CA1162571A - Process for preparing high assay dicamba - Google Patents
Process for preparing high assay dicambaInfo
- Publication number
- CA1162571A CA1162571A CA000376929A CA376929A CA1162571A CA 1162571 A CA1162571 A CA 1162571A CA 000376929 A CA000376929 A CA 000376929A CA 376929 A CA376929 A CA 376929A CA 1162571 A CA1162571 A CA 1162571A
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- CA
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- Prior art keywords
- acid
- methoxy
- percent
- weight
- mixture
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
- C07C51/493—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification whereby carboxylic acid esters are formed
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C62/00—Compounds having carboxyl groups bound to carbon atoms of rings other than six—membered aromatic rings and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
- C07C62/02—Saturated compounds containing hydroxy or O-metal groups
- C07C62/04—Saturated compounds containing hydroxy or O-metal groups with a six-membered ring
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C63/00—Compounds having carboxyl groups bound to a carbon atoms of six-membered aromatic rings
- C07C63/04—Monocyclic monocarboxylic acids
- C07C63/06—Benzoic acid
- C07C63/10—Halides thereof
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT
The present invention discloses a process for preparing high purity 2-methoxy-3,6-dichlorobenzoic acid from a mixture of said acid with its 3, 5-dichloro isomer by selective esterification.
The present invention discloses a process for preparing high purity 2-methoxy-3,6-dichlorobenzoic acid from a mixture of said acid with its 3, 5-dichloro isomer by selective esterification.
Description
~ 7~77l VCC-5014 PROCESS FOR PREPARING HIGH ASSAY DICAMBA
_ __ _ __ _ Specification Dicarnba or 2-methoxy-3,6-dichlorobenzoic acid, is a valuable herbicide that is produced in large commercial quantities. Technical dicamba, that is the product that is used to prepare commercial formulations, is not of high purity but typically contains about 84 percent of the compound 2-methoxy-3,6-dichlorobenzoic acid. The predominant impurity is the isomer 2-methoxy-3,5-dichlorobenzoic acid. The reason for this is that dicamba is prepared from 1,2,4-trichloro-benzene in a three-stage process which alwa~7s results in the formation of a substantial quantity of the 3,5-isomer. In the first stage of the process, the trichlorobenzene is con-verted to the 2,5-dichlorophenol by treatment with methanol and sodium hydroxide. During this reaction 2,4-dichlorophenol is always formed. The dichlorophenols are then treated with carbon dioxide under pressure to give 2-hydroxy-3,6-dichloro-benzoic acid and the 3,5-dichloro isomer. The hydroxyl group is then methylated to yield the technical dicamba. Each OI
the intermediate isomeric mixtures are difficult to separate due to their close boiling points. Further, the final product isomer mixture is difficult to separate, since they are solids with similar solubility properties. For example, the
_ __ _ __ _ Specification Dicarnba or 2-methoxy-3,6-dichlorobenzoic acid, is a valuable herbicide that is produced in large commercial quantities. Technical dicamba, that is the product that is used to prepare commercial formulations, is not of high purity but typically contains about 84 percent of the compound 2-methoxy-3,6-dichlorobenzoic acid. The predominant impurity is the isomer 2-methoxy-3,5-dichlorobenzoic acid. The reason for this is that dicamba is prepared from 1,2,4-trichloro-benzene in a three-stage process which alwa~7s results in the formation of a substantial quantity of the 3,5-isomer. In the first stage of the process, the trichlorobenzene is con-verted to the 2,5-dichlorophenol by treatment with methanol and sodium hydroxide. During this reaction 2,4-dichlorophenol is always formed. The dichlorophenols are then treated with carbon dioxide under pressure to give 2-hydroxy-3,6-dichloro-benzoic acid and the 3,5-dichloro isomer. The hydroxyl group is then methylated to yield the technical dicamba. Each OI
the intermediate isomeric mixtures are difficult to separate due to their close boiling points. Further, the final product isomer mixture is difficult to separate, since they are solids with similar solubility properties. For example, the
2,9- and 2,5-dichlorophenols boil at 2C9-210 C and 211 C
respectively.
