These common heterocyclic compound, 288-13-1, name is 1H-Pyrazole, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. Quality Control of 1H-Pyrazole
4-Nitropyrazole is available commercially from the N.D. Zelinsky Institute, Organic Chemistry, Leninsky prospect 47, 117913 Moscow B-334, Russia. The compound may also be prepared as follows :-; Fuming nitric acid (9.5 ml) was added drop wise to a stirred solution of pyrazole (13.6 g) in glacial acetic acid (51 ml) that had been cooled to -10°C using an ice-salt bath. A voluminous precipitate was formed. Acetic anhydride (27 ml) was added dropwise and the resultant mixture was stirred at ambient temperature for 2.5 hours. The mixture was poured onto ice and the acidity of the mixture was reduced to peta5 by the addition of potassium carbonate. The precipitate was isolated by filtration. The resultant solid was dissolved in water and the aqueous solution was extracted with diethyl ether. The organic solution was dried over magnesium sulphate and filtered. Petroleum ether (b.p. 60-800C, 50 ml) was added to the filtrate which was concentrated by evaporation to a volume of about 50 ml. A precipitate formed which was isolated by filtration. This solid was believed to be 1-nitropyi-azole (20.6 g); 1H NMR Spectrum: (DMSOd6) 6.71 (s, IH), 7.88 (s, IH), 8.81 (s, IH). The compound may be explosive and should be handled cautiously.
The synthetic route of 1H-Pyrazole has been constantly updated, and we look forward to future research findings.
Reference:
Patent; ASTRAZENECA AB; ASTRAZENECA UK LIMITED; WO2007/113565; (2007); A1;,
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics