DK152039B - Process for preparing 1-chloro-2,6-dinitro-4- (trifluoromethyl)benzene which does not contain nitrozating agents - Google Patents
Process for preparing 1-chloro-2,6-dinitro-4- (trifluoromethyl)benzene which does not contain nitrozating agents Download PDFInfo
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- DK152039B DK152039B DK180082A DK180082A DK152039B DK 152039 B DK152039 B DK 152039B DK 180082 A DK180082 A DK 180082A DK 180082 A DK180082 A DK 180082A DK 152039 B DK152039 B DK 152039B
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Description
DK 152039 BDK 152039 B
Opfindelsen angår en fremgangsmåde til fremstilling af 1-chlor- 2,6-dinitro-4-(trif!uormethyl)benzen (DINITRO-PCBT), som ikke indeholder nitroserende midler.The invention relates to a process for the preparation of 1-chloro-2,6-dinitro-4- (trifluoromethyl) benzene (DINITRO-PCBT) which does not contain nitrosating agents.
Det er ud fra det herved fremstillede DINITRO-PCBT muligt at 5 fremstille teknisk "TRIFLURALIN" med et specielt lavt nitrosamin-indhold (specielt NDPA).It is possible from the DINITRO-PCBT produced hereby to make technical "TRIFLURALIN" with a particularly low nitrosamine content (especially NDPA).
Det er velkendt, at visse produkter til anvendelse i landbruget kan indeholde nitrosaminer, og disse stoffers farlighed er ligeledes velkendt.It is well known that certain products for use in agriculture may contain nitrosamines and the dangerousness of these substances is also well known.
10 Det har navnlig siden 1976 været offentlig kendt, at nitros aminer er til stede i produkter til anvendelse i landbruget, såsom "TRIFLURALIN" 15 f3c-0-^n(ch2ch2ch3)210 It has been known, in particular, since 1976 that nitros amines are present in products for agricultural use, such as "TRIFLURALIN" 15 f3c-0- ^ n (ch2ch2ch3) 2
NONO
2 som er ti. meget vigtigt selektivt herbicid, og som fremstilles ved følgende reaktion: 20 /P^N°2 F3C \Q/-C1 + (CH3CH2CtV2NH + Na0H --2 which is ten. very important selective herbicide, which is produced by the following reaction: 20 / P ^ N ° 2 F3C \ Q / -C1 + (CH3CH2CtV2NH + NaOH -
NONO
2 25 -► -N(CH2CH2CH3)2+ NaCl + H202 25 -►-N (CH 2 CH 2 CH 3) 2+ NaCl + H2 O
NONO
22
Denne forbindelse indeholder en urenhed i form af N-nitroso-dipropylamin (NDPA), dvs. (CH3CH2CH2)2N-NO, idet denne forbindelse dannes under herbicidsyntesen.This compound contains an impurity in the form of N-nitroso-dipropylamine (NDPA), ie. (CH 3 CH 2 CH 2) 2N-NO, forming this compound during herbicide synthesis.
30 Dette skyldes, at 1-chlor-2,6-dinitro-4-(trifluormethyl)benzen (DINITRO-PCBT), som fremstilles ved dinitrering af 1-chlor-4-(trifluormethyl)benzen (PCBT), og som er udgangsmaterialet for syntesen af "TRIFLURALIN", indeholder opløste nitrogenoxider af forskellig sammensætning, som er ansvarlig for dannelsen af 35 nitrosaminer i overensstemmelse med reaktionen: (ch3ch2ch2)2nh + (no)x -* (ch3ch2ch2)n-no hvilken reaktion forløber i et basisk miljø.This is because 1-chloro-2,6-dinitro-4- (trifluoromethyl) benzene (DINITRO-PCBT), which is produced by the dinitration of 1-chloro-4- (trifluoromethyl) benzene (PCBT), which is the starting material for the synthesis of "TRIFLURALIN", dissolved nitric oxides of different composition responsible for the formation of 35 nitrosamines according to the reaction contain: (ch3ch2ch2) 2nh + (no) x - * (ch3ch2ch2) n-no which reaction proceeds in a basic environment.
