CA1060050A - Purification of hydroquinone - Google Patents
Purification of hydroquinoneInfo
- Publication number
- CA1060050A CA1060050A CA218,859A CA218859A CA1060050A CA 1060050 A CA1060050 A CA 1060050A CA 218859 A CA218859 A CA 218859A CA 1060050 A CA1060050 A CA 1060050A
- Authority
- CA
- Canada
- Prior art keywords
- hydroquinone
- varies
- palladium
- technical grade
- hydrogen
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/86—Purification; separation; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
There is disclosed the method of preparing photographic grade hydroquinone from technical grade hydroquinone which consists of treating a a solution of the technical grade hydroquinone in the presence of a palladium catalyst with hydrogen while ?he hydroquinone solution is at a pH between about 3 and about 6.
There is disclosed the method of preparing photographic grade hydroquinone from technical grade hydroquinone which consists of treating a a solution of the technical grade hydroquinone in the presence of a palladium catalyst with hydrogen while ?he hydroquinone solution is at a pH between about 3 and about 6.
Description
~6~)~50 This invention is directed to the treatment of technical grade hydroquinone to produce photographic grade hydroquinonc. More specifically, it is directed to a new and improved process whereby technlcal grade hydroquinone is treated with hydrogen in the presence of palladium catalyst to produce photographic grade hydroquinone.
Commercially available technical grade hydroquinone has a relatively high platinum~cobalt color number and is not suitable for use in photographic purposes. This relatively high platinum/cobalt color number in technical grade hydroquinone results from the presence of certain impurities which impart a tan to yellow to even brown color in technical grade hydroquinone.
As employed in this application, the term "technical grade hydroquinone" is meant to relate that the hydro-quinone exhibits a platinum/cobalt (pt/co) color number of 45 or even higher and in some cases up to and above 500, The term "photographic grade hydroquinone" is meant that the hydroquinone exhibits a pt/co color number around 20 or slightly higher and up to about 30. -The piatinum/cobalt (ptico) color number as employedin this application is a well-known test, in which most often color is determined by visual comparisons of a test sample of hydroquinone solution against a solution with known concentrations of color solutions on the pt/co scale. The unit of color is defined as that color product produced by one milligram/per liter of platinum in the form of the chloroplatinate ion. The accuracy of , ~ .
, . .
1~)6QC~SO
such a ~risua] test is dependent to a large extent on the judgment of the beholder. To eliminate this error, a spectrophotometry test has been devised. The spectro-photometry test was devised in the fol1owing manner.
In the standard pt/co color test, 1.246 grams of potassiurn chloroplatinate and 1.0 gram of cobaltous .
chloride are dissolved in about 100 ml of water and 100 ml of hydrochlorlc acld and then the solution is diluted with more water to l-liter. To prepare the color standards, dispense varying amounts of this color stock into 100 ml volumetric flasks and dilute to 100 ml with water, for example:
pt/co colorml of stock diluted to 100 ml .
1~ 3 . 7 lo The relationship of the above table goes on up in a similar fashion to higher pt/co color numbers. Measure the absorbance of each standard solution at 390 mu, record the absorbance and its pt/co number and prepare a calibration curve of the absorbance at 390 mu versus the - pt/co number.
. 2 1~16C~C~50 lo obt~in -the pt/co color number of any given samp:le of hydroqllirlone~ weigh 5.0 grams into a 100 ml volun~ctri.c f]ask, add ~O ml of dilute acetic acid and shake to dissolve, make up to 100 ml with dilute acetic acid and measure absorbance at 390 mu versus a reference of dilute acetic acid. Using the calibration curve, obtain the pt/co color number of the test sample of hydroquinone.
It has been found that at 390 millimicrons (mu), the absorbance of hydroquinone is a straight line relationship with the pt/co color number, thus the slope of the curve could be used to calculate the pt/co color number.
Certain processes are known whereby technical grade hydroquinone is upgraded to photographic grade.
