ChemicalBook CAS DataBase List 4-Pyrazolecarboxylic acid

4-Pyrazolecarboxylic acid synthesis

6synthesis methods

Product Name:4-Pyrazolecarboxylic acid
CAS Number:37718-11-9
Molecular formula:C4H4N2O2
Molecular Weight:112.09

2075-45-8 Synthesis

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37718-11-9
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Yield:-

Reaction Conditions:

with hydrogenchloride;n-butyllithium in hexane;water

Steps:

2 2.
2. Preparation of Pyrazole -4-carboxylic acid (4): To a solution 4-bromopyrazole (3) (3.82 g, 0.026 m) in ether (30 ml) at -78° C., was added a solution of 2-4 M n-butyllithium in hexane (21.7 ml, 0.052 m) in drops over a period of 40 minutes. After stirring at -78° C. for 31/2 hours, the solution was warmed to ambient temperature and stirred for a further period of 5 hours. The solution was cooled again to -78° C. and excess dry ice was added. After stirring for 2 hours at -78° C., the reaction mixture was allowed to warm to ambient temperature overnight. Water was added to quench the reaction and the heterogeneous mixture was neutralized to ph 7 by the careful addition of concentrated HCl. The mixture was further diluted with water to dissolve all the solids and was washed with ether. Water was removed from the aqueous layer by distillation under vacuum to yield an off-white solid (4.38 g, crude 4). The product was not purified and was carried on for the subsequent reaction.

References:

The Regents of the Univ. of California US5066479, 1991, A

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7554-65-6 Synthesis