Patent GB-828053-A (GB)
Title: Symmetrical tetrahalo substituted quinacridones and process of preparing same
IPC: C09B48/00
Filed: 1956-12-31
Abstract: The invention comprises symmetrical tetrahalo quinacridone and dihydroquinacridone compounds of the formula <FORM:0828053/IV (b)/1> wherein n is 1 or 2, X is halogen and the halogen substituents are symmetrical with respect to their positions on the end rings.  The quinacridones, which are orange pigments, may be prepared by oxidation of the dihydroquinacridones with an oxidizing agent such as sodium m-nitrobenzene sulphonate, and these tetrahalo-dihydroquinacridones may be made by heating dialkyl tetrahalo-2,5-dianilino-3,6-dihydroterephthalates under non-oxidizing conditions (e.g. under a blanket of nitrogen) in presence of an inert high-boiling liquid, preferably at 240-260 DEG  C.  The high-boiling liquid may be a mixture of biphenyl and diphenyl oxide.  The dialkyl tetrahalo-2,5-dianilino-3,6-dihydroterephthalates may be made by condensing, under non-oxidizing conditions, a dialkyl succinyl succinate with an excess of a dihaloaniline in presence of an acid catalyst.  The quinacridone pigments may be reduced in particle size to a surface area greater than 60 square metres per gram by salt-milling.  Examples refer to the condensation of 2,3-, 2,4-, 2,5-, 3,4- and 3,5-dichloranilines, of 2,4-, 3,4-, and 2,5-dibromaniline, of 2,4-, and 2,5-difluoroaniline, and of 2,4-diiodoaniline with diethyl succinyl succinate in alcohol in presence of hydrochloric acid giving the corresponding diethyl tetrahalo-2,5-dianilino - 3,6 - dihydroterephthalates, which are cyclized to the dihydroquinacrodones as above and these are then oxidized as above to the quinacridones.  Specifications 828,051 and 828,052, [Group IV (c)], are referred to.ALSO:The invention comprises symmetrical tetrahalo quinacridone and dihydroquinacridone compounds of the formula <FORM:0828053/IV(c)/1> wherein n is 1 or 2, X is halogen and the halogen substituents are symmetrical with respect to their positions on the end rings.  The quinacridones, which are orange pigments, may be prepared by oxidation of the dihydroquinacridones with an oxidizing agent such as sodium m-nitrobenzene sulphonate, and these tetrahalo-dihydroquinacridones may be made by heating dialkyl tetrahalo-2.5-dianilino-3,6-dihydroterephthalates under p non-oxidizing conditions (e.g. under a blanket of nitrogen) in presence of an inert high-boiling liquid, preferably at 240-260 DEG C.  The high-boiling liquid may be a mixture of biphenyl and diphenyl oxide.  The dialkyl tetrahalo-2,5-dianilino-3,6-dihydroterephthalates may be made by condensing, under non-oxidizing conditions, a dialkyl succinyl succinate with an excess of a dihaloaniline in presence of an acid catalyst.  The quinacridone pigments may be reduced in particle size to a surface area greater than 60 square metres per gram by salt-milling.  Examples refer to the condensation of 2,3-, 2,4-, 2,5-, 3,4-, and 3,5-dichloranilines, of 2,4-, 3,4-, and 2,5-dibromaniline, of 2,4-, and 2,5-difluoroaniline, and of 2,4-diiodoaniline with diethyl succinyl succinate in alcohol in presence of hydrochloric acid giving the corresponding diethyl tetrahalo-2,5-dianilino-3,6-dihydroterephthalates, which are cyclized to the dihydroquinacridones as above and these are then oxidized as above to the quinacridones.  Specifications 828,051, [Group IV (b)], and 828,052, are referred to.