CS272750B1 - Method of 2-ethyl-6-methyl-n-/1-methoxy-2-propyl/chlorethanilide - Google Patents

Abstract

The invention concerns the method of preparation of the herbicide metolachlor by hydroalkylation of 2-ethyl-6-methyl-aniline by methoxypropanone in an environment of 1-methoxy-2-propanol as a solvent in the presence of a platinum hydrogenation catalyst and hydrochloric acid as a proton catalyst, in a quantity of 6.1 to 27 % by weight adjusted to the used 2-ethyl-6-methylaniline and reaction of the resulting product, which, after isolation of the used platinum hydrogenation catalyst, water, solvent and the un-reacted methoxypropanone, consists of 2-ethyl-6-methyl-N-(1'-methoxy-2'-propyl)aniline and 2-ethyl-6-methyl N-(1'-methoxy-2'-propyl)aniline hydrochloride, with chloroacetyl chloride in a molar ratio of 1:1.1 to 2 in an environment of an inert organic solvent selected from a group including aliphatic, cycloaliphatic and aromatic hydrocarbons. As proton catalyst the hydrochloric acid can be used in a gaseous form or absorbed in 1-methoxy-2-propanol, in a mixture of 1-methoxy-2-propanol and 2-ethyl-6-methylaniline, or in a mixture of 1-methoxy-2-propanol, 2-ethyl-6-methylaniline and methoxypropanone. Part of the hydrochloric acid arising at the stage of chloroacetylation can be returned to the process of hydroalkylation of 2-ethyl-6-methylaniline by methoxypropanone, as a proton catalyst.

Description

(57) Risásnia concerns the method for the preparation of motolachlor herbicide by nitrogensation α1. by acylation of 2-ethyl-G-methyl-aniline with methoxypropanone in 1-methoxy-2-propanol as solvent / in the presence of a platinum hydrogenation catalyst and hydrochloric acid as a proton catalyst in an amount of 6% to 27% by weight based on the 2- Methyl-6-methylaniline and reacting the resulting product, which after isolation of the used platinum hydrogenation catalyst, water, solvent and unreacted methoxypropanone, zombies from 2-style-S-methyl-N- (1'-methoxy-2H-propyl) aniline and 2-ethyl-S-butterfly N- / 1. -methoxy-2'-propyl (aniline hydrochloride) with chloroacetyl chloride in a molar ratio of ls1, 1 to 2 in an inert organic solvent selected from the group consisting of aliphatic; cycloaliphatic and aromatic hydrocarbons. Hydrochloric acid as the proton catalyst is. can be used in gaseous forms or absorbed in 1-methoxy-2-propanol, in a mixture of 1-methoxy-2-propanol and 2-ethyl-6-motylaniline or in a mixture of 1-methoxy-2-propanoyl, 2-ethyl-G- ijotylaniline and motoxypropanone. The hydrogen chloride produced in the chloroacetylation stage can be recycled to the process by 2-ethyl-5-methylaniline-methoxypropanone hydronic acid alkylation as a proton catalyst.

CS 272760

272 750 (11) (13) Bl (52) Int. C1. ^WITH

OJ C 07 C 233/07

CS 272 750 Bl

The present invention relates to a process for the preparation of 2-ethyl-6-Mstyle N / L ^R -mstoxy-2 ^/, propyl / chlóracatanilidu, known as the generic názvtfm herbicide metolachlor.

We know that 2-ethyl-6-methyl-N- (1'-methoxy-2'-propyl) chloroacetanilide can be prepared by reaction of 2-ethyl-6-methyl-N- (1'-hydroxy-1'-propyl) (aniline with a chloroacetylating agent such as chloroacetic anhydride or halide) (CS 169 · 841).

