Preparation of 1-(2-methoxyphenyl)piperazine hydrobromide:
Place 189g of diethanolamine and 2000ml of 40% hydrobromic acid in a three-mouth flask equipped with stirring, reflux condenser and a thermometer, and heat to reflux for 12h. After the reaction, the condenser was converted into a Vigro fractionation column to fractionate until there was no distillate. The first fraction was discarded, and the continuing fraction was recovered for reuse. Cooling, add 670ml ethanol, remove the fractionation column, install the condenser, slowly add 243g o-aminoanisole, heated reflux 10h, add 90g anhydrous sodium carbonate, and then continue to reflux for 10h, pour into a beaker while still hot, cooling, filter out the crystals, and then recrystallize from ethanol to obtain a white scaly crystals, yield of 155g, m.p. 232.4 ~ 234.6 , yield of 31.6%.
Preparation of 1-(2-methoxyphenyl) piperazine:
Suspend 155g of 1-( 2-methoxyphenyl) piperazine hydrobromide in 150ml of water, add 40% of sodium hydroxide solution, neutralize to strong alkaline, leave to stand, extract the oil layer, remove water by pressure-reduced distillation and collect the fraction at 129134 0.1mmHg, yield 103.2g, content 97.5%98.2%. Content: 97.5%-98.2%. It is colorless oily liquid with 95% yield. The total yield was calculated as 30% with diethanolamine.
