CS226250B1 - Method of preparing 4-amino-1-phenyl-5-chloro-6-oxo-1h-pyridazine - Google Patents

Description

The present invention relates to a process for preparing 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine by reacting 4,5-diohloro-1-phenyl-6-oxo-1H-oyridazine with aqueous ammonia in the presence of a catalyst.

4-Amino-1-phenyl-5-fluoro-6-oxo-1H-pyridazine is a herbicide primarily intended for selective weed control in sugar beet (Burex, Pyramine).

One known process for preparing 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine is the amination of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine with ammonia gas at the temperature maintaining the reaction mixture. in the form of melt / MS. pat.č. 120,858 /. The process yielded a technical product containing 70-75% 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine. Čs.pat.č. 122 103 describes the extraction of the present undesired isomer of 5-amino-1-phenyl-4-chloro-6-oxo-1H-pyridazine to give a product with a purity of over 90% ·

The preparation of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine by reacting 4,5-diohoro-1-phenyl-6-oxo-1H-pyridazine with aqueous ammonia solution under pressure and at elevated temperature is the subject Brit.pat. no. 871 674.

This gives a product containing about 80% by weight of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine. Further, it is known to react 4 ' 5-diohoro-1-phenyl-6-oxo-1H-pyridazine with aqueous ammonia under pressure in the presence of a number of acids which form an ammonium salt in the reaction mixture. OPI, Seo, D 22, p 10, 1981]. A high purity product is obtained.

We have now found a process for preparing 4-amino-1-phenyl-5-chloro-6'-oxo-1H-pyridazine by reacting 4,5-diohoro-1-phenol-6-oxo-1H-pyridazine with an aqueous ammonia solution according to the invention. .

The invention is based on the fact that the reaction is carried out in the presence of a catalyst, namely the sodium and / or potassium salts of 4-hydroxyphenylacetic acid and / or 4-hydroxybenzoic acid and / or phenol-4-sulfonic and / or naphtholsulfonic acid, 200 ° 0 and a pressure of 0.1 to 5.0 MPa, the molar ratio

226,250 between 4,5-dihalo-6-oxo-1H-pyiddazine, ammonia and catalyst is 1: 2 'to 50: 0,01 to 0,7 ·

An advantage of the process according to the invention is that the purity as well as the yield of the product obtained are increased over the currently known process in which the catalysts are freed of free acids.

The reaction may be discontinuous as well as continuously in the flow cascade of such reactors. It is possible to recycle the urine several times in a tubular reactor, whereby the mother liquor with the catalyst after isolation of the product, if added with ammonia and a catalyst.

The following examples illustrate but do not limit the invention.

Example · 1 / previous procedure /

9 g of 4,5'-dichloro-1-phenyl-et-oxo-11-pyidazine, 64.5 g of a 15% aqueous ammonia solution and 3.25 g of phenol-4-sulfonic acid were introduced into a pressure vessel. The reaction mixture was heated to 130 ° C and held at that temperature for 4 hours, resulting in a pressure of 0.6 MPa in the reaction vessel. After cooling the reaction mixture, the product was recrystallized. 7 g of technical 4-amino-phenyl-5-chloro-6-cyclo-11-pyridylzine having a purity of 97.4% were obtained. represents 82.4% of theory.

Example 2 (new procedure)

120.5 g of 4,5-dihydroxyphenyl-6-oxo-1H-pyridazine, 863.5 g of a 15% aqueous ammonia solution and 43.5 g of sodium phenol were added to the bag reactor. The reaction mixture was heated to 130 ° C and held at that temperature for 4 hours, while the doss-Hol pressure in the reaction vessel was 0.6 MPa. After cooling the reaction mixture, the product was filtered off. 97.7 g of technical 4-amino-phenyl-5-chloro-6 were obtained. The oxo-11-pyridazine having a purity of 99-5% yields 87.6% of theory.

Example 1 and 3

To this reactor 120.5 g of 4,5-dichloro-4-chloro-6-chloro-6-oxyl-piperazin and the filtrate from Example 2, which was 86.3 g of 15% aq. solution of ammonia and 4.3 g · sodium salts of feyol-4-sulfonyl acid · the other procedure was identical to Example 2 · ^{228 250}

It obtained 99.8 g of technical 4-ininool-phenyl-5-chloro-5-chloro-oxo-1 H -pyridine with a purity of 99% · Yield 89.2% of theory ·

Example 4

By the procedure and the weighting of Example 2, except that the catalyst was a potassium salt of 4-hydroxyphenylacetic acid, it obtained 97.6 g of technical 4-mono-4-chloro-6-chloro-6-oxo-1H-pyrimidine. % »The yield represents 87.9% of theory ·

Example 5

120.5 g of 4,5-aichlorotriol-10-oxo-1H-pyradiol (800 g) of 20% aqueous solutions were pre-loaded into the press reactor. ammonia and 15 g of potassium 4-hydroxybenzoic acid potassium salt. The reaction mixture was heated to 150 ° C for 1 h. After cooling off the reaction mixture, 11.2 g (101.2 g of the technical product, 4-chloro-phenyl-5-chloro-6-hexylpyridazine) having a purity of 98.5% were isolated. The yield was 89.9% of theory.

Example 6

By weighing as in Example 5, except that the catalyst was a potassium salt of L, N, N ^, R ^, R, R, and R, the yield of 100.5 g of technical grade. 1-5-0,0-O-oxo-1 H -pyrrolidone with a purity of 97.9%. 88.8% of theory.

Annex 7 d «

120.5 g of 4,5-dihydro-4'-hexyl-4-phenyl-looxo-HH-piperazine were preceded by 700 g of a 25% aqueous ammonia solution. g of 4-hydroxybutyric acid sodium salt · The reaction mixture was allowed to stir at 140 ° C for 2 hours. After enclosing the product you insulate! Yield: 102.5 g of 4,9-chloro-11-yl-15-chloro-6-oxyl-11H-pyridine with a purity of 99.9%. The yield is 92.4% of theory.

Claims (1)

A process for preparing 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine by reacting 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine with an aqueous ammonia solution, characterized in that the reaction is carried out in the presence of a catalyser, namely a ^sodium salt of 4-hydroxyphenylacetic acid and / or 4-hydroxybenzoic acid and / or phenol-4-sulphonylphenol / or naphtholsulfonic acid, at 50 to 200 ° C and pressure 0.1 to 5.0 MPa, the molar ratio between 4,5-dichloro-6-oxo-1H-pyridazine, ammonia and catalyst being 1: 2 to 50: 0.01 to 0.7;