The starting 2-ethyl-6-methyl-N- (1'-methoxy-2'-propyl) aniline can be prepared by condensation of 2-ethyl-6-m 3 -tylaniline with methoxypropanone and simultaneous or subsequent hydrogenation of the resulting 2-ethyl-S- methyl-N- / ^l-methoxy-2, -propylidón / aniline in a solvent in the presence of a platinum / US 4 200 451, DE 2328340 /, a palladium / 163,841 CS / or mecinatochroraitého / PV 9575-87 / hydrogenation catalyst, and the presence of a proton catalyst such as sulfuric acid (OE 2 328 340, US 4200 451, CS 169 841, PV · 393-89), acetic acid (CS 219 855); 2-methyl-5-ethylaniline hydrochloride / 2-methyl-6-ethylaniline semihydrogénsulfát / 2-methyl-6-ethylaniline trihydrogénfoafát, 2-methyl-6-ethyl-N / L ^of -mstoxy 2-propyl ^R / aniline hydrochloride , '2-methyl-6-ethyl-N / I ^/ 2 * -mstoxy-propyl / aniline dihydrogen sulphate, 2-methyl-6-ethyl-N / l-methoxy-2''- propyl / aniline di - (trihydrogenphosphate) (PV 4257-88), trihydrogenphosphoric acid or hydrochloric acid used in an amount of 0.5 to 6/0% by weight, based on the 2-ethyl-5-methylaniline used (AO 4265-88, AO 4258-88 / AO 4259 -88 (AO 393-89), the above-mentioned proton catalysts are most preferably from the operational point of view hydrochloric acid (which, however, in amounts of from about 4% to about 5% by weight with respect to the 2-ethyl-S-diethylaniline used) the conversion step, requiring a longer reaction time, or the use of multiple amounts of platinum hydrogenation catalyst. It is essential to ensure that the proton catalyst used is of high purity in order to prevent hydrogenation catalyst inhibitors (especially heavy metal ions) being drilled into the hydrogenation process. After completion of the hydrogenation of the resulting Căetu 2-ethyl-6-methyl-N- / ^{l-methoxy-2-propyl R} / aniline acid bound to present as a quaternary salt; where a number of ways of its use are known, or isolation. AO 4259-88 and AO 393-89 propose recycling of the isolated quaternary salt as a proton catalyst to the next cycle of hydrogenation-alkylation. A significant disadvantage of these solutions is that, due to the corrosion of the process equipment, the heavy metal concentration in the pratone catalyst is gradually increased, which in addition to decreasing the activity of the hydrogenation catalyst in the 3 < 5 > According to DE 2 328 340, by adding triethylamine to the reaction mixture, the acid used as the proton catalyst is precipitated in the form of the triethylammonium salt, which is filtered off. The disadvantage of this solution is that triethylamine is necessary to be regenerated by means of an aqueous solution of an inorganic base, which is associated with the formation of waste defects with a high salt content. A method according to US 4 200 451 is that the resulting reaction mixture from hydrogenated alkylation is directly distilled under vacuum without isolation of the sulfuric acid used as proton catalyst. A shortcoming of this procedure is that the sulfuric acid acts as a sulfonating agent at the distillation temperature, resulting in losses on the desired product. Finally, after concentrating the resulting reaction mixture from the hydrogenation alkylation and separating the upper layer of the reaction product according to AO 4259-88 or AO 393-89, the 3-layer quaternary salt layer is no longer processed but discarded e.g. incineration, which also increases operating costs and reduces the degree of utilization of the raw materials.

The resulting 2-ethyl-6-methyl-N- (1'-metaxyl-1'-propyl) aniline prepared by the above procedures was treated with 2-aryl-6-methyl-N- (1'-methoxy-2 *) before Salsi. -propyl / chloroacetanilide reacts with a chloroacetylating agent to distil under vacuum, increasing the cost of invasion and energy consumption.

