CA1070328A - Process for the preparation of cycloalkanones and cycloalkanols - Google Patents
Process for the preparation of cycloalkanones and cycloalkanolsInfo
- Publication number
- CA1070328A CA1070328A CA253,976A CA253976A CA1070328A CA 1070328 A CA1070328 A CA 1070328A CA 253976 A CA253976 A CA 253976A CA 1070328 A CA1070328 A CA 1070328A
- Authority
- CA
- Canada
- Prior art keywords
- conversion
- catalyst
- reaction mixture
- cycloalkanones
- temperature
- 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
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
- C07C45/53—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition of hydroperoxides
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 OF THE DISCLOSURE
An improved process for preparing cycloalkanones and cycloalkanols from cycloalkylhydroperoxides. Cycloalkyl-hydroperoxides are converted under the influence of a solid heterogeneous chromium oxide catalyst and the reaction mixture is stripped with a stripping gas which reduces the content of water which is formed in the reaction mixture during conver-sion. As a result, the catalyst activity and selectivity is maintained.
An improved process for preparing cycloalkanones and cycloalkanols from cycloalkylhydroperoxides. Cycloalkyl-hydroperoxides are converted under the influence of a solid heterogeneous chromium oxide catalyst and the reaction mixture is stripped with a stripping gas which reduces the content of water which is formed in the reaction mixture during conver-sion. As a result, the catalyst activity and selectivity is maintained.
Description
. ~o703Z8 This invention relates to a process for preparing cycloalkanones and cycloalkanols by conversion of cycloalkyl hydroperoxides in the presence of a solid heterogeneous chromium oxide catalyst.
Such a known process provides a high selectivity of conversion into the desired products cycloalkanone and cycloalkanol, a avourably low ratio in which the ketone and the alkanol are obtained, and a high initial rate of conversion of cycloalkyl hydroperoxides into cycloalkanones and cyclo- -alkanols. However the known process has the disadvantage that the activity of the heterogeneous chromium oxide catalyst rapidly decreases during the reaction, while the selectivity of the reaction into cycloalkanone and cycloalkanol is also reduced. -The invention is based on the observation that the decreasing catalyst activity and selectivity is caused by the water that is formed as a by-product in the reaction and accumulates in the reaction mixture as hitherto it could not be discharged sufficiently rapidly from the reaction mixture. In order to maintain the activity and selectivity of the catalyst it is important that no separate aqueous phase, not even in the dispersed state, is formed in addition to the organic phase in the conversion.
The invention provides a process for preparing cycloalkanones and cycloalkanols by conversion of a cycloalkyl hydroperoxide in a liquid hydro-carbon in the presence of a solid heterogeneous chromium oxide catalyst, wherein the conversion is effected at a temperature of between 30 and 150C
and wherein during the conversion, water is stripped from the reaction mixture with a stripping gas such that the water content of the reaction mixture re-mains at or below the saturation concentration.
Suitable stripping gases that may be used according to the invention are inert gases or vapours, e.g. nitrogen, argonJ carbon dioxide and vapour from the liquid used in the reaction. When low reaction temperatures are appliedJ air diluted with nitrogen or carbon dioxide may be used with good effect.
The reaction mixture should as indicated above be stripped to such ~_~ . - 2 - 1r~
~ i ,~
'1070328 extent that the water content of the reaction mixture remains at or below ~
the saturation concentration. - :
~ 2a -.,~ ,, " ~
.. . . . .. . . . . .
The catalysts used in the process according to the invention may be supported on a carrier, e.g. silica, alumina, titanium dioxide, molecular sieves, magnesium oxide, tin oxide and charcoal. Various modifications oi the carriers may be used e.g. the carrier may be microporous or macroporous.
Particularly suitable silica carriers are more ob~ained under the Trade Marks AEROSIL and KETJENSIL. The catalyst particles may be in the i'orm of globules, saddles, or tablets or other particulate i'orm. Use is preferably made of a ;
iixed catalyst bed, but the catalyst may also be finely divided in the reaction mixture as a suspension.
The method oi' preparation of the catalyst has a considerable effect on the speci~ic conversion rate. The catalyst preferably used is chromium oxide obtained by heating a suitable chromium compound, e.g. chromic hydroxide.
