Application of 694-48-4,Some common heterocyclic compound, 694-48-4, name is 1,3-Dimethyl-1H-pyrazole, molecular formula is C5H8N2, 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.
In a 5 L reactor, equipped with a stirrer, a reflux condenser, an argon inlet, thermometer and dropping funnel, 1,3-dimethyl-1H-pyrazole(500 g, 5.2 mol) was added slowly with stirring to acetic anhydride (1950 mL, 2125 g, 20.8 mol), while maintaining the temperature below 45 C. Concd H2SO4(50 mL, 92 g, 0.94 mol) was added with cooling and stirring and the mixture then was gradually heated to reflux and held at reflux for 6 h. The mixture was then cooled, evaporated at 70 C/7 Torr, and treated with crushed ice (2 kg). By carefully addition of 40% NaOH solution, the pH of the reaction mixture was adjusted to pH 8, then the organic phase was separated and the aqueous phase was extracted with CH2Cl2(2 × 1000 mL).The combined organic phases were washed successively with H2O(500 mL) and brine (500 mL), and dried over MgSO4. The solvent was removed at 7 Torr, and the residue was distilled (110-112 C/10 Torr) to afford the target ketone (452 g, 63%) as thick, light yellow oil, which crystallized upon standing.
These compound has a wide range of applications. It is believed that with the continuous development of the source of the synthetic route 1,3-Dimethyl-1H-pyrazole, its application will become more common.
Reference:
Article; Taydakov, Ilya V.; Krasnoselskiy, Sergey S.; Synthesis; vol. 45; 15; (2013); p. 2188 – 2192;,
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics