CS226941B1

CS226941B1 - Method of izolating 4-isopropylaniline from an isomer mixture

Info

Publication number: CS226941B1
Application number: CS554082A
Authority: CS
Inventors: Albert Ing Jaras; Milan Ing Rupcik; Karol Ing Dulak
Original assignee: Albert Ing Jaras; Milan Ing Rupcik; Dulak Karol
Priority date: 1982-07-20
Filing date: 1982-07-20
Publication date: 1984-04-16

Description

Vynález sa týká spósobu izolácie 4-izopropylanilínu zo zmesi izomérov.The invention relates to a process for the isolation of 4-isopropylaniline from a mixture of isomers.

4-izopropylanilín je dóležitým medziproduktom pri výrobě herbicídnych prostriedkov na báze N-(4-izopropylfenyl]-N‘,N‘-dimetylmočoviny. Dá sa získat podlá známého postupu nitráciou izopropylbenzénu, izoláciou vzniknutého 4-nitroizopropylbenzénu a jeho následnou redukciou na 4-izopropylanilín. Postup je skomplikovaný ‘tým, že při nitrácii vzniká zmes nitroizopropylbenzénov s přibližným zložením 24 % 2-niitro-, 6 °/o 3-nitro- a 70 % 4-nitroizopropylbenzénu. Žiadaný 4-nitroizopropylbenzén sa získá zo zmesi vakuovou rektifikáciou. Ako je však známe, táto operácia je spojená s rizikom explózie, preto je vhodnejšie najprv nerozdelenú zmes nitroizopropylbenzénov zredukovat na zmes, obsahujúcu zodpovedajúce množstva 2-izopropylanilínu, 3-izopropylanilínu a 4-izopropylanilínu. Na izoláciu potřebného 4-izopropylanilínu pre velmi blízké body varu rektifikácia nie je vhodná.4-Isopropylaniline is an important intermediate in the preparation of herbicidal compositions based on N- (4-isopropylphenyl) -N ', N'-dimethylurea It can be obtained according to a known method by nitration of isopropylbenzene, isolation of the resulting 4-nitroisopropylbenzene and subsequent reduction to 4-isopropylaniline The process is complicated by the fact that nitration produces a mixture of nitroisopropylbenzenes with an approximate composition of 24% 2-nitro-, 6% - 3-nitro- and 70% 4-nitroisopropylbenzene, and the desired 4-nitroisopropylbenzene is obtained from the mixture by vacuum rectification. however, it is known that this operation is associated with the risk of explosion, so it is preferable to first reduce the undivided mixture of nitroisopropylbenzenes to a mixture containing the corresponding amounts of 2-isopropylaniline, 3-isopropylaniline and 4-isopropylaniline. is not appropriate.

Podlá známého postupu [Brit. pat. č.According to a known procedure [Brit. pat. no.

554 929 (1979)] podařilo sa izolovat 4-izopropylanilín z uvedenej zmesi tak, že zmes sa rozpustí vo vhodnom bezvodom organickom rozpúšťadle, ktoré sa nemieša s vodou (alifatické a aromatické uhlovodíky, připadne chlórované ako benzén, toluén, xylén, chlórbenzén, hexán, petroléter; chloroform, dichlóretán atď.) a do roztoku sa přidá 1,0-1,5 molu bezvodého chlórovodíka na 1 mól 4-izopropylanilínu. Tým sa vyzráža v pevnej formě hydrochlorid 4-izopropylanilínu. Odfiltruje sa, vysuší a známým postupom sa získá z hydrochloridu volný 4-izopropylanilín v značné čistom stave, obsahujúci len malé množstvá ostatných izomérov.554 929 (1979)] isolated 4-isopropylaniline from said mixture by dissolving the mixture in a suitable anhydrous organic solvent not mixed with water (aliphatic and aromatic hydrocarbons, optionally chlorinated as benzene, toluene, xylene, chlorobenzene, hexane , petroleum ether; chloroform, dichloroethane, etc.) and 1.0-1.5 moles of anhydrous hydrogen chloride per mole of 4-isopropylaniline are added to the solution. This precipitates 4-isopropylaniline hydrochloride in solid form. It is filtered off, dried and, in a known manner, free 4-isopropylaniline is obtained from the hydrochloride in a substantially pure state, containing only small amounts of the other isomers.

