3-O-Ethyl-L-Ascorbic Acid (Stable Vitamin C) Professional cosmetic ingredient — not a finished product. Make high-performance Vitamin C serums that stay clear and effective for months — not days. If you’ve ever watched a Vitamin C serum turn brown and useless within a week, you’ve experienced the core problem with L-Ascorbic Acid: it oxidizes rapidly on contact with air, light, and trace metals. 3-O-Ethyl Ascorbic Acid solves this at the molecular level. By etherifying the 3-position of the ascorbic acid molecule, this derivative resists oxidation while retaining the ability to convert back to active Vitamin C in the skin — delivering brightening, antioxidant, and collagen-stimulating benefits in a formula that stays stable for months. What Is 3-O-Ethyl Ascorbic Acid? 3-O-Ethyl Ascorbic Acid (3-O-EAC) is a stable, water-soluble Vitamin C derivative where an ethyl group is bonded to the 3-position of the ascorbic acid ring. This modification prevents the rapid oxidation that makes L-Ascorbic Acid so difficult to formulate with, while the molecule retains its ability to be enzymatically converted to ascorbic acid in the skin. Unlike L-Ascorbic Acid, which requires a pH below 3.5 for optimal efficacy and causes significant irritation at effective concentrations, 3-O-EAC is effective at a more skin-friendly pH of 4.0–6.0 and is well-tolerated even by sensitive skin. It is one of the most widely used stable Vitamin C derivatives in professional cosmetic formulation. Key Specs INCI 3-O-Ethyl Ascorbic Acid CAS No. 86404-04-8 Appearance White to off-white crystalline powder Solubility Soluble in water and ethanol; limited solubility in oils Typical Usage Rate 0.5–3% (brightening); up to 5% (intensive antioxidant/brightening) pH Range 4.0–6.0 preferred; optimal stability and efficacy at pH 4.0–4.5 Processing Add at cool-down (below 40°C); avoid prolonged heat and alkaline pH Stability Significantly more stable than L-Ascorbic Acid; use chelator + antioxidant for maximum shelf life Grade Cosmetic grade; vegan-friendly Key Benefits Stable Vitamin C delivery — resists oxidation that degrades L-Ascorbic Acid; formulas stay clear and active for months when properly stabilized with a chelator Brightening & anti-hyperpigmentation — inhibits tyrosinase and reduces melanin synthesis; effective on dark spots, PIH, and uneven skin tone Antioxidant protection — neutralizes free radicals and reactive oxygen species; protects skin from UV-induced oxidative damage when used alongside SPF Collagen synthesis support — Vitamin C is a required cofactor for collagen cross-linking; supports skin firmness and reduces the appearance of fine lines over time Skin-friendly pH range — effective at pH 4.0–6.0, significantly less irritating than L-Ascorbic Acid which requires pH
