CS242170B1 - Process for preparing 2-methyl-4-chlorophenoxyacetic acid - Google Patents
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Abstract
Spósob rieši přípravu 2-metyl-4-chlórfenoxyoctovej kyseliny chloráciou 2-metylfenoxyoctovej kyseliny a/alebo Je] sodnej soli a dochlórovaním reakčnej zmesi s chlórňanom sodným. 2-metyl-4-chlórfenoxyoctová kyselina sa získá z reakčnej zmesi vyzrážaním v přebytku minerálnej kyseliny. Mólový poměr chlóru ku 2-metylfenoxyoctovej kyselině a/alebo jej sodnej soli je 0,01 až 0,59 : : 1 a chlór sa používá vo formě odplynu z rozkladu alkalických chlórňanov. Spósob je možno použiť pri výrobě herbicídnych prípravkov.The method provides for the preparation of 2-methyl-4-chlorophenoxyacetic acid by chlorination of 2-methylphenoxyacetic acid and/or its sodium salt and subsequent chlorination of the reaction mixture with sodium hypochlorite. 2-methyl-4-chlorophenoxyacetic acid is obtained from the reaction mixture by precipitation in excess of mineral acid. The molar ratio of chlorine to 2-methylphenoxyacetic acid and/or its sodium salt is 0.01 to 0.59 : : 1 and the chlorine is used in the form of off-gas from the decomposition of alkali hypochlorites. The method can be used in the production of herbicide preparations.
Description
242170242170
Vynález sa týká chlorácie 2-metylfenoxy-octovej kyseliny s chlórom a dochlórovanias chlórňanom sodným.The present invention relates to chlorination of 2-methylphenoxyacetic acid with chlorine and chlorinating with sodium hypochlorite.
Chloráciu sodnej soli 2-metylfenoxyocto-vej kyseliny chlórom, pričom mólový poměr2-metylfenoxyoctovej kyseliny ku chlóru je1:0,6 až 1,25, na získaná zmes sa působíNaOH a roztok sa zbaví nezreagovanej sod-nej soli 2-metylfenoxyoctovej kyseliny a fa-rebných nečistot dochlórovaním s vodnýmroztokom NaClO pri teplote 10 až 50 °C po-pisuje čs. AO 172 188. Nedostatkom postupuje, že sa nepoužívá odpadový chlór prl chlo-rácii a po chlorácii s chlórom sa musí pri-viesť reakčná zmes do alkalickej oblasti sNaOH a dochlórovanie s NaClO sa výhodnej-šie robí v přítomnosti minerálnej kyseliny.Chloráciu 2-metylfenoxyoctovej kyselinyplynným chlórom pri hodnotě pH 4 až 6popisuje FR pat. č. 1 116 266. Chloráciu vod-ným roztokom NaClO připraveného vopredalebo „in šitu“ v reakčnej zmesi pri teplo-te 50 °C opisuje GB pat. č. 722 625. Chloráciususpendovanej 2-metylfenoxyoctovej kyseli-ny pri hodnotě pH 1 v heterogénnej fáze zapřítomnosti kyseliny chlorovodíkovej s chlór-ňanom sodným pri teplote 20 °C popisujeDAS č. 1 027 687. Spůsob založený na půso-bení hydroxidu sodného alebo uhličitanusodného' na vodný roztok sodnej soli 2-me-tylfenoxyoctovej kyseliny a chloráciu chló-rom opisuje US pat. č. 2 770 651. Chloráciasodnej soli v přítomnosti hydrogénuhličita-nu sodného je popísaná v GB pat. č. 855 504.Výrobu 2-metyl-4-chlórfenoxyoctovej kyseli-ny chloráciou vodným roztokem chlornanusodného sodnej soli 2-metylfenoxyoctanusodného v přítomnosti minerálnej alebokarboxylovej kyseliny, pričom sa reakčnázmes vnesie do přebytku vodného rozto-ku minerálnej kyseliny a vyzrážaná 2-metyl--4-chlórfenoxyoctová kyselina sa od mateč-ných kyselin oddělí filtráciou a následné vy-suší pri teplote 105 °C opisuje CS AO č.179 200.Chlorination of the sodium salt of 2-methylphenoxyacetic acid with chlorine, the molar ratio of 2-methylphenoxyacetic acid to chlorine being 1: 0.6 to 1.25, treated with NaOH and freed from unreacted 2-methylphenoxyacetic acid sodium salt. post-chlorinating impurities with aqueous NaClO solution at 10 to 50 ° C. A drawback is that chlorine waste is not used for chlorination and, after chlorination with chlorine, the reaction mixture must be introduced into the alkaline region with NaOH and the chlorination with NaCl is more preferably carried out in the presence of mineral acid.Chlorination of 2-methylphenoxyacetic acid with chlorine gas at pH 4-6, FR Pat. No. 1,116,266. Chlorination with an aqueous solution of NaClO prepared in advance or "in situ" in the reaction mixture at 50 ° C is described in GB Pat. No. 722,625. Chloroacid-suspended 2-methylphenoxyacetic acid at pH 1 in the heterogeneous phase of the presence of hydrochloric acid with sodium chloride at 20 ° C is described by DAS No. 1,027,687. A process based on sodium hydroxide or carbonate sodium hydroxide U.S. Pat. No. 4,766,596 to the aqueous solution of 2-methylphenoxyacetic acid sodium chloride and chlorine chlorination. No. 2,770,651. The chlorination sodium salt in the presence of sodium bicarbonate is described in GB Pat. No. 855,504. Production of 2-methyl-4-chlorophenoxyacetic acid by chlorination with an aqueous solution of 2-methylphenoxyacetic acid sodium hypochlorite in the presence of a mineral butyrocarboxylic acid, while the reaction mixture is poured into an excess of aqueous mineral acid and precipitated with 2-methyl- The 4-chlorophenoxyacetic acid is separated from the mother acids by filtration and subsequently dried at 105 ° C to describe CSA No.179,200.
