CA2064564A1 - Process for preparing 2,6-dicholoroquinoxaline - Google Patents
Process for preparing 2,6-dicholoroquinoxalineInfo
- Publication number
- CA2064564A1 CA2064564A1 CA 2064564 CA2064564A CA2064564A1 CA 2064564 A1 CA2064564 A1 CA 2064564A1 CA 2064564 CA2064564 CA 2064564 CA 2064564 A CA2064564 A CA 2064564A CA 2064564 A1 CA2064564 A1 CA 2064564A1
- Authority
- CA
- Canada
- Prior art keywords
- chloro
- hydroxyquinoxaline
- sodium salt
- oxide
- sodium hydroxide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D241/00—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings
- C07D241/36—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings condensed with carbocyclic rings or ring systems
- C07D241/50—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings condensed with carbocyclic rings or ring systems with hetero atoms directly attached to ring nitrogen atoms
- C07D241/52—Oxygen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D241/00—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings
- C07D241/36—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings condensed with carbocyclic rings or ring systems
- C07D241/38—Heterocyclic compounds containing 1,4-diazine or hydrogenated 1,4-diazine rings condensed with carbocyclic rings or ring systems with only hydrogen or carbon atoms directly attached to the ring nitrogen atoms
- C07D241/40—Benzopyrazines
- C07D241/44—Benzopyrazines with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to carbon atoms of the hetero ring
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Plural Heterocyclic Compounds (AREA)
Abstract
Abstract of the disclosure Process for the preparation of 2,6-dichloroquinoxaline A process for the preparation of 2,6-dichloroquinoxaline by hydrogenating 6-chloro-2-hydroxyquinoxaline-N-oxide in aqueous sodium hydroxide solution in the presence of about 0.001 to about 0.5 mol percent of a platinum shell catalyst, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, at temperatures of about 20 to about 120°C at a hydrogen pressure of about 1 to about 100 bar, about 1 to about 3 equivalents of sodium hydroxide, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, being added, and after separating off the catalyst from the hot solution depositing the 6-chloro-2-hydroxyquinoxaline dissolved therein in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 0 to about 20°C, drying azao-tropically with an inert solvent and chlorinating using a chlorinating agent in a customary manner to give 2,6-dichloroquinoxaline.
Description
2 ~ 6 4 HOECHST AXTIENGESELLSCHAET ~OE 89/F 249 Dr. .~U/rh Description Proces~ for the preparation of 2,6-dichloroquinoxaline The invention relates to an Lmproved process, compared to the prior rt, for the preparation of 2,6-dichloro-quinoxaline by reduction of 6-chloro-2-hydroxy-quinoxaline-N-oxide to 6-chloro-2 hydroxyquinoxaline, crystallization of its sodium salt, removal of the water and chlorination in a manner known per se.
2,6-Dichloroquinoxaline is an important precur~or for the pr~paration of plant protection agent~ (EP 276,741A; DE-OS 3,004,770). In this connection, it is important that the 2,6-dichloroquinoxalino i~ employed in pur~ form.
All known proces-~es for the preparation of 2,6-dichloro-quinoxaline (cf.EP0,295,815; EP0,295,797; USP4,636,S62, Sakata et al., Heterocycles 23, 143, 2025 (1985); DE
2,6-Dichloroquinoxaline is an important precur~or for the pr~paration of plant protection agent~ (EP 276,741A; DE-OS 3,004,770). In this connection, it is important that the 2,6-dichloroquinoxalino i~ employed in pur~ form.
All known proces-~es for the preparation of 2,6-dichloro-quinoxaline (cf.EP0,295,815; EP0,295,797; USP4,636,S62, Sakata et al., Heterocycles 23, 143, 2025 (1985); DE
3,901,406; European Patent Application 89 106 784.5, in combination with Houben-Weyl, vol. VIII, 359 et seq.
(1952), or Organikum, Berlin 1975, VEB Deutscher Verlag der Wissenqcha ten) lead ~o a product whose quality is insu ficient for immediat~ furthor proc2~ing to the plant protection agon~ and to other product~, which is why the 2,6-dichloroquinoxaline obtainable by the known proce~o3 ha~ to b0 sub~ected to compli~ated purification stEps before further proce~sing. There was thu~ a need for a preparation proce~s in which tho 2,6-dichloro-quinoxaline is obtainod in ~uch a high d~gree of purity th~t it ca~. ba further proc~ssed to the d~ired ~inal product Lmmadiately without complic~ed purifica~ion operation~.
It ha~ now urpri3ingly b~en found that 2,6~dichloro-quinoxaline can be pr~pared in a high degre~ o~ purity and at the 3ame ti~0 in Y~ry good yiold by hydro~enating 6-ch}oro-2~hydroxyquinoxalin0-N-o~id~ in ~queou~ ~odium hydroxide ~olution in thQ preLq0nce of about 0.001 to 2 ~ 6 4 about 0.5 mol percent, preferably 0.01 to about 0.05 mol percent, of a platinum shell catalyst, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, at tempera-t~res of about 20 to about 120C, preferably of about 60 to about 100C, at a hydrogen pressure of a~out 1 to about 100 bar, preferably of about 5 to about 20 bar, about 1 to about 3 equivalent~ of sodium hydroxide, relative to 6 chloro-2-hydroxyquinoxaline-N-oxide employed, being added, after separating off the catalyst from the hot solution depositing the 6-chloro-2-hydroxy-quinoxaline dissolved therein in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 0 to about 20C, preferably about 5 to about 10C, drying azeotropically u3ing an inert solvent and chlorinating with a chlorinating agent in a manner customary per se to give 2,6-dich~oroquinoxaline.
In the proce~ according to the invantion, the following may be carried ol-t in particular:
As a rule, it i~ expedient to ~ub~ect the 6-chloro-2-hydroxyquinoxaline~N-oxide to the hydrogenation in suspen~ed form in the aqueous 30dium hydroxide 301ution in a concentration of about 15 to about 30 pexcent by weight, preferably of about 20 to about 25 percent by weight.
Depending on the reaction para~e~ers, the catalytie hydrog~nation take3 about 30 minu~e~ to about 5 hour~, a~
a rule about 1 to about 3 hour3.
Shell cataly~t~ are designa~ed as tho~e hydrogena~ion cataly.Rt~ in which the noble m~t~l, for example platinum, i~ di~tributed in extremQly fine form pxQdo~ina~tly on the surface of a ~upport ma~erial p~r~icl~, for example active carbon, in contra~t to the co~monly designated noble metal cat ly~t3 which h~ve a pr~dominantly uniform di~tribution of th~ noble m~tal also inside (via pore~
2~6456~
etc.) of a support material particle.
The catalyst employed can be employed repeatedly.
The sodium salt of the 6-chloro-2-hydroxyquinoxaline formed by the hydrogenation is present under the reaction conditions in dissolved form and can be separated off from the catalyst in a sLmple manner. On subsequent cooling to about 0 t~ about 20 DC t preferably about 5 to about 10C, it precipitates out virtually quanti~atively.
~he product thus obtained is of excellent quality.
For further processing, it is added, preferably in water-moist form, to an inert diluent which can form an azeo-trope with water. Suitable diluents which may be men-tioned are, for example, benzene, toluene, xylenes (all isomers and their mixture~), cumene, chlorobenzene, 1~ ethylbenzene, carbon tatrachloride, trichloromethane, cyclohexane, hexane, heptane and suitable petroleum ether fractions. The water prQsent is then separated off azeotropically.
The product is ~ubsequently chlsrinated in a manner known per se uQing one of the customary chlorina~ing agent~, such as, for example, thionyl chloride, pho3phorus pentachloride, pho3gene or preferably pho~phoru3 oxy-chloride (se~, for example, Houben-Weyl, vol. VIII, 359 et ~eq. (1952~; Organikum, ~erlin 1986, VEB DQut~char Verla~ der Wi son~chaften).
The chlorinating agen~, which i3 2mployed in exces~
separated o~f and can be used for further bat~he3 t just lik~ the diluent which can be recover~d again.
Working-up i8 carried out in a cuetomary manner. The final product~ 2,6~dichloroquinoxaline, i~ obtained in the required high purity and a~ditionally in ~ery good yi01d .
