Sodium formate: Difference between revisions

{{short description|Chemical compound}}

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 422111969

| Name = Sodium formate

| ImageSize = 125px

| SystematicName = Sodium methanoate

| OtherNames = formic acid, sodium salt

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 141-53-7

| ChEBI = 62965

| ChEMBL_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 183491

| EINECS = 205-488-0

| PubChem = 2723810

| SMILES = [Na+].[O-]C=O

| MolarMass = 68. g/mol

| Density = 1.92 g/cm³ (20°C)

| Solubility = 97 g/100 mL (20°C)

| SolubleOther = insoluble in [[ether]] <br> soluble in [[glycerol]], [[alcohol]]

| = 253

}}

| Section5 = {{Chembox Thermochemistry

| DeltaHf = -666.5 kJ/mol

| DeltaGf = -599.9 kJ/mol

| Entropy = 103.8 J/mol K

| HeatCapacity = 82.7 J/mol K

| NFPA-F =

| NFPA-R =

For commercial use, sodium formate is produced by absorbing [[carbon monoxide]] under pressure in solid [[sodium hydroxide]] at 130&nbsp;°C and 6-8 bar pressure:<ref name="TCS">Arnold Willmes, ''Taschenbuch Chemische Substanzen'', Harri Deutsch, Frankfurt (M.), 2007.</ref>

: + NaOH → ₂

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 [[Neutralization (chemistry)|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 [3-hydroxy-2,2-bis(hydroxymethyl)propanal].<ref>H.-J. Arpe, ''Industrielle Organische Chemie'', 6., vollst. überarb. Aufl., Wiley-VCH Verlag, 2007, {{ISBN|978-3-527-31540-6}}</ref>

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]].

::CHCl₃ + 4 NaOH → HCOONa + 3 NaCl + 2 H₂O

::C₂HCl₃(OH)₂ + NaOH → CHCl₃ + HCOONa + H₂O

== Properties ==

=== Physical properties ===

[[File:Sodium formate dihydrate.jpg|thumb|Some sodium formate dihydrate crystals]]

Sodium formate crystallizes in a [[monoclinic crystal system]] with the [[lattice parameter]]s a&nbsp;=&nbsp;6,19&nbsp;Å, b&nbsp;=&nbsp;6,72&nbsp;Å, c&nbsp;=&nbsp;6,49&nbsp;Å and β&nbsp;=&nbsp;121,7°.<ref name="Zachariasen">W. H. Zachariasen: "The Crystal Structure of Sodium Formate, NaHCO₂" in ''[[J. Am. Chem. Soc.]]'', '''1940''', ''62''(5), S. 1011–1013. {{doi|10.1021/ja01862a007}}</ref>

=== Chemical properties ===

On heating, sodium formate decomposes to form [[sodium oxalate]] and hydrogen.<ref name="Meisel" /> The resulting sodium oxalate can be converted by further heating to [[sodium carbonate]] upon release of carbon monoxide:<ref name="Yoshimori">T. Yoshimori, Y. Asano, Y. Toriumi, T. Shiota: "Investigation on the drying and decomposition of sodium oxalate" in ''[[Talanta]]'' '''1978''', ''25''(10) S. 603-605. {{doi|10.1016/0039-9140(78)80158-1}}</ref><ref name="Meisel">T. Meisel, Z. Halmos, K. Seybold, E. Pungor: "The thermal decomposition of alkali metal formates" in ''[[Journal of Thermal Analysis and Calorimetry]]'' '''1975''', ''7''(1). S. 73-80. {{doi|10.1007/BF01911627}}</ref>

:<chem>2HCOONa ->[\Delta] {(COO)2Na2} + H2\!\uparrow</chem>

:<chem>(COO)2Na2 ->[{} \atop >\ \ce{290^{o}C}] {Na2CO3} + CO\!\uparrow</chem>

As a [[Salt (chemistry)|salt]] of a weak acid ([[formic acid]]) and a [[Base (chemistry)|strong base]] ([[sodium hydroxide]]) sodium formate reacts in aqueous solutions basic:

:<chem>HCOO^- + H2O <<=> HCOOH + OH^-</chem>

A solution of formic acid and sodium formate can thus be used as a [[Buffer (chemistry)|buffer]] solution.