One method of overcoming this problem is described ( /
by Carlson in U.S. Patent ~,09~,913 wherein pure 2,5-di-chlorophenol is prepared by reacting l-bromo-2,5-dichloro-benzene ~ith alkali metal hydroxide and methanol in the presence of copper catalyst. This pure phenol can then he used to prepare high purity dicamba.
To utilize this process, however, requires that the long and difficult commercial procedure be utilized.
Since technical dicamba is already an item of commerce and readily available, it would be desirable to have a relatively simple procedure of preparing relatively pure 2-methoxy-
respectively.
One method of overcoming this problem is described ( /
by Carlson in U.S. Patent ~,09~,913 wherein pure 2,5-di-chlorophenol is prepared by reacting l-bromo-2,5-dichloro-benzene ~ith alkali metal hydroxide and methanol in the presence of copper catalyst. This pure phenol can then he used to prepare high purity dicamba.
To utilize this process, however, requires that the long and difficult commercial procedure be utilized.
Since technical dicamba is already an item of commerce and readily available, it would be desirable to have a relatively simple procedure of preparing relatively pure 2-methoxy-
3,6-dichlorobenzoic acid from the technical grade product.
It has now surprisingly been found that high assay dicamba, in excess of 95 percent by weight purity and often of 99 percent purity, can be prepared in a single reaction step from a mixture of 2-methoxy-3,6-dichlorobenzoic acid and its 3,5-dichloro isomer through selective esterification under certain conditions.
More specifically, one embodiment of the present invention resides in a process for preparing 2-methoxy-3,6-dichlorobenzoic acid of a purity in excess of 95 percent byweight from a mixture containing 2-methoxy-3,6-dichlorobenzoic acid and 2-methoxy-3,5-dichlorobenzoic acid which comprises reacting said mixture with an alkanol in a liquid inert organic reaction medium, in the presence of an acid catalyst at a temperature sufficiently elevated to remove the water of esterification and thereafter recovering the 2-methoxy-3,6-dichlorobenzoic acid.
In the foregoing process the 3,5-isomer is surprisingly 1 16~71 selectively es'~erified by the alkanol to the exclusion of the 3,6-isomer. The alkane ester formed is typically a liquid product and can readily be separated from the remain-ing acid. Moreover, the esters are more soluble in organic solvents and therefore also permit the selective precipita-tion of the desired purified product from the reac~ion medium.
Technical dicamba as prepared on a commercial scale typically contains from 80 to 90 percent by weight of 2-methoxy-3,6-dichlorobenzoic acid and from 10 to 20 percent by weight of the corresponding 3,5-dichloro isomer. It is this mixture that is specifically intended as the starting mixture in the process of this invention. However, the in-vention is not limited thereto but can be utilized to separate the named components in any relative proportion. Accordingly, proportions ranging from 10:90 to 90:10 of the respective isomers can be separated by the present process.
The alkanols which are useful in the process of the present invention are the lower alkanols such as the alkanols having from one to ten carbon atoms. Moreover, either straight or branched alkanols can be used. Exemplary of such alkanols are ethanol _-propanol, isopro-panol, _-butanol, sec-butanol, pentanol, ?-methylpentanol, hexanol, heptanol, octanol, nonanol, decanol and the like. A
molar or excess molar equivalent of the alkanol to the 2-methoxy-3,5-dichlorobenzoic acid present in the starting mixture can be used.
The process of the present invention is carried out in a liquid inert organic reaction medium capable of dissolving l 1 62~71 the starting isomer mixture at reaction temperatures. While the choice of reaction medium is not critical, it is de-sirable to use an organic solvent in which the al~anol ester is more soluble than the 2-methoxy-3,6-dichloroben-zoic acid. The use of a solvent that preferentially dis-solves the ester will facilitate the recovery of the desired product. Solvents particularly useful for this purpose are aromatic hydrocarbons such as benzene an~ alkylbenzenes, including toluene, ethyl benzene, xylene and the like or mixtures thereof.
The process of the present invention is carried out in the presence of a catalytic amount of an acid cata-lyst. Typically an amount ranging from about 0.001 percent to about 5 percent by weight of the isomeric starting mix-ture of substituted benzoic acids can be suitably used.
