Indanthrene (CI 69800) is a chemical compound, a synthetic blue dye with an anthraquinone unit and is also known as Food Blue 4.

Chemical Name

6,15-Dihydroanthrazine-5,9,14,18-tetrone

Dyes that contain anthraquinone (an organic aromatic compound derived from anthracene) are characteristically bright in colour.

Chemical Industrial Synthesis Process

• Preparation of reagents. The main raw materials include phthalic anhydride, benzene, and concentrated sulfuric acid.
• Synthesis of anthraquinone intermediate. The production of CI 69800 begins with the condensation of phthalic anhydride with benzene in the presence of concentrated sulfuric acid, forming the anthraquinone intermediate.
• Substitution. The anthraquinone is further treated with specific reagents to introduce functional groups that impart the desired color. This may include sulfonation, nitration, or other substitution reactions.
• Oxidation. The functionalized structure undergoes an oxidation reaction to complete the formation of the anthraquinone chromophore, which is responsible for the coloring properties of CI 69800.
• Purification. The crude CI 69800 product is purified using techniques such as crystallization, filtration, and chromatography to remove impurities and achieve a high-purity colorant.
• Stabilization. The purified CI 69800 is stabilized to ensure its stability during transportation and storage, preventing degradation and oxidation.
• Quality control. The CI 69800 undergoes rigorous quality testing to ensure it meets standards for purity, color intensity, and safety. These tests include chemical analysis, spectroscopy, and microbiological testing.

What it is used for and where

Cosmetics

Restricted cosmetic ingredient as IV/95 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Substance or ingredient reported:

• 6,15-Dihydroanthrazine-5,9,14,18-tetrone

Cosmetics - INCI Functions

Colorant. This ingredient has the function of colouring the solution in which it is inserted in a temporary, semi-permanent or permanent manner, either alone or in the presence of the complementary components added for colouring.

Molecular Formula    C₂₈H₁₄N₂O₄

Molecular Weight  442.4 g/mol

CAS     81-77-6

EC number 201-375-5

UNII R68OT0N83K

DTXSID2026280

Synonyms:

Food Blue 4

CI 69800

Indanthrone