Uvedené nedostatky sú zmiernené postu-pom podlá vynálezu, podstata ktorého' spo-čívá v tom, že sa 2-metylfenoxyoctová kyseli-na a!jej sodná sol' chlóruje chlórom, pričommólový poměr chlóru ku 2-metylfenoxyocto-vej kyselme a/alebo jej sodnej soli je 0,01 až0,59 :1 a získaná reakčná zmes sa dochlórujevodným roztokom chlórňanu sodného a 2--metyl-4-chlórfenoxyoctová kyselina sa zís-ká vnesením reakčnej zmesi do přebytku mí-nerálnej kyseliny. Z reakčnej zmesi unikáchlór, vzniklý reakciou přebytečného chlór-ňanu sodného vo formě odplynu. Zo suspen-zie sa 2-metyl-4-chlórfenoxyoctová kyselinaoddělí filtráciou. Dochórovanie reakčnejzmesi s chlórňanom sodným prebieha v pro-středí minerálnej a/alebo organickej kyseli-ny. Na chloráciu s chlórom sa používá chlórvo formě odplynu z rozkladu alkalickýchchlórňanov. Tento rozklad prebieha samo-volné, napr. v zásobníkoch, připadne preby-točný chlórňan sodný sa rozloží vnesením reakčnej zmesi po dochlórovaní s NaClO dopřebytku minerálnej kyseliny. Výhodou podlá vynálezu je, že sa použijeodplyn chlóru, ktorý doteraz unikal doovzdušia a nevyužíval sa. Oproti čs. AO č.179 200 sa zníži spotřeba NaClO, ako i mi-nerálnej kyseliny. Vzhladom k tomu, že sachlór nebude odvádzať do ovzdušia, zabrá-ni sa tvorbě exhalátov z výrobně. Súčasnesa znížením spotřeby minerálnych kyselinzníži množstvo minerálnych solí v odpado-vých vodách. Časť minerálnych kyselin sanahradí 2-metyl-4-chlórfenoxyoctovou kyse-linou, vzniklou pri chlorácii s chlórom. O-proti čs. AO 172 188 je sposob podlá vyná-lezu výhodnější z toho důvodu, že pri mólo-vom pomere chlóru ku kyselině 2-metylfen-oxyoctovej a/alebo jej sodnej soli, nie je nut-ná úprava hodnoty pH přidáním alkalickéhohydroxidu ku reakčnej zmesi před dochló-rovaním s NaClO. Převedeme vynálezu jenenáročné a jednoduché. Spočívá v napoje-ní zásobníkov s NaClO a odplynu zo zráža-nia 2-metyl-4-chlórfenoxyoctovej kyselinyprebytkom minerálnej kyseliny na absorp-čnú kolonu, v ktorej bude cirkulovat 2-me-tylfenoxyoctová kyselina a/alebo jej sodná sol. Okrem odplynu z rozkladu NaClO jemožné použit' odpadový chlór z iných pro-cesov, napr. so skvapalňovanie chlóru, při-padne odpadový chlór po chlorácii organic-kých látok po jeho vyčistění a od nečistůt,predovšetkým od chlorovodíka. Příklad 1The aforementioned drawbacks are alleviated by the process according to the invention, characterized in that the 2-methylphenoxyacetic acid and its sodium chloride is chlorinated, the chlorine to 2-methylphenoxyacetic acid ratio and / or sodium salt is 0.01-0.59: 1, and the resulting reaction mixture is made up of an aqueous sodium hypochlorite solution and 2-methyl-4-chlorophenoxyacetic acid is obtained by introducing the reaction mixture into an excess of mineral acid. From the reaction mixture, the non-chlorine formed by the reaction of excess sodium hypochlorite in the form of a flue gas. From the suspension, 2-methyl-4-chlorophenoxyacetic acid was removed by filtration. Dochorination of the reaction mixture with sodium hypochlorite takes place in a mineral and / or organic acid medium. For chlorination with chlorine, chlorine is used as the off-gas from the decomposition of alkaline chlorates. This decomposition takes place self-loosely, e.g. in containers, eventually excess sodium hypochlorite is decomposed by introducing the reaction mixture after chlorinating with NaClO excess mineral acid. It is an advantage of the present invention that a chlorine gas is used which has so far escaped and has not been used. Compared to MS. NO.179,200 reduces the consumption of NaClO as well as