Exemplary acid catalysts useful in the present process are sulfuric acid, para-toluenesulfonic acid, phosphoric acid, phosphonic acid, titanium alcoholates such as titanium tetraproproxide, benzenesulfonic acid, and anhydrous hydro-chloric acid.
The process of the present invention is carried out at elevated temperatures ranging up to the reflux tempera-ture of the reaction mixture. Temperatures sufficiently high to remove the water of esterification are required. This can be conveniently effected by azeotropic distillation when using an aromatic hydrocarbon solvent. Accordingly, reflux temperatures can be preferably used and the water of ester-ification can thereby be removed by conventional means.
Furthermore, the reaction can be monitored for completion by collecting and measuring the amount of water of esterifi-cation that is formed.
After the reaction is completed, i.e., when all of the 2-methoxy-3,5-dichlorobenzoic acid has been selectively esterified, the desired product 2-methoxy-3,6-dichlorobenzoic acid can be readily recovered by conventional means. One convenient method of recovery comprises cooling the reaction mixture sufficiently to precipitate the desired product and recovering the precipitate by filtration.
The process of the present invention is more speci-fically illustrated by the following examples.
EY~ PLE l Technical dicamba (578 grams) containing 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and 9 percent by weight 2-methoxy-3,5-dichlorobenzoic acid, xylene (750 ml), n-butanol (62 ml) and ~-toluenesulfonic acid (1.5 grams) were charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser fitted with a Dean-Stark trap. The reaction mixture was heated at reflux for a period of about 9 hours. After this time, 6 ml of water was collected. The reaction mixture was then concentrated by distilling off 250 ml of xylene and was thereafter cooled to 0C resulting in the formation of a precipitate. The precipitate was recovered by filtration and was ~ashed three times ~ith cold Y~ylene (100 ml; 8 C) .
The washed precipitate was then reslurried in xylene and filtered. The filtered solid was washed again with cold xylene (100 ml~ and was thereafter dried under reduced pressure (about 25 in of Hg) at 50C to yield the desired product 2-methoxy-3,6-dichlorobenzoic acid having a purity of 99.03 percent by weight and containing 0.86 percent by weight of the 3,5-isomer as determined by gas chromato-gra~hy.
Technic~l dicamba (264 grams) containing 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and 9 percent by weight 2-methoxy-3,5-dichlorobenzoic acid, a mix-ture of xylenes (340 ml), _-butanol (30 ml) and ~-toluene-sulfonic acid (1 gram) were charged into a glass reactionvessel equipped with a magnetic stirrer, thermometer and reflux condenser fitted with a Dean-Stark trap. The reaction mixture was heated at reflux for a period of abou' 24 hours resulting in the trapping of 3.1 ml of water. The reaction mixture was then concentrated by distilling off about 170 ml of xylene and was thereafter cooled to about 4C result-ing in the formation of a precipitate. The precipitate was recovered by filtration and was washed with the stripped off xylenes obtained from the distillation and cooled to about 10C and was air dried to yield a first crop of desired 2-methoxy-3,6-dichlorobenzoic (150.14 grams) having a 97.58 percent by weight purity and containing 2.17 percent of the I 1 ~;25~ 1 3,5-isomer. The mo,her liquor from the filtration was com-bined with the washing and was concentrated by distillation to a volume of 150 ml. The resulting mixture was cooled to about 4C ylelding a second precipitate. This precipi-tate was recovered by filtration, was washed three timeswith cold toluene (50 ml portions; 8C) and air dried to yield an additional 30.6 grams of desired product assaying 98.17 percent by weight and containing 1.71 percent by weight of the 3,5-isomer.
Technical dicamba (lOOO grams) comprising about 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and about 9 percent 2-methoxy-3,5-dichlorobenzoic acid, n-octanol (120 ml), ethylbenzene (1500 ml) and benzenesulfonic15 acid (lO grams) are charged into a glass reaction vessel equipped with a stirrer thermometer and reflux condenser ritted with a water trap. The reaction mixture is heated at ref]ux for a period of ahout 18 hours. After this time the mixture is cooled to about 3C to precipitate 2-methoxy-20 !
