CA2058359A1 - Diaryl carbonate process - Google Patents
Diaryl carbonate processInfo
- Publication number
- CA2058359A1 CA2058359A1 CA002058359A CA2058359A CA2058359A1 CA 2058359 A1 CA2058359 A1 CA 2058359A1 CA 002058359 A CA002058359 A CA 002058359A CA 2058359 A CA2058359 A CA 2058359A CA 2058359 A1 CA2058359 A1 CA 2058359A1
- Authority
- CA
- Canada
- Prior art keywords
- reaction
- aromatic hydroxy
- phenol
- phosgene
- hydroxy compound
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/96—Esters of carbonic or haloformic acids
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT
Diaryl carbonates are prepared by the catalyzed reaction of an aryl hydroxide with a carbonyl halide in the liquid phase at a temperature from greater than 100 to less than 150°C.
38,580-F
Diaryl carbonates are prepared by the catalyzed reaction of an aryl hydroxide with a carbonyl halide in the liquid phase at a temperature from greater than 100 to less than 150°C.
38,580-F
Description
2D~3~
:
DIARYL CARBONATE PROCESS
The present învention relates to a process for the production of diaryl carbonates, and more particularly to a process for the liquid phase reaction of aromatic hydroxy compounds with carbonyl halides for ; the produckion Or high purity diaryl carbonates with the elimination of anhydrous hydrogen halide.
Diaryl carbonates are useful as starting materials along with bisphenols for the preparation of polycarbonates by melt processes. This melt process typically is conducted at temperatures up to 320C in order to drive off the aryl hydroxy by-prcduct and inorease the molecular weight of the resulting polycarbonate to useful levels. Small amounts ( 1-10 ppm) of basic ester exchange catalysts, such as alkali metal hydroxides, are commonly employed. An important advantage of this ~elt process over the solution process is that the polymer product melt may be directly extruded and chopped into pellets for sale. Isolation and purification from viscous solutions is not neceqsary, nor is the handling and recycling of large ;
volumes of solvent.
U.S. Patent No. 2,362,865 discloses the reaction of phenol and phosgene to form diphenyl 38,580-F -1-j:
-.;,, .
' , . .
~ $ ~ ~3~
~ .
:.
carbonate. The reaction employed amphoteric metal catalysts and reaction temperatures from 150 to 250C, v preferably 180 to 250C. The reaction is conducted in the melt without a solvent, that is, under neat conditions. U.S. Patent No. 3,251,873 discloses a 5 similar process utilizing non-amphoteric metal catalysts and an organic solvent. Suitable reaction temperatures are from 50 to 250C depending on the reflux temperatures of the organic solvent at atmospheric pressure. U~S. Patent No. 2,837,555 discloses ammonium 10 halide catalysts, neat reaction conditions and reactor temperatures from 150-to 250C for a process similar to that of U.S. Patent No. 3,251,873. U.S. Patent No.
4,012,406 discloses the reaction of phenols and phosgene using heterocyclic basic nitrogen catalysts and temperatures from 25 to 200C in a gaseous reaction medium.
The invention of this application is a process for the production of a diaryl carbonate and hydrogen 20 halide comprising contacting an aromatic hydroxy compound with a carbonyl halide in the presence of an aluminum containing catalyst under liquid phase reaction conditions at a reaction temperature of greater than 100 25 and less than 150C. Preferred reaction temperatures are 110 to 145C, most preferably 125 to 135C.
It has been found advantageous for the process of this invention to be carried out in the specified 30 temperature range both in terms of production rate and in ease of operation. At high temperature9, that is, greater than 150C, the phenolic reactants are volatilized from the reaction mixture and tend to solidify in the condensor employed for recycle of carbonyl halide. Thus the use of lower temperatures 3~,580-F` -2-3 ~ ~
reduces the severity of this problem. Most surprisingly, however, it has been found that the temperature range of the process of the instant invention achieves an enhanced diphenyl carbonate production rate compared to the use of lower or higher temperatures. This result is entirely unexpected based on knowledge of the prior art.
