METHOD FOR SEPARATING DICHLOROBENZENE MIXTURE CONTAINING m-DICHLOROBENZENE AND p-DICHLOROBENZENE AND USE OF PHOSPHORIC ACID ESTER AND PHOSPHINE OXIDE AS EXTRACTANT

PROBLEM TO BE SOLVED: To provide a method based on extractive rectification, capable of separating a mixture containing m-dichlorobenzene (m-DCB) and p-dichlorobenzene (p-DCB) into the m-DCB and the p-DCB. SOLUTION: An extractant used in the method comprises a phosphoric acid ester expressed by general formula (I) (R1to R3are each an aliphatic or alicyclic alkyl or an aliphatic or alicyclic alkenyl, and R1to R3together have 3 to 12 carbon atoms in total), a mixture of the phosphoric acid esters of which the types are different from each other, a phosphine oxide expressed by general formula (II) (R1to R3are each an aliphatic or alicyclic alkyl, an aliphatic or alicyclic alkenyl or H, and R1to R3together have 3 to 12 carbon atoms in total), another mixture of the phosphine oxides of which the types are different from each other or the other mixture of the phosphoric acid ester and the phosphine oxide. COPYRIGHT: (C)2004,JPO