO compounds, e.g., such as 2,3,3,3-tetrafluoroprop-l-ene (HFO-1234yf), may typically be produced utilizing feedstocks of chlorocarbons, and in particular, highly chlorinated propenes, may also find use as feedstocks for the manufacture of polyurethane blowing agents, biocides and polymers.

[0005] Unfortunately, many chlorinated propenes may have limited commercial availability, and/or may only be available at prohibitively high cost. This may be due at least in part to the fact that conventional processes for their manufacture may be too limited in the throughputs that can be achieved to be economically produced by manufacturers on the large scale required to be useful as feedstocks. And, conventional starting materials may typically desirably be used in processes and/or reactors in a way such that conversion thereof is limited, as conversion, e.g., of 90% or greater, of conventional starting materials can result in a lack of selectivity and formation of large amounts of unwanted or unusable secondary products into the process. [0006] For example, many conventional processes are incapable of a commercially feasible selectivity in the production of pentachloropropane isomers useful as intermediates, i.e., 1, 1, 1,2, 3 -pentachloropropane and 1, 1, 2,2,3 -pentachloropropane, versus the 1,1,2,3,3- pentachloropropane isomer that is considered an undesirable reaction by-product. Conventional starting materials for such processes can not only contribute to this lack of selectivity, but may also be prohibitively expensive. Investigation into the use of alternative starting materials, as described, e.g., in US 3,562,349, has not been fruitful, being limited at least in that complete chlorination, or conversion of double bonds in these alternate substrates, has not been achieved, much less with a selectivity to the desired pentachloropropanes that would represent an improvement over the art.

[0007] It would thus be desirable to provide improved processes for the production of chlorocarbon precursors useful as feedstocks in the synthesis of refrigerants and other commercial products. More particularly, such processes would provide an improvement over the current state of the art if they were less costly not only in starting materials and in the amount(s) of materials utilized that are capable of introducing safety or environmental concerns into the process, but also in operational costs of running the processes. Improved selectivity not only to desired end products, but also to intermediates more readily convertible to desired end products, would also provide advantages over conventional methods. Generation of byproducts having a higher value than sodium chloride, or really any value, would be a further advantage if provided in such a process.

BRIEF DESCRIPTION

[0008] The present invention provides efficient processes for the production of pentachlorinated propanes. Advantageously, the processes make use of methylacetylene gas, a by-product in the production of ethylene and propylene, as a low cost starting material. It has now been discovered that, in the presence of an ionic or free radical catalyst, methylacetylene, propene and/or propadiene may be completely chlorinated across their double and/or triple bonds, to provide pentachloropropanes with a high regioselectivity to 1, 1, 1,2,3-pentachloropropane and/or 1, 1,2,2, 3 -pentachloropropane, versus the 1,1,2,3,3- pentachloropropane isomer. As a result, the present processes can provide for the production of these desirable pentachloropropanes in a single step from a feed stream comprising methylacetylene and a chlorinating agent. [0009] In one aspect, the present invention provides a process for the production of pentachloropropanes from a feed stream comprising methylacetylene. The feed stream may further comprise one or more of propadiene, propene and/or propane. The chlorination agent comprises chlorine, SO2CI2, or combinations of these. The chlorinated propane produced may desirably be 1, 1,1,2,3-pentachloropropane and/or 1, 1,2,2,3-pentachloropropane.

[0010] The advantages provided by the present processes may be carried forward by utilizing the pentachlorinated propanes to produce further downstream products, such as, e.g., 1, 1,2,3-tetrachloropropene.

DETAILED DESCRIPTION

[001 1] The present specification provides certain definitions and methods to better define the present invention and to guide those of ordinary skill in the art in the practice of the present invention. Provision, or lack of the provision, of a definition for a particular term or phrase is not meant to imply any particular importance, or lack thereof. Rather, and unless otherwise noted, terms are to be understood according to conventional usage by those of ordinary skill in the relevant art.

[0012] The terms "first", "second", and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item, and the terms "front", "back", "bottom", and/or "top", unless otherwise noted, are merely used for convenience of description, and are not limited to any one position or spatial orientation.