This result is illustrated in Figure 1 which is a graphic representation of time required to reach phenol conversions of 50 percent (1) and 75 percent (2) at various temperatures as predicted from a model derived from data generated by Example 2. Actual conversions of phenol at three temperatures are shown in Figure 2.
Suitable aromatic hydroxy starting materials for the present process are represented by the general formula:
OH
~Ar] (I) ~n where Ar is an aryl or substituted aryl group containlng 6 to 16 carbon atoms, R independently selected each occurrence is alkyl, aryl, alkenyl7 aryloxy, or alkoxy of 1-12 carbon atoms, and n is an in'ceger. Preferred aromatic hydroxy starting materials are represented by the formula:
38,580-F _3 3~9 OH
,. I
(II) Rn where R independently each occurrence is alkyl, aryl, alkenyl, aryloxy, or alkoxy of 1 12 carbon atoms, and n is an integer o~ 0-5. More highly preferred are compounds of formula II wherein R independently eaoh occurrence is alkyl, aryl, alkenyl, aryloxy, or alkoxy i of 1-6 carbon atoms and n is an integer of 0 3. A most preferred aromatic hydroxy compound is phenol.
15Carbonyl halide reactants include bromophosgene and phosgene. A preferred carbonyl halide starting reactant is phosgene.
. ~
In a preferred embodiment the aromatic mono-` 20 hydroxy compound is phenol, the carbonyl halide is i~
phosgene and the products of the reaction are diphenyl carbonate (DPC) and anhydrous hydrogen chloride.
.;
- Suitable aluminum containing catalysts ~or the process of the present invention include aluminum salts, organoaluminum compounds and aluminum metal. Preferred aluminum containing materials include aluminum halide, sulfide, carbide, hydroxide and carbonate salts as well as aluminum C6_12 aryloxides, arylalkoxides, haloaryloxides, as well as C1_1z alkoxides, haloalkoxides, and mixtures thereof. A most preferred catalyst is aluminum trichloride.
A catalytic amount of the catalyst may be dissolved or dispersed or supported in the reaction 38,580-F _4_ . . .
.
~ -5~ s~
. .
medium. In one embodiment of the present invention the catalyst is simply dispersed in the reaction medium. If the reaction medium includes a noninteracting solvent it is desirable that the catalyst dissolve in the solvent.
The concentration of ca~alyst which provides a catalytic amount of the catalyst in the reaction system of the process of the present invention preferably ranges from 0.001 to 10 mole percent based on the number of moles of the aromatic hydroxy compound. A highly preferred range for the concentration of the catalyst is from 0.05 to 1 mole percent, with the most preferred range being from 0.1 mole percent to 0.5 mole percent.
The mole ratio of the reactants are not critical to success. However, a preferred ratio of carbonyl halide to aromatic hydroxy compound is from 1:1 to 1.3, most preferably 1:1.5 to 1:2.5.
The hydrogen chloride produced in the reaction can be removed continuously or inter~ittently, as desired, and as necessary to relieve the pressure build-up due to the production of this gaseous product.
The process of the present invention desirably is carried out neat, that is, under conditions in which a melt of the aromatic hydroxy compound serves as the reaction medium for the reaction. Accordingly a melt is established. A catalytic amount of the catalyst is added to the melt and dispersed~ The carbonyl halide is then introduced to the reaction mixture preferably under conditions to promote gas/liquid contact, for example by using a stirred reaotor or bubble column reactors, etcO
The hydrogen halide gas coproduct is allowed to exit from the reactor through a gas condensor, which traps 38 7 580-F _5_ :
: :
:
:, ` ' ' . ' .
6-- ~ ~3 e.~
carbonyl halide and returns it to the reactor. Carbonyl halide is added until pre~erably at least about 80 percent conversion of the aromatic hydroxy compound is achieved, and the crude material is then distilled preferably under vacuum, to remove unreacted aromatic hydroxy compound and diaryl carbonate product. The residues remaining after distillation contain residual active catalyst which may be reused.