3,6-dichlorobenzoic acid. The precipitate is recovered by filtration, is washed with cold toluene and dried to yield the desired product having a purity in excess of 95 percent by weight~
1 ~ fi~5~1 _AMPLE ~
A mixture comprising equal parts by weight of 2-methoxy-3,6-dichlorobenzoic acid and 2-methoxy-3,5-dichloro-benzoic acid (600 grams), toluene (800 ml), isopropanol (75 ml) and titanium tetrapropoxide (0.6 grams) were charged into a glass reaction vessel equipped with a stirrer, ther-mometer and reflux condenser fitted with a water trap. The reaction mixture is heated at reflux for a period of about 12 hours. After this time the reaction mixture is concen-trated by distilling off about 300 ml of toluene. The remain-ing mixture is then cooled to a temperature of about 5C to precipitate the desired product. This product is then re-covered by filtration, is washed with three portions of cold toluene (5C; 100 ml) and is dried to yield 2-methoxy-3,6-di-chlorobenzoic acid.
It has now surprisingly been found that high assay dicamba, in excess of 95 percent by weight purity and often of 99 percent purity, can be prepared in a single reaction step from a mixture of 2-methoxy-3,6-dichlorobenzoic acid and its 3,5-dichloro isomer through selective esterification under certain conditions.
More specifically, one embodiment of the present invention resides in a process for preparing 2-methoxy-3,6-dichlorobenzoic acid of a purity in excess of 95 percent byweight from a mixture containing 2-methoxy-3,6-dichlorobenzoic acid and 2-methoxy-3,5-dichlorobenzoic acid which comprises reacting said mixture with an alkanol in a liquid inert organic reaction medium, in the presence of an acid catalyst at a temperature sufficiently elevated to remove the water of esterification and thereafter recovering the 2-methoxy-3,6-dichlorobenzoic acid.
In the foregoing process the 3,5-isomer is surprisingly 1 16~71 selectively es'~erified by the alkanol to the exclusion of the 3,6-isomer. The alkane ester formed is typically a liquid product and can readily be separated from the remain-ing acid. Moreover, the esters are more soluble in organic solvents and therefore also permit the selective precipita-tion of the desired purified product from the reac~ion medium.
Technical dicamba as prepared on a commercial scale typically contains from 80 to 90 percent by weight of 2-methoxy-3,6-dichlorobenzoic acid and from 10 to 20 percent by weight of the corresponding 3,5-dichloro isomer. It is this mixture that is specifically intended as the starting mixture in the process of this invention. However, the in-vention is not limited thereto but can be utilized to separate the named components in any relative proportion. Accordingly, proportions ranging from 10:90 to 90:10 of the respective isomers can be separated by the present process.
The alkanols which are useful in the process of the present invention are the lower alkanols such as the alkanols having from one to ten carbon atoms. Moreover, either straight or branched alkanols can be used. Exemplary of such alkanols are ethanol _-propanol, isopro-panol, _-butanol, sec-butanol, pentanol, ?-methylpentanol, hexanol, heptanol, octanol, nonanol, decanol and the like. A
molar or excess molar equivalent of the alkanol to the 2-methoxy-3,5-dichlorobenzoic acid present in the starting mixture can be used.
The process of the present invention is carried out in a liquid inert organic reaction medium capable of dissolving l 1 62~71 the starting isomer mixture at reaction temperatures. While the choice of reaction medium is not critical, it is de-sirable to use an organic solvent in which the al~anol ester is more soluble than the 2-methoxy-3,6-dichloroben-zoic acid. The use of a solvent that preferentially dis-solves the ester will facilitate the recovery of the desired product. Solvents particularly useful for this purpose are aromatic hydrocarbons such as benzene an~ alkylbenzenes, including toluene, ethyl benzene, xylene and the like or mixtures thereof.
The process of the present invention is carried out in the presence of a catalytic amount of an acid cata-lyst. Typically an amount ranging from about 0.001 percent to about 5 percent by weight of the isomeric starting mix-ture of substituted benzoic acids can be suitably used.