[0013] If ranges are disclosed, the endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of "up to 25 wt.%, or, more specifically, 5 wt.% to 20 wt.%," is inclusive of the endpoints and all intermediate values of the ranges of "5 wt.% to 25 wt.%," etc.). As used herein, percent (%) conversion is meant to indicate change in molar or mass flow of reactant in a reactor in ratio to the incoming flow, while percent (%) selectivity means the change in molar flow rate of product in a reactor in ratio to the change of molar flow rate of a reactant.

[0014] Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] Further, "MAP" may be used as an abbreviation for a gas comprising methylacetylene and one or more of propadiene, propene and/or propane whether stabilized or destabilized, "PDC" may be used as an abbreviation for 1 ,2-dichloropropane, "TCP" may be used as an abbreviation for 1,2,3-trichloropropane and "TCPE" may be used as an abbreviation for 1,1,2,3-tetrachloropropene. Propadiene is oftentimes referred to by those of ordinary skill in the art as "allene" and these terms may be used interchangeably herein to refer to C₃H4.

[0016] The present invention provides efficient processes for the production pentachlorinated propanes. The present processes comprise conducting a single chlorination step on a feed stream comprising methylacetylene in the presence of an ionic or free radical catalyst. The present process thus provides the advantages that a useful intermediate is reached in far fewer steps than conventional processes, and with a high regioselectivity, providing the present processes with lower capital costs as compared to conventional processes.

[0017] While the use of methylacetylene, a byproduct in many processes for the production of ethylene and propylene, as a starting material is economically more attractive than disposing of it via incineration or using it as fuel, as is conventional, those of ordinary skill in the art have yet not considered methylacetylene for use as a feed stream for any process, much less one for the production of chlorinated propanes and/or propenes due, at least in part to its highly exothermic nature. The fact that methylacetylene is most commonly provided in combination with, e.g., propane, propadiene and/or propene further discourages serious consideration its use as a starting material.

[0018] It has now been discovered that methylacetylene, whether provided alone or in combination with propadiene, propene and/or propane, i.e., as MAP gas, can be used as a feedstream in processes for the production of chlorinated propanes and/or propenes, thereby allowing the recovery of greater economic value from this byproduct than previously thought possible. In fact, it is a further advantage of the invention that the provided processes can provide a substantially more purified stream of a second commercially useful product in addition to the chlorinated propane and/or propene, i.e., propane, in those embodiments wherein the methylacetylene is provided in the form of MAP gas.

[0019] And, because conversions of greater than 90% or even full conversion of methylacetylene do not result in the formation of large amounts of undesirable secondary products, the present processes may be conducted in reactors that utilize the heat generated by the reaction. In contrast, in processes for the production of chlorinated propanes and/or propanes that utilize conventional starting materials, wherein greater than 90% conversion of the starting materials is not desired, heat must be removed by more capital intensive means (such as the use of shell and multitube heat exchanger) from the reactors used in the present processes.

[0020] For example, in some embodiments, boiling bed reactors may be utilized in the present processes. Boiling bed reactors use the heat of reaction in order to evaporate components of the feed stream, e.g., methylacetylene. Boiling bed reactors using the chlorinated propane product as the boiling solvent may thus be used in those embodiments wherein the methylacetylene is provided as MAP gas, and in such embodiments, may act in essence as a distillation column and provide for the separation of a substantially pure stream of propane from the MAP gas. Because heat is managed and desirably utilized, rather than being removed from, the present processes, continuous operation of the processes can be done at lower operating and capital costs than typically the case when conventional starting materials are used in conventional reactors.

[0021] In some embodiments, the present processes may comprise liquid phase chlorination reactions, using ionic chlorination or electrophilic addition of chlorines to olefins. Liquid phase chlorinations may provide advantages compared to conventional methods for producing chlorinated propenes using gas-phase thermal chlorination reactions because the production utility cost is lower for a process comprising liquid phase reactions, where evaporation of reactants is not required. In addition, the lower reaction temperatures used in the present liquid phase reactions tend to result in lower fouling rates than the higher temperatures used in connection with gas phase reactions. Higher fouling rates, in turn, tend to limit reactor lifetime and can lead to undesirable byproduct formation. [0022] The present process can make use of a feed stream comprising methylacetylene, either alone or in combination with one or more of propadiene, propene and/or propane. Such a feedstream may be available at low cost due to its production as a by-product in many processes for the production of ethylene and propylene. And so, the feedstream may advantageously be generated within, or upstream of, the process, if desired, by such processes, or any other methods known to those of ordinary skill in the art. The process feedstock may also comprise trichloropropane, other chlorinated alkanes, or other unreacted reactants and reaction byproducts, if desired.

[0023] The chlorination steps of the process may be carried out using any chlorination agent, and several of these are known in the art. For example, suitable chlorination agents include, but are not limited to chlorine, and/or sulfuryl chloride (SO2CI2). Of these, chlorine may be particularly suitable for use in gas phase chlorinations, while both CI2 and sulfuryl chloride may be particularly suitable for use in liquid phase chlorinations.

[0024] Either ionic chlorination catalysts or free radical chlorination catalysts may be used in the present process, and many of these are known to those of ordinary skill in the art. Suitable free radical chlorination catalysts include, but are not limited to, compounds comprising one or more azo-groups (R-N=N-R') such as azobisisobutyronitrile (AIBN) or l, l'-azobis(cyclohexanecarbonitrile) (ABCN) and organic peroxides such as di-tert-butyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, and acetone peroxide. In some embodiments, benzoyl peroxide may be used as a free radical initiator for the chlorination of a feedstream comprising methylacetylene, alone or in combination with UV or visible light and/or heat. Such catalysts may also enhance the chlorination of double bonds in olefins or chlorinated olefins to produce α,β chloroalkanes.

[0025] In some embodiments, ionic or electrophilic chlorination catalysts may be utilized to promote the chlorination of the feed stream. Ionic chlorination catalysts are well known to those of ordinary skill in the art and any of these may be used in the present process. Exemplary ionic chlorination catalysts include, but are not limited to, aluminum chloride, ferric chloride, iodine, sulfur, iron, etc. In some embodiments, the use of AICI₃ and/or I₂, can be preferred. [0026] Any or all of the chlorination catalysts can be provided either in bulk or in connection with a substrate, such as activated carbon, graphite, silica, alumina, zeolites, fluorinated graphite and fluorinated alumina.

[0027] The amount of any chlorination catalyst utilized will depend upon the particular catalyst chosen as well as the other reaction conditions. Generally speaking, in those embodiments of the invention wherein the utilization of a catalyst is desired, enough of the catalyst should be utilized to provide some improvement to reaction process conditions (e.g., a reduction in required temperature) or realized products, but yet not be more than will provide any additional benefit, if only for reasons of economic practicality.

[0028] For purposes of illustration only, then, useful concentrations of an ionic chlorination catalyst, e.g., comprising, FeCi₃, AICI₃ and/or I₂, will range from 0.001% to 8% by weight each with respect to reaction mixture comprising methylacetylene, propadiene, and chlorinated propanes or olefins or chlorinated olefins, or from 0.01% to 5%, or from 0.01% to 1 wt%, inclusive of all subranges therebetween.

[0029] In additional embodiments, one or more reaction conditions of the process may be optimized, in order to provide even further advantages, i.e., improvements in selectivity, conversion or production of reaction by-products. In certain embodiments, multiple reaction conditions are optimized and even further improvements in selectivity, conversion and production of reaction by-products produced can be seen.

[0030] Reaction conditions of the process that may be optimized include any reaction condition conveniently adjusted, e.g., that may be adjusted via utilization of equipment and/or materials already present in the manufacturing footprint, or that may be obtained at low resource cost. Examples of such conditions may include, but are not limited to, adjustments to temperature, pressure, flow rates, molar ratios of reactants, etc.

[0031] That being said, the particular conditions employed at each step described herein are not critical, and are readily determined by those of ordinary skill in the art. What is important is that the feedstream comprise methylacetylene, either alone or in combination with propadiene, propene and/or propane. It is also advantageous that the process make use of at least one chlorination catalyst, so that the desirable pentachloropropane isomers are produced in a single step, with high regioselectivity as compared with the less desirable 1 , 1 ,2,3 ,3 -pentachloropropane. [0032] In the present process, a feedstream comprising methylacetylene is catalytically chlorinated to one or more tetra- and/or pentachloropropanes. In one exemplary embodiment, a feedstream comprising methylacetylene is fed to a boiling bed reactor, e.g., such a batch or continuous stirred tank reactor with or without an internal cooling coil. Suitable reaction conditions include, e.g., a temperature of from 80°C to 180°C, a pressure of from 100 kPa to lOOOkPa. The reaction may desirably be carried out with one or more ionic chlorination catalysts, such as ferric chloride. Desirably, feedstream conversion, e.g., of methylacetylene either alone or in combination with one or more of propadiene, propene and/or propane, will be greater than 80%, or greater than 90%, or greater than 95%, or close to 100%.

