Sodium formate

Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder. Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder. For commercial use, sodium formate is produced by absorbing carbon monoxide under pressure in solid sodium hydroxide at 130 °C and 6-8 bar pressure: Because of the low-cost and large-scale availability of formic acid by carbonylation of methanol and hydrolysis of the resulting methyl formate, sodium formate is usually prepared by neutralizing formic acid with sodium hydroxide. Sodium formate is also unavoidably formed as a by-product in the final step of the pentaerythritol synthesis and in the crossed Cannizzaro reaction of formaldehyde with the aldol reaction product trimethylol acetaldehyde . In the laboratory, sodium formate can be prepared by neutralizing formic acid with sodium carbonate. It can also be obtained by reacting chloroform with an alcoholic solution of sodium hydroxide. or by reacting sodium hydroxide with chloral hydrate. The latter method is, in general, preferred to the former because the low aqueous solubility of CHCl3 makes it easier to separate out from the sodium formate solution, by fractional crystallization, than the soluble NaCl would be. Sodium formate may also be created via the haloform reaction between ethanol and sodium hypochlorite in the presence of a base. This procedure is well documented for the preparation of chloroform. Sodium formate crystallizes in a monoclinic crystal system with the lattice parameters a = 6,19 Å, b = 6,72 Å, c = 6,49 Å and β = 121,7°. On heating, sodium formate decomposes to form sodium oxalate and hydrogen. The resulting sodium oxalate can be converted by further heating to sodium carbonate upon release of carbon monoxide: