Synthesis method of tetrahydroquinoxaline

The invention discloses a synthetic method of tetrahydroquinoxaline, and relates to the technical field of tetrahydroquinoxaline synthesis. The synthesis method comprises the following steps: preparing o-nitrochlorobenzene, ethanolamine and a catalyst nickel in proportion; the preparation method comprises the following steps: adding o-nitrochlorobenzene and ethanolamine into a reaction kettle, heating to 120-130 DEG C under the protection of nitrogen, and reacting for 5 hours; cooling, adding a catalyst nickel, introducing hydrogen, keeping the pressure of the reaction kettle at 15 kg, and preserving heat for 3 hours; raising the temperature to 180-200 DEG C, and keeping the temperature for 3 hours; and cooling, and recrystallizing with methanol to obtain tetrahydroquinoxaline. The method has the advantages that the tetrahydroquinoxaline is directly synthesized in the reaction kettle through the o-nitrochlorobenzene and the ethanolamine, the synthesis route is shortened, the cost is remarkably reduced, the po