Nevýhody tohoto postupu sú, že třeba pracovat v bezvodom prostředí, čo vyžaduje azeotropické odvodnenie použitého rozpúšťadla a reakčného prostredia, ďalej filtráciu a premývanie relativné objemnej zrazeniny hydrochloridu 4-izopropylanilínu ako aj jej vysušenie a regeneráciu rozpúšťadla, čo vyžaduje příslušné technologické zariadenia, čas, priestor i energiu.The disadvantages of this process are that it is necessary to work in an anhydrous environment, requiring azeotropic dewatering of the solvent and reaction medium used, filtration and washing of the relative bulk precipitate of 4-isopropylaniline hydrochloride as well as drying and regeneration of the solvent. energy.

Uvedené nevýhody odstraňuje spósob izolácia 4-izopropylanilínu zo zmesi izomérov podlá vynálezu.The above-mentioned disadvantages are overcome by the process of isolating 4-isopropylaniline from the mixture of isomers of the invention.

Podstata vynálezu je založená na zistení, že 2-izopropylanilín a 3-izopropylanilín reagujú 1'ahšie s formaldehydom ako 4-izopropylanilín podlá reakčnej schémy:The present invention is based on the finding that 2-isopropylaniline and 3-isopropylaniline react more readily with formaldehyde than 4-isopropylaniline according to the reaction scheme:

ch^ CW_{3 x}ch₃ ch ^ CW _{3 x} ch ₃

CH Η N CH CH \cHgQ226941CH-N CH CH \ cHgQ226941

Premena 2-izopropylanilínu a 3-izopropylanilínu na zlúčeniny celkom odlišných vlastností umožňuje dobré oddelenie 4-izopropylanilínu s vysokou čistotou. Spotřeba vodného roztoku formaldehydu zodpovedá stechionjetrii na súčst množstiev 2-izopropylanilínu a 3-izopropylanilínu, podfa známého zloženia zmesi izomérov. Reakcia sa uskutočňuje vo vodnom prostředí, okyselenom kyselinou solnou alebo inou minerálnou kyselinou. Teplota reakčného prostredia sa udržiava v rozmedzí 20 až 100 °C, najvýhodnejšie pri 70 až 100 ,°C.Conversion of 2-isopropylaniline and 3-isopropylaniline to compounds of completely different properties allows good separation of 4-isopropylaniline with high purity. The consumption of aqueous formaldehyde solution corresponds to stechionitrile to the sum of the amounts of 2-isopropylaniline and 3-isopropylaniline, according to the known composition of the mixture of isomers. The reaction is carried out in an aqueous medium, acidified with hydrochloric acid or another mineral acid. The temperature of the reaction medium is maintained at 20 to 100 ° C, most preferably at 70 to 100 ° C.

Žiadaný 4-izopropylanilín sa izoluje z reakčnej zmesi po jej zalkalizovaní vhodným činidlom (napr. alkalické lúhy alebo uhličitany), známým spůsobom, napr. oddestilovaním_..vadnou ..parou .alebo. . extrakciou vhodnými rozpúšťadlami (napr. aromatickými uhfovodíkmi, ako sú benzén, toluén, xylén a i.).The desired 4-isopropylaniline is isolated from the reaction mixture after it has been basified with a suitable reagent (e.g., alkaline lyes or carbonates), in a known manner, e.g. by distilling off the defective steam or. . extraction with suitable solvents (e.g. aromatic hydrocarbons such as benzene, toluene, xylene and the like).

PřikladlEXAMPLE

Na izoláciu 4-izopropylanilínu sa použila zmes izomérov s obsahom 70 % 4-izopropylanilínu, 24 % 2-izopropylanilínu a 6 % 3-izopropylánilínu.A mixture of isomers containing 70% 4-isopropylaniline, 24% 2-isopropylaniline and 6% 3-isopropylaniline was used to isolate 4-isopropylaniline.

