Difference between revisions of "Sodium nitrite"

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(Some updates regarding availability, and other information)
 
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| PIN =
 
| PIN =
 
| SystematicName =
 
| SystematicName =
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| OtherNames = Nitrous acid, sodium salt
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| OtherNames = E250<br>Nitrous acid, sodium salt
 
<!-- Images -->
 
<!-- Images -->
 
| ImageFile = Sodium nitrite sample.jpg
 
| ImageFile = Sodium nitrite sample.jpg
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| Solvent3 = diethyl ether
 
| Solvent3 = diethyl ether
 
| Solvent =  
 
| Solvent =  
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| VaporPressure =  
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| VaporPressure = ~0 mmHg
 
   }}
 
   }}
 
| Section3 = {{Chembox Structure
 
| Section3 = {{Chembox Structure
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   }}
 
   }}
 
| Section6 = {{Chembox Hazards
 
| Section6 = {{Chembox Hazards
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| AutoignitionPt = 489 °C
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| AutoignitionPt = Non-flammable
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| ExploLimits =  
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| ExploLimits = Non-flammable
 
| ExternalMSDS = [http://www.sciencecompany.com/msds/Sodium_Nitrite_MSDS.pdf ScienceCompany]
 
| ExternalMSDS = [http://www.sciencecompany.com/msds/Sodium_Nitrite_MSDS.pdf ScienceCompany]
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| FlashPt =  
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| FlashPt = Non-flammable
 
| LD50 = 180 mg/kg (rats, oral)
 
| LD50 = 180 mg/kg (rats, oral)
 
| LC50 =  
 
| LC50 =  
−
| MainHazards =  
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| MainHazards = Toxic
 
| NFPA-F =  
 
| NFPA-F =  
 
| NFPA-H =  
 
| NFPA-H =  
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'''Sodium nitrite''' is the inorganic compound, the nitrate salt of nitrous acid with the chemical formula '''NaNO<sub>2</sub>'''.
+
'''Sodium nitrite''' is the inorganic compound, the sodium salt of [[nitrous acid]] with the chemical formula '''NaNO<sub>2</sub>'''.
  
 
==Properties==
 
==Properties==
 
===Chemical===
 
===Chemical===
−
Sodium nitrite will react with [[sodium chloroacetate]] in aqueous solution to give [[nitromethane]]:<ref>http://www.orgsyn.org/demo.aspx?prep=CV1P0401</ref>
+
Sodium nitrite reacts with strong acids to yield nitrous acid, which, at high conc. breaks down into nitric oxide which rapidly oxidizes in air to nitrogen dioxide.
  
−
:NaNO<sub>2</sub> + ClCH<sub>2</sub>COONa + H<sub>2</sub>O → CH<sub>3</sub>NO<sub>2</sub> + NaCl + NaHCO<sub>3</sub>
+
: 2 NaNO<sub>2</sub> + H<sub>2</sub>SO<sub>4</sub> → 2 HNO<sub>2</sub> + Na<sub>2</sub>SO<sub>4</sub>
 +
: 2 HNO<sub>2</sub> → NO<sub>2</sub> + NO + H<sub>2</sub>O
  
−
Sodium nitrite is a poor oxidizing agent, compared to its nitrate cousin.
+
In presence of organic amines, N-nitroso compounds are produced.
 +
 
 +
: HONO + R<sub>2</sub>NH → R<sub>2</sub>N-NO + H<sub>2</sub>O
 +
 
 +
Sodium nitrite will react with [[sodium chloroacetate]] in aqueous solution to produce nitroacetic acid, which decomposes upon heating to yield [[nitromethane]]:<ref>http://www.orgsyn.org/demo.aspx?prep=CV1P0401</ref>
 +
 
 +
: NaNO<sub>2</sub> + ClCH<sub>2</sub>COONa + H<sub>2</sub>O → CH<sub>3</sub>NO<sub>2</sub> + NaCl + NaHCO<sub>3</sub>
 +
 
 +
In the laboratory, sodium nitrite can be used to destroy excess [[sodium azide]].
 +
 
 +
: 2 NaN<sub>3</sub> + 2 NaNO<sub>2</sub> + 4 H<sup>+</sup> → 3 N<sub>2</sub> + 2 NO + 4 Na<sup>+</sup> + 2 H<sub>2</sub>O
 +
 
 +
Above 330 °C sodium nitrite decomposes (in air) to sodium oxide, nitric oxide and nitrogen dioxide.
 +
 
 +
: 2 NaNO<sub>2</sub> → Na<sub>2</sub>O + NO + NO<sub>2</sub>
 +
 
 +
Sodium nitrite is a poor oxidizing agent, compared to its nitrate cousin, and thus it has limited use in flash powders.
  
 
===Physical===
 
===Physical===
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==Availability==
 
==Availability==
−
Sodium nitrite can be found as food additive. It is usually dyed pink to differentiate it from table salt. The dye can be removed by washing it with a solvent and further purification can be achieved by recrystallizing the sodium nitrite.
+
Sodium nitrite can be found as food additive, E250. It is usually dyed pink to differentiate it from table salt. The dye can be removed by washing it with a solvent and further purification can be achieved by recrystallizing the sodium nitrite. It is found in curing salts, where it's found in conc. of around 0.5-1% (Europe) or 6.25% (USA), the rest being table salt.
 +
 
 +
eBay has globally prohibited the sale of sodium nitrite since 2019, and Amazon seems to have done the same. In the US, in the same year, all products with a sodium nitrite concentration of greater than 10% by volume are to be banned under the Consumer Product Safety Act.
 +
 
 +
In the EU countries, the sale of this compound has also been restricted since at least late 2010s, though it's still possible to find various sellers from mostly Eastern Europe that still sell the stuff, either pure or altered.
  
 
==Preparation==
 
==Preparation==
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The resulting slag is grounded and the sodium nitrite is purified by recrystallizing it from water. This procedure has the disadvantage of contaminating the product with lead oxide, making it less safe to handle without proper protection. It is also temperature sensitive.
 
The resulting slag is grounded and the sodium nitrite is purified by recrystallizing it from water. This procedure has the disadvantage of contaminating the product with lead oxide, making it less safe to handle without proper protection. It is also temperature sensitive.
 +
 +
Allegedly there's a more accessible route that replaces lead metal with [[iron]] powder.
  
 
The thermal reduction of sodium nitrate with [[calcium sulfite]] will also yield sodium nitrite.<ref>https://www.google.com/patents/US670021</ref>
 
The thermal reduction of sodium nitrate with [[calcium sulfite]] will also yield sodium nitrite.<ref>https://www.google.com/patents/US670021</ref>
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*Electrochemical grinding
 
*Electrochemical grinding
 
*Meat curing
 
*Meat curing
 +
*Synthesis of iodobenzene
 
*Intravenous mixture of sodium nitrite and [[sodium thiosulfate]] can be used as antidote for cyanide poisoning.
 
*Intravenous mixture of sodium nitrite and [[sodium thiosulfate]] can be used as antidote for cyanide poisoning.
  
 
==Handling==
 
==Handling==
 
===Safety===
 
===Safety===
−
Sodium nitrite is harmful if inhaled or ingested and proper protection should be worn when handling the compound.
+
Sodium nitrite is harmful if inhaled or ingested and proper protection should be worn when handling the compound. Methylene blue is often used as antidote.
  
 
===Storage===
 
===Storage===

Latest revision as of 21:26, 28 November 2025

Sodium nitrite
Sodium nitrite sample.jpg
Sodium nitrite sample on a watch glass.
Names
IUPAC name
Sodium nitrite
Other names
E250
Nitrous acid, sodium salt
Identifiers
Jmol-3D images Image
Properties
NaNO2
Molar mass 68.9953 g/mol
Appearance White or slight yellowish solid
Odor Odorless
Density 2.168 g/cm3
Melting point 271 °C (520 °F; 544 K)
Boiling point 320 °C (608 °F; 593 K) (decomposes)
71.4 g/100 mL (0 °C)
84.8 g/100 mL (25 °C)
160 g/100 mL (100 °C)
Solubility Very soluble in anhydrous ammonia
Soluble in ethanol
Solubility in ethanol 3 g/100 ml
Solubility in methanol 4.4 g/100 ml
Solubility in diethyl ether 0.3 g/100 mL
Vapor pressure ~0 mmHg
Acidity (pKa) ~9
Thermochemistry
106 J·mol-1·K-1
−359 kJ/mol
Hazards
Safety data sheet ScienceCompany
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
180 mg/kg (rats, oral)
Related compounds
Related compounds
 Lithium nitrite
Potassium nitrite
Rubidium nitrite
Caesium nitrite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium nitrite is the inorganic compound, the sodium salt of nitrous acid with the chemical formula NaNO2.

Properties

Chemical

Sodium nitrite reacts with strong acids to yield nitrous acid, which, at high conc. breaks down into nitric oxide which rapidly oxidizes in air to nitrogen dioxide.

2 NaNO2 + H2SO4 → 2 HNO2 + Na2SO4
2 HNO2 → NO2 + NO + H2O

In presence of organic amines, N-nitroso compounds are produced.

HONO + R2NH → R2N-NO + H2O

Sodium nitrite will react with sodium chloroacetate in aqueous solution to produce nitroacetic acid, which decomposes upon heating to yield nitromethane:[1]

NaNO2 + ClCH2COONa + H2O → CH3NO2 + NaCl + NaHCO3

In the laboratory, sodium nitrite can be used to destroy excess sodium azide.