Som omtalt er nitrosaminers farlighed velkendt. De udøver en akut hepatotoxisk virkning og er især carcinogene, mutagene og DK 152039 B j i z teratogene. Det er derfor vigtigt, at mængden af NDPA i "TRI-FLURALiN" er så lav som mulig, og lovgivningen i mere udviklede lande betragter et NDPA-indhold i det tekniske produkt på mindre end 1 ppm som acceptabelt.As mentioned, the danger of nitrosamines is well known. They exert an acute hepatotoxic effect and are especially carcinogenic, mutagenic and DK 152039 B j in z teratogenic. It is therefore important that the amount of NDPA in "TRI-FLURALiN" is as low as possible, and legislation in more developed countries considers an NDPA content of the technical product of less than 1 ppm as acceptable.
5 Af den indtil nu udførte forskning fremgår det, at hvis : DINITRO-PCBT syntetiseres uden specielle oprensningsprocesser, forekommer der en sådan mængde opløste nitrogenoxider, at der udvikles et NDPA-indhold på mellem 150 og 500 ppm i det tekniske TRIFLURALIN, der senere produceres. Hvis der indføres oprens 10 ningsprocesser (f.eks. de i beskrivelsen til US patent nr. 4.120.905 omtalte proceser), nedsættes indholdet af nitroserende midler i DINITRO-PCBT, men de opnåede resultater er ikke konstante, og det er ikke muligt at opnå teknisk TRIFLURALIN med et NDPA- j indhold pi under 1 ppm.5 The research conducted so far shows that if: DINITRO-PCBT is synthesized without special purification processes, there is such an amount of dissolved nitrogen oxides that an NDPA content of between 150 and 500 ppm is developed in the technical TRIFLURALIN subsequently produced . If purification processes are introduced (e.g., the processes disclosed in U.S. Patent No. 4,120,905), the content of nitrosating agents in DINITRO-PCBT is reduced, but the results obtained are not constant and it is not possible to obtain technical TRIFLURALIN with an NDPA-j content pi below 1 ppm.
15 Man har derfor søgt at finde metoder, ved hjælp af hvilke de j dannede nitrosaminer kan elimineres fra slutproduktet.Therefore, attempts have been made to find methods by which the nitrosamines formed can be eliminated from the final product.
Selv om der opnås et slutprodukt med tilfredsstillende egenskaber har fremgangsmåder, som omfatter destruktion af dannede nitrosaminer, den meget alvorlige ulempe at være farlig pi grund af 20 tilstedeværelsen af nitrosaminer på visse trin i fremgangsmåden, ! hvor der altid vil være mulighed for kontakt, herunder ved uheld,“ med omgivelser og driftspersonale.Although an end product with satisfactory properties is obtained, processes involving destruction of formed nitrosamines have the very serious disadvantage of being dangerous due to the presence of nitrosamines at certain stages of the process. where there will always be the possibility of contact, including in the event of an accident, ”with the surroundings and operating personnel.
Det har derfor været ønskeligt at finde fremgangsmåder, som udelukker dannelsen af nitrosaminer for at kunne anvende disse 25 fremgangsmåder i stedet for fremgangsmåder, ved hvilken man ødelægger allerede dannede nitrosaminer, og ansøgers forskning er j iTherefore, it has been desirable to find methods which preclude the formation of nitrosamines in order to use these processes in place of methods by which already formed nitrosamines are destroyed and the applicant's research is
gået i denne retning. Igone in this direction. IN
Opfindelsens formål er at tilvejebringe en fremgangsmåde til fremstilling af 1-chlor-2,6-dinitro-4-(trifluormethyl)benzen (DINITRO-30 PCBT), der ikke indeholder nitroserende midler.The object of the invention is to provide a process for the preparation of 1-chloro-2,6-dinitro-4- (trifluoromethyl) benzene (DINITRO-30 PCBT) containing no nitrosating agents.
