The Synthetic Routes of Ethyl 2,3-dihydro-3-oxo-4-pyridazinecarboxylate

Ethyl 2,3-dihydro-3-oxo-4-pyridazinecarboxylate is a versatile intermediate in the chemical industry that can be used in the production of various chemicals and pharmaceuticals.
The most common synthetic routes for the preparation of this compound are through the use of hydrazoic acid and hydrogen peroxide, or through the use of nitrous acid and sodium hydroxide.

The first synthetic route involves the use of hydrazoic acid and hydrogen peroxide.
Hydrazoic acid is a strong acid that is capable of forming a stable azeotrope with water, while hydrogen peroxide is a weak acid that can easily be decomposed into water and oxygen.
By reacting these two compounds in the presence of a solvent such as ethyl acetate or benzene, the ethyl 2,3-dihydro-3-oxo-4-pyridazinecarboxylate can be produced.
The reaction is exothermic and it should be performed with caution.
The reaction mixture is stirred at room temperature for 1 hour, then left to stand overnight.
The mixture is then filtered, and the organic phase is washed with 2 x 50 mL of water and 2 x 50 mL of saturated aqueous sodium bicarbonate.
The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated.
The residue is purified by flash chromatography on silica gel with a 20% ethyl acetate/hexane solution as the eluent.
The desired product is obtained as a white solid that is recrystallized from ethyl acetate/hexane to yield pure product.

Another synthetic route for the preparation of ethyl 2,3-dihydro-3-oxo-4-pyridazinecarboxylate involves the use of nitrous acid and sodium hydroxide.
Nitrous acid is a strong acid that can easily be decomposed into nitrogen dioxide and water, while sodium hydroxide is a strong base that can easily decompose into water and sodium hydroxide.
By reacting these two compounds in the presence of a solvent such as ethyl acetate or benzene, the ethyl 2,3-dihydro-3-oxo-4-pyridazinecarboxylate can be produced.
The reaction is exothermic and it should be performed with caution.
The reaction mixture is stirred at room temperature for 1 hour, then left to stand overnight.
The mixture is then filtered, and the organic phase is washed with 2 x 50 mL of water and 2 x 50 mL of saturated aqueous sodium bicarbonate.
The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated.
The residue is purified by flash chromatography on silica gel with a 20% ethyl acetate/hexane solution as the eluent.
The desired product is obtained as a white solid that is recrystallized from ethyl acetate/hexane to yield pure product.

Both synthetic routes have their advantages and disadvantages, and the choice of route depends on the availability of the reagents, the scale of the production, and the desired purity of the final product.
The route using hydrazoic acid and hydrogen peroxide is less expensive and easier to perform, but the product obtained may have a lower purity than the one obtained through the route using nitrous acid and sodium hydroxide.
The route using nitrous acid and sodium hydroxide is more expensive and requires more specialized equipment, but it can provide a higher purity