Back to results
US 12,269,954 B2Granted
Process for the preparation of Indigotindisulfonate sodium (indigo carmine)
AssigneeProvepharm Life Solutions
InventorsManik Reddy Pullagurla, Jagadeesh Babu Rangisetty
Life of this patent
Estimating the term…
Abstract
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.
Claims27
A process for preparing Indigotindisulfonate sodium having a purity greater than 99.0%, comprising:
- treating a 2-nitrobenzaldehyde with a base to give a 2,2′-biindolylidene-3,3′-dione;
- converting the 2,2′-biindolylidene-3,3′-dione into crude Indigotindisulfonate sodium by treating with sulphuric acid;
- and
- purifying the crude Indigotindisulfonate sodium by recrystallizing from suitable solvents to provide pure Indigotindisulfonate sodium.
1 more element
A process for purifying Indigotindisulfonate sodium comprising:
- suspending crude Indigotindisulfonate sodium in suitable solvents selected from the group consisting of protic solvents, aprotic solvents, and mixtures thereof;
- heating the suspension to 60-65° C.;
- cooling the suspension to 20-25° C.;
- filtering the suspension and washing with a suitable protic solvent at 20-25° C., to isolate a crystalline form of Indigotindisulfonate sodium;
- and
- optionally repeating the process with a mixture of solvents to increase a purity of Indigotindisulfonate sodium.
3 more elements
Dependencies are inferred from the claim text.