Sodium formate is slightly water-hazardous and inhibits some species of bacteria but is degraded by others.

==Uses==

Sodium formate is used in several fabric dyeing and printing processes. It is also used as a [[buffering agent]] for strong mineral acids to increase their [[pH]], as a food additive (E237), and as a [[de-ice|de-icing]] agent.

In [[structural biology]], sodium formate can be used as a [[cryoprotectant]] for X-ray diffraction experiments on protein crystals,<ref>{{citation | doi=10.1107/S0907444910015416 | first1=G. | last1=Bujacz | first2=B. | last2=Wrzesniewska | first3=A. | last3=Bujacz | title=Cryoprotection properties of salts of organic acids: a case study for a tetragonal crystal of HEW lysozyme | year=2010 | periodical=Acta Crystallographica Section D: Biological Crystallography | volume=66 | issue=7 | pages=789–796| pmid=20606259 }}</ref> which are typically conducted at a temperature of 100 K to reduce the effects of [[radiation damage]].

Sodium formate plays a role in the [[Synthesis (chemistry)|synthesis]] of [[formic acid]], it is converted by sulfuric acid via the following reaction equation:

:<math>\mathrm{2\ HCOONa + H_2SO_4 \longrightarrow 2\ HCOOH + Na_2SO_4}</math>

:<small>Sodium formate is converted with sulfuric acid to formic acid and [[sodium sulfate]].</small>

The [[urticating hair]] of [[stinging nettles]] contain sodium formate as well as formic acid.

Solid sodium formate is used as a non-corrosive agent at [[airport]]s for de-icing of runways in mix with corrosion inhibitors and other additives, which rapidly penetrate solid snow and ice layers, detach them from the asphalt or concrete and melt the ice rapidly. Sodium formate was also used as a road deicer in the city of [[Ottawa]] from 1987 to 1988.<ref>{{cite book|author=Frank M. D'Itri|url=https://books.google.com/books?id=NkGCKevsmpkC&q=Sodium+formate&pg=PA167|title=Chemical Deicers and the Environment|via=[[Google Books]]|year=1992|isbn=9780873717052|page=167| publisher=CRC Press }}</ref>

The high freezing point depression e.g. in comparison to the still frequently used [[urea]] (which is effective but problematic due to [[eutrophication]]) effectively prevents the re-icing, even at temperatures below −15&nbsp;°C. The thawing effect of the solid sodium formate can even be increased by moistening with aqueous [[potassium formate]] or [[potassium acetate]] solutions. The degradability of sodium formate is particularly advantageous with a chemical oxygen demand (COD) of 211&nbsp;mg [[Oxygen|O₂]]/g compared with the de-icing agents [[sodium acetate]] (740&nbsp;mg O₂/g) and urea with (> 2,000&nbsp;mg O₂/g).<ref>{{cite web |url=http://www.deicersnowmeltingthawing.com/ |title=Deicer Anti-icing Snow melting Thawing Chemicals Manufacturers |access-date=2022-03-02 |archive-date=2018-08-05 |archive-url=https://web.archive.org/web/20180805095557/http://deicersnowmeltingthawing.com/ |url-status=dead }}</ref>

Saturated sodium formate solutions (as well as mixtures of other alkali metal formates such as potassium and cesium formate) are used as important drilling and stabilizing aids in gas and [[oil exploration]] because of their relatively high density. By mixing the corresponding saturated alkali metal formate solutions any densities between 1,0 and 2,3 g/cm³ can be set. The saturated solutions are [[Biocide|biocidal]] and [[Long-term stability|long-term stable]] against microbial degradation. Diluted, on the other hand, they are fast and completely biodegradable. As alkali metal formates as drilling aids make it unnecessary to add solid fillers to increase the density (such as [[baryte]]s) and the formate solutions can be recovered and [[Recycling|recycled]] at the drilling site, formates represent an important advance in exploration technology.<ref>William Benton and Jim Turner, Cabot Specialty Fluids: [http://large.stanford.edu/publications/coal/references/docs/m-cabot.pdf Cesium formate fluid succeeds in North Sea HPHT field trials] (PDF; 88&nbsp;kB); In: Drilling Contractor, Mai/Juni 2000.</ref>

* [[ acetate]]

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