CRYSTAL MODIFICATION 3,3-BIS(2,2-BIS(P-DIMETHYLAMINOPHENYL) ETHENYL)-4,5,6,7-TETRABROMOPHTHALIDE AND CHROMIC RECORDING MEDIUM USING SAID MODIFICATION

摘要

NEW MATERIAL:A crystal modification of a compound expressed by formula I, which has strong peaks at angles of diffraction (2theta) of 7.8, 15.8, 21.8 and 23.8 in X-ray diffraction method with Cu-Ka radiation. USE:A chromophore of a chromic recording medium. PREPARATION:One mol tetrabromphthalic anhydride expressed by formula II is reacted with 2mol 1,1-bis(p-dimethylaminophenyl)ethylene expressed by formula III in the presence of a condensing and dehydrating agent such as acetic anhydride at 50-100 deg.C for several hours. Then after cooling to 10-20 deg.C, precipitates are filtered off and dissolved in a mixed solvent of an alkaline aqueous solution such as sodium hydroxide with an organic solvent such as toluene at 80-90 deg.C. Then the organic solvent layer is concentrated to crystallize an alpha-type crystal, which is then dissolved in chloroform in an amount of 5-10 times, etc. After mixing, a crystal is precipitated to afford the beta-type modification.