One consists of treating the tec-hnical grade hydroquinone while in solution with activated carban to adsorb the imp~rities from the solution of hydroquinone~ but this process uses rather large amounts of activated carbon.
.Another.method employed is to reduce technical grade hydroqulnone with inorganic reducing agents, however..this process leaves residues of the inorganic reducing agents in .
the resulting hydroquinone ~hich in themsel~es are impurities. For these reasons, these processes leave something to be desired.
It has now been found in accordance with this invention that a sllghtly acid solution of technical grade hydroquinone can be treating with hydrogen in the presence of palladium catalyst to produce photographic grade hydroquinone.
A more detailed description of the invention is ' ' .. .
- ' . , ' ' ' ' ' ~06~)050 that tech~lical grade hydroquinone is put into solution using aIly solvent. The pH of the technical grade hydroquinone solut;ion should be adjusted between about 3 and abou-t ~ for best results. If the pH of the solution of the technical grade hydroquinone is neutral, basic or has a pH much below 3, the process yields dark crystalline hydro~uinone unsuited for photographic grade. Any solvent system in which hydroquinone is soluble could be employed, so long as the solvent does not adversely affect the catalyst activity or the hydroquinone. However~
water is ideal as a solvent because of the ease of adjusting the pH to the proper level and the ease of recovery of lhe reduce or photographic grade hydroquinone~
As has been indicated, the invention is the reduction of the impurities in technical grade hydro-quinone while said hydroquinone is in a solution adjusted so that the p~ ranges from about 3.0 to about 6. o . This reduction takes place in the presence of a palladium catalyst and hydrogen is used as a reducing agent.
The actual operating conditions other than those -menkioned in the previous paragraph are not critical to the actual invention. For instance~ the temperature, the pressure of hydrogen, the residence times and even the amount of catalyst are all interdependent on each other, the kind and amount of impurities present in the technical grade hydroquinone as well as the purity desired o~ the photographic grade. These operating conditions also depend on other factors 9 such as, the dilution or concentration of the hydroquinone, the proper contact .
~t6~C~50 bet;w(cn the impllrities and the hydrogen and. the catalyst and other factors which those skilled in the art will readily hc able to determine without undue experimentation~
It has been found, however, that the reduction of the technical grade hydroquinone impurities or color bodies can be successfully carried out at temperatures ranging between about 25 and about 125C, with about 50 to about 80C being more preferred. It has been observed that if the solution of hydroquinone in its solvent is at too high a temperature there may be a tendency to cause a reduction of the aromatic ring of the hydroquinone. On the other hànd, care must be taken that too low a temperature is not used so that some of the hydroquinone will not fully be dissolved in the solvent employed and therefore its impurities will not be in contact with either the hydrogen of the catalyst~
The concentration of the hydroquinone in its solvent has not been found to be at all critical. It must be appreciated however that a sufflcient amount of solvent be employed so that the hydroquinone is soluble at the operating.temperatures chosen.
The pressure of the hydrogen employed in this invention has not been found critical and can vary from atmospheric pressure to several hundred atmosphers with about 5 to about 150 psig being more preferred.
~he amount of hydrogen required in the reduction of the impurities in the practice of this invention depends, of course~ on the quantity and type of impurities in the .technical grade and the purity of the photographic grade .
~ -5 .
.,, ., .. ,.... .. . ...... . . ~.
. ~06~050 desired as well as the contact of the hydroquinone with the catalyst. Also, the time required would have some bearing on the amount of hydrogen to be employed. As indicated, good results have been obtained using hydro~en pressure varying between about 5 and about 150 psig.
The tim~ referred to as contact ime required for the reduction of the impurities like some of the other operating conditions depends on various other factors such as, the type and amount of impurities, the hydrogen pressure, the temperature and amount and type of impurities also the purity desired in the final product. Times varying between ten seconds and two hours have been satisfactorily employed with thirty seconds to ten minutes being preferred.