In a preferred embodiment the process is conducted as a continuous process. The carbonyl halide is added continuously to the reaction medium, which is continuously supplemented by the addition of aromatic hydroxy compound. The reaction product is drained off continuously and distilled to separate the diaryl carbonate product from unreacted aromatic hydroxy cGmpound and catalyst, both of the latter of which may be recycled.
In another embodiment the process of the present invention desirably is carried out in an inert reaction medium which comprises an inert atmosphere, - preferably nitrogen. The reaction may be run with or without a noninteracting liquid diluent. Suitable diluents include aromatic hydrocarbons, which may be halogenated, of from 6 to 16 carbon atoms. Examples include xylene, toluene, ethylbenzene, cumene, diisopropylbenzene, chlorobenzene and dichlorobenzene.
Other desirable diluents include aliphatic halogenated hydrocarbons such as trichloroethylene, methylene chloride and tetrachloroethylene. A preferred diluent is dichlorobenzene. A mixture of two or more diluents may be used.
38,580-F -6-. .
.
Operation within the above indicated temperature limitations has numerous advantages for the process of the present invention in addition to the inherent economic advantage due to energy savings when compared to operating at elevated temperatures.
To illustrate further the advantages of the present invention, a reaction of phenol and phosgene is illustrated.
The normal boiling point of phosgene is 6C. In order to prevent the escape of this hazardous material and to use it efficiently, condensor means normally cooled to a temperature below 6C are employed. In a typical prior art process run at 170C or higher, the vapor pressure o~ phenol is high, approximately 0.7 atm (70 kPa)O A condensor operating at a temperature of 6C
would be quickly blocked with phenol which solidifies at 41C. There is then a danger of explosion due to a buildup of the hydrogen chloride generated in the ~20 reaction of the process. Any pathway provided for the ;escape of hydrogen chloride would be similarly plugged by phenol. To avoid such events~ a second condensing means to remove the phenol from the gas stream before the phosgene is condensed must be used. This adds considerable expense to the process design.
However, in the process of the present invention, which is carried out at lower temperatures, the vapor pressure of phenol is much less, for example, 33 about 0.054 atm (5.4 kPa) at 100C. Phosgene can be condensed and returned to the reaction medium by a single condensor means. The problem of phenol freezing and condensor fouling is insignificant.
38,580-F _7_ : ,,, . :
. ;,, . . ~ :
., . : i ,~ - .
Surprisingly, it has also been found that rates of reaction for the process of the present invention carried out in the temperature ranges discussed above, ;
with all other factors being equal, are better than the rates of reaction observed in processes conducted at 5 higher or lower temperatures. ;~
The reasons for the improved performance at the specified temperature range in a liquid reaction medium are believed to be as follows: The reaction between phenol and a carbonyl halide is temperature dependent.
The rate of this reaction increases with increasing temperature. However, it has no~ been discovered that the solubility of carbonyl halide in aromatic hydroxide or other liquid reaction medium drops dramatically as temperature increases. Moreover in an open system, i.e.
one in which total gaseous components are controlled by a condensor or similar means, the partial pressure of phosgene in the reactor diminishes rapidly as the boiling point of the aromatic hydroxy compound is ; approached9 that is, temperature greater than 150C.
The combined effect of the last two principles operates to limit the rate of mass transfer of phosgene into the liquid phase. Thus, the observed rate of phenol conversion in a liquid phase system is a function of both the rate of reaction and the rate of phosgene mass transfer. If highly efficient aluminum containing catalysts are employed the rate of mass transfer is found to be the rate limiting step and the total process reaohes an optimum at a temperature in the range previously ~peoified.
The following example is provided to illustrate the process of the present invention, and is not 38,580-F -8-:
., ~. .
, 1' .
intended to limit the scope of the present invention in any way.
Example 1 A 2-liter 4-necked Morton flask having indented sides, equipped with a dry-ice condensor on top of a Vigreux column9 mechanical stirring, a gas inletg and an internal thermometer was used in the experiments. The flask was also equipped with a sampling port, which consisted of a side-arm normally closed with a Teflon stopcock and sealed with a septum. The flask was heated with a heating mantle, and the temperature was measured using a thermocouple inserted to the bottom of a glass well and was immersed under the liquid level.
