CS247568B1 - Process for preparing N-phenyl-N ', N'-dimethylurea derivatives - Google Patents

Abstract

The solution relates to a method for preparing N-phenyl-N',Ν'-dimethylurea derivatives by reacting dimethylamine with a phenylisocyanate derivative in an organic solvent environment at a molar ratio of dimethylamine to phenylisocyanate derivative of 1.01 to 1.50:1.00 and a temperature of -10 to 80 °C. The essence of the invention lies in the fact that the organic solvent used in the reaction is replaced by mother liquors remaining from the previous production of the respective N-phenyl-N',Ν'-dimethylurea derivatives, with a content of 0.01 to 10% dimethylamine and 0.1 to 5% N-phenyl-N',N'-dimethylurea.

Description

(54) A process for preparing N-phenyl-N ', N'-dimethylurea derivatives

The invention relates to a process for the preparation of N-phenyl-N ', Ν'-dimethylurea derivatives by reacting dimethylamine with a phenylisocyanate derivative in an organic solvent medium at a molar ratio of dimethylamine to phenylisocyanate derivative of 1.01 to 1.50: 1.00 and -10 to 80 ° C. The principle of the invention consists in replacing the organic solvent used in the reaction with the mother liquors resulting from the previous production of the corresponding N-phenyl-N ', Ν'-dimethylureas derivatives containing from 0.01 to 10% dimethylamine and from 0.1 to 5% N-phenyl-N ', N'-dimethylurea.

The present invention relates to a process for the preparation of N-phenyl-N ', N'-dimethylureas derivatives of the general formula (I):

/ ^CH 3

NHCON ^. _CHa (I)

R ₂ in which R represents -CH _3, -CH (CH _{3) 2} Cl, -OCH ₃ R ₂ -H, by reacting dimethylamine with a phenyl isocyanate derivative in an inert organic solvent. Said N-phenyl-N ', Ν'-dimethylurea derivatives find use as biologically active substances in the production of herbicidal preparations for cereals.

Most of the industrially used processes for preparing N-phenyl-N ', Ν'-dimethylurea derivatives are based on the reaction of dimethylamine with the corresponding arylisocyanate in an organic inert solvent such as benzene, toluene, anlsole, chlorobenzene.

Dimethylamine is used either as a gas or as an aqueous solution or as a solution in organic inert solvents. Continuous processes for the preparation of N-phenyl-N ', Ν'-dimethylurea derivatives are also disclosed. The use of dimethylamine as an aqueous solution is disadvantageous for the increased formation of by-products, especially symmetrical N, N'-bis (aryl) -ureas.

Therefore, anhydrous reactants diluted with an inert organic solvent are used to prepare N-phenyl-N ', Ν'-dimethylurea derivatives. It is difficult and relatively inefficient to treat the mother liquors from the product isolation containing a considerable amount of the desired N-phenyl-N ', N'-dimethylurea (at least 5 to 10% of the theoretical yield).

After concentrating the mother liquors to about 20 to 30% of the original volume by distilling off the solvent, a further product is obtained in an amount of 2 to 3% of the theoretical yield. This second product fraction, however, contains from 1 to 4% of by-products resulting from thermal exposure to the solvent being distilled off.

From a hygienic point of view, the isolation of the distillation residues, which must be isolated after distillation of the organic solvent from the mother liquors after isolation of the second crop, is a liquid slowly solidifying distillation residue at a temperature of 70 to 100 ° C.

This disadvantage is overcome by the process for the preparation of N-phenyl-N, N'-dimethylurea derivatives by reaction of dimethylamine with phenylisocyanate derivatives in an inert organic solvent at a molar ratio of dimethylamine to phenylisocyanate derivative of 1.01 to 1.50: 1.00 and -10 to + 80 ° C according to the invention.

The principle is that 5 to 100% of the amount of organic solvent used in the reaction is replaced by mother liquors resulting from the previous production of N-phenyl-N ', Ν'-dimethylurea, containing in addition to the solvent 0.01 to 10% dimethylamine and 0.1 to 5% N-phenyl-N ', Ν'-dimethylurea.