The reaction of 2-ethyl-S-methyl-N- / ^{l-methoxy-2 /} propyl / aniline chloracetylačným agent, especially chloroacetyl chloride, to prepare a 2-Allyl-S-methyl-N- / l-methoxy-2 ^z- propyl / chloroacetanilide can be carried out either in the presence or in the absence of inorganic bases such as alkali metal hydroxides, carbonates or bicarbonates or alkaline earths in aqueous or non-aqueous media / US 4 200 451, CS 227 535 , CS 169 841 /. A significant disadvantage of these processes is that they generate large amounts of fall salts in solid or aqueous solutions, which compromises the ecological characteristics of the process. The use of organic bases such as triethylamine, pyridine and some others (CS 169 841) seems to solve this problem, but regeneration of the used organic base is necessary in the case of sulfur. The reaction can also be carried out without the acceptor formed therein in an inert organic solvent by trapping the hydrogen chloride gas in water. The reaction of 2-ethyl-6-methyl-N- / L ^d '-methoxy-2''- propyl / aniline chlóracatylchloridom in approximately equimolar amounts, however, occurs relatively slowly, requiring a long reaction time and is accompanied by the undesirable formation of relatively large amounts of resin products . This drawback is partially remedied by the method of CS 226 439 based on the reaction of isolated 2-ethyl-6-methyl-N- (1'-methoxy-2'-propyl) aniline with chloroacetyl chloride used in a 1- to 19-fold molar excess, with chloroacetyl chloride filling. in the process also the role of the solvent. The disadvantage is that the reaction does not have a clear course. It generates by a large amount of by-product 2-ethyl-6-methyl-N- / ^{l-chloro-2-propyl} / -chlóracetanilidu that can not be separated from the reaction product, resulting in us-lower-Ledok extract the product unsatisfactory quality.

The shortcomings of the screen the material removed spbsob 2-Ethyl-6-methyl; - / l ^f -RR, ethoxy-2-propyl / chloroacetanilide hydrogenation alkylation of 2-ethyl-6-methylaniline metoxypropanonom in a 1 to 1.1 and 2 in a 1-methoxy-2-propanol environment as a solvent, in the presence of a platinum hydrogenation catalyst and hydrochloric acid as a proton catalyst at a temperature of 20 to 100 ° C and a hydrogen pressure of 1 to 7.0 MPa, optionally hydrogenation catalyst, 1-methoxy-2-propanol and unreacted methoxypropanone isolated from the resulting reaction mixture, to the next cycle of hydrogenation alkylation and reaction of the obtained 2-ethyl-6-methyl-N- (1'-rotoxyxy-2'-propyl) aniline with chloroacetyl chloride at a temperature of from 70 ° C to the reflux of the reaction mixture according to the invention. The invention is based on the fact that in the hydrogenation alkylation step of 2-ethyl-6-methylaniline with methoxypropanone, hydrochloric acid is used as a proton catalyst in an amount of 6.1 to 27% by weight, based on the

2-ethyl-6-methylaniline and the resulting reaction product which, after isolation of the used platinum hydrogenation catalyst, water, solvent and unreacted methoxypropanone, consists of 2-ethyl-6-methyl-N- (1H ^- methoxy-2'-propyl) aniline to 2-ethyl-6-methyl--N- (1-methoxy-2'-propyl) aniline hydrochloride is reacted without further purification operations with chloroborohydride in an inert organic solvent in a molar ratio of 1: 1.1 · 2 to 2, Suitable inert organic solvents are suitable aliphatic, cyclcaliphatic and aromatic hydrocarbons such as heptane, octane, cyclohexane, hydrocarbon mixtures in gasoline fractions, preferably boiling in the range of 30 to 110 ° C; benzene, toluene.

Oe preferred; when the hydrochloric acid is used in gaseous form or absorbed in 1-methoxy-2-propanol, in a mixture of 1-methoxy-2-propanol and 2-ethyl-6-methylaniline or in a mixture of 1-methoxy-2-propanol, 2-ethyl-6-methylaniline and methoxypropenoate · Cast anhydrous hydrogen chloride generated in the reaction mixture of step 2-ethyl-6-raetyl N / l-methoxy-2-propyl ^z / aniline and the hydrochloride with chloroacetyl chloride is preferably returned to the process hydrogenačnsj alkylation of 2-ethyl-6-methylaniline with methoxypropanone as a proton catalyst. The other hydrogen chloride gas produced can be used to prepare concentrated hydrochloric acid by absorption in water or directly filled into pressurized bottles. The process according to the invention can be carried out discontinuously, continuously or in such a way that the hydrogenation alkylation step is carried out discontinuously and the chloroacetylation step continuously. Continuous chloroacetylation may be carried out, for example, by adding a mixture of 2-style-6-methyl-N- (1'-methoxy-2 ⁾ -propyl] aniline and its hydrochloride and chloroacetyl chloride simultaneously to a reactor at room temperature. consisting of one to three stages involved in a cascade. 2-ethyl-6-methyl "N / l-methoxy-N / l * 2-methoxy--pro3 ^° E 272 750 81 propyl / chloroacetanilide was isolated from the resulting reaction mixture by evaporation of the solvent, washing with water and / or water alkali solution at a temperature of up to 30 ° C and addition by distillation.