It should be pointed out that the temperature, the pressure and the time all will have a bearing on the economics of the process. If the pressures are extremely high, the temperature extremely high and the times extremely long? there is a likelihood of the reduction o~ the aromatic ring of the hydroquinoneO On the other hand, if these variables are too low or too short, the reduction may not be sufficient to remove the color bodies or impurities and photographic grade may not be obtained.
Those skilled in the art will readily adjust the various operating parameters to give the best and most economical results.
The catalyst employed in this invention is palladium. In order to effect economies~ it is preferred that the palladium be supported on any inert support .
~U6~50 which would not adversely affect the reaction. Any of the Tnore co~on supports which are inert in a hydro-genatlon reaction can be employed. It has been found that palladium on alumina and palladium on carbon worXs very well. If the palladium is employed on a support, the catalyst loading on the support can vary rather widely from about O.OOl to about 10 percent by weight.
It has been found that catalyst loadings of much below O.l and much above 1.0 have certain minor deficiencies.
If the loading is much below O.l percent, the product produced still had some color indicating an incomplete reduction of the impurities. On the other hand, if the catalyst laoding exceeds ~uch above 1 percent, there is a danger of excessive reduct on of the aromatic ring of the hydroquinone and the expense of unneeded catalyst.
The process herein described may be carried out either batch-wise or as a continuous process. The .
process is 9 as indicated, carried out in solution~ The process is preferably carried out in the absence of oxy-gen as oxygen will tend to oxidize hydroquinone as well as the impurities when it is in solution. Furthermore, .
the palladium catalyst employed in the process in addition to being a reducing catalyst is an excellent oxidatlve catalyst The oxidation products of hydroquinone lend calor to the flnal product, thus it is preferable that air or oxygen be excluded from the process.
The product hydroquinone after being reduced with hydrogen over the palladium catalyst is cooled to a temperature whereby the hydroquinone crystallizes and is .
.
. . .
106~ 50 usually flltered or centrifuged to remove excess solverlt and thc hydroquinone dried. Any hydroquinone which remains in solution during the filtering or centrlfuging step can be recycled to the process for further reduction and/or recovery.
The invention is further illustrated by reference to the following examples which are intended to be illustrative rather than limiting of the scope of the invention.
EXAMPLE I
Into a l-liter stainless steel autoclave equipped with a turbine stirrer~ baffles, thermocouple wells, electric heaters and a temperature controller was charged 100 grams technical grade hydroquinone, l gram of powdered catalyst composed of 0.5 percent by weight of palladium on carbon~ 400 milliliters of distilled water.
The autoclave was closed and-hydrogen gas was introduced to a pressure of 60 psig. The reaction mixture was stirred with the stirrer and the mixture was heated to 60~C and held at that temperature for 1.5 hours. At the-end of that time 9 the stirrer was stopped and the excess hydrogen was vented from the autoclave and the reduced hydroquinone was withdrawn from the autoclave. The solution was immediately filtered to remove it from the catalyst and then lO grams of activated charcoal was added to the mixture and was stirred at 800C under an atmosphere of nitrogen. The activated charcoal was separated by filtration and the solution was cooled to 15~C with no agitation under an atmosphere of nitrogen.
. . . .. . :: . . ' ' 10~05~
e crystalline hydroquinone was filtered off and dried in a vacuum oven at 60oC for approximately 15 hours.
About 60 grams of hydroquinone having a pt/co color number of 19 was obtained~ The original technical grade hydroquinone had a pt/co number above 500. The total hydroquinone balance was 98 percent.