2~56~
It is in this respect to be consider~d surprising that the sodium salt of the 6-chloro-2-hydroxyquinoxaline can be caused to deposit in crystalline form virtually quantitatively according to the invention, as it is S ntrinsically very easily soluble both in the presence of heat and also on relatively high dilution.
The extreme purification effect associated with the virtually quantitative crystalline deposition of the sodium salt of 6-chloro-2-hydroxyquinoxaline achieved is to be judged as particularly surprising, since owing ~o its low solubility in the customary ~olvent~, even at relatively high temperature, and the great YLmilarity to the relevant impurities, rec~ystallization of the neutral 6-chloro-2-hydroxyquinoxaline is ~u~t as ~atisfactory as recrystallization of the subsequent ~tage ~2,6-dichloro-quinoxaline) synthesized under con~entional condition~.
In addikion to advantage of the process according to the invention already mentioned further above, there is a further Lmportant advantage, in particular from the ecological point of view, in the great reduction ~f the salt load of the total procesq a~ a result of the omis-sion of an intermediate i~olation of the 6-chloro-2-hydroxyquinoxalina ~ormsd as an intermediate and the neutralization as30ciated therewith.
If it i~ de~ired to recovor the 6-chloro-2-hydroxy-quinoxaline obtained at the end of the hydrogenation step in a high degree of purity and in ve~y good yield a~ such in pure form, it can be obtained pure in a simple m~nn2r by adding a mineral acidr 3uch a~, ~ox exæmpl~, ~ulfuric or hydrochloric acid9 to the depo~ited ~odium salt of ~he 6-chloro-2-hydroxyquinox21ine or prefexably to an a~ueous ~olution of this compound.
The axample below erve to illu~rata ~ha process according ~o the invention, withou~ lLmi~ing i~ thereto.
~ o ~
E~ample 593 g (l mol) of 6-chloro-2 hydroxyquinoxaline-N-oxide sodium salt in industrially moist form were suspended in 757 g of water and heated to 80 - 90~C in the presence of 2 g of platinum shell catalyst ~type ~.5 Pt/C, F 101 KY/W
containing about 50 percent by weight of water (DEG~SSA)) and hydrogenated in an autoclave using hydrogen under a pressure of 10 bar for 1.5 hours. The catalyst was subs~quently separated off at 80 - 90C by means of a pressure filter, the filtrate was cooled to abou~ 5C and the precipitat~ was filtered off through a filter.
369.5 g (0.9 mol) of 6-chloro-2-hydroxyquinoxaline were obtained in the form of the sodium salt as a moist product.
I~omeric chlorohydroxyquinoxalines were not detectable, and 6-chloro-2,3-dihydroxyquinoxaline or its sodium salt were only detectable in the smallest traces (in each case by HPLC, qualitativs).
A dried ~ample of the sodium salt howed the following analytical ddta:
C: 42.0 %; H: 2.7 %; N: 12.0 %; O: 12.9 %;
Cl: 15.2 %; Na: 10.2 %.
Purity about 89 ~ (HPLC: ext. standard) 164.2 ~ (0.4 mol) of the moi~t product were then su~pen-ded in about 700 ml of xylena and dried azeotropically,and 245.0 g (1.6 mol) o~ pho~phoru~ oxychloride were added under reflux. Af~er stirring for a fur~her 30 minute~, the exces~ chlorinating agent wa3 removed by distillation, the re~iduo wa~ diluta~ with abou~ 290 ml of xylene, and the mixture wa~ neu~ralized, clarified whilo hot and ~read from ~olYent by s~eam di~tillation.
~he product which crystallized out was fil~er~d off with suction and dried.
72.2 g of 2,6-dichloroquinoxalln~ having a puri~y of
(1952), or Organikum, Berlin 1975, VEB Deutscher Verlag der Wissenqcha ten) lead ~o a product whose quality is insu ficient for immediat~ furthor proc2~ing to the plant protection agon~ and to other product~, which is why the 2,6-dichloroquinoxaline obtainable by the known proce~o3 ha~ to b0 sub~ected to compli~ated purification stEps before further proce~sing. There was thu~ a need for a preparation proce~s in which tho 2,6-dichloro-quinoxaline is obtainod in ~uch a high d~gree of purity th~t it ca~. ba further proc~ssed to the d~ired ~inal product Lmmadiately without complic~ed purifica~ion operation~.
