Phosphotungstic acid anhydrous (PTA) is a chemical reagent that is used as a solid catalyst for organic reactions. PTA has acidic properties and is soluble in water, methanol, and acetone. It is not soluble in most organic solvents. This compound is typically used to catalyze the reaction of esters with alcohols in the presence of methyl ethyl ketone or methanol solvent. The active form of this chemical reagent may be picolinic acid or zirconium oxide. The hydroxyl group on PTA reacts with the carbonyl carbon atom on the ester molecule to form a phosphotungsten carbonyl intermediate complex that can undergo hydrolysis to produce the desired product. Protonation or deprotonation of this intermediate complex will determine whether this reaction will proceed to completion or not. Fatty acids react readily with PTA in a process called transesterification which produces glycerides||Synonyms:|Tungstophosphoric Acid Hydrate; 12-Tungstophosphate Hydrate; 12-Tungstophosphoric Acid Hydrate||CAS No:|12501-23-4||Molecular Formula:|H3[P(W3O10)4]·xH2O||Molecular Weight:|2880.04 anhy||Purity (Assay):|65-70% (Assay)||Appearance:|White crystalline powder ||Melting Point:|95ºC (lit)||Heavy Metals:|≤0.005%||Sulfate (SO42-):|≤0.02%||Chloride (Cl-):|≤0.3%||Nitrate (NO3-):|≤0.01%||Iron (Fe):|≤0.002%||Ammonium (NH4+):|≤0.02%||Insoluble Material:|≤0.02%||Storage and Stability:|Powder may be stored at RT. Stable for 12 months at RT after receipt.||Warning:|Corrosive!