The flask was charged with molten phenol (1007093 g), and the catalyst (10.30 g AlC13) was carefully added. After the solution temperature had equilibrated at 100C, phosgene was delivered from a 1-liter holding cylinder placed on a balance accurate to 0.1 g. This gas stream was mixed with 0.1 mL/min N2 to prevent oxygen intrusion and to reduce the possibility of the reaction solution backing up into the gas delivery system. After entering the reaction flask 2S through the gas inlet (no sparge tube was used), the gases exited through Vigreux column and past the dry ice condensor, and finally into a scrubber column. A rate of about 1.5 g/min (0.91 moles/hour) of phosgene was mairltained t;hroughout the reaction. After 307 min a 3 total of 498.5 g of phosgene had been added. A 50uL
aliquot was removed at thiq point, and gas-chromatographic analysis revealed an 82 percent conversion of phenol. Phosgene was added for 34 more minut;es until 551.0 g total had been added. Further 38,580-F _9_ . :
- lo -phosgene addition was stopped. Heating at 100C was continued for an additional 30 minutes to reduce the concentration of phenyl chloroformate below detectable limits. The crude product was distilled using water aspirator vacuum with a short path still on top of a 30 cm Vigreux column. The first fraction (bp 88 170C, 122.12 g) was a mixture of recovered phenol (68 wt.
percent) and diphenyl carbonate (32 wt. percent). A
higher boiling fraction (bp 175-178C, 934.43 g) consisted of diphenyl carbonate and 0.47 wt. percent phenol. The pot residue (85.16 g) consisted of undistilled diphenyl carbonate and catalyst residue.
' Example_2 The reaction kinetics and mass transfer rates for the process at different temperatures were determined in a 1 L9 4-necked flask equipped with a gas inlet for nitrogen and phosgene, an internal thermocouple, mechanical stirring (semicircular polytetrafluoroethylene paddle), a dry-ice condensor, and a caustic scrubber to neutralize the exit gases.
The flask was charged with phenol, an internal standard for gas chromatographic analysis (diphenyl methane), and anhydrous aluminum chloride (0.20 mole percent based in phenol). The yellow slurry was heated to the desired temperature and phosgene was introduced at an appropriate rate to maximize conversion without waste of phosgene. The catalyst eventually completely 3 dissolved to form a red-orange solution within about 80 minutes after the phosgene addition was started.
Samples (50 uL) were removed at 3-4 minute intervals, 38,580-F -lO--;.' .' ~
.
3 ~ ~
dissolved in 2 mL toluene and analyzed by gas chromatography.
Results, expressed as time (minutes) to reach 50 and 75 percent conversion of phenol at 100, 1109 120, 130, 140, 150 and 160C were simulated based on a model derived from the above rate and reaction kinetics data.
~esults are contained in Figure 1. As may be seen, the time to produce a given conversion of phenol is observed to reach a minimum for temperatures between 100 and i 10 150C, preferably 110 and 140C.
Actual conversions at 100, 130 and 160C versus time are provided in Figure 2. It is seen that operation at 130C achieves improved performance compared to operation at either 100 or 160C thereby substantiating the surprising result that maximum effeciency is achieved at temperatures in the region between 100 and 150C.
38,580-F -11-, ; : :
'
:
DIARYL CARBONATE PROCESS
The present învention relates to a process for the production of diaryl carbonates, and more particularly to a process for the liquid phase reaction of aromatic hydroxy compounds with carbonyl halides for ; the produckion Or high purity diaryl carbonates with the elimination of anhydrous hydrogen halide.