the mineral acid. Due to the fact that sachlor will not be discharged into the air, the formation of exhalates from the plant is prevented. At the same time, by reducing the mineral acid consumption, the amount of mineral salts in the wastewater. Part of the mineral acids are substituted by 2-methyl-4-chlorophenoxyacetic acid formed by chlorination with chlorine. O-against MS. No. 172,188,18 is the preferred method according to the invention, since at a molar ratio of chlorine to 2-methylphenoxyacetic acid and / or its sodium salt, adjusting the pH by adding the alkali hydroxide to the reaction mixture is not necessary before with NaClO. We will make the invention simple and simple. It consists in connecting the NaClO reservoirs and the degassing of 2-methyl-4-chlorophenoxyacetic acid with an excess of mineral acid to an absorption column in which 2-methylphenoxyacetic acid and / or its sodium salt will circulate. In addition to the decomposition of the NaClO decomposition, waste chlorine from other processes such as chlorine liquefaction, waste chlorine after chlorination of the organic substances after purification and impurities, especially from hydrogen chloride, can be used. Example 1
Do 950 g vodného roztoku obsahujúceho 13.3 % hmot. 2-metylfenoxyoctanu sodnéhosa vháňal plyn, obsahujúci 3,4 % obj. chló-ru. Po 1 hodině sa vháňanie odstavilo a ana-lýzou sa zistilo, že reakčná zmes obsahova-la 3,1 % hmot. 2-metyl-4-chlórfenoxyoctovejkyseliny a 0,8 °/o hmot. iných chlórderivá-tov 2-metylfenoxyoctovej kyseliny. K reak-čnej zmesi sa přidalo potom 525 g vodnéhoroztoku 12,5 % hmot. NaClO a 112 g 35,6 %hmot. kyseliny sírovej. Zmes sa miešala 2hodiny. Potom sa vliala do 600 g 8,1 % hmot.H2SO4 a vyzrážaná 2-metyl-4-chlórfenoxy-octová kyselina sa odfiltrovala, premyla vo-dou a vysušila. Získalo sa 137,2 g produktus obsahom 87,2 % hmot. 2-metyl-4-chlórfen-oxyoctovej kyseliny, 5,8 % hmot. 2-metyl-6--chlórfenoxyoctovej kyseliny, 2,2 % hmot.2-metylfenoxyoctovej kyseliny, 1,2 % hmot.2-metyl-4,6-dichlórfenoxyoctovej kyseliny. Příklad 2To 950 g of an aqueous solution containing 13.3 wt. 2-methylphenoxyacetate sodium was injected with gas containing 3.4% by volume of chlorine. After 1 hour, the blowing was stopped and the reaction mixture found to contain 3.1% by weight. 2-methyl-4-chlorophenoxyacetic acid and 0.8% wt. other 2-methylphenoxyacetic acid chloro derivatives. Then, 525 g of an aqueous solution of 12.5 wt% was added to the reaction mixture. NaClO and 112 g 35.6 wt. sulfuric acid. The mixture was stirred for 2 hours. It was then poured into 600 g of 8.1% wt H2SO4 and the precipitated 2-methyl-4-chlorophenoxyacetic acid was filtered off, washed with water and dried. 137.2 g of product were obtained with a content of 87.2% by weight. 2-methyl-4-chlorophenoxyacetic acid, 5.8 wt. 2-methyl-6-chlorophenoxyacetic acid, 2.2% by weight of 2-methylphenoxyacetic acid, 1.2% by weight of 2-methyl-4,6-dichlorophenoxyacetic acid. Example 2
Postupovalo sa podlá příkladu 1 s týmrozdielom, že na chloráciu chlórom sa pou-žilo 940 g vodného roztoku s obsahom 12.4 % hmot. 2-metyl-4-chlórfenoxyoctanusodného a 0,9 % hmot. 2-metyl-4-chlórfen-oxyoctovej kyseliny. Hodnota pH po chlorá-cii chlórom bola 6,1. Získaná 2-metyl-4-The procedure of Example 1 was followed, except that 940 g of an aqueous solution containing 12.4% by weight of chlorine was used for chlorination. Of 2-methyl-4-chlorophenoxyacetic acid and 0.9 wt. 2-methyl-4-chlorophenoxyacetic acid. The chlorine pH was 6.1. 2-Methyl-4-
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