EXhMPLE II
In an autoclave like that o~ Example I was charged 100 grams technical grade hydroquinone~ 5 grams of powdered catalyst composed of 0.5 percent by weight of palladium on carbon~ 400 milliliters of distilled water. The autoclave was closed and pressured with hydrogen to 60 psig. The mixture was stirred and heated to 600C and maintained for 1.5 hours. ~he reduced hydroquinone was recovered in the same manner as in Example I. The L pt/co color of-the orlginal hydroquinone was ~4~ the color after hydrogena~ion was 21 and after being trea~ed with the activated charcoal~ the color was 1~. The total hydroquinone balance was 100 percent~
Thus, the invention is the method of preparing photographic grade hydroquinone ~rom technical grade hydroquinone which consists of treating a solution of the technical grade hydroquinone in the presence of a palladium catalyst with hydrogen while the hydroquinone solution is at a pH between about 3 and about 6, at tem-peratures ranging from about 25 to about 125C. and for periods of time varying from about 10 seconds to about
Commercially available technical grade hydroquinone has a relatively high platinum~cobalt color number and is not suitable for use in photographic purposes. This relatively high platinum/cobalt color number in technical grade hydroquinone results from the presence of certain impurities which impart a tan to yellow to even brown color in technical grade hydroquinone.
As employed in this application, the term "technical grade hydroquinone" is meant to relate that the hydro-quinone exhibits a platinum/cobalt (pt/co) color number of 45 or even higher and in some cases up to and above 500, The term "photographic grade hydroquinone" is meant that the hydroquinone exhibits a pt/co color number around 20 or slightly higher and up to about 30. -The piatinum/cobalt (ptico) color number as employedin this application is a well-known test, in which most often color is determined by visual comparisons of a test sample of hydroquinone solution against a solution with known concentrations of color solutions on the pt/co scale. The unit of color is defined as that color product produced by one milligram/per liter of platinum in the form of the chloroplatinate ion. The accuracy of , ~ .
, . .
1~)6QC~SO
such a ~risua] test is dependent to a large extent on the judgment of the beholder. To eliminate this error, a spectrophotometry test has been devised. The spectro-photometry test was devised in the fol1owing manner.
In the standard pt/co color test, 1.246 grams of potassiurn chloroplatinate and 1.0 gram of cobaltous .
chloride are dissolved in about 100 ml of water and 100 ml of hydrochlorlc acld and then the solution is diluted with more water to l-liter. To prepare the color standards, dispense varying amounts of this color stock into 100 ml volumetric flasks and dilute to 100 ml with water, for example:
pt/co colorml of stock diluted to 100 ml .
1~ 3 . 7 lo The relationship of the above table goes on up in a similar fashion to higher pt/co color numbers. Measure the absorbance of each standard solution at 390 mu, record the absorbance and its pt/co number and prepare a calibration curve of the absorbance at 390 mu versus the - pt/co number.
. 2 1~16C~C~50 lo obt~in -the pt/co color number of any given samp:le of hydroqllirlone~ weigh 5.0 grams into a 100 ml volun~ctri.c f]ask, add ~O ml of dilute acetic acid and shake to dissolve, make up to 100 ml with dilute acetic acid and measure absorbance at 390 mu versus a reference of dilute acetic acid. Using the calibration curve, obtain the pt/co color number of the test sample of hydroquinone.
It has been found that at 390 millimicrons (mu), the absorbance of hydroquinone is a straight line relationship with the pt/co color number, thus the slope of the curve could be used to calculate the pt/co color number.
Certain processes are known whereby technical grade hydroquinone is upgraded to photographic grade.
One consists of treating the tec-hnical grade hydroquinone while in solution with activated carban to adsorb the imp~rities from the solution of hydroquinone~ but this process uses rather large amounts of activated carbon.
.Another.method employed is to reduce technical grade hydroqulnone with inorganic reducing agents, however..this process leaves residues of the inorganic reducing agents in .
the resulting hydroquinone ~hich in themsel~es are impurities. For these reasons, these processes leave something to be desired.
It has now been found in accordance with this invention that a sllghtly acid solution of technical grade hydroquinone can be treating with hydrogen in the presence of palladium catalyst to produce photographic grade hydroquinone.
A more detailed description of the invention is ' ' .. .
- ' . , ' ' ' ' ' ~06~)050 that tech~lical grade hydroquinone is put into solution using aIly solvent. The pH of the technical grade hydroquinone solut;ion should be adjusted between about 3 and abou-t ~ for best results. If the pH of the solution of the technical grade hydroquinone is neutral, basic or has a pH much below 3, the process yields dark crystalline hydro~uinone unsuited for photographic grade. Any solvent system in which hydroquinone is soluble could be employed, so long as the solvent does not adversely affect the catalyst activity or the hydroquinone. However~
water is ideal as a solvent because of the ease of adjusting the pH to the proper level and the ease of recovery of lhe reduce or photographic grade hydroquinone~
As has been indicated, the invention is the reduction of the impurities in technical grade hydro-quinone while said hydroquinone is in a solution adjusted so that the p~ ranges from about 3.0 to about 6. o . This reduction takes place in the presence of a palladium catalyst and hydrogen is used as a reducing agent.
The actual operating conditions other than those -menkioned in the previous paragraph are not critical to the actual invention. For instance~ the temperature, the pressure of hydrogen, the residence times and even the amount of catalyst are all interdependent on each other, the kind and amount of impurities present in the technical grade hydroquinone as well as the purity desired o~ the photographic grade. These operating conditions also depend on other factors 9 such as, the dilution or concentration of the hydroquinone, the proper contact .
~t6~C~50 bet;w(cn the impllrities and the hydrogen and. the catalyst and other factors which those skilled in the art will readily hc able to determine without undue experimentation~
It has been found, however, that the reduction of the technical grade hydroquinone impurities or color bodies can be successfully carried out at temperatures ranging between about 25 and about 125C, with about 50 to about 80C being more preferred. It has been observed that if the solution of hydroquinone in its solvent is at too high a temperature there may be a tendency to cause a reduction of the aromatic ring of the hydroquinone. On the other hànd, care must be taken that too low a temperature is not used so that some of the hydroquinone will not fully be dissolved in the solvent employed and therefore its impurities will not be in contact with either the hydrogen of the catalyst~
The concentration of the hydroquinone in its solvent has not been found to be at all critical. It must be appreciated however that a sufflcient amount of solvent be employed so that the hydroquinone is soluble at the operating.temperatures chosen.
The pressure of the hydrogen employed in this invention has not been found critical and can vary from atmospheric pressure to several hundred atmosphers with about 5 to about 150 psig being more preferred.
~he amount of hydrogen required in the reduction of the impurities in the practice of this invention depends, of course~ on the quantity and type of impurities in the .technical grade and the purity of the photographic grade .
~ -5 .
.,, ., .. ,.... .. . ...... . . ~.
. ~06~050 desired as well as the contact of the hydroquinone with the catalyst. Also, the time required would have some bearing on the amount of hydrogen to be employed. As indicated, good results have been obtained using hydro~en pressure varying between about 5 and about 150 psig.
The tim~ referred to as contact ime required for the reduction of the impurities like some of the other operating conditions depends on various other factors such as, the type and amount of impurities, the hydrogen pressure, the temperature and amount and type of impurities also the purity desired in the final product. Times varying between ten seconds and two hours have been satisfactorily employed with thirty seconds to ten minutes being preferred.
It should be pointed out that the temperature, the pressure and the time all will have a bearing on the economics of the process. If the pressures are extremely high, the temperature extremely high and the times extremely long? there is a likelihood of the reduction o~ the aromatic ring of the hydroquinoneO On the other hand, if these variables are too low or too short, the reduction may not be sufficient to remove the color bodies or impurities and photographic grade may not be obtained.
Those skilled in the art will readily adjust the various operating parameters to give the best and most economical results.
The catalyst employed in this invention is palladium. In order to effect economies~ it is preferred that the palladium be supported on any inert support .