Diaryl carbonates are useful as starting materials along with bisphenols for the preparation of polycarbonates by melt processes. This melt process typically is conducted at temperatures up to 320C in order to drive off the aryl hydroxy by-prcduct and inorease the molecular weight of the resulting polycarbonate to useful levels. Small amounts ( 1-10 ppm) of basic ester exchange catalysts, such as alkali metal hydroxides, are commonly employed. An important advantage of this ~elt process over the solution process is that the polymer product melt may be directly extruded and chopped into pellets for sale. Isolation and purification from viscous solutions is not neceqsary, nor is the handling and recycling of large ;
volumes of solvent.
U.S. Patent No. 2,362,865 discloses the reaction of phenol and phosgene to form diphenyl 38,580-F -1-j:
-.;,, .
' , . .
~ $ ~ ~3~
~ .
:.
carbonate. The reaction employed amphoteric metal catalysts and reaction temperatures from 150 to 250C, v preferably 180 to 250C. The reaction is conducted in the melt without a solvent, that is, under neat conditions. U.S. Patent No. 3,251,873 discloses a 5 similar process utilizing non-amphoteric metal catalysts and an organic solvent. Suitable reaction temperatures are from 50 to 250C depending on the reflux temperatures of the organic solvent at atmospheric pressure. U~S. Patent No. 2,837,555 discloses ammonium 10 halide catalysts, neat reaction conditions and reactor temperatures from 150-to 250C for a process similar to that of U.S. Patent No. 3,251,873. U.S. Patent No.
4,012,406 discloses the reaction of phenols and phosgene using heterocyclic basic nitrogen catalysts and temperatures from 25 to 200C in a gaseous reaction medium.
The invention of this application is a process for the production of a diaryl carbonate and hydrogen 20 halide comprising contacting an aromatic hydroxy compound with a carbonyl halide in the presence of an aluminum containing catalyst under liquid phase reaction conditions at a reaction temperature of greater than 100 25 and less than 150C. Preferred reaction temperatures are 110 to 145C, most preferably 125 to 135C.
It has been found advantageous for the process of this invention to be carried out in the specified 30 temperature range both in terms of production rate and in ease of operation. At high temperature9, that is, greater than 150C, the phenolic reactants are volatilized from the reaction mixture and tend to solidify in the condensor employed for recycle of carbonyl halide. Thus the use of lower temperatures 3~,580-F` -2-3 ~ ~
reduces the severity of this problem. Most surprisingly, however, it has been found that the temperature range of the process of the instant invention achieves an enhanced diphenyl carbonate production rate compared to the use of lower or higher temperatures. This result is entirely unexpected based on knowledge of the prior art.
This result is illustrated in Figure 1 which is a graphic representation of time required to reach phenol conversions of 50 percent (1) and 75 percent (2) at various temperatures as predicted from a model derived from data generated by Example 2. Actual conversions of phenol at three temperatures are shown in Figure 2.
Suitable aromatic hydroxy starting materials for the present process are represented by the general formula:
OH
~Ar] (I) ~n where Ar is an aryl or substituted aryl group containlng 6 to 16 carbon atoms, R independently selected each occurrence is alkyl, aryl, alkenyl7 aryloxy, or alkoxy of 1-12 carbon atoms, and n is an in'ceger. Preferred aromatic hydroxy starting materials are represented by the formula:
38,580-F _3 3~9 OH
,. I
(II) Rn where R independently each occurrence is alkyl, aryl, alkenyl, aryloxy, or alkoxy of 1 12 carbon atoms, and n is an integer o~ 0-5. More highly preferred are compounds of formula II wherein R independently eaoh occurrence is alkyl, aryl, alkenyl, aryloxy, or alkoxy i of 1-6 carbon atoms and n is an integer of 0 3. A most preferred aromatic hydroxy compound is phenol.
15Carbonyl halide reactants include bromophosgene and phosgene. A preferred carbonyl halide starting reactant is phosgene.
. ~
In a preferred embodiment the aromatic mono-` 20 hydroxy compound is phenol, the carbonyl halide is i~
phosgene and the products of the reaction are diphenyl carbonate (DPC) and anhydrous hydrogen chloride.