The method according to the invention has several significant advantages over the known methods. The use of hydrochloric acid as the proton catalyst in the hydrogenation alkylation step of 6-1 to 27.0% by weight, based on the 2-ethyl-6-methyl-aniline used, unexpectedly increases the degree of conversion of the reactants and hence the purity of the product while reducing reaction time and reducing the amount of platinum hydrogenation catalyst required. The use of a mixture of 2-ethyl-5-methyl-N- (1'-methoxy-2'-propyl) aniline and its hydrochloride in reaction with chloroacetyl chloride enables the investment, energy and operationally demanding operation of vacuum distillation of the reaction product previously deprived of used platinum hydrogenation catalyst. and the volatile constituents consisting of water, 1-methoxy-2-propanol and unreacted mstoxypropanone, and more efficiently utilizing the feedstock, to obtain a high purity product.

Example 1

A 750 ml Teflon autoclave with a magnetic stirrer was charged with 60.0 g of 2-ethyl-5-methylaniline, 49/0 g of methoxypropanone, 90 g of 1-methoxy-2-propanol, 17.5 g of a saturated solution of hydrogen chloride in 1-methoxy- 2-propanol and 300 mg of platinum catalyst containing 3% platinum on activated carbon. The mixture was hydrogenated at 55 ° C and 3 MPa for 3 hours.

After completion of the reaction, the mixture was cooled. the platinum catalyst was filtered off and the reaction water, unreacted methoxypropanone and 1-methoxy-2-propanol were distilled off from the filtrate. The resulting mixture of 74? 4% by weight of 2-ethyl-6-methyl-N- / L ^{J -Methoxy-yl-propyl} 2 * / js aniline and 25.6 by weight of 2-ethyl-6-methyl-N- / L ' The methoxy-2'-propyl / aniline hydrochloride, together with 180 ml of toluene, was transferred to a flask equipped with a stirrer, a thermometer and an addition funnel. Chloroacetyl chloride was metered in with cooling at 20-30 ° C? in an amount of 100.3 g. The mixture was then heated to reflux and maintained for 1 hour whenever the evolution of hydrogen chloride ceased. Excess unreacted chloroacetyl chloride, along with toluene, was distilled off under reduced pressure. Toluene and 5% sodium hydroxide solution were added to the distillation residue. to maintain the pH of the reaction mixture at 8. The mixture was stirred at 60 ° C.

After washing with water, the organic layer was cooled? separated? ' dried and concentrated under vacuum. The product was distilled at 144 ° C / 3.4 Pa. Yield: 117? 5 g / 93? 3% of theory / 2-ethyl-6-BUTTERFLY N / ^{l-methoxy-2-propyl} / chlpracetanilidu.

* Hydrogen chloride? The reaction resulting from the reaction was removed from the top of the bad condenser and was taken up in 1-methoxy-2-propanol to give a saturated solution (containing 20-8% hydrogen chloride at 20 ° C). The remainder of the hydrogen chloride was absorbed into water.

A mixture of toluene and chloroacetyl chloride from the distillation was used in the next chloroacetylation cycle.

Example 2

A solution prepared from 60.0 g of 2-8-ethyl-6-methylaniline and 130 g of 1-methoxy-2-propanol was saturated with 15.0 g of hydrogen chloride gas. The mixture was then transferred to a hydrogenation autoclave, 52-9 methoxypropanone and 350 mg of platinum catalyst containing 3% platinum on activated carbon were added, and the mixture was hydrogenated at 60 ° C and 20 bar for 3-5 hours.

