CS236650B1 - Manufacturing process of 4,5-dichlor-1-fenyl-6-oxo-pyridazine - Google Patents

Abstract

The invention relates to a process for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine reaction reaction mixture containing phenylhydrazine hydrochloride, obtained by diazotizing aniline, reduction of benzenediazonium chloride and following hydrolysis of phenylhydrazinedisulfonate with sodium hydrochloric acid, with mucochloric acid continuously v flow reactor at 70-100 ° C degrees Celsius. Reaction mixture with content 3.6 to 8.0% by weight of phenylhydrazine hydrochloride at a temperature of 50 to 95 ° C is metered into the flow reactor simultaneously 4 to 10 ° / mucochloric acid solution) in the mother liquor after isolation by reaction of the resulting 4,5-dichloro-1-phenyl-6- oxo-lH-pyridazine.

Description

The present invention relates to a process for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine by reacting a reaction mixture containing phenylhydrazine hydrochloride with mucoic acid.

4,5-Dichloro-1-phenyl-6-oxo-1H-pyridazine is an intermediate in the production of a selective herbicidal preparation (Burex, Pyrazine).

Several methods for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine are known to date.

The reaction of phenylhydrazine with mucochloric acid in an organic solvent environment is described in DAS 1,086,238. AO 205 592 the reaction of phenylhydrazine and mucochloric acid takes place in a mixture of an organic non-polar solvent and water. Other known methods are based on the reaction of mucochloric acid and phenylhydrazine hydrochloride in an aqueous medium. According to US Pat. 2,628,181 is carried out by reacting phenylhydrazine hydrochloride and mucochloric acid in water in the presence of sodium carbonate, isolating the resulting phenylhydrazone mucochloric acid product and boiling in glacial acetic acid to 4,5-dichloro-1-phenyl-6-oxo-1H- pyridazine.

Other known processes for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine involve the reaction of mucochloric acid and phenylhydrazine in a dilute mineral acid medium (British Pat. No. 881616; DOS 1 545 595; US AO). 220 299).

A common feature of the above procedures is that phenylhydrazine hydrochloride and the like are used to prepare 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine. phenylhydrazine isolated from its reaction medium.

MS. AO 195 128 describes a discontinuous process for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine in the reaction medium of phenylhydrazine hydrochloride produced with mucochloric acid. This process has a number of disadvantages such as energy consumption, individual dosing of the reaction components, and subsequent discontinuous filtration of the resulting product.

We have now found a process for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine by reacting a reaction mixture containing phenylhydrazine hydrochloride obtained by diazotization of aniline, reduction of benzenediaziazonium chloride and subsequent hydrolysis of sodium phenylhydrazine disulfonate with hydrochloric acid in a mucoacetic acid reactor. 70 to 100 ° C according to the invention.

SUMMARY OF THE INVENTION The reaction mixture at a concentration of 3.6 to 8.6% by weight of phenylhydrazine hydrochloride at a temperature of 50 to 95 ° C is continuously fed into the flow reactor simultaneously with a 4 to 10% mucochloric acid solution at a temperature of 40 to 80 ° C. ° C dissolved in the mother liquor obtained after isolation by reaction of the resulting 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine.

The advantage of the new process is its ease of implementation, energy efficiency due to the continuous process, whereby the resulting 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine is continuously filtered on a weighted rotary filter and used in the preparation of the herbicidal preparation without treatment. Burex. The continuous procedure eliminates the difficulties of stirring the reaction mixture using higher concentrations of the phenylhydrazine hydrochloride reaction solution.

It should also be pointed out that the process according to the invention prevents the penetration of phenylhydrazine as a particularly dangerous poison in the process of its production into waste water, which is of no great importance in environmental protection.

The following example illustrates but does not limit the scope of the invention.

Example

The boiler was dosed with 872 kg of water. Under stirring and cooling, 1156.8 kg of 32% hydrochloric acid were added. After cooling the contents of the boiler to 10 ° C, 404.6 kg of aniline was added at a temperature of 10-15 ° C.

After addition of the aniline, the mixture was cooled to +2 ° C and 741.8 kg of a 40% aqueous sodium nitrite solution were metered below the surface. Upon completion of diazotization, the reaction mixture was discharged into a reduction vessel in which 2530.2 40% sodium bisulfite and 609.7 kg 40% sodium hydroxide were introduced at a rate such that the temperature of the mixture was maintained between 30-35 ° C. C. After heating to 85 ° C, 5.5 kg of zinc dust and 1.7 kg of bleaching clay were added. The mixture was held at 90 degrees Celsius for 2 h. After filtration, the reaction mixture was charged to boilers containing 1090.6 kg of 32% hydrochloric acid. Hydrolysis was performed for 4 h at 90 ° C.

The phenylhydrazine hydrochloride suspension was diluted with 2247 kg of water at 75 ° C to give a 5.7% phenylhydrazine hydrochloride solution.

To a flow reactor consisting of three boilers connected to each other in a cascade and equipped with a stirrer, 12.15 kg of 5.7% phenylhydrazine hydrochloride prepared at 75 ° C and 13.3 kg of a 6% aqueous mucochloric acid solution were charged hourly. containing 0.03 kg of free hydrocarbon at 60 ° C.

The reaction mixture was held in the reactor at 95 ° C and held for 1 h. The technical product 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine was isolated by filtration. In 1 hour 1.13 kg of product having a purity of 98.7% was obtained. The yield was 97% of theory.

A portion of the mother liquor after isolation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine was used to prepare a 6% solution of 2,366,650 mucochloric acid. The procedure was 240 h. After that time, 1.14 kg of industrial 4,5-dichloro-1-phenyl-6-oxo-pyridazine was obtained with a purity of 98.95% per hour.

Claims (1)

A process for the preparation of 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine by reacting a reaction mixture containing phenylhydrazine hydrochloride obtained by diazotizing aniline, reducing the benzenediaziazonium chloride followed by hydrolyzing sodium phenylhydrazine disulfonate with hydrochloric acid, with a mucochloric acid flow rate. 100 ° C, characterized in that the reaction mixture at a concentration of 3.6 to 8.0% by weight of phenylhydrazine hydrochloride at a temperature of 50 to 95 ° C is continuously fed into the flow reactor simultaneously with a 4 to 10% mucochloric acid solution at a temperature of 40 to 95 ° C. 80 ° C dissolved in the mother liquor after isolation by reaction of the resulting 4,5-dichloro-1-phenyl-6-oxo-1H-pyridazine.