Formic Acid

[64-18-6] CH2O2 (MW 46.03) InChI = 1S/CH2O2/c2-1-3/h1H,(H,2,3) InChIKey = BDAGIHXWWSANSR-UHFFFAOYSA-N (formation of formate esters,3 amides;7 reductions;10 transfer hydrogenation;12 rearrangements22) Alternate Name: methanoic acid. Physical Data: strongest of the simple organic acids; pKa 3.77 (4.77 for acetic acid). Pure acid, mp 8.4 °C; bp 100.7 °C, 50 °C/120 mmHg, 25 °C/40 mmHg. Formic acid and water form an uncommon maximum boiling azeotrope, bp 107.3 °C, containing 77.5% acid. The dielectric constant of formic acid is 10 times greater than acetic acid. Solubility: misc water in all proportions; misc EtOH, ether; mod sol C6H6. Form Supplied in: commercially available as 85–95% aqueous solutions and as glacial formic acid, containing 2% water. Analysis of Reagent Purity: formic acid is determined by titration with base. If other acids are present, formic acid content can be determined by a redox titration based on oxidation with potassium permanganate. Methods for analysis of trace organic and inorganic materials are presented.2, 23 Purification: fractional distillation in vacuo; dehydration over CuSO4 or boric anhydride.24 Handling, Storage, and Precautions: the strongly acidic nature of formic acid is the primary safety concern. Contact with the skin will cause immediate blistering. Immediately treat affected areas with copious amounts of water. Do not use dilute base solutions as a first treatment. Formic acid has a large heat of solution; the combined heat of neutralization and dilution will lead to thermal burns. Eye protection, gloves, and a chemical apron should be worn during all operations with concentrated formic acid. Volatile; vapors will cause intense irritation to mouth, nose, eyes, skin, and upper respiratory tract. Use of an appropriate NIOSH/MSHA respirator is recommended. Use in a fume hood. During storage, glacial formic acid decomposes to form water and carbon monoxide. Pressure can develop in sealed containers and may result in rupture of the vessel. Ventilation should be provided to prevent the buildup of carbon monoxide in storage areas. Storage temperatures above 30 °C should be avoided. Formic acid is incompatible with strong oxidizing reagents, bases, and finely powdered metals, furfuryl alcohol, and thallium nitrate. Contact with conc sulfuric acid will produce carbon monoxide from decomposition.