CS218153B1

CS218153B1 - A method for preparing 2-methyl-4-chlorophenoxyacetic acid

Info

Publication number: CS218153B1
Application number: CS534878A
Authority: CS
Inventors: Peter Hauskrecht; Zlatica Skrdlova
Original assignee: Peter Hauskrecht; Zlatica Skrdlova
Priority date: 1978-08-16
Filing date: 1978-08-16
Publication date: 1983-02-25

Abstract

Vynález sa týká spósobu přípravy 2-metyl- -4-chlórfenoxyoctovej kyseliny. Vynález rieši výrobu 2-metyl-4-chlórfenoxyoctovej kyseliny z 2-metylfe’noxyoctanu alkalického kovu alebo z 2-metylfenoxyoctovej kyseliny chloráciou chlórom a chlórňanom sodným. - Roztokom alkalickej soli 2-metyl-4-chlórfenoxyoctovej kyseliny, vznikriutej chloráciou vodného roztoku 2-metylfenoxyoctanu alkalického kovu alebo suspenzie 2-metylfenoxyoctovej kyseliny a 2-metylfenoxyoctanu alkalického kovu vodným roztokom chlornanu sodného, sa. pósobí na emulziu alebo na suspenziu 2-metyl-4-chlórfenoxyoctovej kyseliny v zriedenej kyselině chlorovodíkové], vzniknutej chloráciou alkalickej soli 2-metyl-4-chlórfenoxyoctovej kyseliny chlórom. Výsledná hodnota pH je 3 až 6. 2- -metyl-4-chlórfenoxyoctová kyselina sa od reakčného roztoku oddělí po ochladerií filtráoiou. Vynález možno využit pri výrobě herbicídnych prípravkov na báze 2-metyl-4-chlórfenoxyoctovej kyseliny.The invention relates to a method for preparing 2-methyl-4-chlorophenoxyacetic acid. The invention provides for the production of 2-methyl-4-chlorophenoxyacetic acid from alkali metal 2-methylphenoxyacetate or from 2-methylphenoxyacetic acid by chlorination with chlorine and sodium hypochlorite. - A solution of the alkali salt of 2-methyl-4-chlorophenoxyacetic acid, formed by chlorination of an aqueous solution of alkali metal 2-methylphenoxyacetate or a suspension of 2-methylphenoxyacetic acid and alkali metal 2-methylphenoxyacetate with aqueous sodium hypochlorite, is applied to an emulsion or suspension of 2-methyl-4-chlorophenoxyacetic acid in dilute hydrochloric acid, formed by chlorination of the alkali salt of 2-methyl-4-chlorophenoxyacetic acid with chlorine. The resulting pH value is 3 to 6. 2-methyl-4-chlorophenoxyacetic acid is separated from the reaction solution after cooling by filtration. The invention can be used in the production of herbicidal preparations based on 2-methyl-4-chlorophenoxyacetic acid.

Description

Vynález sa týká spósobu přípravy 2-metyl-4-chlórfenoxyoctovej kyseliny.The invention relates to a process for the preparation of 2-methyl-4-chlorophenoxyacetic acid.

