Sodium 6-Hydroxy-2-Naphthalenesulfonate CAS 135-76-2

Introduction to Sodium 6-Hydroxy-2-Naphthalenesulfonate

Sodium 6-Hydroxy-2-Naphthalenesulfonate is an aromatic naphthalene derivative featuring a hydroxyl group at the 2-position and a sulfonic acid sodium salt at the 6-position. Its molecular architecture provides a highly activated aromatic ring for electrophilic substitution, while the sulfonate group ensures excellent aqueous solubility. At room temperature, the material appears as a white to off-white crystalline powder. It dissolves readily in water and alkaline solutions, remaining stable under standard processing conditions.

The hydroxyl group strongly directs electrophilic attack to the adjacent 1-position, enabling highly regioselective azo coupling. The hydrophilic sulfonate moiety imparts complete water solubility to final dye molecules, preventing precipitation in hard water dye baths and promoting uniform fiber penetration during textile processing.

Sodium 6-Hydroxy-2-Naphthalenesulfonate Chemical & Physical Properties

Applications of Sodium 6-Hydroxy-2-Naphthalenesulfonate

Azo and reactive dye synthesis: Acts as a primary coupling component. It reacts with diazonium salts to produce vibrant red, orange and yellow acid dyes for wool, silk and leather. Its specific substitution pattern guarantees brilliant color shades and high tinctorial strength, with excellent leveling and build-up properties on textile fibers.

Optical brightening agents: Serves as a foundational building block for synthesizing fluorescent whitening agents used in paper, textiles and detergents. The rigid naphthalene core enhances the fluorescence quantum yield of the final optical brightener, delivering superior whitening performance.

Pigment lakes: Precipitated with metal salts like barium or calcium to form insoluble pigment lakes utilized in printing inks, plastics and industrial coatings. These lakes offer good lightfastness and chemical resistance for durable color applications.

Storage & Safety Precautions for Schaeffer’s Salt

• Store in tightly sealed, opaque fiber drums or multi-wall kraft bags below 25 °C. The powder is slightly hygroscopic and can darken upon prolonged UV exposure, which degrades coupling reactivity and color yield.
• Use local exhaust ventilation and wear N95 respirators during bag slitting and dry blending operations. Fine crystalline dust poses a mild respiratory nuisance; avoid prolonged inhalation.
• Wear safety goggles and nitrile gloves during handling. The material can cause mild mechanical irritation to the eyes and skin upon prolonged contact. Rinse thoroughly with water in case of contact.
• When preparing aqueous coupling baths, dissolve the powder completely in warm water and adjust pH with soda ash before adding the diazonium salt. Incomplete dissolution leads to localized high-concentration spots and unwanted byproduct formation.

Schaeffer’s Salt FAQ

Q: How is Sodium 6-Hydroxy-2-Naphthalenesulfonate used in dye synthesis?

A: It acts as a crucial coupling component for synthesizing azo dyes. Its hydroxyl and sulfonate groups direct the coupling reaction, yielding vibrant acid and reactive dyes with excellent water solubility and high lightfastness for textile dyeing.

Q: Why does this product provide high dye solubility?

A: It contains a strongly hydrophilic sodium sulfonate group. This ionic moiety ensures the resulting azo dyes dissolve completely in aqueous dye baths, promoting uniform fiber penetration and preventing uneven spotting during textile processing.

Q: What storage conditions are required for Schaeffer’s Salt?

A: It is moderately hygroscopic and sensitive to prolonged light exposure. Store the crystalline powder in tightly sealed, opaque drums in a cool, dry warehouse to prevent moisture caking and preserve its chemical reactivity for dye coupling reactions.