Description

2-(1,3-Dihydro-3-Oxo-5-Sulpho-2H-Indol-2-Ylidene)-3-Oxoindoline-5-Sulphonic Acid is a high-purity, water-soluble organic dye intermediate belonging to the indoline class of compounds. Its core value proposition lies in its role as a critical precursor for synthesizing vibrant and stable dyes and pigments, particularly in the production of acid dyes and food colorants. This compound is essential for manufacturers in the textile, ink, and specialty chemical industries who require consistent quality and reliable supply for their colorant formulations.

Application

• Primary Intermediate for Acid Dyes: A key building block in the synthesis of acid dyes used for coloring nylon, silk, wool, and other protein-based fibers.
• Food Colorant Production: Used in the manufacture of certain synthetic food dyes (where regulatory approved) to achieve specific yellow to red shades.
• Ink and Pigment Manufacturing: Serves as a precursor for organic pigments and specialty inks, including those for security printing and high-performance applications.
• Biological Staining Reagents: Potential use in the synthesis of stains and indicators for histological and cytological applications in laboratories.
• Research & Development: Employed in chemical research for developing new chromophores, fluorescent markers, and functional dyes.
• Photographic Industry: Can be utilized in the synthesis of sensitizing dyes for photographic films and papers.

Basic Information

Product Name	2-(1,3-Dihydro-3-Oxo-5-Sulpho-2H-Indol-2-Ylidene)-3-Oxoindoline-5-Sulphonic Acid
CAS No.	483-20-5
Molecular Formula	C16H8N2O8S2
Molecular Weight	420.37 g/mol
Synonyms	5-Sulfo-2-(3-oxo-5-sulfo-1,3-dihydro-2H-indol-2-ylidene)-2,3-dihydro-1H-indole; Acid Yellow 23 Impurity; C.I. 19140; Food Yellow 4 Intermediate; Tartrazine Intermediate; Trisodium 5-hydroxy-1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl)azo]-1H-pyrazole-3-carboxylate precursor; 2-(3-Oxo-5-sulfo-1,3-dihydro-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one-5-sulfonic acid
EINECS	207-605-5

Quality Control

Our production of 2-(1,3-Dihydro-3-Oxo-5-Sulpho-2H-Indol-2-Ylidene)-3-Oxoindoline-5-Sulphonic Acid adheres to stringent quality management systems to ensure batch-to-batch consistency and high purity. The material is characterized and tested against comprehensive in-house specifications, which include identity confirmation, assay (purity), and control of key impurities. A Certificate of Analysis (COA) detailing all test results is provided with each shipment to support your quality assurance protocols.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at a controlled room temperature (15-25°C). Due to its hygroscopic (moisture-sensitive) nature, the container must be kept sealed when not in use to prevent absorption of atmospheric moisture, which can affect product quality and handling properties.

Specification

Item	Specification
Appearance	Yellow to orange-yellow powder
Identification (IR)	Conforms to reference spectrum
Assay (HPLC)	≥ 95.0%
Loss on Drying	≤ 5.0%
Sulfated Ash	≤ 1.0%
Heavy Metals (as Pb)	≤ 20 ppm
Related Substances (HPLC)	Total impurities ≤ 3.0% Any single impurity ≤ 1.0%
Solubility (1% in Water)	Clear, yellow solution

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.