CS239213B1 - Process for isolating o- (3-alkoxycarbonylaminophenyl-) -N-arylcarbamates - Google Patents

Abstract

A method for isolating pure o-(3-alkoxycarbonylaminophenyl)-N-arylcarbamates from a mixture formed by the reaction of phosgene with phenol derivatives in a polar aprotic solvent in the presence of a tertiary amine, which are used as an active ingredient for selective herbicidal agents, especially for sugar beet. The essence is the extraction of the resulting tertiary amine hydrochloride by reaction with water with the addition of 0.01 to 10% by weight of inorganic or organic acid.

Description

The invention relates to a process for the isolation of O- (3-alkoxycarbonylaminophenyl-) H-arylcarbamates of the formula pNH 'C00

B ⁴

Λ

NHCOOR in which denotes

R-alkyl 0 _χ R ¹ = R ² -H, alkyl C to C 8, -NOg, NR 6, where R * = alkyl Ο _χ ΒΖ C 9 or H, halo, -haloalkyl 0 _χ to C 8, cyano, alkoxy 0 _χ to Cg from a mixture formed by the reaction of phosgene with phenol derivatives, in particular with N-hydroxyphenylcarbamic acid esters in a polar aprotic solvent in the presence of a hydrogen chloride-binding tertiary amine.

The biscarbamates of the general formula are characterized by a high biological activity against weeds and for this reason they are a key active ingredient of selective herbicidal compositions used especially for sugar beet.

They are industrially prepared by the predominant reaction of an arylisocyanate with a substituted phenol in an organic solvent medium under the catalytic action of trialkylamine such as triethylamine. This process is particularly suitable for large-scale production. since the preparation of aryl isocyanates is both technologically and apparatus intensive. It is necessary to work with a large excess of phosgene, which necessitates its regeneration.

- 2 239 213 very good quality and small amount of waste ·

Also described is the preparation of the so-called Hofftean degradation of substituted benzoic amides by sodium hypochlorite, where the resulting aryl isocyanate subsequently reacts with the substituted phenol (DOS 2,548,573). However, this procedure is of rather preparative importance.

Another method suitable for medium tonnage production is by reacting arylamine and substituted phenol with an equimolar amount of phosgene in the presence of a proton acceptor or separately preparing an aryl chlorofomate which is subsequently reacted with an aromatic amine. This relatively simple procedure gives the product in good yield but in poor quality, since it contains a considerable amount of symmetrical diarylurea and other by-products, which are mainly produced by the reaction mixture, since the formed bisphosphates are thermally unstable at elevated temperature and conditions.

in

This disadvantage is partially eliminated by a process for the isolation of O- (3-alkoxycarbonylaminophenyl -) - N-arylcarbamates from a mixture resulting from the reaction of phosgene with phenol derivatives in a polar aprotic solvent in the presence of a tertiary amine according to the invention. SUMMARY OF THE INVENTION The present invention is characterized in that after the reaction is completed, the target is. The amine hydrochloride and unreacted components are extracted with water with the addition of an inorganic and / or organic acid such as hydrochloric, sulfuric, phosphoric, acetic, citric, formic, preferably phosphoric and acetic acid in an amount of 0.01 to 10% by weight. The presence of the acidic components in the organic phase has a stabilizing effect on the end product of the reaction, thereby allowing a substantial reduction in the content of by-products. In this way, the biscarbamates are obtained not only in very good yield, but also in high purity. From the reaction mixture the solvent is distilled off at a temperature of max. 135 ° C (optionally under reduced pressure) and the distillation residue containing biscarbamate and the corresponding target. The amine hydrochloride is mixed with a suitable, low-miscible or water-immiscible solvent so that the biscarbamate is in solution at about 80 ° C and the target is extracted. the amine hydrochloride first with water, in further water extractions in the presence of an inorganic or organic acid to remove

- 3,239,213 also the free amine, causing a decrease in stability while ensuring the stabilizing effect of the acid environment. After extraction, the solution may be azeotroped and crystallized. The product obtained contains min. 97% of active substance. Suitable solvents are hydrolysis-stable aromatic hydrocarbons such as benzene, toluene, xylene or chlorinated aliphatic hydrocarbons such as dichloroethane, tetrachloroethane, or chlorinated aromatic hydrocarbons such as chlorobenzene, dichlorobenzenes. The extraction itself is preferably carried out at a temperature just below the boiling point of the water-organic solvent azeotrope. The presence of the solvent in the extraction is not a necessary condition for the preparation of the substance but for the complete removal of the reaction target. amine hydrochloride which is incomplete in solid-phase scrubbing. ,

In this way, biscarbamate is obtained in a yield of over 85% of theory, with the content of individual by-products being tenths of a percent.

