formic+acid


 * Formic acid ** (also called ** methanoic acid ** ) is the simplest [|carboxylic acid] . Its [|chemical formula] is [|H] [|C] [|O] [|OH] or HCO 2 H. It is an important intermediate in [|chemical synthesis] and occurs naturally, most notably in the [|venom] of [|bee] and [|ant stings] . In fact, its name comes from the [|Latin] word for ant, // [|formica]  //, referring to its early isolation by the [|distillation] of ant bodies. [|Esters] , salts, and the anion derived from formic acid are referred to as [|formates].

Formic acid is a colorless liquid having a highly pungent, penetrating odor at room temperature. It is [|miscible] with [|water] and most polar [|organic] [|solvents], and is somewhat soluble in [|hydrocarbons]. In hydrocarbons and in the vapor phase, it consists of [|hydrogen-bonded] dimers rather than individual molecules.Owing to its tendency to hydrogen-bond, gaseous formic acid does not obey the [|ideal gas law] .Solid formic acid (two [|polymorphs] ) consists of an effectively endless network of hydrogen-bonded formic acid molecules. This relatively complicated compound also forms a low-boiling [|azeotrope] with water (22.4%) and liquid formic acid also tends to supercool.

When [|methanol] and [|carbon monoxide] are combined in the presence of a strong [|base], the formic acid derivative [|methyl formate] results, according to the [|chemical equation] :

CH3OH + CO → HCO2CH3 In industry, this reaction is performed in the liquid phase at elevated pressure. Typical reaction conditions are 80 °C and 40 atm. The most widely-used base is [|sodium methoxide]. [|Hydrolysis] of the methyl formate produces formic acid:

HCO2CH3 + H2O → HCO2H + CH3OH Efficient hydrolysis of methyl formate requires a large excess of water. Some routes proceed indirectly by first treating the methyl formate with [|ammonia] to give [|formamide], which is then hydrolyzed with [|sulfuric acid] :

HCO2CH3 + NH3 → HC(O)NH2 + CH3OH2 HC(O)NH2 + 2 H2O + H2SO4 → 2HCO2H + (NH4)2SO4 This approach suffers from the need to dispose of the [|ammonium sulfate] byproduct. This problem has led some manufacturers to develop energy efficient means for separating formic acid from the large excess amount of water used in direct hydrolysis. In one of these processes (used by [|BASF] ) the formic acid is removed from the water via [|liquid-liquid extraction] with an organic base.