Vynález rieši výrobu 2-metyl-4-chlórfenoxyoctovej kyseliny z 2-metylfe’noxyoctanu alkalického kovu alebo z 2-metylfenoxyoctovej kyseliny chloráciou chlórom a chlórňanom sodným. Roztokom alkalickej soli 2-metyl-4-chlórfenoxyoctovej kyseliny, vznikriutej chloráciou vodného roztoku 2-metylfenoxyoctanu alkalického kovu alebo suspenzie 2-metylfenoxyoctovej kyseliny a 2-metylfenoxyoctanu alkalického kovu vodným roztokom chlornanu sodného, sa. pósobí na emulziu alebo na suspenziu 2-metyl-4-chlórfenoxyoctovej kyseliny v zriedenej kyselině chlorovodíkové], vzniknutej chloráciou alkalickej soli 2-metyl-4-chlórfenoxyoctovej kyseliny chlórom. Výsledná hodnota pH je 3 až 6. 2-metyl-4-chlórfenoxyoctová kyselina sa od reakčného roztoku oddělí po ochladerií filtráoiou.The invention solves the production of 2-methyl-4-chlorophenoxyacetic acid from 2-methylphenoxyacetic acid 2-methylphenoxyacetate or from 2-methylphenoxyacetic acid by chlorination with chlorine and sodium hypochlorite. A solution of the alkali metal salt of 2-methyl-4-chlorophenoxyacetic acid formed by chlorination of an aqueous solution of 2-methylphenoxyacetate or a suspension of 2-methylphenoxyacetic acid and an alkali metal 2-methylphenoxyacetate with an aqueous solution of sodium hypochlorite is added. it acts on an emulsion or suspension of 2-methyl-4-chlorophenoxyacetic acid in dilute hydrochloric acid] formed by chlorination of the alkali salt of 2-methyl-4-chlorophenoxyacetic acid. The resulting pH is 3 to 6. The 2-methyl-4-chlorophenoxyacetic acid is separated from the reaction solution after cooling by filtration.

Vynález možno využit pri výrobě herbicídnych prípravkov na báze 2-metyl-4-chlórfenoxyoctovej kyseliny.The invention can be used in the manufacture of herbicidal formulations based on 2-methyl-4-chlorophenoxyacetic acid.

Vy’nález sa týká spósobu přípravy 2-metyl- to spósobom výroby, pri najnižších nákladoch -4-chlórfenoxyoctovej kyseliny (MCPA vyš- na změnu súčasiiej technologie, šej čistoty, ako sa dosahuje v súčasnosti tým- MCPA sa připravuje podl’a týchto reakcií:The present invention relates to a process for the preparation of 2-methyl by the method of production, at the lowest cost of -4-chlorophenoxyacetic acid (MCPA is a change in current technology, more pure than currently achieved by MCPA is prepared according to these reactions :

C1CH₂COOH + Na₂CO₃—>2 ClCH₂C00Na + Η_£0 + 00_£ /2/C1CH ₂ COOH + Na ₂ CO ₃ -> 2 ClCH ₂ C00 Na + Η _£ 0 + 00 _£ / 2 /

* cr* cr

NaCl /4/NaCl / 4 /

SO₂Cl₂—>SO ₂ Cl ₂ ->

NaClO —>NaClO ->

Cl + Š0₂ + NaCl /5/ + H₂0 /6/Cl + SO ₂ + NaCl / 5 / + H ₂ 0/6 /

Zavádzanie chlóru do vodného roztoku sodných, draselných alebo sodnodraselných solí 2-metylfenoxyoctovej kyseliny (MPA) pri teplote 0—120 °C a hoďnote pH 3—4 chrání čs. pat. 91 160. Nepřetržitá chlorácia s chlórom v kolóne je daná čs. pat. 99 892. Roztok lalkalickej soli kyseliny monochlóroctovej (MCA) a roztok krezolátu alkalického kovu sa kondenzuje v kaskádě reaktorov za vzniku alkaliickej soli MPA o hodnotě pH 6—7, ktorá sa nepřetržíte odkrezoluje na kolóne priagnou parou a chlóruje za vzniku MCPA, ktorá vo formě taveniny nepřetržíte sa neutralizuje na alkalickú sol’ ako udává čs. pat. 107 807. Chloráciu v parafíne chrání švéd. pat. 154 441, chloráciu vo vodnom roztoku NaHCO_:! udává V. Brit. pat. 855 504. Čiastočné 'nachlórovanie MPA chlórom a dochlórovaruie chlórňanom sodným udává čs. autorské osvedčenie 172 188,The introduction of chlorine into an aqueous solution of sodium, potassium or sodium potassium 2-methylphenoxyacetic acid (MPA) at a temperature of 0-120 ° C and a pH of 3-4 protects the MS. pat. 91 160. Continuous chlorination with chlorine in the column is given by MS. pat. 99,892. The alkali metal monochloroacetic acid (MCA) solution and the alkali metal cresolate solution are condensed in a cascade of reactors to form an alkali metal salt of MPA at pH 6-7 which is continuously stripped on the column by vapor and chlorine to form MCPA. The melt will not be continuously neutralized to the alkaline salt as indicated by the MS. pat. 107 807. Chlorination in paraffin is protected by swedish. pat. 154 441, chlorination in aqueous NaHCO 3 solution _. according to V. Brit. pat. 855 504. Partial chlorination of MPA with chlorine and post-chlorination with sodium hypochlorite is given in U.S. Pat. author's certificate 172 188,

Tavenina po chlorácii podfa čs. pat. 99 892 obsahuje 2,5—5 % hmot. chlórovaných kre3 zolov a 80—85 % hmot. sumy fenoxyoctových kyselin, ktorá sa skládá z 5—15 % hmot. MPA, 60—70 % hmot. MCPA, 5—10 % hmot. 2-metyl-4,6-dichlórfenoxyoctovej kyseliny a určité množstvo· nedefinovaných organických; látok. Vodná emulzia taveniny má pH 0—2. Emulzia taveniny tuhne pri teplote 75—85 °C.Melt after chlorination according to MS. pat. 99,892 contains 2.5 - 5 wt. % chlorinated crystals and 80-85 wt. % of phenoxyacetic acids, which is comprised of 5-15% wt. MPA, 60-70 wt. MCPA, 5-10% wt. 2-methyl-4,6-dichlorophenoxyacetic acid and some undefined organic; substances. The aqueous melt emulsion has a pH of 0-2. The melt emulsion solidifies at 75-85 ° C.

Vyššie uvedené nedostatky sú odstráne'né spósobom výroby 2-m.etyl-4-chlórfenoxyoctovej kyseliny pódia vynálezu, ktorého podstata spočívá v tom, že sa roztokom alkalickej soli 2-metyl-4-chlórfenoxyoctovej kyseliny, ktorá vznikla, chloráciou vodného roztoku 2-metylfenoxyoctanu alkalického kovu alebo vodnej suspenzie 2-metylfenoxyoctovej kyseliny a 2-metylfenoxyoctanu alkalického kovu, voďným roztokom chlornanu sodného, pósobí na emulziu alebo suspenziu 2-metyl-4-chlórfenoxyoctovej kyseliny v zriedenej kyselme chlorovodíkové], vzniknutej chloráciou alkalickej soli 2-metylfenoxyoctovej kyseliny chlórom. Výsledná hodnota pH je 3 až 6. Vzniknutá 2-metyl-4-chlórfeinoxyoctová kyselina sa oddělí od reakčného roztoku po ochladení filtráciou.The above drawbacks are overcome by the process for the preparation of 2-methyl-4-chlorophenoxyacetic acid according to the invention, which is characterized in that the solution of the 2-methyl-4-chlorophenoxyacetic acid alkali salt formed by chlorination of aqueous 2- an alkali metal methylphenoxyacetate or an aqueous suspension of 2-methylphenoxyacetic acid and an alkali metal 2-methylphenoxyacetate, aqueous sodium hypochlorite solution, acts to emulsify or suspend 2-methyl-4-chlorophenoxyacetic acid in dilute hydrochloric acid], formed by chlorination of the alkali metal 2-chloroacetate . The resulting pH was 3-6. The resulting 2-methyl-4-chlorophenoxyacetic acid was separated from the reaction solution after cooling by filtration.

Nový účinok spočívá v tom, že sa jednoduchým zásahom, s malými nákladmi do súčas’nej technologie zvýši obsah MCPA v sumě fenoxyoctových kyselin nad 75 % hmot., obsah chlórkrezolov 1—2 % hmot. Okrem toho sa zlepší kvalita odpadných vod znížením kyslosti vod po oddělení taveniny fe'noxyoctových kyselin. Na jednotku produkcie sa zníži' množstvo odpadných vod a množstvo solí v odpadných vodách.The new effect is that by simply intervening, with little cost to the present technology, the MCPA content in the sum of phenoxyacetic acids exceeds 75% by weight, the chlorocresols content is 1-2% by weight. In addition, the quality of the waste water is improved by reducing the acidity of the waters after separation of the phenoxyacetic acid melt. The amount of waste water and the amount of salts in the waste water are reduced per unit of production.

