60481-51-8

White to pink or beige-brown powder

3,4-Dimethylphenylhydrazine hydrochloride, is used as a reactant with ethyl 3-ethoxy-2-ethoxycarbonylprop-2-enoate to produce 2-(3,4-dimethyl-phenyl)-3-oxo-2,3-dihydro-1H-pyrazole-4-carboxylic acid ethyl ester. This reaction will need reagent K2CO3, and the menstruum ethanol.

General procedure for the synthesis of 3,4-dimethylphenylhydrazine hydrochloride from 4-bromo-1,2-xylene: in a 15 mL screw-top capped test tube, CuBr (36 mg, 0.25 mmol, 2.5 mol%), ligand L3 (110 mg, 0.4 mmol, 4 mol%), H2O (0.5 mL), and K3PO4 (254 mg, 1.2 mmol). STAC (110 mg, 0.3 mmol, 3 mol%) and aryl bromide (10 mmol) were then added and the reaction mixture was stirred at 80-110°C (oil bath temperature) for 10 minutes. Then K3PO4 (2.29 g, 10.8 mmol) and N2H4-H2O (1 g, 20 mmol) were added and argon gas (flow rate 5-7 mL/min) was bubbled through the reaction mixture for 5 minutes. The reaction mixture was stirred in a closed test tube at 80-110°C for 1-2 h. The progress of the reaction was monitored by TLC (eluent: hexane) until the feedstock was completely consumed. After completion of the reaction, it was cooled to room temperature and diluted with dichloromethane (50 mL). The reaction solution was filtered and the organic phase was washed with saturated saline (225 mL). A 37% aqueous HCl solution was added dropwise to the dichloromethane solution and the pH was adjusted to 3-4. The precipitate precipitated was filtered, washed with dichloromethane (15 mL) and dried at room temperature. NMR analysis of the partially synthesized arylhydrazine hydrochloride showed the presence of 1-5 mol% impurities of the corresponding aniline hydrochloride (see Supplementary Data). To obtain an analytically pure sample, the precipitate can be purified by adding 2-3 volumes of diethyl ether from a methanol solution.

[1] Chinese Journal of Chemistry, 2018, vol. 36, # 11, p. 1003 - 1006
[2] Tetrahedron, 2014, vol. 70, # 26, p. 4043 - 4048