It is advantageous to activate the catalyst before use by heating at a temperature in the range of 300 -500 C in an atmosphere of a gas containing molecular oxygen, e.g. air. Particularly high speciiic conversion rates can be obtained by means oi catalysts prepared by the method described in Applicant's British Patent Specification 1,220,105.
When catalysts on a carrier are used, the degree of loading of the carrier with catalytically active material is also important. Use is prei'erably made of a low degree oi loading, e.g. not more than l5 ~ by weight oi chromium oxide, calculated as Cr. Such a catalyst appears to have a high activity compared with catalyst with a relatively high degree oi loading.
The chromium in the catalyst may have various valencies, e.g. it may be trivalent or hexavalent. A very active catalyst with a long li~e in which the chromium is contained predominantly as chromium~VI)oxide, can be obtained by heating chromium(III)oxide at a temperature in the range 300 to 500 C in an atmosphere o~ a gas containing molecular oxygen, e.g. air.
It is also possible to prepare the catalyst ~rom a chromium compound that changes into chromium(III)oxide when heated, e.g. chromium(III)hydroxide.
A substantially complete conversion oi chromium(III) into chromium(VI) is . _ 3 _ ~070328 obtained in catalysts with a low degree o~ loading, particularly those that are X-ray amorphous.
The process for preparing cycloalkanones and cycloalkanols according to the invention is preferably effected at a temperature of from 30 to 150 C. At temperatures below 30 C the conversion rate iq insu~ficiently high. Non-specific thermal decomposition of peroxide usually causes a lower yield of desired products at temperatures higher than 120 C, unless use is made of an extremely active catalyst system. m e temperature range o~ 60 to 110 C is a good compromise between a low reaction rate at low temperature and a low selectivity at high temperature.
The reaction pressure is not critical. The reaction is generally carried out with a solution o~ the cycloalkyl hydroperoxide in a liquid vehicle, so that it will then be necessary to use a pressure at which a ~ ~ :
liquid phase is maintained in the system. A pressure oi 1 atmosphere or slightly higher is pre~erred although lower and higher pressures may be used e.g. in the range O.l to 20 atmospheres, depending upon the liquid vehicle and cycloalkyl hydroperoxide used. m e peroxide concentration is usually irom 2 to 20 % by weight.
Operable liquid vehicles are those that are inert under the reaction conditions and also the cycloalkane corresponding to the cycloalkyl hydro-peroxide used. The last is to be prei'erred since more than one molecule oi cycloalkanone or cycloalkanol may then be iormed per molecule oi~ cycloalkyl hydroxyperoxide put in. Particular examples oi' suitable inert vehicles are aromatic hydrocarbons e.g. benzene and toluene.
In the conversion according to the invention, the-yield o~' the desired products cycloalkanone and cycloalkanol is high, and usually amounts to more than 100 % ii the corresponding cycloalkane is used as a vehicle.
It will remain at a high level ior a long reaction period. The reaction rate also remains high ~'or a long reaction period. As a result, the useful life of the catalyst may be very long, e.g. more than six months as against at ~` most two weeks in process as ~urtherto used.
;
...
~o~703z8 The cycloalkyl hydroperoxide can be prepared by oxidation of the corresponding cycloalkane in the liquid phase at elevated temperature by means of a gas containing oxygen, such as air. The process is effected at low conversions based on the cycloalkane fed in, e.g. from 1 to 12 ~.
Suitable oxidation temperatures are in the range from 120 to 200 C, preferably from 140 to 180 C. The operating pressure is not critical but should be such that a liquid phase Is maintained in the system. The pressure is usually from 4 to 50 atmospheres.
m e oxidation reaction yields a hot somewhat dilute solution of cycloalkyl hydroperoxide in cycloalkane under pressure. It is expedient to allow the resulting solution to expand to a lower pressure e.g. to about 1 atmosphere. If the cycloalka~e is cyclopentane, cyclohexane or cyclo-heptane, so much cycloalkane will evaporate in this expansion that the temperature drops to a temperature of from 60 to 100 C. It is this temperature range that is particularly suitable for the conversion according to the invention, so that the resulting concentrated solution of cycloalkyl hydroperoxide can be subjected as such to the process according to the invention. However it is useful at least partly to free the crude solution of impurities, e.g. by washing with water, thereby inhibiting contamination of the catalyst. It is also possible first to separate pure cycloalkyl hydroperoxide oxidation product mixture, e.g. by extraction with an aqueous hydroxide solution and subsequent acidification and further processing of the extract, and to use the pure peroxide as the starting material.
