摘要:
A process for purifying indigo comprises stripping the as-synthesized aqueous alkaline indoxylate solution before its oxidation to indigo of impurities in the absence of oxygen by distillation or by passing in steam or an inert gas and then treating the indigo precipitated on oxidation of the stripped indoxylate solution with dilute hydrogen peroxide solution.
摘要:
A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.
摘要:
A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.
摘要:
This invention relates to a process for the purification of indigo, wherein the indigo is heated in an inert organic solvent at from 150.degree. to 250.degree. C. and preferably from 180.degree. to 220.degree. C.
摘要:
A process for preparing halogenated indigo by reacting indigo with bromine and/or chlorine in the presence or absence of iodine as catalyst comprises using thionyl chloride as reaction medium.
摘要:
A process for the purification of indigo comprises treating the indigo with sulfuric acid to give indigo sulfate, separating off and subsequently hydrolyzing the latter to re-form indigo, and then treating the dye with dilute hydrogen peroxide solution.
摘要:
Pure 1-amino-2-phenoxy-4-hydroxyanthraquinone is prepared by reacting 1-amino-2-halo-4-hydroxyanthraquinone with phenol in aqueous suspension at pH 9-13 and 130.degree.-160.degree. C., adjusting the reaction mixture pH to 9.5-11.5 after the reaction has ended, separating the reaction product from the liquid phase, and ,washing it with alkaline hypochlorite solution.
摘要:
A process for purifying indigo comprises extracting an aqueous leuco indigo alkali metal salt solution with an inert solvent under oxygen-excluding conditions and conventionally regenerating the indigo by oxidation.
摘要:
The preparation of anthraquinone imide compounds by condensation of anthraquinone compounds containing at least one primary amino group with halogenized aromatics or by condensation of halogenized anthraquinone compounds with primary aromatic amines, in the presence of a vat-dyeing catalyst and an acid-binding agent in an organic solvent, in which the organic solvent used is an alkyl benzoate.