HU191899B - Process for preparing 4-amino-1-phenyl-5-chloro-6-oxo-1h-pyridazine - Google Patents

Abstract

The present invention relates to a process for the preparation of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine. In the process, 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine is reacted with aqueous ammonia solution, namely, 4-hydroxy (phenylacetic acid) and / or 4-hydroxybenzoic acid and / or phenol-4-sulfonic acid. and / or in the presence of sodium and / or potassium salts of naphthol sulfonic acid, at a temperature of 50-200 ° C, at a pressure of 0.1-5.0 MPa. The 4,5-dichloro-6-oxo-1H-pyridazine, ammonia, catalyst molar ratio is 1: 2-50 .0.01 to 0.7. The 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine herbicidal activity) is a compound which is particularly suitable for selective extinction of stubble from sugar beet. -1-

Description

The present invention relates to a novel process for the reaction of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine with aqueous ammonia in the presence of a catalyst.

4-Amino-1-phenyl-5-chloro-6-oxo-1H-pyridazyl is a herbicidal compound useful primarily for the selective killing of turnip from sugar beet (Burex, Pyramine).

One known process for the preparation of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine is described in Czechoslovak Patent No. 120,858. Accordingly, 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine is animated with ammonia gas by controlling the temperature of the reaction mixture so that the mixture is molten. The technical product thus obtained contains 70-75% of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine. U.S. Patent No. 122,103,103 discloses the extraction of the undesired 5-amino-1-phenyl-4-chloro-6-oxo-1H-pyridazine isomer present which yields a product of greater than 90% purity.

British Patent No. 871,674 discloses the preparation of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine, 4,5-dichloro-1-phenyl-6-oxo. H-piridazinbó! aqueous ammonia solution! under pressure at elevated temperature. This process yields about 80% by weight of a product containing 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine. 28-359. According to the process known from European Patent Application No. 4,125, 4,5-dichloro-1-phenyl-6-oxo-1-pyridazine is reacted with aqueous ammonia under pressure using an acid capable of forming an ammonium salt in the reaction mixture (ref. CPI, Sect. C, D22 p). 10, 1981). By this method, a very pure product is obtained.

To prepare 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine, 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine was dissolved in aqueous ammonia. We have found a suitable procedure for reacting with.

The process according to the invention is a catalyst, in particular sodium and / or potassium salt of 4-hydroxy (phenylacetic acid) and / or sodium and / or potassium salt of 4-hydroxybenzoic acid and / or sodium and / or potassium salt of pheneno-sulfonic acid and / or in the presence of the sodium and / or potassium salt of naphthenesulphonic acid at 50 to 200 ° C and a pressure of 0.1 to 5.0 MPa, 1: 2-50: 0.01-0.7 4,5-dichloro-6-oxo-1H pyridazine, ammonia, catalyst molar ratio.

The process according to the invention has the advantage that both the purity and the yield of the product are improved compared to the processes using the free acid as catalyst.

The reaction can be carried out in either a batch flow or a cascade reactor, a pressurized reactor or a tubular reactor. If necessary, the catalyst-containing mother liquor can be recycled several times after isolation of the product or addition of ammonia and catalyst.

The invention will now be illustrated by the following examples. The examples are not limiting.

Example 1

A pressurized reaction vessel was charged with 9 g of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine, 64.5 g of 15% aqueous ammonia and 3.25 g of phenol-4-sulfonic acid. The reaction mixture was heated to 130 ° C and maintained at this temperature for 4 hours while the reaction mixture was stirred for 2 hours. Example

120.5 g of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine, 863.5 g of 15% aqueous ammonia solution and 43.5 g of phenol-4-sulfonic acid sodium salt in a pressurized reaction vessel We are added. The temperature of the reaction mixture was raised to 130 ° C and maintained at this temperature for 4 hours. The reactor pressure reaches 0.6 MPa. The reaction mixture was cooled and the product filtered off. 97.7 g (87.6%) of technical 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine are obtained. The product was 99.2% pure.

Example 3

120.5 g was charged to a pressurized reactor

4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine and the mother liquor remaining after filtration of the product of Example 2, previously treated with 86.3 g of 15% aqueous ammonia and 4.3 g phenol-4-sulfonic acid sodium salt. In the following, the procedure described in Example 2 is used. 99.8 g (89.2%) of technical 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine were swallowed. The product obtained has a purity of 99%.

Example 4

The procedure of Example 2 was repeated except that the 4-hydroxy (phenylacetic acid) potassium salt was used as the catalyst. 97.6 g of technical 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine are obtained in 87.9% yield. The product obtained has a purity of 99.8%.

Example 5

120.5 g of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine, 800 g of 20% aqueous ammonia solution and 15 g of 4-hydroxybenzoic acid potassium salt are introduced into a pressurized reactor. The reaction mixture was heated to 150 ° C and maintained at this temperature for 1 hour. The reaction mixture was cooled and the product filtered off. This gives 101.2 g (89.9%) of technical 4-amino-1-phenyl-5-chloro-6-lH-pyridazine. The purity of the product obtained was 98.5%.

Example 6

Example 5 was repeated except that the 1-naphthol-5-sulfonic acid potassium salt catalyst was used. 100.5 g of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine are obtained in a yield of 88.8%. The product was 97.9% pure.

-2191,899

Example 7

120.5 g of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine, 700 g of 25% aqueous ammonia solution, 20 g of phenol-4-sulfonic acid sodium salt and 20 g of 4 sodium hydroxide-benzoic acid. The reaction mixture was heated to 140 ° C and stirred at this temperature for 2 hours. After cooling the reaction mixture, the product is isolated by filtration. 102.5 g (92.4%) of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine are obtained. The product was 99.9% pure.

Claims (1)

A process for the preparation of 4-amino-1-phenyl-5-chloro-6-oxo-1H-pyridazine by reacting 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine with aqueous ammonia, characterized in that Sodium and / or potassium salts of 4-hydroxy (phenylacetic acid) and / or sodium and / or potassium salts of phenol-4-sulfonic acid and / or sodium and / or naphthol sulfonic acid; or potassium salt in the presence of a catalyst at 50 to 200 ° C, at a pressure of 0.1 to 5.0 MPa, 1: 2 to 50: 0.01 to 0.7 4,5-dichloro-6-oxo-1H-pyridazine, ammonia, molar catalyst.