Do 500 mL trojhrdlovej banky s miešadlom, teplomerom, a spatným chladičom sa navážilo 30,0 g zmesi izomérov izopropylanilínú vyššie uvedeného zloženia. Prilialo sa 100 ml. vody a za miešania sa přidalo 24,0 g koncentrovanej kyseliny solnéj, pričom zmes izomérov přešla do roztoku. Potom sa přidalo ešte 5,7 g vodného roztoku formaldehydu o koncentráeii 35,3 % a reakčná zmes sa zahriala na 80 °C. Pri teplote 80 až 90 °C sa zmes miešala 5 hodin.Weigh 30.0 g of a mixture of isopropylaniline isomers of the above composition into a 500 mL three-necked flask with stirrer, thermometer, and reflux condenser. 100 ml was added. of water and with stirring, 24.0 g of concentrated hydrochloric acid was added while the mixture of isomers went into solution. Then 5.7 g of an aqueous solution of formaldehyde of 35.3% concentration was added and the reaction mixture was heated to 80 ° C. The mixture was stirred at 80-90 ° C for 5 hours.

Ochladila sa a za miešania sa zalkalizovala prídavkom 10,0 g hydroxidu sodného. Obsah sa prelial do 500 ml destilačnej banky, ktorá sa připojila na destilačnú aparatúru, zariadenú na destiláciu vodnou parou a oddestiloval sa 4-izopropylanilín. Oddestilovaný podiel, obsahujúci 4-izopropylani-< lín a vodu sa pretrepal postupné v deliacom lieviku 3 x 50 ml benzénu a jednotlivé benzénové vrsstvy sa oddělili. Spojené benzénové vrstvy sa vysušili bezvodým síranom sodným, ktorý sa potom odfiltroval. Benzénový roztok sa přebal do destilačnej banky a táto sa připojila na vákuovú destilačnú aparatúru a benzén sa oddestiloval, ku konců za vakua. Zvyšok po oddestilovaní benzénu o váhe 21,0 g bol surový 4-izopropylanilín. Jeho destiláciou za vakua sa získalo 18,0 g čistého 4-izopropylanilínu s b. v. 105—106 °C pri tlaku 1,86.10³ Pa (85,7 proč. teorie).It was cooled and made alkaline by stirring with 10.0 g of sodium hydroxide. The contents were poured into a 500 ml distillation flask which was connected to a distillation apparatus equipped for steam distillation and 4-isopropylaniline was distilled off. The distilled portion containing 4-isopropylaniline and water was shaken successively in a separatory funnel with 3 x 50 ml benzene and the individual benzene layers were separated. The combined benzene layers were dried over anhydrous sodium sulfate, which was then filtered off. The benzene solution was transferred to a distillation flask and this was connected to a vacuum distillation apparatus and the benzene was distilled off to the ends under vacuum. The 21.0 g benzene distillation residue was crude 4-isopropylaniline. Its vacuum distillation yielded 18.0 g of pure 4-isopropylaniline having a bp of 105-106 ° C at a pressure of 1.86 x 10 ³ Pa (85.7% of theory).

Rovnaký výsledok sa dosiahol, keď sa reakčný produkt po zalkalizovaní lúhom sodným namiesto d&stilácie vodnou parou extrahoval v deliacom lieviku postupné 3 X 70 mililitrov benzenu a spojené benzenové extrakty sa spracovali rovnakým spčsobom ako je uvedené vyššie. Tým sa preukázalo, že oddestilovanie 4-izopropylanilínu vodnou parou zo surověj reakčnej zmesi možno vynechat.The same result was obtained when the reaction product, after being basified with caustic soda instead of steam distillation, was extracted in a separatory funnel successively with 3 x 70 ml of benzene and the combined benzene extracts were treated in the same manner as above. This has shown that steam distillation of 4-isopropylaniline from the crude reaction mixture can be omitted.

Kontrolou čistoty izolovaného 4-izopropylanilínu chromatografiou na tenkej vrstvě a ^J3C—NMR spekitroskopiou sa zistilo, že obsahuje len stopy ostatných izomérov.By controlling the purity of the isolated 4-isopropylaniline by thin layer chromatography and ^{J 3} C-NMR spekitroskopiou found to contain only a trace of the other isomer.

Claims

SUBJECT

Method for isolating 4-isopropylaniline from a mixture of isomers containing

2-isopropylaniline,

3-Isopropylaniline and 4-Isopropylaniline by steam distillation or extraction with organic solvents or mixtures thereof, characterized in that the mixture of isomers in aqueous solution is reacted with an amount of formaldehyde at elevated temperature.

YNALEZ by corresponding stoichiometry to the sum of the amounts of 2-isopropylaniline and 3-isopropylaniline in the mixture but which is no longer sufficient to react with 4-isropropylaniline and then

The 4-isopropylaniline is separated from the reaction mixture by, for example, steam distillation or extraction.