The quality of the product is maintained during the preparation process - the content of by-products in the product is below 1% and the yield is very high. By replacing 80-100% of the required organic solvent with the mother liquor, an almost quantitative yield of the desired N-phenyl-N ', Ν'-dimethylurea derivative can be achieved.

A further advantage of the process according to the invention is that the regeneration of excess dimethylamine is eliminated, since the dimethylamine is recycled with the mother liquors to a subsequent operation, and the isolation of the second product fraction is also omitted. The frequency of organic solvent regeneration operations and distillation residue isolation operations is greatly reduced, and consequently the cost of constructing a recovery plant for the solvents used is reduced.

Due to the reduced frequency of organic solvent regeneration operations, the energy costs of producing N-phenyl-N ', Ν'-dimethylureas are also reduced. The method of the invention reduces the exhalation of dimethylamine and organic solvent. The recovery of mother liquors can be solved by replacing the entire amount of mother liquors with at least three times re-cyclase, preferably up to 5 to 10 times recycling or by substituting a constant partial amount of organic inert solvent with mother liquors, at least 5% solvent but preferably 50 to 90% organic solvent. .

The mother liquor recycles can advantageously be used in both continuous and batch processes for the preparation of N-phenyl-N ', N'-dimethyl iodine derivatives.

In order to further elucidate the invention, the following examples are provided:

Example 1

1000 g of chlorobenzene mother liquors from a previous N- (4-isopropylphenyl) -N ', Ν'-dimethylurea containing 1.2% by weight of dimethylamine and 1.1% N- (4-isopropylphenyl) - were charged into a stirred flask. N ', Ν'-dimethylurea.

The mother liquors were cooled to 5 ° C and 53 g of dimethylamine were metered in at this temperature. Over the next 3 hours, 200 g of 4-isopropylphenyl isocyanate was charged to the solution of dimethylamine in the mother liquors at 5 to 15 ° C. After the addition of 4-isopropylphenyl isocyanate, the reaction mixture was stirred at 15 ° C for 1 hour.

After cooling the product suspension to 0 [deg.] C., the product was isolated on a laboratory centrifuge and washed with 120 g of chlorobenzene and dried at 70-80 [deg.] C. and a pressure of 1 bar. 251 g of N- (4-isopropylphenyl) -N ', Ν'-dimethylurea were obtained, i.e. in 98% yield on 4-isopropylphenyl isocyanate and 1,074 g of mother liquors containing 0.81 * dimethylamine and 1.388% of N- (4-isopropylphenyl) isocyanate. 4-isopropylphenyl) -N ', Ν'-dimethylurea.

The product was determined by liquid chromatography to contain 0.15 N, N'-bie- (4-isopropylphenyl) -urea and 0.04% N- (4-isoproylphenyl) -N'-methylurea.

Example 2

200 g of 4-isopropylphenyl isocyanate and 500 g of mother liquors of Example 1 were charged into a stirred flask. Over the next 2 hours, 617 g of dimethylamine solution was prepared to the 4-isopropylphenyl isocyanate solution prepared by dissolving 67 g of dimethylamine in 550 g of mother liquors. experiment 1.

The temperature of the reaction mixture rose from the original 25 ° C to 55 ° C during dosing of the dimethylamine solution. The reaction mixture was then heated to 80 ° C and then cooled evenly to 0 ° C over 4 hours.

The isolated product was washed with 100 g of chlorobenzene and dried at a temperature of 70-80 ° C and a pressure of 1 bar. 255 g of N- (4-isopropylphenyl) -N ', Ν'-dimethylurea were obtained in a yield of 99, βt per 4-isopropylphenyl isocyanate and 1,135 g of mother liquors containing 1.49% dimethylamine and 1.1.1% N - (4-isopropylphenyl) -N ', N'-dimethylurea.

The product was determined by liquid chromatography to contain 0.11% symmetrical N, N'-bie- (4-isopropylphenyl) urea and 0.05% N- (4-isopropylphenyl) -N'-methylurea.