The process according to the invention may be effected either batch-wise and continuously.
The following Examples of the invention are provided, together with comparative experiments.
Example I
In a continuous process, a solution obtained by oxidation of cyclo--30~ ~hexane in the liquid phase by means of oxygen from air and containing ~0703Z8 1.20 moles/kg of cyclohexyl hydroperoxide, 0.16 mole/kg of cyclohexanone, 0.19 mole/kg of cyclohexanol and 12 meq/kg of other cyclohexane oxidation products (determined as acids) was passed at the rate of 55 ml~hour through two series-connected columns of 5 mm cross-section and each partly filled with 24 grams of catalyst tablets at a temperature of 100 C and a super-atmospheric pressure of 1.7-2.2 atmospheres gauge. The catalyst was 3.1 %
by weight of Cr203 on silica obtained under the Trade Mark EETJENSIL.
The retention time in each column was about 30 minutes. All the water formed was continuously removed from the reaction liquor by stripping with nitrogen.
The amount of stripping gas was varied from 2 to 15 litres/hour. Eve~y six .
hours the resulting reaction product was sampled and analyzed for cyclohexanol, cyclohexanone, acid and peroxide. m e analyses showed that the conversion ^~
set to a substantially constant value of about 90 % after a short time and then stayed at this value for many weeks. The yield of usei'ul cyclohexanone and cyclohexanol products was to 108 %, based on the cyclohexyl hydroperoxide converted.
Comparative experiment A
The process according to Example I was repeated, but no stripping gas was used. The conversion decreased to 73 % in a short time and did not subsequently exceed this value. The yield of cyclohexanone and cyclohexanol based on to peroxide converted was subctantially equal to that in Example I.
Comparative experiment B and Example II
The process according to Example I was carried out except that the temperature was 80 C, the superatmospheric pressure 0.4 atmospheres gauge, and the throughput rate of the peroxide solution 45 ml/hour. The retention time of the cyclohexane was 45 minutes in each column. The oxidate passed through the columns was sampled every six hours and analyzed. The analyses of the products sampled showed that the conversion of the cyclohexyl hydro-peroxide soon dropped to a value of 74 % to 76 % and did not subsequently exceed this value. After 500 hours of operation stripping the reacting ``: 1070328 liquor with 1.5 litres/hour of nitrogen was commenced, and the water removed from the reaction mixture. As a result, the activity of the catalyst increased, the conversion rising from 74 to 85 % and then stayed at this value. Whether the stripping was used or not did not strongly affect the yield of cyclohexanone and cyclohexanol based on cyclohexyl hydroperoxide converted.
Such a known process provides a high selectivity of conversion into the desired products cycloalkanone and cycloalkanol, a avourably low ratio in which the ketone and the alkanol are obtained, and a high initial rate of conversion of cycloalkyl hydroperoxides into cycloalkanones and cyclo- -alkanols. However the known process has the disadvantage that the activity of the heterogeneous chromium oxide catalyst rapidly decreases during the reaction, while the selectivity of the reaction into cycloalkanone and cycloalkanol is also reduced. -The invention is based on the observation that the decreasing catalyst activity and selectivity is caused by the water that is formed as a by-product in the reaction and accumulates in the reaction mixture as hitherto it could not be discharged sufficiently rapidly from the reaction mixture. In order to maintain the activity and selectivity of the catalyst it is important that no separate aqueous phase, not even in the dispersed state, is formed in addition to the organic phase in the conversion.
The invention provides a process for preparing cycloalkanones and cycloalkanols by conversion of a cycloalkyl hydroperoxide in a liquid hydro-carbon in the presence of a solid heterogeneous chromium oxide catalyst, wherein the conversion is effected at a temperature of between 30 and 150C
and wherein during the conversion, water is stripped from the reaction mixture with a stripping gas such that the water content of the reaction mixture re-mains at or below the saturation concentration.
Suitable stripping gases that may be used according to the invention are inert gases or vapours, e.g. nitrogen, argonJ carbon dioxide and vapour from the liquid used in the reaction. When low reaction temperatures are appliedJ air diluted with nitrogen or carbon dioxide may be used with good effect.
