Cas 6153-56-6 99.6% Oxalic Acid Dihydrate C2H2O4 Industrial Grade for Acid Pickling

COA meets GB/T1626-2008:

References: Riel Chemical Lab1&2, National public service platform for standards information.

Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula HO−C(=O)−C(=O)−OH, also written as (COOH)2 or (CO2H)2 or H2C2O4. It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water.

Its name is derived from early investigators who isolated oxalic acid from flowering plants of the genus Oxalis, commonly known as wood-sorrels. It occurs naturally in many foods. Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.

• Molecular weight: 126.07 g/mol
• Appearance: White transparent crystal or powder, industrial products may be slightly yellow due to impurities
• Odor: Tasteless or slightly sour
• Density: 1.65 g/cm³ (20°C)
• Melting point: The dihydrate lost its crystalline water at 101-102°C and was converted to anhydrous oxalic acid (H₂C₂O₄). Anhydrous oxalic acid sublimates at about 189.5°C and decomposes at high temperatures
• Solubility: Water: soluble in cold water (about 10 g/100 mL, 20°C), hot water solubility is higher. Ethanol: slightly soluble (approx. 5.7g /100 mL, 20°C)
• Acid: Binaric acid, acidic stronger than acetic acid (pKa₁=1.25, pKa₂=4.14); It can react with bases, metal oxides, carbonates to form salts (such as sodium oxalate, calcium oxalate)
• Reducibility: Under acidic conditions can be oxidized by strong oxidants (such as potassium permanganate) to produce CO₂ and H₂O
• Complexation: Oxalate (C₂O₄²⁻) forms a soluble complex with metal ions (e.g. Fe³+, Al³+). It is used in metal cleaning or rust removal
• Thermal decomposition: Decomposition when heated above 150°C, producing CO, CO₂ and H₂O

Oxalic acid is produced primarily by oxidizing carbohydrates or glucose with nitric acid or air in the presence of vanadium pentoxide. Another method is to regenerate nitric acid using oxygen, using a variety of precursors, including glycolic acid and glycol. As of 2011, only the Japanese company Mitsubishi has used this process.

A newer method requires oxidative carbonylation of alcohols to obtain dioxalate: 4 ROH + 4 CO + O 2 -> 2 (CO 2 R) 2 + 2 H 2 O. These diesters are then hydrolyzed to oxalic acid. About 120,000 tons are produced annually.

Historically, oxalic acid was prepared by applying a caustic base (such as sodium hydroxide or potassium hydroxide) to sawdust and then acidifying the oxalate with an inorganic acid (such as sulfuric acid). Oxalic acid can also be formed by heating sodium formate in the presence of an alkaline catalyst.

The main uses of oxalic acid include cleaning or bleaching, especially for rust removal (iron complexing agent). Its use in rust remover is due to the fact that it forms a stable water-soluble salt with trivalent iron, namely the iron oxalate ion.

Oxalic acid is an ingredient in some teeth whitening products. About 25% of oxalic acid is used as a mordant in the dyeing process. It is also used in bleach, especially for pulping wood, cork, straw, rattan, feathers, as well as for rust removal and other cleaning, for baking powder, and as a third reagent in silica analysis instruments.

• Technical advantages: Mature production technology with over 20 years of experience in nitric acid production, ensuring stable quality that exceeds national standards.
• Product quality advantage: High standard quality control with products that meet EU REACH certification, suitable for high-end applications. Focus on green manufacturing and environmental sustainability.
• Industrial chain advantage: Complete industrial chain from nitric acid to potassium nitrate, magnesium nitrate, and nitro water-soluble fertilizer products, enhancing production efficiency and market competitiveness.
• Market and customer advantages: Extensive supply network with stable relationships with quality customers and suppliers, plus international market presence in over 20 countries.
• Environmental protection and energy saving advantages: Energy saving technologies reduce consumption, with a strong commitment to green manufacturing and sustainable development.