Example 3

To a stirred flask was charged 1,070 g of mother liquors from Example 2 and 400 g of 4-isopropylphenyl isocyanate. Within 3 hours, 555 g of the chlorobenzene solution of dimethylamine containing 111 g of dimethylamine was metered into the present solution of 4-isopropylphenyl isocyanate. The temperature of the reaction mixture was maintained at 45-55 ° C during dosing of the dimethylamine solution.

Then the contents of the flask were evenly cooled to 5 ° C over 3 hours and the product was isolated. 501 g of N- (4-isopropylphenyl) -N ', ,'-dimethylurea, ie 97.9% of theory, were obtained. Liquid chromatography determined a symmetrical content of N, N'-bis- (4-isopropylphenyl) -urea of 0.19% and an N- (4-isopropylphenyl-N'-methylurea content of 0.05%),

Example 4

To the flask was charged 100 g of anhydrous toluene and 800 g of toluene mother liquors from the preparation of N- (3-chloro-4-methoxyphenyl) -N ', Ν'-dimethylureas containing 1.8% of N- (3-chloro-4-methoxyphenyl) ) -N ', Ν'-dimethylurea and 0.1% dimethylamine. The contents of the flask were then cooled to -10 ° C and 27 g of dimethylamine and 100 g of 3-chloro-4-methoxyphenylisocyanate were simultaneously metered in over 1 hour while cooling the reaction mixture to -10 to 0 ° C.

123.9 g of N- (3-chloro-4-methoxyphenyl) -N ', 4 ' -dimethylurea were obtained, i.e. in 99.5% yield on 3-chloro-4-methoxyphenyl isocyanate. The content of symmetrical Ν, Ν'-bis- (3-chloro-4-methoxyphenyl) -urea 0.05% and the content of N- (3-chloro-4-methoxyphenyl) -N'-methylmolamine were determined by liquid chromatography. 0.045%.

Example 5

1000 g of chlorobenzene (4), 450 g of 3-chloro-4-methylphenylisocyanate and 100 g of mother liquors from N- (3-chloro-4-methylphenyl) -N ', Ν'-dimethylurea containing 4, 8% dimethylamine 2,1% N- (3-chloro-4-methylphenyl) -N ', Ν'-dimethylurea,

0.4% sym. N, N'-bis- (3-chloro-4-methylphenyl) -urea.

Then, 500 g of a dimethylamine solution containing 120 g of dimethylamine was metered in uniformly over 2.5 hours. During the addition of the dimethylamine solution, the temperature of the reaction mixture rose from 20 ° C to 45 ° C. The product was isolated at 0 ° C and washed with 200 g of chlorobenzene.

553 g of N- (3-chloro-4-methylphenyl) -N ', Ν'-dimethylurea (i.e. in 95.5% yield on 3-chloro-4-methylphenylisocyanate) were obtained. The content of symmetrical Ν, Ν'-bis- (3-chloro-4-methylphenyl) -urea in the product 0.08% and the content of N- (3-chloro-4-methylphenyl) -N -N'-methylurea were determined by liquid chromatography. 0.02%.

Claims (1)

OBJECT OF THE INVENTION «1 NHCON ch ₃ ch ₃ where R _x denotes -CH ₃ , -CH (CH ₃ ) ₂ , -Cl, -OCH ₃ R ₂ denotes -H, Cl by reacting dimethylamine with the corresponding phenylisocyanate derivative in an inert organic solvent at a dimethylamine to mole ratio of a phenylisocyanate derivative of 1.01 to 1.50: 1.00 and at a temperature of -10 to +80 ° C, characterized in that 5 to 100% of the amount of organic solvent used in the reaction is replaced by mother liquors which have been removed in the previous production of the corresponding N-phenyl -N ', Ν'-dimethylurea, the caustic solution containing 0.01-10% dimethylamine, 0.1-5% N-phenyl-N', Ν'-dimethylurea and a solvent.