The reaction mixture should as indicated above be stripped to such ~_~ . - 2 - 1r~
~ i ,~
'1070328 extent that the water content of the reaction mixture remains at or below ~
the saturation concentration. - :
~ 2a -.,~ ,, " ~
.. . . . .. . . . . .
The catalysts used in the process according to the invention may be supported on a carrier, e.g. silica, alumina, titanium dioxide, molecular sieves, magnesium oxide, tin oxide and charcoal. Various modifications oi the carriers may be used e.g. the carrier may be microporous or macroporous.
Particularly suitable silica carriers are more ob~ained under the Trade Marks AEROSIL and KETJENSIL. The catalyst particles may be in the i'orm of globules, saddles, or tablets or other particulate i'orm. Use is preferably made of a ;
iixed catalyst bed, but the catalyst may also be finely divided in the reaction mixture as a suspension.
The method oi' preparation of the catalyst has a considerable effect on the speci~ic conversion rate. The catalyst preferably used is chromium oxide obtained by heating a suitable chromium compound, e.g. chromic hydroxide.
It is advantageous to activate the catalyst before use by heating at a temperature in the range of 300 -500 C in an atmosphere of a gas containing molecular oxygen, e.g. air. Particularly high speciiic conversion rates can be obtained by means oi catalysts prepared by the method described in Applicant's British Patent Specification 1,220,105.
When catalysts on a carrier are used, the degree of loading of the carrier with catalytically active material is also important. Use is prei'erably made of a low degree oi loading, e.g. not more than l5 ~ by weight oi chromium oxide, calculated as Cr. Such a catalyst appears to have a high activity compared with catalyst with a relatively high degree oi loading.
The chromium in the catalyst may have various valencies, e.g. it may be trivalent or hexavalent. A very active catalyst with a long li~e in which the chromium is contained predominantly as chromium~VI)oxide, can be obtained by heating chromium(III)oxide at a temperature in the range 300 to 500 C in an atmosphere o~ a gas containing molecular oxygen, e.g. air.
It is also possible to prepare the catalyst ~rom a chromium compound that changes into chromium(III)oxide when heated, e.g. chromium(III)hydroxide.
A substantially complete conversion oi chromium(III) into chromium(VI) is . _ 3 _ ~070328 obtained in catalysts with a low degree o~ loading, particularly those that are X-ray amorphous.
The process for preparing cycloalkanones and cycloalkanols according to the invention is preferably effected at a temperature of from 30 to 150 C. At temperatures below 30 C the conversion rate iq insu~ficiently high. Non-specific thermal decomposition of peroxide usually causes a lower yield of desired products at temperatures higher than 120 C, unless use is made of an extremely active catalyst system. m e temperature range o~ 60 to 110 C is a good compromise between a low reaction rate at low temperature and a low selectivity at high temperature.
The reaction pressure is not critical. The reaction is generally carried out with a solution o~ the cycloalkyl hydroperoxide in a liquid vehicle, so that it will then be necessary to use a pressure at which a ~ ~ :
liquid phase is maintained in the system. A pressure oi 1 atmosphere or slightly higher is pre~erred although lower and higher pressures may be used e.g. in the range O.l to 20 atmospheres, depending upon the liquid vehicle and cycloalkyl hydroperoxide used. m e peroxide concentration is usually irom 2 to 20 % by weight.
Operable liquid vehicles are those that are inert under the reaction conditions and also the cycloalkane corresponding to the cycloalkyl hydro-peroxide used. The last is to be prei'erred since more than one molecule oi cycloalkanone or cycloalkanol may then be iormed per molecule oi~ cycloalkyl hydroxyperoxide put in. Particular examples oi' suitable inert vehicles are aromatic hydrocarbons e.g. benzene and toluene.
In the conversion according to the invention, the-yield o~' the desired products cycloalkanone and cycloalkanol is high, and usually amounts to more than 100 % ii the corresponding cycloalkane is used as a vehicle.
It will remain at a high level ior a long reaction period. The reaction rate also remains high ~'or a long reaction period. As a result, the useful life of the catalyst may be very long, e.g. more than six months as against at ~` most two weeks in process as ~urtherto used.
;
...