.;
- Suitable aluminum containing catalysts ~or the process of the present invention include aluminum salts, organoaluminum compounds and aluminum metal. Preferred aluminum containing materials include aluminum halide, sulfide, carbide, hydroxide and carbonate salts as well as aluminum C6_12 aryloxides, arylalkoxides, haloaryloxides, as well as C1_1z alkoxides, haloalkoxides, and mixtures thereof. A most preferred catalyst is aluminum trichloride.
A catalytic amount of the catalyst may be dissolved or dispersed or supported in the reaction 38,580-F _4_ . . .
.
~ -5~ s~
. .
medium. In one embodiment of the present invention the catalyst is simply dispersed in the reaction medium. If the reaction medium includes a noninteracting solvent it is desirable that the catalyst dissolve in the solvent.
The concentration of ca~alyst which provides a catalytic amount of the catalyst in the reaction system of the process of the present invention preferably ranges from 0.001 to 10 mole percent based on the number of moles of the aromatic hydroxy compound. A highly preferred range for the concentration of the catalyst is from 0.05 to 1 mole percent, with the most preferred range being from 0.1 mole percent to 0.5 mole percent.
The mole ratio of the reactants are not critical to success. However, a preferred ratio of carbonyl halide to aromatic hydroxy compound is from 1:1 to 1.3, most preferably 1:1.5 to 1:2.5.
The hydrogen chloride produced in the reaction can be removed continuously or inter~ittently, as desired, and as necessary to relieve the pressure build-up due to the production of this gaseous product.
The process of the present invention desirably is carried out neat, that is, under conditions in which a melt of the aromatic hydroxy compound serves as the reaction medium for the reaction. Accordingly a melt is established. A catalytic amount of the catalyst is added to the melt and dispersed~ The carbonyl halide is then introduced to the reaction mixture preferably under conditions to promote gas/liquid contact, for example by using a stirred reaotor or bubble column reactors, etcO
The hydrogen halide gas coproduct is allowed to exit from the reactor through a gas condensor, which traps 38 7 580-F _5_ :
: :
:
:, ` ' ' . ' .
6-- ~ ~3 e.~
carbonyl halide and returns it to the reactor. Carbonyl halide is added until pre~erably at least about 80 percent conversion of the aromatic hydroxy compound is achieved, and the crude material is then distilled preferably under vacuum, to remove unreacted aromatic hydroxy compound and diaryl carbonate product. The residues remaining after distillation contain residual active catalyst which may be reused.
In a preferred embodiment the process is conducted as a continuous process. The carbonyl halide is added continuously to the reaction medium, which is continuously supplemented by the addition of aromatic hydroxy compound. The reaction product is drained off continuously and distilled to separate the diaryl carbonate product from unreacted aromatic hydroxy cGmpound and catalyst, both of the latter of which may be recycled.
In another embodiment the process of the present invention desirably is carried out in an inert reaction medium which comprises an inert atmosphere, - preferably nitrogen. The reaction may be run with or without a noninteracting liquid diluent. Suitable diluents include aromatic hydrocarbons, which may be halogenated, of from 6 to 16 carbon atoms. Examples include xylene, toluene, ethylbenzene, cumene, diisopropylbenzene, chlorobenzene and dichlorobenzene.
Other desirable diluents include aliphatic halogenated hydrocarbons such as trichloroethylene, methylene chloride and tetrachloroethylene. A preferred diluent is dichlorobenzene. A mixture of two or more diluents may be used.
38,580-F -6-. .
.
Operation within the above indicated temperature limitations has numerous advantages for the process of the present invention in addition to the inherent economic advantage due to energy savings when compared to operating at elevated temperatures.
To illustrate further the advantages of the present invention, a reaction of phenol and phosgene is illustrated.
The normal boiling point of phosgene is 6C. In order to prevent the escape of this hazardous material and to use it efficiently, condensor means normally cooled to a temperature below 6C are employed. In a typical prior art process run at 170C or higher, the vapor pressure o~ phenol is high, approximately 0.7 atm (70 kPa)O A condensor operating at a temperature of 6C
would be quickly blocked with phenol which solidifies at 41C. There is then a danger of explosion due to a buildup of the hydrogen chloride generated in the ~20 reaction of the process. Any pathway provided for the ;escape of hydrogen chloride would be similarly plugged by phenol. To avoid such events~ a second condensing means to remove the phenol from the gas stream before the phosgene is condensed must be used. This adds considerable expense to the process design.
