Sodium formate

Natriummethanoat

Colorless, deliquescent, bitter - salty -tasting, rhombic prisms or plates

Fixed

1.92 g · cm -3 ( 20 ° C)

261 ° C ( decomposition)

550 g · l-1 (20 ° C ) in water

-666.5 KJ / mol

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Sodium is the sodium salt of formic acid.

Representation

Technically sodium from sodium hydroxide and carbon monoxide at 130 ° C and 6-8 bar pressure is produced:

Because of the low-cost large-scale availability of formic acid by carbonylation of methanol and hydrolysis of the resulting methyl formate Sodium formate is usually produced by neutralization of formic acid with sodium hydroxide. Sodium formate is also produced as an unavoidable product in the last stage of the synthesis of pentaerythritol, of the crossed Cannizzaro reaction of formaldehyde with the aldol reaction product trimethylolacetaldehyde [3 -hydroxy-2 ,2-bis (hydroxymethyl ) propanal ].

Properties

Physical Properties

Sodium formate crystallizes in the monoclinic crystal system in space group C21 / n with lattice parameters a = 6.19 Å, b = 6.72 Å, c = 6.49 Å and β = 121.7 °.

Chemical Properties

When heated, sodium formate decomposes initially to form sodium oxalate and hydrogen. The resulting sodium oxalate proceeds with evolution of carbon monoxide in sodium carbonate on further heating.

As the salt of a weak acid ( formic acid) and a strong base ( sodium hydroxide solution), a solution of sodium formate in water reacts as a base:

A solution of formic acid and sodium formate can thus be used as a buffer solution.

Use

Sodium plays a role in the synthesis of formic acid, in this case it is reacted with sulfuric acid under the following reaction equation to the following:

The stinging hairs of nettles contain, besides formic acid, among others, also sodium.

Sodium formate is slightly hazardous for water and inhibits some bacterial species from other but it is degraded.

Solid sodium formate at airports for deicing of start and runways, taxiways and aprons, treated with corrosion inhibitors and other additives used as non-corrosive scattering agent quickly into solid snow and ice from penetrating, it separates from asphalt or concrete and the ice melts rapidly ( " de -icing effect" ). The high freezing point depression, for example, compared to the more commonly used, but problematic because of its eutrophication effect Taumittel urea effectively prevents re-icing ( "anti -icing effect" ), even at very low temperatures below -15 ° C. The de-icing of the solid sodium formate can be increased by wetting with aqueous potassium formate or potassium acetate solutions. The degradability of the sodium formate is particularly advantageous with a chemical oxygen demand COD of 211 mg O2 / g compared to the Enteisungmitteln sodium acetate with 740 mg O2 / g and urea with > 2,000 mg O2 / g.

Saturated sodium formate solutions as well as mixtures of other alkali metal formates, eg Potassium and cesium, on account of their relatively high density drilling and used as important aids in stabilizing the oil and gas exploration. By mixing the corresponding saturated alkali metal solutions arbitrary densities from 1.0 to 2.3 g/cm3 can be adjusted. The saturated solutions are biocidal and long-term stability against microbial degradation. Thinned they in turn are rapidly and completely biodegradable. Since one in alkali metal formates as drilling aids to the addition of rigid fillers such as Can dispense with barite to increase the density and recovered formate solutions at the well site and can be recycled, formates provide an important advancement in exploration technology dar.

Sodium formate is also used for the preparation of oxalic acid.