The following examples are provided to further illustrate the invention:

Example 1: O- (3-methoxycarbonylaminophenyl -) - N- (3-methylphenyl) carbamate

To 50.8 g (0.51 mol) of phosgene dissolved in 200 ml of anhydrous ethyl acetate was added dropwise at 15 ° C with cooling.

80.2 g (0.480 mol) of 3-methoxycarbonylaminophenol 100% and 77.2 g (0.518 mol) of Ν, Ν-diethylaniline with a content of over 99.5% th. dissolved in 180 mL of anhydrous ethyl acetate. At the end of dosing the temperature rose to 20 ° C

Heated to 50 ° C and stirred for 30 minutes at 50 ° C, the reaction mixture was cooled to 30 ° C, at which temperature a solution of 51.4 g (0.480 mol) of 3-toluidine and 71.5 g (0.480 mol) was added dropwise. of diethylaniline in 72 mL of anhydrous ethyl acetate. After the addition, the reaction mixture was heated to 70 ° C and held at this temperature for 30 min. The volatiles were then distilled off to a temperature of 125 ° C in the distillation residue, to which 1500 ml of toluene and 200 ml of water were added, heated to 80 ° C, and after stirring for 10 minutes the aqueous phase was allowed to separate. The organic phase was extracted 3 more times

- 4,239,213

200 ml of 5% acetic acid · After careful separation of the last aqueous phase, azeotropic dewatering of the toluene solution was performed and cooled to 0 ° C. The precipitated crystals were vigorously aspirated, washed with 100 ml of toluene and dried under reduced pressure at a maximum of 80 ° C. 126 g of product containing 98.5% of the active substance, i.e. 85% of theory, were obtained. · By cooling of the aqueous phase from the extraction, a further 5 β product was recovered, which can be returned to the reaction mixture before extraction.

Example 2: O- (3-ethoxycarbonyleminophenyl -) - N-phenylcarbamate

Execution of an example similar to Example 1 except that an equivalent amount of 3-ethoxycarbonylaminophenol and aniline was used, after heating to 50 ° 0 in the preparation of chloroformate, the remaining phosgene was distilled off from 150 ml of ethyl acetate, followed by aniline reaction. Reaction and distillation of ethyl acetate, the reaction mixture was diluted with 1500 ml of xylene and 200 ml of water, the same procedure as in the case of 1 · 135 g of product was obtained containing 99.2% of active substance, i.e. 91% of theory

The following were prepared analogously:

Ethyl N- (3-N- (2-chlorophenyl) carbamoyloxyl) phenyl) carbamate m.p. 117-119 ° C. 86%

Ethyl N- (3- (N- (3-trifluoromethylphenyl) carbamoyloxy) phenyl) carbamate m.p. 130-131 ° C. 90%

Ethyl N- (3- (N- (3-chloro-4-methylphenyl) carbamoyloxy) phenyl) carbamate m.p. 150-151 ° C. 87%

Butyl N- (3- (N- (3-nitrophenyl) carbamoyloxy) -4-dimethylaminophenyl) carbamate m.p. 203-205 ° C. 86%

Methyl -N- (3- (N- (3-cyanophenyl) carbamoyloxy) -4-ethoxyphenyl) carbamate

m.p. 212 DEG-215 DEG C .; 85,5%

Claims (1)

SUBJECT OF THE INVENTION 239 213 A process for the isolation of O- (3-alkoxycarbonyleainophenyl -) - R-arylcarbamates of general formula R ⁴ f \ -NHCOO-T \ ^ _{<Ν Η} (ί00Ρ. Wherein R @ 1 denotes C1 -C6 alkyl, R @ 1 R @ 1 denotes H, C1 -C6 alkyl, --NO8, --NR @ 8, wherein R @ 1 = C1 -C6 alkyl, - halogen, C1 -C8 haloalkyl, cyano C1 -C8 alkoxy from a mixture formed by the reaction of phosgene with phenol derivatives in a polar aprotic solvent in the presence of a tertiary amine and subsequent reaction with a primary aromatic amine in the presence of a tertiary amine, characterized in that the tertiary amine hydrochloride formed is extracted with water - 10% of inorganic or organic acids, such as hydrochloric, sulfuric, phosphoric, acetic, citric, formic.