After the hydrogenation was complete, the platinum catalyst was aspirated and the solvent was distilled off under reduced pressure. After cooling, the distillation residue crystallized. It contained a mixture of 106.1 g of the composition of 7.9% by weight of 2-ethyl-6-methyl-N- / l-methoxy-2 ^# -prGpyl / aniline 9Z, l% by weight of 2-ethyl-5-methyl-N - / ' ^raatoxy-2, ~ prapyl / _anilin hydrochloride.

To mixture 3a was added 300 ml of toluene, while the distillation condenser was replaced with a bad condenser. To the suspension! 100.3 g of chloroacetyl chloride were metered in with stirring and cooling for 30 minutes and the mixture was refluxed for a further 1 hour. Thereafter, unreacted chloroacetylchloride was distilled off, along with some toluene, and the mixture was concentrated to half volume. After cooling, the concentrated reaction mixture was washed with 10% sodium carbonate and water. Toluene was distilled off from the organic layer under reduced pressure of 13 kPa. The item-2-S-Qtyl Mstyle-M / l ^of -inetoxy-propyl ^R 2 / -chlóracetanilid distilled at 142 ° C / 3 mbar in an amount of 116.8 g / 92 · 7% of theory / HCl gas escaping portion it was removed from the reaction space during chloroacetylation and absorbed in a mixture of 2-otyl-S-methylaniline and 1-methoxy-2-propanol so as to obtain a solution of the necessary concentration until the next stage of the hydrogenation alkylation. The remaining hydrogen chloride ea absorbed in water.

Example 3

5.0 g of hydrogen chloride gas were absorbed in a mixture of 50.0 g of 2-ethyl-S-methylaniline and 131 g of 1-methoxy-2-propanol. After the addition of 47.0 g of methoxypropanone and 120 mg of platinum-on-carbon catalyst with a platinum content of 5% c and the mixture was hydrogenated at 40 ° C and a hydrogen pressure of 7.0 MPa for 3.5 hours.

After complete hydrogenation, the mixture was cooled, the platinum catalyst was filtered off and the filtrate was concentrated, finally under vacuum. A sufficient residue in an amount of H8.1 g was a mixture of 59.1% by weight of 2-ethyl-5-methyl-N- (1'-methoxy-2'-propyl) aniline, and

40.9% by weight of 2-ethyl-S-methyl-N / L ^/ methoxy "2'-propyl / anllin · HCl. 150 ml of cyclohexane were added to the mixture, and 57.7 g of chloroacetyl chloride was added from a dropping funnel with stirring 3a _. The temperature of the reaction mixture 3a was maintained at 30-40 ° C.

After the chloroacetyl chloride 3a was dispensed, the reaction mixture 3 was heated to reflux for 2 hours, and after completion of the evolution of hydrogen chloride, one third of the toluene together with the unreacted chloroacetyl chloride was de-aerated from the reaction mixture and washed with water and sodium carbonate solution. After distilling off the solvent, the product was distilled under vacuum at a temperature of 148 ° C / 4 Pa. 17.7 g (93.4% of theory) of 2-ethyl-N-methyl-N- (1'-methoxy-2 ⁾ -propyl) -chloroacetanilide were obtained as a pale yellow viscous liquid. Hydrogen chloride gas released during chloroacetylation was partially removed for adsorption into a solution of 2-ethyl-5-methylaniline in 1-hydroxy-2-propanols and the remainder absorbed in water.

Example 4

A mixture of 50.0 g of 2-ctyl-6-methylaniline, 131 g of 1-methoxy-2-propanol, 45.0 g of methoxypropanane and 22b mg of platinum catalyst 3 activated carbon and containing 3% platinum was saturated 3 3) 7 g hydrogen chloride gas. The temperature of the mixture rose to 40 ° C. The mixture was poured into a Teflon autoclave with a magnetic entrainer and hydrogenated for 3.5 hours at 50 ° C and 50 psi hydrogen pressure. The annual mixture was cooled after completion of the hydrogenation, the platinum catalyst was filtered off, the filtrate was concentrated, finally under vacuum. The impurity of 93.7 g was a mixture of 2-otyl-B-methyl-N '/ 1'-motoxy-2'-propyl / aniline and 2-otyl-O-methyl-N-Z1-m-methoxy-5'-methyl-N'. -propyl / aniline hydrochloride.

