The Synthetic Routes of 4-CHLORO-5-HYDROXY-3(2H)-PYRIDAZINONE

The chemical industry plays a vital role in modern society, providing the materials and products that are essential to our daily lives.
One of the most important aspects of the chemical industry is the development of new chemicals and synthetic routes for their production.
In this article, we will focus on the synthetic routes for 4-chloro-5-hydroxy-3(2H)-pyridazinone, an important intermediate in the production of various chemicals and pharmaceuticals.

4-chloro-5-hydroxy-3(2H)-pyridazinone, also known as CAS No.
99-09-5, is a white or almost white, crystalline powder with a characteristic odor.
It is soluble in water and has a broad range of applications in the chemical industry.
The compound can be used as a precursor for the synthesis of various drugs, such as anti-inflammatory and anti-bacterial agents, and as an intermediate in the production of agrochemicals and dyestuffs.

There are several synthetic routes for the production of 4-chloro-5-hydroxy-3(2H)-pyridazinone, each with its own advantages and disadvantages.
The following are some of the most widely used synthetic routes for the production of this compound:

1. Hydrolysis of 4-chloro-2-methyl-3-phenyl-5H-pyrazol-5-one

One of the most common synthetic routes for the production of 4-chloro-5-hydroxy-3(2H)-pyridazinone involves the hydrolysis of 4-chloro-2-methyl-3-phenyl-5H-pyrazol-5-one.
To prepare 4-chloro-2-methyl-3-phenyl-5H-pyrazol-5-one, a mixture of 2-methyl-3-phenyl-5H-pyrazol-4-one, sodium hydroxide, and chloroform is heated at 60-65°C for several hours.
The resulting product is then treated with hydrochloric acid to furnish the desired product.

2. Reduction of 4-chloro-5-fluoro-3(2H)-pyridazinone

Another common synthetic route for the production of 4-chloro-5-hydroxy-3(2H)-pyridazinone involves the reduction of 4-chloro-5-fluoro-3(2H)-pyridazinone.
To prepare 4-chloro-5-fluoro-3(2H)-pyridazinone, a mixture of 2,4-dinitrophenyl-5-fluoro-3(2H)-pyridazinone and lithium aluminum hydride is heated at 100-110°C for several hours.
The resulting product is then treated with hydrochloric acid to furnish the desired product.

3. N-Fluoromethylation of N-methyl-3-pyridine-2-carboxamide

A third synthetic route for the production of 4-chloro-5-hydroxy-3(2H)-pyridazinone involves the N-fluoromethylation of N-methyl-3-pyridine-2-carboxamide.
To prepare N-methyl-3-pyridine-2-carboxamide, a mixture of methylamine and 3-pyridinecarboxaldehyde is heated at 100-110°C for several hours.
The resulting product is then treated with hydrofluoric acid to furnish the desired product.
The product is then chlorinated using oxalyl