Exemplary acid catalysts useful in the present process are sulfuric acid, para-toluenesulfonic acid, phosphoric acid, phosphonic acid, titanium alcoholates such as titanium tetraproproxide, benzenesulfonic acid, and anhydrous hydro-chloric acid.
The process of the present invention is carried out at elevated temperatures ranging up to the reflux tempera-ture of the reaction mixture. Temperatures sufficiently high to remove the water of esterification are required. This can be conveniently effected by azeotropic distillation when using an aromatic hydrocarbon solvent. Accordingly, reflux temperatures can be preferably used and the water of ester-ification can thereby be removed by conventional means.
Furthermore, the reaction can be monitored for completion by collecting and measuring the amount of water of esterifi-cation that is formed.
After the reaction is completed, i.e., when all of the 2-methoxy-3,5-dichlorobenzoic acid has been selectively esterified, the desired product 2-methoxy-3,6-dichlorobenzoic acid can be readily recovered by conventional means. One convenient method of recovery comprises cooling the reaction mixture sufficiently to precipitate the desired product and recovering the precipitate by filtration.
The process of the present invention is more speci-fically illustrated by the following examples.
EY~ PLE l Technical dicamba (578 grams) containing 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and 9 percent by weight 2-methoxy-3,5-dichlorobenzoic acid, xylene (750 ml), n-butanol (62 ml) and ~-toluenesulfonic acid (1.5 grams) were charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser fitted with a Dean-Stark trap. The reaction mixture was heated at reflux for a period of about 9 hours. After this time, 6 ml of water was collected. The reaction mixture was then concentrated by distilling off 250 ml of xylene and was thereafter cooled to 0C resulting in the formation of a precipitate. The precipitate was recovered by filtration and was ~ashed three times ~ith cold Y~ylene (100 ml; 8 C) .
The washed precipitate was then reslurried in xylene and filtered. The filtered solid was washed again with cold xylene (100 ml~ and was thereafter dried under reduced pressure (about 25 in of Hg) at 50C to yield the desired product 2-methoxy-3,6-dichlorobenzoic acid having a purity of 99.03 percent by weight and containing 0.86 percent by weight of the 3,5-isomer as determined by gas chromato-gra~hy.
Technic~l dicamba (264 grams) containing 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and 9 percent by weight 2-methoxy-3,5-dichlorobenzoic acid, a mix-ture of xylenes (340 ml), _-butanol (30 ml) and ~-toluene-sulfonic acid (1 gram) were charged into a glass reactionvessel equipped with a magnetic stirrer, thermometer and reflux condenser fitted with a Dean-Stark trap. The reaction mixture was heated at reflux for a period of abou' 24 hours resulting in the trapping of 3.1 ml of water. The reaction mixture was then concentrated by distilling off about 170 ml of xylene and was thereafter cooled to about 4C result-ing in the formation of a precipitate. The precipitate was recovered by filtration and was washed with the stripped off xylenes obtained from the distillation and cooled to about 10C and was air dried to yield a first crop of desired 2-methoxy-3,6-dichlorobenzoic (150.14 grams) having a 97.58 percent by weight purity and containing 2.17 percent of the I 1 ~;25~ 1 3,5-isomer. The mo,her liquor from the filtration was com-bined with the washing and was concentrated by distillation to a volume of 150 ml. The resulting mixture was cooled to about 4C ylelding a second precipitate. This precipi-tate was recovered by filtration, was washed three timeswith cold toluene (50 ml portions; 8C) and air dried to yield an additional 30.6 grams of desired product assaying 98.17 percent by weight and containing 1.71 percent by weight of the 3,5-isomer.
Technical dicamba (lOOO grams) comprising about 85 percent by weight 2-methoxy-3,6-dichlorobenzoic acid and about 9 percent 2-methoxy-3,5-dichlorobenzoic acid, n-octanol (120 ml), ethylbenzene (1500 ml) and benzenesulfonic15 acid (lO grams) are charged into a glass reaction vessel equipped with a stirrer thermometer and reflux condenser ritted with a water trap. The reaction mixture is heated at ref]ux for a period of ahout 18 hours. After this time the mixture is cooled to about 3C to precipitate 2-methoxy-20 !
