2′-anilino-6′-[ethyl(3-methylbutyl)amino]-3′-methylspiro[isobenzofuran-1(3H),9′-[9H]xanthene]-3-one

2′-Anilino-6′-[ethyl(3-methylbutyl)amino]-3′-methylspiro[isobenzofuran-1(3H),9′-[9H]xanthene]-3-one (CAS: 70516-41-5), commonly known as WinCon-205, is a black fluoran thermosensitive dye primarily used in the thermal paper industry.

🔬 Chemical Properties

• Molecular Formula: C₃₄H₃₄N₂O₃

• Molecular Weight: 518.65 g/mol

• Appearance: Light-colored to colorless crystalline solid

• Melting Point: 164–168°C

• Solubility: Slightly soluble in water (100 μg/L), soluble in organic solvents

• LogP: 4.2 (indicating moderate lipophilicity)

• Storage Conditions: Store under inert gas (nitrogen or argon) at 2–8°C

• pKa: Approximately 5.24

• Vapor Pressure: 0 Pa at 25°C

• Density: Approximately 1.25 g/cm³ chemdad.com

🧪 Mechanism of Action

WinCon-205 functions as a color former in thermal paper. Upon heating, it undergoes a chemical reaction with an acidic developer (such as bisphenol A or clay), leading to the cleavage of the lactone ring and resulting in the formation of a black-colored compound. This reaction is reversible and temperature-dependent, making it ideal for use in thermal printing applications.

🛠️ Applications

• Thermal Paper: Used in fax paper, receipt paper, and other thermal printing products.

• Thermochromic Inks: Incorporated into inks that change color with temperature variations.

• Security Printing: Utilized in anti-counterfeiting measures due to its reversible color change properties.