~U6~50 which would not adversely affect the reaction. Any of the Tnore co~on supports which are inert in a hydro-genatlon reaction can be employed. It has been found that palladium on alumina and palladium on carbon worXs very well. If the palladium is employed on a support, the catalyst loading on the support can vary rather widely from about O.OOl to about 10 percent by weight.
It has been found that catalyst loadings of much below O.l and much above 1.0 have certain minor deficiencies.
If the loading is much below O.l percent, the product produced still had some color indicating an incomplete reduction of the impurities. On the other hand, if the catalyst laoding exceeds ~uch above 1 percent, there is a danger of excessive reduct on of the aromatic ring of the hydroquinone and the expense of unneeded catalyst.
The process herein described may be carried out either batch-wise or as a continuous process. The .
process is 9 as indicated, carried out in solution~ The process is preferably carried out in the absence of oxy-gen as oxygen will tend to oxidize hydroquinone as well as the impurities when it is in solution. Furthermore, .
the palladium catalyst employed in the process in addition to being a reducing catalyst is an excellent oxidatlve catalyst The oxidation products of hydroquinone lend calor to the flnal product, thus it is preferable that air or oxygen be excluded from the process.
The product hydroquinone after being reduced with hydrogen over the palladium catalyst is cooled to a temperature whereby the hydroquinone crystallizes and is .
.
. . .
106~ 50 usually flltered or centrifuged to remove excess solverlt and thc hydroquinone dried. Any hydroquinone which remains in solution during the filtering or centrlfuging step can be recycled to the process for further reduction and/or recovery.
The invention is further illustrated by reference to the following examples which are intended to be illustrative rather than limiting of the scope of the invention.
EXAMPLE I
Into a l-liter stainless steel autoclave equipped with a turbine stirrer~ baffles, thermocouple wells, electric heaters and a temperature controller was charged 100 grams technical grade hydroquinone, l gram of powdered catalyst composed of 0.5 percent by weight of palladium on carbon~ 400 milliliters of distilled water.
The autoclave was closed and-hydrogen gas was introduced to a pressure of 60 psig. The reaction mixture was stirred with the stirrer and the mixture was heated to 60~C and held at that temperature for 1.5 hours. At the-end of that time 9 the stirrer was stopped and the excess hydrogen was vented from the autoclave and the reduced hydroquinone was withdrawn from the autoclave. The solution was immediately filtered to remove it from the catalyst and then lO grams of activated charcoal was added to the mixture and was stirred at 800C under an atmosphere of nitrogen. The activated charcoal was separated by filtration and the solution was cooled to 15~C with no agitation under an atmosphere of nitrogen.
. . . .. . :: . . ' ' 10~05~
e crystalline hydroquinone was filtered off and dried in a vacuum oven at 60oC for approximately 15 hours.
About 60 grams of hydroquinone having a pt/co color number of 19 was obtained~ The original technical grade hydroquinone had a pt/co number above 500. The total hydroquinone balance was 98 percent.
EXhMPLE II
In an autoclave like that o~ Example I was charged 100 grams technical grade hydroquinone~ 5 grams of powdered catalyst composed of 0.5 percent by weight of palladium on carbon~ 400 milliliters of distilled water. The autoclave was closed and pressured with hydrogen to 60 psig. The mixture was stirred and heated to 600C and maintained for 1.5 hours. ~he reduced hydroquinone was recovered in the same manner as in Example I. The L pt/co color of-the orlginal hydroquinone was ~4~ the color after hydrogena~ion was 21 and after being trea~ed with the activated charcoal~ the color was 1~. The total hydroquinone balance was 100 percent~
Thus, the invention is the method of preparing photographic grade hydroquinone ~rom technical grade hydroquinone which consists of treating a solution of the technical grade hydroquinone in the presence of a palladium catalyst with hydrogen while the hydroquinone solution is at a pH between about 3 and about 6, at tem-peratures ranging from about 25 to about 125C. and for periods of time varying from about 10 seconds to about
2 hours, said palladium on an inert support varies from about 0.001 to about 10 percent by weight of the support.
