A PROCESS FOR PREPARING 1-METHYL-3-PHENYL-PIPERAZINE

摘要

A process for preparing 1-Methyl-3-phenyl-piperazine, which comprises: (i) mixing 1-Benzyl-2-phenyl-piperazine with formic acid solution while stirring and then with formaldehyde solution and heating the mixture to a temperature of 70 DEG C to 80 DEG C for 50 to 70 minutes; (ii) reheating the obtained solution of Step (i) to a temperature of 90 to 95 DEG C for 50 to 70 minutes; (iii) checking the obtained mass of Step (ii) for the absence of the starting material (TLC system, Toluene: IMS=6:4) and treating with sodium hydroxide solution while stirring for 50 to 70 minutes at a temperature of below 25 DEG C and filtering; (iv) washing the product of Step (iii) with water and drying to obtain 1-Benzyl-4-methyl-2-phenyl piperazine; (v) adding the product of Step (iv) with acetic acid taken in hydrogenator in the presence of palladium-carbon catalyst under nitrogen atmosphere while continuously stirring the mixture for about 6 to 10 hours keeping hydrogen pressure of 3.5 to 4.0 kg/cm<2>; (vi) checking the product of Step (v) for the absence of the starting material (TLC system, Ethyl acetate: Methanol = 1:1) and filtering under nitrogen and distilling acetic acid completely under vacuum; (vii) stirring the residue of Step (vi) with demineralised water and stirring with sodium hydroxide solution at a temperature up to 25 DEG C and extracting at least twice with hexane; (viii) concentrating the hexane layer to the mass of Step (vii) followed by stirring and filtering at a temperature of O to 5 DEG C, (ix) treating the product of Step (viii) with chilled hexane and drying in an air oven to obtain 1-Methyl-3-phenyl-piperazine.