However, in the process of the present invention, which is carried out at lower temperatures, the vapor pressure of phenol is much less, for example, 33 about 0.054 atm (5.4 kPa) at 100C. Phosgene can be condensed and returned to the reaction medium by a single condensor means. The problem of phenol freezing and condensor fouling is insignificant.
38,580-F _7_ : ,,, . :
. ;,, . . ~ :
., . : i ,~ - .
Surprisingly, it has also been found that rates of reaction for the process of the present invention carried out in the temperature ranges discussed above, ;
with all other factors being equal, are better than the rates of reaction observed in processes conducted at 5 higher or lower temperatures. ;~
The reasons for the improved performance at the specified temperature range in a liquid reaction medium are believed to be as follows: The reaction between phenol and a carbonyl halide is temperature dependent.
The rate of this reaction increases with increasing temperature. However, it has no~ been discovered that the solubility of carbonyl halide in aromatic hydroxide or other liquid reaction medium drops dramatically as temperature increases. Moreover in an open system, i.e.
one in which total gaseous components are controlled by a condensor or similar means, the partial pressure of phosgene in the reactor diminishes rapidly as the boiling point of the aromatic hydroxy compound is ; approached9 that is, temperature greater than 150C.
The combined effect of the last two principles operates to limit the rate of mass transfer of phosgene into the liquid phase. Thus, the observed rate of phenol conversion in a liquid phase system is a function of both the rate of reaction and the rate of phosgene mass transfer. If highly efficient aluminum containing catalysts are employed the rate of mass transfer is found to be the rate limiting step and the total process reaohes an optimum at a temperature in the range previously ~peoified.
The following example is provided to illustrate the process of the present invention, and is not 38,580-F -8-:
., ~. .
, 1' .
intended to limit the scope of the present invention in any way.
Example 1 A 2-liter 4-necked Morton flask having indented sides, equipped with a dry-ice condensor on top of a Vigreux column9 mechanical stirring, a gas inletg and an internal thermometer was used in the experiments. The flask was also equipped with a sampling port, which consisted of a side-arm normally closed with a Teflon stopcock and sealed with a septum. The flask was heated with a heating mantle, and the temperature was measured using a thermocouple inserted to the bottom of a glass well and was immersed under the liquid level.
The flask was charged with molten phenol (1007093 g), and the catalyst (10.30 g AlC13) was carefully added. After the solution temperature had equilibrated at 100C, phosgene was delivered from a 1-liter holding cylinder placed on a balance accurate to 0.1 g. This gas stream was mixed with 0.1 mL/min N2 to prevent oxygen intrusion and to reduce the possibility of the reaction solution backing up into the gas delivery system. After entering the reaction flask 2S through the gas inlet (no sparge tube was used), the gases exited through Vigreux column and past the dry ice condensor, and finally into a scrubber column. A rate of about 1.5 g/min (0.91 moles/hour) of phosgene was mairltained t;hroughout the reaction. After 307 min a 3 total of 498.5 g of phosgene had been added. A 50uL
aliquot was removed at thiq point, and gas-chromatographic analysis revealed an 82 percent conversion of phenol. Phosgene was added for 34 more minut;es until 551.0 g total had been added. Further 38,580-F _9_ . :
- lo -phosgene addition was stopped. Heating at 100C was continued for an additional 30 minutes to reduce the concentration of phenyl chloroformate below detectable limits. The crude product was distilled using water aspirator vacuum with a short path still on top of a 30 cm Vigreux column. The first fraction (bp 88 170C, 122.12 g) was a mixture of recovered phenol (68 wt.
percent) and diphenyl carbonate (32 wt. percent). A
higher boiling fraction (bp 175-178C, 934.43 g) consisted of diphenyl carbonate and 0.47 wt. percent phenol. The pot residue (85.16 g) consisted of undistilled diphenyl carbonate and catalyst residue.