~o~703z8 The cycloalkyl hydroperoxide can be prepared by oxidation of the corresponding cycloalkane in the liquid phase at elevated temperature by means of a gas containing oxygen, such as air. The process is effected at low conversions based on the cycloalkane fed in, e.g. from 1 to 12 ~.
Suitable oxidation temperatures are in the range from 120 to 200 C, preferably from 140 to 180 C. The operating pressure is not critical but should be such that a liquid phase Is maintained in the system. The pressure is usually from 4 to 50 atmospheres.
m e oxidation reaction yields a hot somewhat dilute solution of cycloalkyl hydroperoxide in cycloalkane under pressure. It is expedient to allow the resulting solution to expand to a lower pressure e.g. to about 1 atmosphere. If the cycloalka~e is cyclopentane, cyclohexane or cyclo-heptane, so much cycloalkane will evaporate in this expansion that the temperature drops to a temperature of from 60 to 100 C. It is this temperature range that is particularly suitable for the conversion according to the invention, so that the resulting concentrated solution of cycloalkyl hydroperoxide can be subjected as such to the process according to the invention. However it is useful at least partly to free the crude solution of impurities, e.g. by washing with water, thereby inhibiting contamination of the catalyst. It is also possible first to separate pure cycloalkyl hydroperoxide oxidation product mixture, e.g. by extraction with an aqueous hydroxide solution and subsequent acidification and further processing of the extract, and to use the pure peroxide as the starting material.
The process according to the invention may be effected either batch-wise and continuously.
The following Examples of the invention are provided, together with comparative experiments.
Example I
In a continuous process, a solution obtained by oxidation of cyclo--30~ ~hexane in the liquid phase by means of oxygen from air and containing ~0703Z8 1.20 moles/kg of cyclohexyl hydroperoxide, 0.16 mole/kg of cyclohexanone, 0.19 mole/kg of cyclohexanol and 12 meq/kg of other cyclohexane oxidation products (determined as acids) was passed at the rate of 55 ml~hour through two series-connected columns of 5 mm cross-section and each partly filled with 24 grams of catalyst tablets at a temperature of 100 C and a super-atmospheric pressure of 1.7-2.2 atmospheres gauge. The catalyst was 3.1 %
by weight of Cr203 on silica obtained under the Trade Mark EETJENSIL.
The retention time in each column was about 30 minutes. All the water formed was continuously removed from the reaction liquor by stripping with nitrogen.
The amount of stripping gas was varied from 2 to 15 litres/hour. Eve~y six .
hours the resulting reaction product was sampled and analyzed for cyclohexanol, cyclohexanone, acid and peroxide. m e analyses showed that the conversion ^~
set to a substantially constant value of about 90 % after a short time and then stayed at this value for many weeks. The yield of usei'ul cyclohexanone and cyclohexanol products was to 108 %, based on the cyclohexyl hydroperoxide converted.
Comparative experiment A
The process according to Example I was repeated, but no stripping gas was used. The conversion decreased to 73 % in a short time and did not subsequently exceed this value. The yield of cyclohexanone and cyclohexanol based on to peroxide converted was subctantially equal to that in Example I.
Comparative experiment B and Example II
The process according to Example I was carried out except that the temperature was 80 C, the superatmospheric pressure 0.4 atmospheres gauge, and the throughput rate of the peroxide solution 45 ml/hour. The retention time of the cyclohexane was 45 minutes in each column. The oxidate passed through the columns was sampled every six hours and analyzed. The analyses of the products sampled showed that the conversion of the cyclohexyl hydro-peroxide soon dropped to a value of 74 % to 76 % and did not subsequently exceed this value. After 500 hours of operation stripping the reacting ``: 1070328 liquor with 1.5 litres/hour of nitrogen was commenced, and the water removed from the reaction mixture. As a result, the activity of the catalyst increased, the conversion rising from 74 to 85 % and then stayed at this value. Whether the stripping was used or not did not strongly affect the yield of cyclohexanone and cyclohexanol based on cyclohexyl hydroperoxide converted.
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing cycloalkanones and cycloalkanols by con-version of a cycloalkyl hydroperoxide in a liquid hydrocarbon in the presence of a solid heterogeneous chromium oxide catalyst, wherein the conversion is effected at a temperature of between 30° and 150°C and wherein during the conversion, water is stripped from the reaction mixture with a stripping gas such that the water content of the reaction mixture remains at or below the saturation concentration.