~ .
_9_ C
lO~;O(~SO
Water is the best solvent. The hydrogen pressure varies from about atmospheric pressure to several hundred pounds pressure. The contact time varies from about 30 seconds to about ten minutes. The palladium is employed on an inert support, such as carbon or alumina.
While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing ~rom the spirit or scope of the invention.
~d .
~ .
_9_ C
lO~;O(~SO
Water is the best solvent. The hydrogen pressure varies from about atmospheric pressure to several hundred pounds pressure. The contact time varies from about 30 seconds to about ten minutes. The palladium is employed on an inert support, such as carbon or alumina.
While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing ~rom the spirit or scope of the invention.
~d .
Claims (8)
1. The method of preparing photographic grade hydroquinone from technical grade hydroquinone which consists of treating a solution of the technical grade hydroquinone in the presence of a palladium catalyst with hydrogen while the hydroquinone solution is at a pH between about 3 and about 6, at temperatures ranging from about 25 to about 125°C. and for periods of time varying from about 10 seconds to about 2 hours, said palladium on an inert support varies from about 0.001 to about 10 percent by weight of the support.
2. The method according to claim 1 in which the technical grade hydroquinone is in a water solution.
3. The method according to claim 1 in which the hydrogen pressure varies from about atmospheric pressure to several hundred pounds pressure.
4. The method according to claim 3 in which the hydrogen pressure varies from about 5 to about 150 psig.
5. The method according to claim 1 in which the contact time varies from about 30 seconds to about ten minutes.
6. The method according to claim 1 in which the palladium is employed in an inert support.
7. The method according to claim 1 in which the palladium on the inert support varies between about 0.1 and 1.0 weight percent by weight of the support and in which the support is carbon or alumina.
8. The method according to claim 1 wherein the technical grade hydroquinone is treated with hydrogen in the presence of a palladium catalyst in which the tempera-ture varies from about 50 to about 80°C., the hydrogen pressure varies from about 5 to about 150 psig, and in which the contact time varies from about 30 seconds to about two hours and in which the palladium varies from about 0.1 to about 1 percent by weight on a support which is alumina or carbon.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US44536374A | 1974-02-25 | 1974-02-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1060050A true CA1060050A (en) | 1979-08-07 |
Family
ID=23768618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA218,859A Expired CA1060050A (en) | 1974-02-25 | 1975-01-28 | Purification of hydroquinone |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS50117726A (en) |
| BE (1) | BE825586A (en) |
| CA (1) | CA1060050A (en) |
| DE (1) | DE2505271A1 (en) |
| FR (1) | FR2262014B1 (en) |
| GB (1) | GB1464072A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52232A (en) * | 1975-06-23 | 1977-01-05 | Jo Eguchi | Process for purification of hydroquinone |
| JPS525717A (en) * | 1975-06-27 | 1977-01-17 | Jo Eguchi | Process for purification of hydroquinone |
| US7521505B2 (en) | 2006-06-12 | 2009-04-21 | Sabic Innovative Plastics Ip B.V. | Method of stabilization of dihydric phenols |
-
1975
- 1975-01-28 CA CA218,859A patent/CA1060050A/en not_active Expired
- 1975-01-31 GB GB429875A patent/GB1464072A/en not_active Expired
- 1975-02-07 DE DE19752505271 patent/DE2505271A1/en active Pending
- 1975-02-12 FR FR7504290A patent/FR2262014B1/fr not_active Expired
- 1975-02-14 BE BE153411A patent/BE825586A/en unknown
- 1975-02-25 JP JP2338375A patent/JPS50117726A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2505271A1 (en) | 1975-08-28 |
| FR2262014B1 (en) | 1977-04-15 |
| FR2262014A1 (en) | 1975-09-19 |
| BE825586A (en) | 1975-05-29 |
| GB1464072A (en) | 1977-02-09 |
| JPS50117726A (en) | 1975-09-16 |
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