' Example_2 The reaction kinetics and mass transfer rates for the process at different temperatures were determined in a 1 L9 4-necked flask equipped with a gas inlet for nitrogen and phosgene, an internal thermocouple, mechanical stirring (semicircular polytetrafluoroethylene paddle), a dry-ice condensor, and a caustic scrubber to neutralize the exit gases.
The flask was charged with phenol, an internal standard for gas chromatographic analysis (diphenyl methane), and anhydrous aluminum chloride (0.20 mole percent based in phenol). The yellow slurry was heated to the desired temperature and phosgene was introduced at an appropriate rate to maximize conversion without waste of phosgene. The catalyst eventually completely 3 dissolved to form a red-orange solution within about 80 minutes after the phosgene addition was started.
Samples (50 uL) were removed at 3-4 minute intervals, 38,580-F -lO--;.' .' ~
.
3 ~ ~
dissolved in 2 mL toluene and analyzed by gas chromatography.
Results, expressed as time (minutes) to reach 50 and 75 percent conversion of phenol at 100, 1109 120, 130, 140, 150 and 160C were simulated based on a model derived from the above rate and reaction kinetics data.
~esults are contained in Figure 1. As may be seen, the time to produce a given conversion of phenol is observed to reach a minimum for temperatures between 100 and i 10 150C, preferably 110 and 140C.
Actual conversions at 100, 130 and 160C versus time are provided in Figure 2. It is seen that operation at 130C achieves improved performance compared to operation at either 100 or 160C thereby substantiating the surprising result that maximum effeciency is achieved at temperatures in the region between 100 and 150C.
38,580-F -11-, ; : :
'
Claims (8)
1. A process for the production of a diaryl carbonate and hydrogen halide comprising contacting an aromatic hydroxy compound with a carbonyl halide in the presence of an aluminum containing catalyst under liquid phase reaction conditions at a reaction temperature of greater than 100 and less than 150°C.
2. The process of Claim 1 wherein the reaction temperature is from 110°C to about 145°C.
3. The process of Claim 2 wherein the reaction temperature is from about 125°C to about 135°C.
4. The process of Claim 1 wherein the aromatic hydroxy compound is phenol and the carbonyl halide is phosgene.
5. The process of Claim 1 wherein the catalyst is aluminum trichloride.
6. The process of Claim 1 wherein the reaction is conducted neat in a melt of the aromatic hydroxy compound.
38,580-F
38,580-F
7. The process of Claim 1 wherein the ratio of carbonyl halide to aromatic hydroxy compound is 1:1 to 1:3.
8. The process of Claim 1 wherein the catalyst is present in an amount from 0.001 to 10 mole percent based on aromatic hydroxy compound.
38,580-F -13-
38,580-F -13-
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63462290A | 1990-12-27 | 1990-12-27 | |
| US634,622 | 1990-12-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2058359A1 true CA2058359A1 (en) | 1992-06-28 |
Family
ID=24544566
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002058359A Abandoned CA2058359A1 (en) | 1990-12-27 | 1991-12-23 | Diaryl carbonate process |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3135647B2 (en) |
| KR (1) | KR100192715B1 (en) |
| CA (1) | CA2058359A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2014104306A (en) * | 2011-07-08 | 2015-08-20 | Байер Интеллектуэль Проперти Гмбх | METHOD FOR PRODUCING DIARYL CARBONATES |
-
1991
- 1991-12-23 CA CA002058359A patent/CA2058359A1/en not_active Abandoned
- 1991-12-26 JP JP03344287A patent/JP3135647B2/en not_active Expired - Fee Related
- 1991-12-26 KR KR1019910024357A patent/KR100192715B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR920012001A (en) | 1992-07-25 |
| KR100192715B1 (en) | 1999-06-15 |
| JPH04308553A (en) | 1992-10-30 |
| JP3135647B2 (en) | 2001-02-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |