Code of Federal Regulations Title 21. Food and Drugs § 21.74.203 FD&C Green No. 3

(1) The color additive FD&C Green No. 3 is principally the inner salt disodium salt of N–ethyl–N–[4–[[4–[ethyl[ (3– sulfophenyl)methyl]amino]phenyl](4–hydroxy–2–sulfophenyl)methylene]–2,5– cyclohexadien–1–ylidene]–3–sulfobenzenemethanaminium hydroxide (CAS Reg. No. 2353–45–9);  with smaller amounts of the isomeric inner salt disodium salt of N–ethyl–N–[4–[[4–[ethyl[ (3– sulfophenyl)methyl]amino]phenyl](4–hydroxy–2–sulfophenyl)methylene]– 2,5–cyclohexadien–1–ylidene]–4–sulfobenzenemethanaminium hydroxide; of N–ethyl–N–[4–[[4–[ethyl[ (4–sulfophenyl) methyl]amino]phenyl](4–hydroxy–2–sulfophenyl)methylene]– 2,5–cyclohexadien–1–ylidene]–4–sulfobenzenemethanaminium hydroxide and of N–ethyl–N–[4–[[4–[ethyl[ (2–sulfophenyl)methyl]amino]phenyl](4– hydroxy–2–sulfophenyl)methylene]–2,5–cyclohexadien–1–ylidene]– 3–sulfobenzenemethanaminium hydroxide. Additionally, FD&C Green No. 3 is manufactured by the acid catalyzed condensation of one molecule of 2–formyl–5–hydroxybenzenesulfonic acid with two molecules from a mixture consisting principally of 3–[ (ethylphenylamino)methyl] benzensulfonic acid, and smaller amounts of 4–[ (ethylphenylamino)methyl] benzenesulfonic acid and 2–[ (ethylphenylamino)methyl] benzenesulfonic acid to form the leuco base. The leuco base is then oxidized with lead dioxide and acid or with dichromate and acid to form the dye. The intermediate 2–formyl–5–hydroxy–benzenesulfonic acid is prepared by the potassium permanganate oxidation of 2,2′–(1,2–ethenediyl)–bis(5–aminobenzenesulfonic acid) to sodium 5–amino–2–formylbenzenesulfonate. This amine is diazotized and the resulting diazonium salt is hydrolyzed to the desired 2–formyl–5–hydroxybenzenesulfonic acid.

(2) Color additive mixtures for food use (including dietary supplements) made with FD&C Green No. 3 may contain only those diluents that are suitable and that are listed in part 73 of this chapter as safe for use in color additive mixtures for coloring food.