2. A process according to claim 1 wherein the conversion is effected at a temperature of between 60° and 110°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7506790A NL7506790A (en) | 1975-06-07 | 1975-06-07 | PROCESS FOR PREPARING CYCLOAL CANNONS AND CYCLOAL CANONS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070328A true CA1070328A (en) | 1980-01-22 |
Family
ID=19823915
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA253,976A Expired CA1070328A (en) | 1975-06-07 | 1976-06-03 | Process for the preparation of cycloalkanones and cycloalkanols |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS6033809B2 (en) |
| AR (1) | AR206572A1 (en) |
| BE (1) | BE842635R (en) |
| BR (1) | BR7603568A (en) |
| CA (1) | CA1070328A (en) |
| CH (1) | CH608774A5 (en) |
| DD (1) | DD124971A6 (en) |
| DE (1) | DE2625273A1 (en) |
| ES (1) | ES448576A2 (en) |
| FR (1) | FR2313336A2 (en) |
| GB (1) | GB1535869A (en) |
| IT (1) | IT1061404B (en) |
| MX (1) | MX144251A (en) |
| NL (1) | NL7506790A (en) |
| PL (1) | PL101224B3 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1590958A (en) * | 1976-12-31 | 1981-06-10 | Ici Ltd | Oxidation of cyclohexane |
| NL8201695A (en) * | 1982-04-23 | 1983-11-16 | Stamicarbon | PROCESS FOR THE PREPARATION OF CYCLOHEXANOL AND CYCLOHEXANONE. |
| CN104741377B (en) | 2015-03-30 | 2017-01-04 | 宝山钢铁股份有限公司 | There is the milling method of the sheet material of longitudinal different-thickness |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL43433A (en) * | 1972-10-21 | 1976-09-30 | Stamicarbon | Process for preparing cycloalkanones and cycloalkanols |
| CA1049041A (en) * | 1972-11-23 | 1979-02-20 | Stamicarbon B.V. | Process for the preparation of cycloalkanones and/or cycloalkanols |
-
1975
- 1975-06-07 NL NL7506790A patent/NL7506790A/en not_active Application Discontinuation
-
1976
- 1976-01-01 AR AR26349376A patent/AR206572A1/en active
- 1976-06-03 CA CA253,976A patent/CA1070328A/en not_active Expired
- 1976-06-04 ES ES448576A patent/ES448576A2/en not_active Expired
- 1976-06-04 DE DE19762625273 patent/DE2625273A1/en not_active Ceased
- 1976-06-04 GB GB2326776A patent/GB1535869A/en not_active Expired
- 1976-06-04 BE BE167662A patent/BE842635R/en not_active IP Right Cessation
- 1976-06-04 DD DD19319576A patent/DD124971A6/xx unknown
- 1976-06-04 BR BR7603568A patent/BR7603568A/en unknown
- 1976-06-04 FR FR7617017A patent/FR2313336A2/en active Granted
- 1976-06-04 CH CH767120A patent/CH608774A5/en not_active IP Right Cessation
- 1976-06-07 PL PL19019276A patent/PL101224B3/en unknown
- 1976-06-07 JP JP6638276A patent/JPS6033809B2/en not_active Expired
- 1976-06-07 MX MX16500676A patent/MX144251A/en unknown
- 1976-06-07 IT IT2403376A patent/IT1061404B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| NL7506790A (en) | 1976-12-09 |
| CH608774A5 (en) | 1979-01-31 |
| FR2313336A2 (en) | 1976-12-31 |
| MX144251A (en) | 1981-09-18 |
| DD124971A6 (en) | 1977-03-23 |
| PL101224B3 (en) | 1978-12-30 |
| AR206572A1 (en) | 1976-07-30 |
| FR2313336B2 (en) | 1981-06-12 |
| BE842635R (en) | 1976-12-06 |
| JPS6033809B2 (en) | 1985-08-05 |
| BR7603568A (en) | 1977-01-04 |
| JPS51146437A (en) | 1976-12-16 |
| GB1535869A (en) | 1978-12-13 |
| ES448576A2 (en) | 1977-07-16 |
| IT1061404B (en) | 1983-02-28 |
| DE2625273A1 (en) | 1976-12-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |