Study On Synthetic Technology Of Three Important Anthraquinone Intermediates

Anthraquinone dyes are the important class for reactive, disperse, acid and vat dyes. The dyes with anthraquinone chromophore give brilliant shades and light fastness, and are widely used in textile dyeing. The new synthetic technology of some important anthraquinone intermediates derived from 1-amino- anthraquinone, l-amino-4-hydroxy-anthraquinone, l-amino-4-bromo- anthraquinone-2-sulfonic acid (bromamioacid), 1,5- and 1,8 dinitro- anthraquinone, have been studied.The current synthesis of 1-amino-4-hydroxy-anthraquinone is carried out by bromination of 1-amino- anthraquinone, then hydrolyzing the brominated product. Usually more than 1.5 mole of bromine was consumed. A new process to introduce the hydroxyl group directly on 4-position of 1-amino- anthraquinone is suggested based on the adjustment on the reaction rates of halogenation, hydrolysis and oxidation, so called coordinated hydroxylation. The chemistry of coordinated hydroxylation was studied. 1-Amino- anthraquinone derivatives dissolved in 100% sulfuric acid and a small amount of bromine or iodine, potassium bromide or iodide as an initiator, and boric acid as the adjuster, reaction was carried out at high temperature, the hydroxyl group was thus introduced to the para- position of the amino group on the anthraquinone molecule. l-Amino-4-hydroxy- anthraquinone was prepared by 1-amino- anthraquinone, boric acid in the presence of a little potassium iodide giving 88% yield. l-Amino-2-bromo-4-hydroxy- anthraquinone could be obtained by coordinated hydroxylation of l-amino-2- bromo- anthraquinone, boric acid and the initiator potassium iodide or bromide with 97.5%yield and 99% purity. Combined bromination and coordinated hydroxylation, l-amino-4-hydroxy- anthraquinone can be synthesized straightly, 94% yield and 96% purity is achieved, the bromine consumption only 1.05-1.08, it is less than 20% compared with conventional technique.1-Amino-anthraquinone disulfonic acid had been converted to Bromamino-acid by bromination in concentrated sulfuric acid during the preparation of Bromamino-acid was observed. Mechanism study shows that it is via the hydrolysis of the sulfonic group located on the 4-position, then bromination followed. Based on this result, a new technology is suggested, that is by regulating the effective sulphonating contents of 1-amino-anthraquinone, adjusting the concentration of sulfuric acid to hydrolyze 1-amino-anthraquinone disulfonic acid conversing to 1-amino-anthraquinone -2-sulfonic acid, and briminating the hydrolyzed product in 100% sulfuric acid, 87% yield of Bromamino-acid was achieved, 10% higher than the conventional method prepared by "oleum method".A new integrated system of anthraquinone di-nitration process and separation of isomers of dinitroanthraquinone, based on a large molecular ratio of mixed acids (nitric acid and sulfonic acid) to anthraquinone, is established to produce high quality of 1,5-iiidinitro- and 1,8-dinitroanthraquinone. This system consists of the adiabatic nitration, cryogenic crystallization of 1,8-dinitroanthraquinone, circulation of mother liquor based on computer simulation and the treatment of the spent acid is presented.The adiabatic nitration based on large molecular ratio of mixed acid is designed from the heat balance calculation and to meet the demand of technology, which would provide reliable safety measures and production and high efficiency of energy in the nitration system.Based on the research of the solubility of 1,5- and 1,8-dinitro-anthraquinone in the mixed acid, the process of separating 1,5-dinitroanthraquinone is carried out during nitration, and a new separating process of 1,8-dinitroanthraquinone is developed by cryogenic crystallization at low temperature to assure the promising quality of 1,8-dinitroanthraquinone. Since the main components of mixed acid in the mother liquor being kept unchanged during separation, it could be used as the mixed acid for the next batch of nitration directly without any treatment.Based on the computer simulation, the mothe...