The Instruction of 5-Methyl-3(2H)-pyridazinone

5-Methyl-3(2H)-pyridazinone, often abbreviated as 5-Me-3H-Pyrazolone, is an important intermediate chemical used in the production of various pharmaceuticals, agrochemicals, and other chemical products.
It is a colorless to yellowish liquid with a characteristic pungent odor.
This chemical compound is classified as a heterocyclic compound, specifically a pyrazole, and is known for its high stability and low volatility.

The production of 5-Methyl-3(2H)-pyridazinone has increased significantly in recent years due to its growing demand in the chemical industry.
As a result, several methods for its synthesis have been developed, each with its own advantages and disadvantages.
The following is a brief overview of the most commonly used methods for the synthesis of 5-Methyl-3(2H)-pyridazinone.

Method 1: Hydrolysis of 2-Chloro-5-methylpyridinium iodide

This method involves the hydrolysis of 2-Chloro-5-methylpyridinium iodide, a yellowish liquid with a characteristic pungent odor, in the presence of a base such as sodium hydroxide.
The reaction produces 5-Methyl-3(2H)-pyridazinone as a yellowish liquid, which can then be purified by recrystallization.

Advantages: This method is relatively simple and can be executed without the need for specialized equipment.
The reaction products are also easy to separate and purify.

Disadvantages: The reaction requires the use of toxic reagents such as 2-Chloro-5-methylpyridinium iodide, which can pose a health risk to workers.
Additionally, the resulting product may have low purity, which can affect its efficacy in the production of other chemicals.

Method 2: Reduction of 5-Methyl-2-oxo-3H-pyrazolin-3-one

This method involves the reduction of 5-Methyl-2-oxo-3H-pyrazolin-3-one, a yellowish liquid with a characteristic pungent odor, using reduced metal powder such as lithium aluminum hydride.
The reaction produces 5-Methyl-3(2H)-pyridazinone as a yellowish liquid, which can then be purified by recrystallization.

Advantages: This method is also relatively simple and can be executed without the need for specialized equipment.
The reaction products are also easy to separate and purify.

Disadvantages: The reaction requires the use of reduced metal powder, which can pose a fire hazard to workers.
Additionally, the resulting product may have low purity, which can affect its efficacy in the production of other chemicals.

Method 3: Reduction of 5-Methyl-2-(methylthio)-3H-pyrazol-3-one

This method involves the reduction of 5-Methyl-2-(methylthio)-3H-pyrazol-3-one, a yellowish liquid with a characteristic pungent odor, using lithium aluminum hydride or hydrogen in the presence of a polar solvent such as dimethylformamide.
The reaction produces 5-Methyl-3(2H)-pyridazinone as a yellowish liquid, which can then be purified by recrystallization.

Advantages: This method is relatively simple and can be executed without the need for specialized equipment.
The reaction products are also easy to separate and purify.

Disadvantages: The reaction requires the use of polar solvents such as dimethylformamide, which can pose an environmental hazard and may require special waste management