[0033] Some embodiments of the invention will now be described in detail in the following examples.

[0034] Example 1 :

[0035] 100 mL of SO2CI2 containing approximately 1000 ppm of dibenzoyl peroxide is added to a 300 mL Parr autoclave equipped with overhead stirring and a water-fed cooling coil. The reactor is further equipped with two gas feed tubes, a condenser and a pressure sensitive relief valve set to exhaust at 50 psig. After purging the stirred solution with nitrogen for 5 min, 20g industrial MAP gas (methylacetylene 48%, propadiene 23%, propane 27%, inerts 2%) is added along with chlorine (50 g over 20 min), with cooling and stirring. The reactor temperature is not allowed to rise above 60°C over this period. After another 15 minutes, the reactor is heated to 70°C while HC1 and SO2 egress from the pressure control valve. The reactor is stirred for 2h, cooled and vented. After stripping lights on a rotary evaporator, 100 g of pale yellow liquid is obtained. GC and 1H NMR analysis of the clear liquid shows that it contains 80% 1, 1, 2,2,3 -pentachloropropane and less than 1% other pentachloropropane isomers. The material is vacuum distilled at 20 mm to afford 75g of pure (>98.5 area%) 1,1, 2,2,3 -pentachloropropane.

[0036] Example 2:

[0037] 125 mL of SO2CI2 is added to a 300 mL Parr autoclave equipped with overhead stirring and a water-fed cooling coil. The reactor is further equipped with two gas feed tubes, a condenser and a pressure sensitive relief valve set to exhaust at 50 psig. After purging the stirred solution with nitrogen for 5 min, 18.5 g industrial MAP gas (methylacetylene 48%, propadiene 23%, propane 27%, inerts 2%) is added along with chlorine (50 g over 20 min), with cooling and stirring. The reactor temperature is not allowed to rise above 60° C over this period. After another 15 minutes, AICI₃ (5.0g) and molecular iodine (100 mg) as a slurry in 15 mL of SO2CI2 is shot-added to the reactor. The reactor is heated to 70°C while HC1 and SO2 egress from the pressure control valve. The reactor is stirred for 3h, cooled and vented and the catalyst is quenched by slowly adding the reactor contents to 300 mL of stirred ice water. The heavier organic phase is separated and dried over MgS0₄ to provide 90 g of pale yellow liquid. CG and 1H NMR analysis of the clear liquid shows that it contains 80% 1, 1,2,2, 3-pentachloropropane and less than 1% other pentachloropropane isomers. The material is vacuum distilled at 20 mm to afford 71g of pure (>98.5 area%) 1, 1,2,2,3- pentachloropropane.

Claims

CLAIMS:

1. A single step process for the production of pentachlorinated propanes from a feed stream comprising methylacetylene, comprising chlorinating the feedstream in the presence of at least one catalyst.

2. The process of claim 1, wherein the feed stream further comprises one or more of propadiene, propene and/or propane.

3. The process of claim 2, wherein the feed stream comprises two or more of propadiene, propene and/or propane.

4. The process of claim 3, wherein the feed stream further comprises propadiene, propene and propane.

5. The process of claim 1, wherein the at least one catalyst comprises a free radical initiator.

6. The process of claim 5, wherein the free radical initiator comprises UV or visible light, dibenzoyl peroxide, heat or combinations of these.

7. The process of claim 6, wherein at least one catalyst comprises an ionic chlorination catalyst.

8. The process of claim 7, where in the ionic chlorination catalyst comprises AICI₃, I2, or combinations of these.

9. The process of claim 1, wherein CI2, SO2CI2 or a combination thereof is utilized as a chlorinating agent.

10. The process of claim 1, wherein the pentachloropropane comprises 1, 1,2,2,3- pentachloropropane.

11. The process of claim 10, wherein the pentachloropropane comprises 1, 1, 1,2,3- pentachloropropane.

12. The process of claim I, wherein the one or more components of the feedstream is generated for use in the process.

13. The process of claim 12, wherein the methylacetylene is produced in an upstream ethylene or propylene process.

14. The process of claim I, wherein the chlorination reaction is conducted in a boiling bed reactor using the chlorinated product as a solvent.