In a process for preparing p-dichlorobenzene by nuclear chlorination of benzene and/or chlorobenzene as the starting material with chlorine molecules, chlorination is carried out using aluminum chloride in an amount of 0.1-3 millimols per mol of the starting material and phenothiazines such as
10
H-phenothiazine-10-carboxylic acid phenyl ester in an amount of 0.1-0.9 mols per mol of aluminum chloride so as to be a chlorination degree in a range of 1.2-2.5, by which p-dichlorobenzene can be obtained in a high para-selectivity and a short reaction time.
在用
氯分子对作为起始原料的苯和/或
氯苯进行核
氯化制备对二
氯苯的工艺中,
氯化铝的用量为每摩尔起始原料 0.1-3 毫摩尔,
吩噻嗪类如
10
H-
吩噻嗪-10-
羧酸苯酯,
氯化铝的用量为每摩尔 0.1-0.9 毫摩尔,从而使
氯化度在 1.2-2.5 范围内,这样就能以较高的副选择性和较短的反应时间获得对二
氯苯。