It ha~ now urpri3ingly b~en found that 2,6~dichloro-quinoxaline can be pr~pared in a high degre~ o~ purity and at the 3ame ti~0 in Y~ry good yiold by hydro~enating 6-ch}oro-2~hydroxyquinoxalin0-N-o~id~ in ~queou~ ~odium hydroxide ~olution in thQ preLq0nce of about 0.001 to 2 ~ 6 4 about 0.5 mol percent, preferably 0.01 to about 0.05 mol percent, of a platinum shell catalyst, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, at tempera-t~res of about 20 to about 120C, preferably of about 60 to about 100C, at a hydrogen pressure of a~out 1 to about 100 bar, preferably of about 5 to about 20 bar, about 1 to about 3 equivalent~ of sodium hydroxide, relative to 6 chloro-2-hydroxyquinoxaline-N-oxide employed, being added, after separating off the catalyst from the hot solution depositing the 6-chloro-2-hydroxy-quinoxaline dissolved therein in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 0 to about 20C, preferably about 5 to about 10C, drying azeotropically u3ing an inert solvent and chlorinating with a chlorinating agent in a manner customary per se to give 2,6-dich~oroquinoxaline.
In the proce~ according to the invantion, the following may be carried ol-t in particular:
As a rule, it i~ expedient to ~ub~ect the 6-chloro-2-hydroxyquinoxaline~N-oxide to the hydrogenation in suspen~ed form in the aqueous 30dium hydroxide 301ution in a concentration of about 15 to about 30 pexcent by weight, preferably of about 20 to about 25 percent by weight.
Depending on the reaction para~e~ers, the catalytie hydrog~nation take3 about 30 minu~e~ to about 5 hour~, a~
a rule about 1 to about 3 hour3.
Shell cataly~t~ are designa~ed as tho~e hydrogena~ion cataly.Rt~ in which the noble m~t~l, for example platinum, i~ di~tributed in extremQly fine form pxQdo~ina~tly on the surface of a ~upport ma~erial p~r~icl~, for example active carbon, in contra~t to the co~monly designated noble metal cat ly~t3 which h~ve a pr~dominantly uniform di~tribution of th~ noble m~tal also inside (via pore~
2~6456~
etc.) of a support material particle.
The catalyst employed can be employed repeatedly.
The sodium salt of the 6-chloro-2-hydroxyquinoxaline formed by the hydrogenation is present under the reaction conditions in dissolved form and can be separated off from the catalyst in a sLmple manner. On subsequent cooling to about 0 t~ about 20 DC t preferably about 5 to about 10C, it precipitates out virtually quanti~atively.
~he product thus obtained is of excellent quality.
For further processing, it is added, preferably in water-moist form, to an inert diluent which can form an azeo-trope with water. Suitable diluents which may be men-tioned are, for example, benzene, toluene, xylenes (all isomers and their mixture~), cumene, chlorobenzene, 1~ ethylbenzene, carbon tatrachloride, trichloromethane, cyclohexane, hexane, heptane and suitable petroleum ether fractions. The water prQsent is then separated off azeotropically.
The product is ~ubsequently chlsrinated in a manner known per se uQing one of the customary chlorina~ing agent~, such as, for example, thionyl chloride, pho3phorus pentachloride, pho3gene or preferably pho~phoru3 oxy-chloride (se~, for example, Houben-Weyl, vol. VIII, 359 et ~eq. (1952~; Organikum, ~erlin 1986, VEB DQut~char Verla~ der Wi son~chaften).
The chlorinating agen~, which i3 2mployed in exces~
separated o~f and can be used for further bat~he3 t just lik~ the diluent which can be recover~d again.
Working-up i8 carried out in a cuetomary manner. The final product~ 2,6~dichloroquinoxaline, i~ obtained in the required high purity and a~ditionally in ~ery good yi01d .
2~56~
It is in this respect to be consider~d surprising that the sodium salt of the 6-chloro-2-hydroxyquinoxaline can be caused to deposit in crystalline form virtually quantitatively according to the invention, as it is S ntrinsically very easily soluble both in the presence of heat and also on relatively high dilution.