Confuse the preniosla to a flask equipped with a condenser, dropping funnel and thermometer was used as the solvent benzínováj 250 ml fractions with a boiling point of 80 to 110 □ C. ^In the reaction mixture was dosed chlóracstylchlorid in an amount Calková 55) 2 g Boz cooling by The temperature of the suspension was raised spontaneously to 50 ° C. After completion of 3a dosing, the mixture was heated at reflux temperature for 2 hours) when the evolution of hydrogen chloride was complete. The residue was cooled, washed with 5% sodium hydroxide solution and water. Then the solvent was distilled off) finally under vacuum. The residue was subjected to vacuum distilling off the 2-S-ethyl-N- motyl / ^l ~ methoxy-2-propyl / -chlóracetanllid distilled at 142 ° C / 3 mbar. He glared in the extract

134.9 g (95) 2% of theory.

The reaction hydrogen chloride released from the chloro-acetylation was removed at the top of the bad condenser and absorbed in the reaction mixture to nitrogens alkylation.

Claims (3)

OBJECT OF THE INVENTION 1. A process for the preparation of 2-ethyl-S-butterfly-N / L ^of -inetoxY-propyl 2 ^° / chloroacetanilide hydrogenation alkyláciau 2-obese-5-methyl aniline in a molar metoxypropanónom pomëry EXAMPLE 1 from 1.1 to 2 in an L methoxy-2-propanol as a disintegrant; in the presence of a platinum catalyst and hydrogonafiníha chlórovodikoVoj protonic acid catalyst at 20 to 100 ° C and a hydrogen pressure of 0/1 to 70 bar, ^- where ^appropriate, the return of the used catalyst hydrogonačného, l-methoxy-2-propanol and unreacted methoxypropenoate. Isolated from the resulting reaction mixture; ňalšieho the cycle · hydrogonačnej alkylation and reacting the obtained 2-ethyl-S-methyl-N- / L ^of 2-methoxy propyl ^z / aniline with chloroacetyl chloride at a temperature from 70 ° C to the boiling point of the reaction mixture · reflux / wherein in that in the hydrogenation alkylation step of 2-atyl-6-motylaniline with methoxypropanone, hydrochloric acid is used as proton catalyst in an amount of δ / 1 to 27% by weight, based on the 2-ethyl-U-methylaniline used and the resulting reaction product which isolating the platinum hydrogenation catalyst used, water, solvent and unreacted methoxypropanol. It does not consist of two-obese-6-BUTTERFLY N / L ^of 2-methoxy propyl ^z / aniline and 2-ethyl-6-motyl-N / L · *-methoxy-2-propyl ^z / aniline hydrochloride is reacted with chloroacetyl chloride in a molar ratio of 1: 1/1 to 2 in an inert organic solvent selected from the group consisting of aliphatic / cycloaliphatic and aromatic hydrocarbons. 2. The process according to claim 1, wherein the hydrochloric acid is used as proton catalyst in gaseous formo alobo absorbed in 1-methoxy-2-propanol, in a mixture of 1-methoxy-2-propanol and 2-ethyl-5-methylaniline or in a mixture of 1-methoxy-2-propanol, 2-ethyl-5-methylaniline and methoxypropanone. 3. The process according to claim 1 and 2 / wherein, for part of the anhydrous hydrogen chloride formed in step roakcio mixture of 2-ethyl-5-methyl-N- / L ^of 2-methoxy propyl ^z / aniline and 2-obese-S methyl-N / l-2-mGcoxy ^the -propyl / aniline hydrochloride chloracotylchloridom is returned to the alkylation process hydrogenačnoj 2-ethyl-6-methylaniline motoxypropanónom protonic catalyst.