Dette formål opnås med fremgangsmåden ifølge opfindelsen, hvilken fremgangsmåde er ejendommelig ved, at DINITRO-PCBT behandles med en vandig bisulfitopløsning med en SOg-slutkoncen-tration på mellem 1 og 5 vægtprocent ved en pH-værdi på mellem 1 35 og 3 og ved en temperatur mellem 50 og 100°C i fra 1 til 3 timer, at den organiske fase separeres fra den vandige fase, og at surheden og de sidste spor af bisulfitopløsningen fjernes fra den organiske fase med en vandig alkalisk opløsning.This object is achieved with the process according to the invention, which is characterized in that DINITRO-PCBT is treated with an aqueous bisulfite solution having a final SOg concentration of between 1 and 5% by weight at a pH between 1 35 and 3 and at temperature between 50 and 100 ° C for from 1 to 3 hours, separating the organic phase from the aqueous phase and removing the acidity and last traces of the bisulfite solution from the organic phase with an aqueous alkaline solution.
Som det vil fremgå af det følgende, vil det under anvendelse af j I' 3As will be seen from the following, using j I '3
DK 152039 BDK 152039 B
den ved fremgangsmåden ifølge opfindelsen opnåede DINITRO-PCBT være muligt at fremstille teknisk "TRIFLURALIN" med et NDPA-indhold, som altid er mindre end 1 ppm.the DINITRO-PCBT obtained by the process according to the invention can be made technically "TRIFLURALIN" with an NDPA content which is always less than 1 ppm.
Det anvendte bisulfit er fortrinsvis natriumbisulfit, men der kan 5 opnås lignende resultater under anvendelse af andre bisulfiter, såsom kaliumbisulfit eller ammoniumbisulfit. Alternativt kan bisulfitet fremstilles direkte i tanken ved at omsætte SOg med den nødvendige mængde alkali. Som anført ligger S02“ koncentration mellem 1 og 5 vægtprocent. Der anvendes fortrinsvis en koncentration på 1,6%.The bisulfite used is preferably sodium bisulfite, but similar results can be obtained using other bisulfites such as potassium bisulfite or ammonium bisulfite. Alternatively, bisulfite can be prepared directly in the tank by reacting SOg with the required amount of alkali. As stated, the SO2 concentration is between 1 and 5% by weight. Preferably, a concentration of 1.6% is used.
10 Koncentrationer over 5 vægtprocent undgås, fordi udbyttet herved nedsættes uden at renheden forøges.10 Concentrations above 5% by weight are avoided because the yield is thereby reduced without increasing the purity.
pH-Værdien holdes fortrinsvis i nærheden af 2 og må ikke overstige 3 for ikke at nedsætte udbyttet (hvilket f.eks. sker, hvis der anvendes natriumsulfit i stedet for bisulfit), fordi højere pH-værdier 15 begunstiger substitution af det mobile Cl i 1-chlor-2,6-dinitro-4-(tri-fluormethyl)benzenen. For lave pH-værdier begunstiger SOg-elimine-ring og gør således behandlingen ineffektiv. I denne henseende må den oprindelige DINITRO-PCBT ikke indeholde mineralsyrer (såsom H2S04 eller HNOg); disse kan elimineres ved neutralisering.The pH value is preferably kept in the vicinity of 2 and must not exceed 3 so as not to decrease the yield (which occurs, for example, if sodium sulfite is used instead of bisulfite), because higher pH values favor substitution of the mobile Cl 1-chloro-2,6-dinitro-4- (trifluoromethyl) benzene. Too low pHs favor SOg elimination and thus render the treatment ineffective. In this regard, the original DINITRO-PCBT must not contain mineral acids (such as H2SO4 or HNOg); these can be eliminated by neutralization.
20 Temperaturen holdes fortrinsvis på 70-75°C. I den forbindelse er det vigtigt, at temperaturen ikke falder under smeltepunktet for DINITRO-PCBT, medens udbyttet falder ved for høje temperaturer.The temperature is preferably maintained at 70-75 ° C. In this connection, it is important that the temperature does not fall below the melting point of DINITRO-PCBT, while the yield falls at too high temperatures.
Reaktionstiden er fortrinsvis 2 timer. Meget lange reaktionstider giver et dårligt udbytte.The reaction time is preferably 2 hours. Very long reaction times result in poor yields.