The extreme purification effect associated with the virtually quantitative crystalline deposition of the sodium salt of 6-chloro-2-hydroxyquinoxaline achieved is to be judged as particularly surprising, since owing ~o its low solubility in the customary ~olvent~, even at relatively high temperature, and the great YLmilarity to the relevant impurities, rec~ystallization of the neutral 6-chloro-2-hydroxyquinoxaline is ~u~t as ~atisfactory as recrystallization of the subsequent ~tage ~2,6-dichloro-quinoxaline) synthesized under con~entional condition~.
In addikion to advantage of the process according to the invention already mentioned further above, there is a further Lmportant advantage, in particular from the ecological point of view, in the great reduction ~f the salt load of the total procesq a~ a result of the omis-sion of an intermediate i~olation of the 6-chloro-2-hydroxyquinoxalina ~ormsd as an intermediate and the neutralization as30ciated therewith.
If it i~ de~ired to recovor the 6-chloro-2-hydroxy-quinoxaline obtained at the end of the hydrogenation step in a high degree of purity and in ve~y good yield a~ such in pure form, it can be obtained pure in a simple m~nn2r by adding a mineral acidr 3uch a~, ~ox exæmpl~, ~ulfuric or hydrochloric acid9 to the depo~ited ~odium salt of ~he 6-chloro-2-hydroxyquinox21ine or prefexably to an a~ueous ~olution of this compound.
The axample below erve to illu~rata ~ha process according ~o the invention, withou~ lLmi~ing i~ thereto.
~ o ~
E~ample 593 g (l mol) of 6-chloro-2 hydroxyquinoxaline-N-oxide sodium salt in industrially moist form were suspended in 757 g of water and heated to 80 - 90~C in the presence of 2 g of platinum shell catalyst ~type ~.5 Pt/C, F 101 KY/W
containing about 50 percent by weight of water (DEG~SSA)) and hydrogenated in an autoclave using hydrogen under a pressure of 10 bar for 1.5 hours. The catalyst was subs~quently separated off at 80 - 90C by means of a pressure filter, the filtrate was cooled to abou~ 5C and the precipitat~ was filtered off through a filter.
369.5 g (0.9 mol) of 6-chloro-2-hydroxyquinoxaline were obtained in the form of the sodium salt as a moist product.
I~omeric chlorohydroxyquinoxalines were not detectable, and 6-chloro-2,3-dihydroxyquinoxaline or its sodium salt were only detectable in the smallest traces (in each case by HPLC, qualitativs).
A dried ~ample of the sodium salt howed the following analytical ddta:
C: 42.0 %; H: 2.7 %; N: 12.0 %; O: 12.9 %;
Cl: 15.2 %; Na: 10.2 %.
Purity about 89 ~ (HPLC: ext. standard) 164.2 ~ (0.4 mol) of the moi~t product were then su~pen-ded in about 700 ml of xylena and dried azeotropically,and 245.0 g (1.6 mol) o~ pho~phoru~ oxychloride were added under reflux. Af~er stirring for a fur~her 30 minute~, the exces~ chlorinating agent wa3 removed by distillation, the re~iduo wa~ diluta~ with abou~ 290 ml of xylene, and the mixture wa~ neu~ralized, clarified whilo hot and ~read from ~olYent by s~eam di~tillation.
~he product which crystallized out was fil~er~d off with suction and dried.
72.2 g of 2,6-dichloroquinoxalln~ having a puri~y of
Claims (6)
1. A process for the preparation of 2,6-dichloro-quinoxaline which comprises hydrogenating 6-chloro 2-hydroxyquinoxaline-N-oxide in aqueous sodium hydroxide solution in the presence of about 0.001 to about 0.5 mol percent of a platinum shell catalyst, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, at temperatures of about 20 to about 120°C
at a hydrogen pressure of about 1 to about 100 bar, about 1 to about 3 equivalents of sodium hydroxide, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, being added, and after separating off the catalyst from the hot solution depositing the 6-chloro-2-hydroxyquinoxaline dissolved therein in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 0 to about 20°C, drying azeotropically using an inert solvent and chlorinating with a chlorinating agent in a customary manner to give 2,6-dichloroquinoxaline.
at a hydrogen pressure of about 1 to about 100 bar, about 1 to about 3 equivalents of sodium hydroxide, relative to 6-chloro-2-hydroxyquinoxaline-N-oxide employed, being added, and after separating off the catalyst from the hot solution depositing the 6-chloro-2-hydroxyquinoxaline dissolved therein in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 0 to about 20°C, drying azeotropically using an inert solvent and chlorinating with a chlorinating agent in a customary manner to give 2,6-dichloroquinoxaline.