2 NaN3 + 2 NaNO2 + 4 H+ → 3 N2 + 2 NO + 4 Na+ + 2 H2O

Above 330 °C sodium nitrite decomposes (in air) to sodium oxide, nitric oxide and nitrogen dioxide.

2 NaNO2 → Na2O + NO + NO2

Sodium nitrite is a poor oxidizing agent, compared to its nitrate cousin, and thus it has limited use in flash powders.

Physical

Sodium nitrite is a white or white-yellowish hygroscopic solid, soluble in water and slightly soluble in primary alcohols, while insoluble in alkanes and chlorocarbons. It has a density of 2.168 g/cm3. It melts when heated to 271 °C, and will also decompose, with significant decomposition starting above 320 °C.

Availability

Sodium nitrite can be found as food additive, E250. It is usually dyed pink to differentiate it from table salt. The dye can be removed by washing it with a solvent and further purification can be achieved by recrystallizing the sodium nitrite. It is found in curing salts, where it's found in conc. of around 0.5-1% (Europe) or 6.25% (USA), the rest being table salt.

eBay has globally prohibited the sale of sodium nitrite since 2019, and Amazon seems to have done the same. In the US, in the same year, all products with a sodium nitrite concentration of greater than 10% by volume are to be banned under the Consumer Product Safety Act.

In the EU countries, the sale of this compound has also been restricted since at least late 2010s, though it's still possible to find various sellers from mostly Eastern Europe that still sell the stuff, either pure or altered.

Preparation

There are many ways to prepare sodium nitrite.

A known process involves the reduction of sodium nitrate with metallic lead. About 8.5 g of powdered NaNO3 is mixed with 21 g of lead and heated until it melts. The mixture is kept liquid and stirred/agitated for 30-45 minutes until all the lead is oxidized to lead(II) oxide and forming sodium nitrite.

NaNO3 + Pb → NaNO2 + PbO

The resulting slag is grounded and the sodium nitrite is purified by recrystallizing it from water. This procedure has the disadvantage of contaminating the product with lead oxide, making it less safe to handle without proper protection. It is also temperature sensitive.

Allegedly there's a more accessible route that replaces lead metal with iron powder.

The thermal reduction of sodium nitrate with calcium sulfite will also yield sodium nitrite.[2]

NaNO3 + CaSO3 → NaNO2 + CaSO4

Calcium sulfamate can also be used.

Another method involves heating sodium nitrite with carbon in the presence of sodium hydroxide or calcium hydroxide.

2 NaNO3 + 2 NaOH + C → 2 NaNO2 + Na2CO3 + H2O
2 NaNO3 + Ca(OH)2 + C → 2 NaNO2 + CaCO3 + H2O

The latter method is preferred as calcium carbonate is insoluble in water and can be easily removed from the slag.[3]

A mixture of aluminium powder and sodium nitrate heated for 40 minutes will yield sodium nitrite.

The industrial route involves treating an aqueous solution of sodium hydroxide with a mixture of nitrogen dioxide and nitric oxide:

2 NaOH + NO2 + NO → 2 NaNO2 + H2O

This reaction is air-sensitive and traces of oxygen will lead to sodium nitrate.

Very pure sodium nitrite can be obtained by reacting nitrous acid (which can be obtained by adding dinitrogen trioxide to pure water) with sodium hydroxide.

2 NaOH + N2O3 → 2 NaNO2 + H2O

An interesting method involves reducing sodium nitrate using starch and sodium hydroxide.[4]

Projects

  • Make alkyl nitrites
  • Make nitromethane
  • Destroy azides
  • Make azo compounds
  • Electrochemical grinding
  • Meat curing
  • Synthesis of iodobenzene
  • Intravenous mixture of sodium nitrite and sodium thiosulfate can be used as antidote for cyanide poisoning.

Handling

Safety

Sodium nitrite is harmful if inhaled or ingested and proper protection should be worn when handling the compound. Methylene blue is often used as antidote.

Storage

Sodium nitrite should be kept in closed bottles, away from light, moisture and oxygen-rich environment.

Disposal

Heating sodium nitrite above 300 °C will cause it to decompose, leaving behind sodium oxide/hydroxide which can be safely disposed of.

Adding sodium percarbonate to sodium nitrite will convert it to sodium nitrate.

References

  1. ↑ http://www.orgsyn.org/demo.aspx?prep=CV1P0401
  2. ↑ https://www.google.com/patents/US670021
  3. ↑ http://www.google.com/patents/US792515
  4. ↑ http://www.sciencemadness.org/talk/viewthread.php?tid=52&page=10#pid493212

Relevant Sciencemadness threads

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