Sodium Formaldehyde Sulfoxylate: A Powerful Reducing Agent

CAS Registry Number: 149-44-0 (Anhydrous); 6035-47-8 (Dihydrate)

Overview

Sodium formaldehyde sulfoxylate (also known as sodium hydroxymethanesulfinate or by its trade name Rongalite) is an organic compound with the molecular formula CH₃NaO₃S and a molecular weight of 118.09 g/mol. It appears as a white to off-white crystalline solid with a mild garlic-like odor. The compound is highly soluble in water (up to 680,000 mg/L) and slightly soluble in alcohol.

Key Properties

• Melting Point: ~120 °C (decomposes)

• pH: 9.5–10.5 (in aqueous solution)

• Density: 1.744 g/cm³ at 20°C

• Stability: Stable under normal conditions but incompatible with strong oxidizing agents. Decomposes upon heating, releasing formaldehyde and other gases

Applications

Textile Industry

Sodium formaldehyde sulfoxylate is widely used in textile processing as a discharge agent and reducing agent for vat dyes and indigo dyes. Its strong reducing properties make it effective for color stripping and discharge printing applications.

Polymer Industry

• Acts as a polymerization regulator for plastics

• Serves as a redox activator in styrene-butadiene (SB) rubber production

• Used as a reducing agent for redox-catalyzed polymerization reactions

Other Industrial Uses

• Bleaching agent for molasses, soap, and sugar

• Antioxidant in pharmaceutical applications

• Treatment of mercury poisoning

• Food packaging adhesives and food-contact rubber articles

• Stabilizing agent in various chemical processes