Process for the preparation of mixtures of dinitroanthraquinones with a high content of 1,5- and 1,8- dinitroanthraquinone

摘要

A process has been developed for the preparation of mixtures of dinitroanthraquinones with a high content of 1,5- and 1,8- dinitroanthraquinone by nitration with nitric acid in the presence of sulphuric acid with heating wherein anthraquinone, 1-nitroanthraquinone or a mixture of them is treated with about 1.5 to about 2.5 times the amount by weight of nitric acid, relative to the feed material, in the presence of about 0.75 times to twice the amount by weight, relative to nitric acid, of sulphuric acid, the temperature first being kept in the range from room temperature to about 50 C. until at least 50% of the starting material or materials has been dinitrated, then adjusting the temperature to about 50 C. to about 70 C. to complete the dinitration.