25 Valget af den alkaliopløsning, der anvendes til neutralisering og fjernelse af de sidste spor af bisulfitopløsning i den behandlede organiske DINITRO-PCBT fase, er ikke vigtig. NagCO^ Anvendes fortrinsvis af økonomiske grunde, og fordi pH-værdien af den vandige fase ikke er for høj, således at der ikke sker nogen 30 væsentlig reduktion af udbyttet.The choice of the alkali solution used to neutralize and remove the last traces of bisulfite solution in the treated organic DINITRO-PCBT phase is not important. The NagCO2 is preferably used for economic reasons and because the pH of the aqueous phase is not too high, so that no significant reduction of the yield occurs.
Herefter følger nogle eksempler på udførelsesformer for fremgangsmåden ifølge opfindelsen.Following are some examples of embodiments of the method of the invention.
EKSEMPEL 1 35 200 ml HgO og100 g 1-chlor-2,6-dinitro-4-(trifluormethyl)benzen (DINITRO-PCBT), overførtes til en beholder. Blandingen opvarmedes til 70-75°C under kraftig omrøring for at opnå en fuldkommen blanding af den organiske fase med den vandige fase, hvorefter 13,3 g af en natriumbisulfitopløsning indeholdende 25,5% S02 (svarende til 4EXAMPLE 1 200 ml of HgO and 100 g of 1-chloro-2,6-dinitro-4- (trifluoromethyl) benzene (DINITRO-PCBT) were transferred to a container. The mixture was heated to 70-75 ° C with vigorous stirring to obtain a complete mixture of the organic phase with the aqueous phase, after which 13.3 g of a sodium bisulfite solution containing 25.5% SO 2 (corresponding to 4
DK 152039 BDK 152039 B
en samlet slutkoncentration på 1,59 vægtprocent, hvis man tager vandet i blandingen i betragtning), tildryppedes i løbet af ca. 20 minutter.a total final concentration of 1.59% by weight, taking into account the water in the mixture) was added over a period of approx. 20 minutes.
Blandingen holdtes ved 70-75°C i 2 timer under kontinuerlig, i i 5 kraftig omrøring. Omrøringen standsedes, og blandingen henstod til i dekantering. Den nedre organiske fase frasepareredes og sattes til en opløsning indeholdende 200 ml H20 og 5 g Na2C03, som tidligere j var blevet opvarmet til 70-75°C. Massen omrørtes kraftigt i 30-60 j minutter, hvorefter omrøringen standsedes. j i 10 Den nedre organiske fase frasepareredes til frembringelse af j 96g renset DINITRO-PCBT. jThe mixture was kept at 70-75 ° C for 2 hours under continuous, stirring vigorously. Stirring was stopped and the mixture was allowed to decant. The lower organic phase was separated and added to a solution containing 200 ml of H 2 O and 5 g of Na 2 CO 3, which had previously been heated to 70-75 ° C. The mass was stirred vigorously for 30-60 j minutes, after which the stirring was stopped. The lower organic phase was separated to give j 96g of purified DINITRO-PCBT. j
De efterfølgende resultater opnåedes ved at omdanne prøver af ! den oprindelige DINITRO-PCBT og den rensede DINITRO-PCBT til j "TRIFLURALIN" og analysere de opnåede produkter for nitrosamin: ! i 15 iThe subsequent results were obtained by converting samples of! the original DINITRO-PCBT and the purified DINITRO-PCBT for j "TRIFLURALIN" and analyze the obtained products for nitrosamine :! i 15 i
Under anvendelse af den 156 ppm NDPA til stede i det oprindelige DINITRO-PCBT: fremstillede "TRIFLURALIN" 20 Under anvendelse af 0,5 ppm NDPA til stede i det renset DINITRO-PCBT: fremstillede "TRIFLURALIN"Using the 156 ppm NDPA present in the original DINITRO PCBT: produced "TRIFLURALIN" 20 Using 0.5 ppm NDPA present in the purified DINITRO PCBT: produced "TRIFLURALIN"
Som det fremgår er NDPA-indholdet i TRIFLURALIN fremstillet under anvendelse af det ved fremgangsmåden ifølge opfindelsen 25 fremstillede DINITRO-PCBT yderst lav og lig med halvdelen af den maximalt tilladte værdi under den strengeste nuværende lovgivning.As can be seen, the NDPA content of TRIFLURALIN is produced using the DINITRO-PCBT produced by the process of the invention 25 extremely low and equal to half the maximum permitted value under the most stringent current legislation.
