Acid Green 25 (CI 61570)  is a synthetic green dye used in pharmaceuticals and cosmetics.

The name defines the structure of the molecule:

• CI stands for Color Index,  a reference database managed by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It is used to standardize the names of dyes and pigments.
• 61570 is the specific number assigned to this dye in the color index.

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 61570 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 61570.
• Purification. The crude CI 61570 product is purified using techniques such as crystallization, filtration, and chromatography to remove impurities and achieve a high-purity colorant.
• Stabilization. The purified CI 61570 is stabilized to ensure its stability during transportation and storage, preventing degradation and oxidation.
• Quality control. The CI 61570 undergoes rigorous quality testing to ensure it meets standards for purity, color intensity, and safety. These tests include chemical analysis, spectroscopy, and microbiological testing.

Cosmetics

CI 61570 is a restricted ingredient as  IV/92 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Ingredient at risk: Disodium 2,2'-(9,10-dioxoanthracene-1,4-diyldiimino)bis(5-methylsulphonate)

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.

CI 61570 studies

• Molecular Formula   C₂₈H₂₀N₂Na₂O₈S₂
• Molecular Weight  622.58
• CAS  4403-90-1
• EINECS 224-546-6

Synonyms:

• CI 61570
• D&C Green No. 5
• Alizarin Cyanine Green F
• Erionyl Green GL
• Alizarine Green J
• Aquamine Green GL
• Disodium 2,2'-(9,10-dioxoanthracene-1,4-diyldiimino)bis(5-methylsulphonate)
• Benzenesulfonic acid, 2,2'-((9,10-dihydro-9,10-dioxo-1,4-anthracenediyl)diimino)bis(5-methyl-, disodium salt
• 2,2'-(1,4-Anthraquinonylenediimino)bis(5-methylbenzenesulfonic acid) disodium salt
• 1,4-Bis(o-sulfo-p-toluino)anthraquinone, disodium salt
• m-Toluenesulfonic acid, 6,6'-(1,4-anthraquinonylenediimino)di-, disodium salt
• disodium 5-methyl-2-[[4-(4-methyl-2-sulfonatoanilino)-9,10-dioxoanthracen-1-yl]amino]benzenesulfonate
• sodium 6,6'-(9,10-dioxo-9,10-dihydroanthracene-1,4-diyl)bis(azanediyl)bis(3-methylbenzenesulfonate)
• dipotassium 5-methyl-2-({4-[(4-methyl-2-sulfonatophenyl)amino]-9,10-dioxoanthracen-1-yl}amino)benzenesulfo