This invention relates to an improved method for the preparation of highly or substantially pure Indigotindisulfonate sodium (1). It further relates to the novel crystalline form I of Indigotindisulfonate sodium (1) and the process for its preparation.

This invention relates to an improved method for the preparation of highly or substantially pure Indigotindisulfonate sodium (1). It further relates to the novel crystalline form I of Indigotindisulfonate sodium (1) and the process for its preparation.

Stable aqueous leucoindigo solution comprising an aromatic amine in the form of aniline or aniline and N-methylaniline, wherein said leucoindigo is in the form of an alkali metal salt;

wherein the concentration of the aromatic amine is below 40 ppm determined according to ISO 14362-1:2017(E); and
wherein the concentration of the leucoindigo salt is in a concentration range of from 10 to 45% by weight based on the total weight of the solution, and wherein the stability of the solution is measured at a temperature of 23 C.; or
wherein the concentration of the leucoindigo salt is in a concentration range of from 45 to 65% by weight based on the total weight of the solution, and wherein the stability of the solution is measured at a temperature of 60 C.

Stable aqueous leucoindigo solution comprising an aromatic amine in the form of aniline or aniline and N-methylaniline, wherein said leucoindigo is in the form of an alkali metal salt;

wherein the concentration of the aromatic amine is below 40 ppm determined according to ISO 14362-1:2017(E); and
wherein the concentration of the leucoindigo salt is in a concentration range of from 10 to 45% by weight based on the total weight of the solution, and wherein the stability of the solution is measured at a temperature of 23 C.; or
wherein the concentration of the leucoindigo salt is in a concentration range of from 45 to 65% by weight based on the total weight of the solution, and wherein the stability of the solution is measured at a temperature of 60 C.

Described herein are compositions including O,O-diacetyl leucoindigo. Also described herein are methods of pre-dyeing fibers with O,O-diacetyl leucoindigo, followed by developing the pre-dyed fibers using hydrolysis or oxidation conditions to form indigo-dyed fibers. Also disclosed are indigo-dyed fibers, textiles, and fabrics made using O,O-diacetyl leucoindigo, wherein cellulose, polyester, polyacrylonitrile, nylon, wool, and other compositional fiber types are suitably dyed with indigo dye using the described compositions and methods.

Described herein are compositions including O,O-diacetyl leucoindigo. Also described herein are methods of pre-dyeing fibers with O,O-diacetyl leucoindigo, followed by developing the pre-dyed fibers using hydrolysis or oxidation conditions to form indigo-dyed fibers. Also disclosed are indigo-dyed fibers, textiles, and fabrics made using O,O-diacetyl leucoindigo, wherein cellulose, polyester, polyacrylonitrile, nylon, wool, and other compositional fiber types are suitably dyed with indigo dye using the described compositions and methods.

The present disclosure relates to the biosynthesis of indigoid dye precursors and their conversion to indigoid dyes. Specifically, the present disclosure relates to methods of using polypeptides to produce indigoid dye precursors from indole feed compounds, and the use of the indigoid dye precursors to produce indigoid dyes.

The present disclosure relates to the biosynthesis of indigoid dye precursors and their conversion to indigoid dyes. Specifically, the present disclosure relates to methods of using polypeptides to produce indigoid dye precursors from indole feed compounds, and the use of the indigoid dye precursors to produce indigoid dyes.

Process for preparing disodium 5,5-indigosulfonate, the feedstock being indigo, this process including the following steps: i) the indigo is subjected to a sulfonation treatment resulting in a mixture that contains 5,5-indigosulfonic acid, this process including: ii) a reduction treatment is applied to the mixture obtained in step i), and optionally a purification step, so as to obtain a composition including leuco-5,5-indigosulfonic acid, iii) the leuco-5,5-indigosulfonic acid is isolated from the composition resulting from step ii), iv) the leuco-5,5-indigosulfonic acid resulting from step iii) is oxidized to give disodium 5,5-indigosulfonate.

Process for preparing disodium 5,5-indigosulfonate, the feedstock being indigo, this process including the following steps: i) the indigo is subjected to a sulfonation treatment resulting in a mixture that contains 5,5-indigosulfonic acid, this process including: ii) a reduction treatment is applied to the mixture obtained in step i), and optionally a purification step, so as to obtain a composition including leuco-5,5-indigosulfonic acid, iii) the leuco-5,5-indigosulfonic acid is isolated from the composition resulting from step ii), iv) the leuco-5,5-indigosulfonic acid resulting from step iii) is oxidized to give disodium 5,5-indigosulfonate.