3,6-dichlorobenzoic acid. The precipitate is recovered by filtration, is washed with cold toluene and dried to yield the desired product having a purity in excess of 95 percent by weight~
1 ~ fi~5~1 _AMPLE ~
A mixture comprising equal parts by weight of 2-methoxy-3,6-dichlorobenzoic acid and 2-methoxy-3,5-dichloro-benzoic acid (600 grams), toluene (800 ml), isopropanol (75 ml) and titanium tetrapropoxide (0.6 grams) were charged into a glass reaction vessel equipped with a stirrer, ther-mometer and reflux condenser fitted with a water trap. The reaction mixture is heated at reflux for a period of about 12 hours. After this time the reaction mixture is concen-trated by distilling off about 300 ml of toluene. The remain-ing mixture is then cooled to a temperature of about 5C to precipitate the desired product. This product is then re-covered by filtration, is washed with three portions of cold toluene (5C; 100 ml) and is dried to yield 2-methoxy-3,6-di-chlorobenzoic acid.
Claims (10)
1. A process for preparing 2-methoxy-3,6-dichloro-benzoic acid of a purity in excess of 95 percent by weight from a mixture containing from 10 to 90 parts by weight 2-methoxy-3,6-dichlorobenzoic acid and from 90 to 10 parts by weight 2-methoxy-3,5-dichlorobenzoic acid which comprises re-acting said mixture with an alkanol in a liquid inert organic reaction medium in the presence of an acid catalyst at a temperature sufficiently elevated to remove the water of ester-ification as it is formed and thereafter recovering the 2-methoxy-3,6-dichlorobenzoic acid.
2. The process of Claim 1, wherein the alkanol has from two to ten carbon atoms.
3. The process of Claim 2, wherein the alkanol is n-butanol.
4. The process of Claim 1, wherein the reaction medium is an aromatic hydrocarbon of the alkylbenzene series.
5. The process of Claim 4, wherein the reaction medium is selected from the group consisting of toluene, xy-lene and ethylbenzene.
6. The process of Claim 1, wherein the acid catalyst is selected from the group consisting of benzenesulfonic acid, p-toluenesulfonic acid, sulfuric acid, phosphoric acid, phosphonic acid and titanium tetrapropoxide.
7. The process of Claim 1, wherein the reaction temperature is the reflux temperature of the reaction mixture.
8. The process of Claim 4, wherein the water of esterification is removed by azeotropic distillation.
9. The process of Claim 1, wherein the purified 2-methoxy-3,6-dichlorobenzoic acid is recovered by cooling the reaction mixture sufficiently to precipitate it from the reaction medium.
10. The process of Claim 1 wherein said mixture con-tains from about 80 to 90 percent by weight 2-methoxy-3,6-di-chlorobenzoic acid and from about 10 to 20 percent 2-methexy-3,5-dichlorobenzoic acid, the alkanol has from 1 to 10 carbon atoms, the reaction medium is an aromatic hydrocarbon of the alkylbenzene series, and the catalyst is p-toluenesulfonic acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15819680A | 1980-06-11 | 1980-06-11 | |
| US158,196 | 1980-06-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162571A true CA1162571A (en) | 1984-02-21 |
Family
ID=22567061
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376929A Expired CA1162571A (en) | 1980-06-11 | 1981-05-06 | Process for preparing high assay dicamba |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS5728028A (en) |
| KR (1) | KR850001156B1 (en) |
| AT (1) | AT374782B (en) |
