Synthesis Of Aromatic Nitrile Intermediates And Its Application In The DPP Pigments

DPP pigments are one of the most important parts for high performance pigments, with many advantages such as high color strength, strong solvent resistance and excellent thermal stability. They are mainly prepared with nitriles and ester succinate. Nitriles synthesized by the traditional way are harmful to human health and environment for using the highly toxic cyanide. So, we choose a new way to synthsize aromatic nitriles, with these nitriles, five DPP pigments were prepared.For the synthesis of nitriles intermediates, at first, the Friedel-Crafts acylation of biphenyl and trichloroacetyl chloride are studied, the results show that the yield reaches 93% with a lower temperature, dichloroethane solvent, and aliminum chloride catalyst. In the acylation of other aromatics, the results show that the yield is higher with solvent-free than in dichloroethane when the aromatics are liquid; When there are electron withdrawing groups in aromatics, the temperature should increase appropriately; When the aromatics are heterocycles, it is better catalyzed by ZnCl2 than AlCl3. 1-(biphenyl-4-yl)-2,2,2-trichloroethanone is prepared in ammonia, the main factors for this reaction is the ammonia ratio, the yield is up to 91% with the ammonia ratio of the substrate and ammonia of 10. Biphenyl-4-carbonyl cyanide is prepared by dehydration of biphenyl-4-carboxamide with triphosgene, the reaction time decreases from 2h to 0.5h, the yield increases from 83% to 93% adding a catalytic amount of quaternary ammonium. Refering to the synthetic process of biphenyl-4-carbonyl cyanide, a series of other aromatic nitriles are prepared.The synthesis process of DPP pigments are studied, at first, biphenyl-4-carbonyl cyanide reacts with sodium-t-amylate, Pigment Red 264 is prepared, furthermore, with the optimization of temperature, time, molar ratio of the reactants, the final yield is up to 75%. Refering to this synthetic process, four other DPP pigments are prepared, afterwards, these raw pigments are treated with pigmentation process of solvent and surfactant. The application performance shows that compared with traditional azo pigments, DPP are good at the performances like solvent resistance and thermal stability.