EKSEMPEL 2EXAMPLE 2
Fremgangsmåden fra eksempel 1 gentoges, men under anven-30 delse af 26,6 g af en natriumbisulfitopløsning indeholdende 25,5% so2.The procedure of Example 1 was repeated, but using 26.6 g of a sodium bisulfite solution containing 25.5% of SO 2.
Herved opnåedes 93 g renset DINITRO-PCBT.This yielded 93 g of purified DINITRO-PCBT.
NDPA-indholdet af det fremstillede "TRIFLURALIN" er 0,45 ppm i dette tilfælde.The NDPA content of the "TRIFLURALIN" produced is 0.45 ppm in this case.
35 EKSEMPEL 3EXAMPLE 3
Fremgangsmåden fra eksempel 1 gentoges, men under anvendelse af 6,4 g af kaliummetabisulfit indeholdende 53% S02 opløst i 10 ml H20, svarende til en SOg-slutkoncentration på 1,59 vægtprocent.The procedure of Example 1 was repeated, but using 6.4 g of potassium metabisulphite containing 53% SO2 dissolved in 10 ml of H 2 O, corresponding to a final concentration of SO9 of 1.59% by weight.
DK 152039 BDK 152039 B
55
Der opnåedes 95 g renset DINITRO-PCBT.95 g of purified DINITRO-PCBT were obtained.
Indholdet i det fremstillede "TRIFLURALIN" er 0,7 ppm.The content of the "TRIFLURALIN" produced is 0.7 ppm.
EKSEMPEL 4 (sammenligningseksempeO 5 Fremgangsmåden fra eksempel 1 gentoges, men der anvendtes 3,3 g natriumsulfit opløst i 10 ml HgO, svarende til en SOg-slutkon-centration på 0,67 vægtprocent.Example 4 (Comparative Example 5) The procedure of Example 1 was repeated, but 3.3 g of sodium sulfite dissolved in 10 ml of HgO was used, corresponding to a final SOg concentration of 0.67% by weight.
Der opnåedes 87 g renset DINITRO-PCBT.87 g of purified DINITRO-PCBT were obtained.
I dette tilfælde førte den for høje pH-værdi til en uacceptabel 10 reduktion i udbyttet.In this case, the too high pH value led to an unacceptable reduction in yield.
EKSEMPEL 5 (sammenligningseksempel)EXAMPLE 5 (Comparative Example)
Fremgangsmåden fra eksempel 1 gentoges, men der anvendtes 8 g 30% NaOH Ϊ alkalibehandlingstrinnet.The procedure of Example 1 was repeated, but 8 g of 30% NaOH Ϊ alkali treatment step was used.
15 Der opnåedes 88 g DINITRO-PCBT.88 g of DINITRO-PCBT were obtained.
Igen førte den for høje pH-værdi til en uacceptabel nedsættelse af udbyttet.Again, the excessive pH led to an unacceptable reduction in yield.
20 25 30 3520 25 30 35
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DK180082A DK152039C (en) | 1982-04-22 | 1982-04-22 | METHOD FOR PREPARING 1-CHLOR-2,6-DINITRO-4- (TRIFLUORMETHYL) -BENZEN WHICH DOES NOT CONTAIN NITROSING AGENTS |
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DK180082 | 1982-04-22 | ||
DK180082A DK152039C (en) | 1982-04-22 | 1982-04-22 | METHOD FOR PREPARING 1-CHLOR-2,6-DINITRO-4- (TRIFLUORMETHYL) -BENZEN WHICH DOES NOT CONTAIN NITROSING AGENTS |
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DK180082A DK180082A (en) | 1983-10-23 |
DK152039B true DK152039B (en) | 1988-01-25 |
DK152039C DK152039C (en) | 1988-07-18 |
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DK180082A DK152039C (en) | 1982-04-22 | 1982-04-22 | METHOD FOR PREPARING 1-CHLOR-2,6-DINITRO-4- (TRIFLUORMETHYL) -BENZEN WHICH DOES NOT CONTAIN NITROSING AGENTS |
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