Příklad 1Example 1

Sodná sol’ MPA o hodnotě pH 9, koncentrácie 14 % hmot. sa protiprúdne chlóruje na náplňovej koloně. Získá sa emulzia tayenirny vo vodě teploty 85—90 °C. Podřel MCPA bol 68,3 %. Druhý podiel sodnej soli MPA sa chlóroval v trojhrdlej banke opatrenej miešadlom, teplomerom a deliacim lievikom na prikvapkávanie roztoku chlornanu sodného. Po přidaní celkového množstva sa roztok 2 hodiny miešal pri teplote 35 °C. Potom sa prilieval do emulzie taveniny po chlorácii, aby výsledná hodnota pH bola 4—5 a teplota neklesla pod 80 °C.Sodium salt MPA at pH 9, 14% by weight. is countercurrently chlorinated on a packed column. A tayenirny emulsion in water of 85-90 ° C is obtained. The MCPA share was 68.3%. A second portion of sodium MPA was chlorinated in a three-necked flask equipped with a stirrer, a thermometer, and a separatory funnel to add sodium hypochlorite solution dropwise. After the addition was complete, the solution was stirred at 35 ° C for 2 hours. It was then poured into the melt emulsion after chlorination so that the resulting pH was 4-5 and the temperature did not fall below 80 ° C.

Tavenina sa oddělila od vody a z taveniny sa oddestilovali chlórkrezoly na háplňovej kolóne vodnou parou. Získaná tavenina mala obsah fenoxyoctových kyselin 87 % hmot., z ktorých bolo 74,2 % MCPA. Obsah chlórkrezolov bol 1,17 % hmot.The melt was separated from the water and chlorocresols were distilled off from the melt on a rock column with water vapor. The melt obtained had a phenoxyacetic acid content of 87% by weight, of which 74.2% was MCPA. The chlorocresols content was 1.17% by weight.

Příklad 2Example 2

Sodná sol’ MPA o hodnotě pH 9 a koncentrácie 14 % hmot. sa chlórovala protiprúdne na kolóne. Získala sa emulzia taveniny s vodou. Tavenina mala obsah fenoxyoctových kyselin 80,1 % hmot., z ktorých bolo 68,6 % MCPA. Druhý podiel suspenzie MPA v sodnej soli MPA o hodnotě pH 6,5 sa chlóroval v trojhrdlej banke opatrenej miešadlom, teplomerom a deliacim lievikom na dávkovanie chlornanu sodného. Po pridahí celkového množstva chlornanu sodného sa roztok 2,5 hodiny miešal. Potom sa prilial do emulzie taveniny po chlorácii chlórom, aby výsledná hodnota pH bola 5 a teplota nepoklesla pod 80 °C. Tavenina sa oddělila od vody a odkrezolovala na kolóne vodnou parou. Výsledná tavenina obsahovala 87,3 % hmot. fenoxyoctových kyselím, z ktorých bolo 75,7 % MCPA, obsah chlórkrezolov bol 1,32 % hmot. Příklad 3Sodium salt MPA having a pH of 9 and a concentration of 14% by weight. was chlorinated countercurrently on the column. A melt-water emulsion was obtained. The melt had a phenoxyacetic acid content of 80.1% by weight, of which 68.6% was MCPA. A second portion of the MPA slurry in MPA sodium salt, pH 6.5, was chlorinated in a three-necked flask equipped with a stirrer, thermometer, and sodium hypochlorite dispensing funnel. After the total amount of sodium hypochlorite was added, the solution was stirred for 2.5 hours. It was then poured into the melt emulsion after chlorination with chlorine so that the resulting pH was 5 and the temperature did not drop below 80 ° C. The melt was separated from the water and descaled on the column with water vapor. The resulting melt contained 87.3 wt. of phenoxyacetic acids, of which 75.7% was MCPA, the chlorocresols content was 1.32% by weight. Example 3