2. The process as claimed in claim 1, wherein the 6-chloro-2-hydroxyquinoxaline-N-oxide is hydrogenated in the aqueous sodium hydroxide solution in the form of the sodium salt in a concentration of about 15 to about 30 percent by weight.
3. The process as claimed in at least one of claims 1 and 2, wherein the 6-chloro 2-hydroxyquinoxalin2-N-oxide is hydrogenated in the aqueous sodium hydroxide solution in the form of the sodium salt in a concentration of about 20 to about 25 percent by weight.
4. The process as claimed in at least one of claims 1 to 3, wherein the 6-chloro-2-hydroxyquinoxaline is deposited in the form of the sodium salt as crystals by cooling the reaction solution to a temperature of about 5 to about 10°C.
5. The process as claimed in at least one of claims 1 to 4, wherein the sodium salt of the 6-chloro-2-hydroxyquinoxaline is chlorinated using thionyl chloride, phosphorus pentachloride, phosgene or phosphorus oxychloride.
6. The process as claimed in at least one of claims 1 to 4, wherein the 6-chloro-2-hydroxyquinoxaline is isolated in high purity by acidifying the deposited sodium salt of the 6-chloro-2-hydroxyquinoxaline or an aqueous solution of this compound with a mineral acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3925969.2 | 1989-08-05 | ||
| DE19893925969 DE3925969A1 (en) | 1989-08-05 | 1989-08-05 | METHOD FOR PRODUCING 2,6-DICHLORCHINOXALINE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2064564A1 true CA2064564A1 (en) | 1991-02-06 |
Family
ID=6386594
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2064564 Abandoned CA2064564A1 (en) | 1989-08-05 | 1990-07-16 | Process for preparing 2,6-dicholoroquinoxaline |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH04507406A (en) |
| CA (1) | CA2064564A1 (en) |
| DE (1) | DE3925969A1 (en) |
| IN (1) | IN169080B (en) |
| WO (1) | WO1991001977A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101914069A (en) * | 2010-07-29 | 2010-12-15 | 安徽丰乐农化有限责任公司 | Novel chlorination technique of 6- chlorine-2-hydroxy quinoxaline |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100345831C (en) * | 2005-11-10 | 2007-10-31 | 吴永虎 | Prepn process of high purity 2, 6-dichloro quinoxaline |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4636562A (en) * | 1982-05-07 | 1987-01-13 | E. I. Du Pont De Nemours And Company | Process for preparing 6-halo-2-chloroquinoxaline |
| IL86416A (en) * | 1987-06-19 | 1993-07-08 | Uniroyal Chem Co Inc | Process for the preparation of 2-quinoxalinol derivatives |
| US4814444A (en) * | 1987-06-19 | 1989-03-21 | Uniroyal Chemical Company, Inc. | Process for the selective reduction of 2-hydroxyquinoxaline-4-oxides |
-
1989
- 1989-08-05 DE DE19893925969 patent/DE3925969A1/en not_active Withdrawn
-
1990
- 1990-07-16 JP JP51067990A patent/JPH04507406A/en active Pending
- 1990-07-16 CA CA 2064564 patent/CA2064564A1/en not_active Abandoned
- 1990-07-16 WO PCT/EP1990/001162 patent/WO1991001977A1/en not_active Application Discontinuation
- 1990-07-18 IN IN601/CAL/90A patent/IN169080B/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101914069A (en) * | 2010-07-29 | 2010-12-15 | 安徽丰乐农化有限责任公司 | Novel chlorination technique of 6- chlorine-2-hydroxy quinoxaline |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04507406A (en) | 1992-12-24 |
| WO1991001977A1 (en) | 1991-02-21 |
| IN169080B (en) | 1991-08-31 |
| DE3925969A1 (en) | 1991-02-07 |
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