| AU (1) | AU538334B2 (en) |
| BE (1) | BE889169A (en) |
| BR (1) | BR8103658A (en) |
| CA (1) | CA1162571A (en) |
| CH (1) | CH646936A5 (en) |
| DE (1) | DE3122073A1 (en) |
| ES (1) | ES502917A0 (en) |
| FR (1) | FR2484405B1 (en) |
| GB (1) | GB2077729B (en) |
| IL (1) | IL62860A (en) |
| IT (1) | IT1142534B (en) |
| NL (1) | NL8102501A (en) |
| SE (1) | SE442196B (en) |
| ZA (1) | ZA813711B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61197365U (en) * | 1985-05-31 | 1986-12-09 | ||
| USD967679S1 (en) * | 2021-07-24 | 2022-10-25 | Li Peng | Lawn coring aerator |
| USD1012640S1 (en) * | 2023-07-26 | 2024-01-30 | Shenzhenshi Wanlian Technology Innovation Co., Ltd. | Lawn aerator |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3012870A (en) * | 1958-08-04 | 1961-12-12 | Velsicol Chemical Corp | Method of destroying undesirable vegetation |
| US3013054A (en) * | 1958-08-04 | 1961-12-12 | Velsicol Chemical Corp | 2-methoxy-3, 6-dichlorobenzoates |
| IE33399B1 (en) * | 1968-10-10 | 1974-06-12 | El Paso Products Co | Esterification and extraction process |
| US4094913A (en) * | 1977-01-07 | 1978-06-13 | Velsicol Chemical Corporation | Process for the preparation of 2,5-dichlorophenol |
| US4215065A (en) * | 1979-01-02 | 1980-07-29 | Monsanto Company | Acid separation |
-
1981
- 1981-05-06 CA CA000376929A patent/CA1162571A/en not_active Expired
- 1981-05-08 CH CH301581A patent/CH646936A5/en not_active IP Right Cessation
- 1981-05-13 IL IL62860A patent/IL62860A/en unknown
- 1981-05-19 AU AU70814/81A patent/AU538334B2/en not_active Ceased
- 1981-05-19 KR KR1019810001725A patent/KR850001156B1/en active
- 1981-05-21 NL NL8102501A patent/NL8102501A/en not_active Application Discontinuation
- 1981-05-22 FR FR8110283A patent/FR2484405B1/en not_active Expired
- 1981-05-27 JP JP8066581A patent/JPS5728028A/en active Granted
- 1981-06-01 IT IT48596/81A patent/IT1142534B/en active
- 1981-06-03 DE DE19813122073 patent/DE3122073A1/en active Granted
- 1981-06-03 ZA ZA00813711A patent/ZA813711B/en unknown
- 1981-06-10 BR BR8103658A patent/BR8103658A/en not_active IP Right Cessation
- 1981-06-10 GB GB8117725A patent/GB2077729B/en not_active Expired
- 1981-06-10 BE BE0/205058A patent/BE889169A/en not_active IP Right Cessation
- 1981-06-10 ES ES502917A patent/ES502917A0/en active Granted
- 1981-06-10 AT AT0258381A patent/AT374782B/en active
- 1981-06-10 SE SE8103635A patent/SE442196B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR830006159A (en) | 1983-09-17 |
| FR2484405B1 (en) | 1985-07-05 |
| FR2484405A1 (en) | 1981-12-18 |
| IL62860A (en) | 1984-09-30 |
| ES8203818A1 (en) | 1982-04-01 |
| JPS5728028A (en) | 1982-02-15 |
| ZA813711B (en) | 1982-06-30 |
| GB2077729A (en) | 1981-12-23 |
| NL8102501A (en) | 1982-01-04 |
| DE3122073A1 (en) | 1982-03-18 |
| SE8103635L (en) | 1981-12-12 |
| CH646936A5 (en) | 1984-12-28 |
| AT374782B (en) | 1984-05-25 |
| ES502917A0 (en) | 1982-04-01 |
| DE3122073C2 (en) | 1989-10-19 |
| AU538334B2 (en) | 1984-08-09 |
| BE889169A (en) | 1981-10-01 |
| KR850001156B1 (en) | 1985-08-16 |
| JPH0114896B2 (en) | 1989-03-14 |
| GB2077729B (en) | 1984-03-14 |
| IL62860A0 (en) | 1981-07-31 |
| IT8148596A0 (en) | 1981-06-01 |
| BR8103658A (en) | 1982-03-02 |
| AU7081481A (en) | 1981-12-17 |
| SE442196B (en) | 1985-12-09 |
| IT1142534B (en) | 1986-10-08 |
| ATA258381A (en) | 1983-10-15 |
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