Sodná sol’ MPA o hodnotě pH 10 a, koncentrácie 16 % hmot. sa chlórovala protiprúdne na kolóne. Získala sa emulzia taveniny MCPA s vodou. Druhý podiel suspe’nzie MPA v sodnej soli MPA o hodnotě pH 6 sa chlóroval alkalickým chlórňanom v trojhrdlej banke opatrenej miešadlom, teplomerom a deliacim lievikom na dávkovanie chlornanu sodného. Po přidání chlornanu sodného sa roztok 2,5 hodiny miešal. Potom sa prilial do emulzie taveniny po chlorácii chlórom, výsledné pH málo hodnotu 5 a teplota bola 83 °C. Tavenina sa oddělila od vody a chlórkrezoly sa oddestilovali vákuovou destiláciou pri tlaku 800—1000 Pa.Sodium salt MPA having a pH of 10 and a concentration of 16% by weight. was chlorinated countercurrently on the column. An MCPA melt emulsion with water was obtained. A second portion of the MPA in MPA sodium salt at pH 6 was chlorinated with an alkaline hypochlorite in a three-necked flask equipped with a stirrer, thermometer, and sodium hypochlorite dispensing funnel. After the addition of sodium hypochlorite, the solution was stirred for 2.5 hours. It was then poured into the melt emulsion after chlorination with chlorine, resulting in a pH of little 5 and the temperature was 83 ° C. The melt was separated from water and the chlorocresols were distilled off by vacuum distillation at a pressure of 800-1000 Pa.

Tavenina obsahovala 85,2 % hmot. fenoxyoctových kyselin, z ktorých bola 74,3 % MCPA, obsah chlórkrezolov bol 1,53 % hmot.The melt contained 85.2 wt. of phenoxyacetic acids, of which 74.3% was MCPA, the chlorocresols content was 1.53% by weight.

Podlá vynálezu sa dá vyrobit kyselina 2-metyl-4-chlórfenoxyoctová o čistotě 75 až 85 % hmot., obsahu chlórkrezolov 1 a,ž 2 % hmot. MCPA sa používá na přípravu alkalických, amonných, aminových solí alebo esterov, ktoré majú herhicídne účinky.According to the invention, 2-methyl-4-chlorophenoxyacetic acid having a purity of 75 to 85% by weight, a chlorocresol content of 1 to 2% by weight, can be prepared. MCPA is used to prepare alkali, ammonium, amine salts or esters that have herhicidal effects.

Z chlórkrezolov sa po oddělení a zalkalizovaní kondenzáciou s chlóroctanom sodným dajú pripraviť fenoxyoctové kyseliny.Phenoxyacetic acids can be prepared from the chlorocresols after separation and alkalization by condensation with sodium chloroacetate.

Claims

OBJECT OF THE INVENTION

A process for preparing 2-methyl-4-chlorophenoxyacetic acid by treating chlorine with an aqueous solution of an alkali salt of 2-methylphenoxyacetic acid to form an emulsion or suspension of 2-methyl-4-chlorophenoxyacetic acid in dilute hydrochloric acid of pH 0 to 5.5, wherein the second portion of an aqueous solution of 2-methylphenoxyacetic acid alkali salt or a suspension of 2-methylphenoxyacetic acid in aqueous alkali metal 2-methylphenoxyacetate is treated with an aqueous sodium hypochlorite solution to form the alkali metal salt of 2-methyl-4-chlorophenoxyacetic acid, a solution of the alkali metal salt of 2-methyl-4-chlorophenoxyacetic acid formed by the chlorination of an aqueous solution of 2-methylphenoxyacetate 2-methylphenoxyacetate or an aqueous suspension of 2-methylphenoxyacetic acid; and

Of 2-J methylphenoxyacetate with an aqueous solution of sodium hypochlorite, acts on an emulsion or suspension of 2-methyl-4-chlorophenoxyacetic acid in dilute hydrochloric acid formed by chlorination of the alkali salt of 2-methylphenoxyacetic acid with chlorine, resulting in a pH of 3 to 6 and methylphenoxyacetic acid is separated from the reaction solution.