PREPARATION OF 2,3-DICHLORO-1,4-NAPHTHOQUINONE

摘要

PURPOSE:In preparing the titled compound by chlorinating 1,4-naphthoquinone, to make filtrate into a solvent and to circulate it for use without causing problems of corrosion of device, etc., and to improve purity and yield, by adding ammonia to the reaction solution in order to remove hydrogen chloride, etc. dissolved in the reaction solution after the reaction completion, neutralizing it. CONSTITUTION:In producing 2,3-dichloro-1,4-naphthoquinone by chlorinating 1,4-naphthoquinone, after the reaction is over, the reaction solution is neutralized with ammonia.Confirmation of the neutralization point is carried out by oxidation-reduction potential. When the oxidation-reduction potential becomes 500mV--100mV, preferably 450mV-300mV, it is considered to reach the neutralization point. After the neutralization, a solid component containing the titled compound is filtered, and the filtrate is circulated and used as a solvent for the next reaction. Before the neutralization with ammonia is carried out, preferably aeration is done. As for condition, the neutralization is carried out at 85-95 deg.C for 30-60min at the same temperature as that in the chlorination.