Potassium nitrite

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Potassium nitrite
Identifiers
3D model (
JSmol
)
ChEMBL
ChemSpider
ECHA InfoCard
 100.028.939 Edit this at Wikidata
EC Number
  • 231-832-4
E number E249 (preservatives)
RTECS number
  • TT3750000
UNII
UN number 1488
  • InChI=1S/K.HNO2/c;2-1-3/h;(H,2,3)/q+1;/p-1 checkY
    Key: BXNHTSHTPBPRFX-UHFFFAOYSA-M checkY
  • InChI=1/K.HNO2/c;2-1-3/h;(H,2,3)/q+1;/p-1
    Key: BXNHTSHTPBPRFX-REWHXWOFAI
  • [K+].[O-]N=O
Properties
KNO2
Molar mass 85.10379 g/mol
Appearance white or slight yellow solid
deliquescent
Density 1.914986 g/cm3
Melting point 440.02 °C (824.04 °F; 713.17 K) (decomposes)
Boiling point 537 °C (999 °F; 810 K) (explodes)
281 g/100 mL (0 °C)
312 g/100 mL (25 °C)
413 g/100 mL (100 °C)
Solubility soluble in alcohol, ammonia
−23.3·10−6 cm3/mol
Thermochemistry
107.4 J/mol K
Std enthalpy of
formation
(ΔfH⦵298)
 -369.8 kJ/mol
Hazards
GHS labelling:
GHS03: OxidizingGHS06: ToxicGHS09: Environmental hazard
Danger
H272, H301, H400
P210, P220, P221, P264, P270, P273, P280, P301+P310, P321, P330, P370+P378, P391, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
3
0
2
OX
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
235 mg/kg
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
 Potassium nitrate
Other cations
 Sodium nitrite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Potassium nitrite (distinct from

crystalline powder that is soluble in water.[1]

It is a strong oxidizer and may accelerate the combustion of other materials. Like other nitrite salts such as

teratogenic
. Gloves and safety glasses are usually used when handling potassium nitrite.

Discovery

Péligot
and the reaction was established as:

Production

Potassium nitrite can be obtained by the reduction of potassium nitrate. The production of potassium nitrite by absorption of nitrogen oxides in potassium hydroxide or potassium carbonate is not employed on a large scale because of the high price of these alkalies. Furthermore, the fact that potassium nitrite is highly soluble in water makes the solid difficult to recover.

Reactions

The mixing of cyanamide and KNO2 produces changes from white solids to yellow liquid and then to orange solid, forming cyanogen and ammonia gases. No external energy is used and the reactions are carried out with a small amount of O2.[3]

Potassium nitrite forms potassium nitrate when heated in the presence of oxygen from 550 °C to 790 °C. The rate of reaction increases with temperature, but the extent of reaction decreases. At 550 °C and 600 °C the reaction is continuous and eventually goes to completion. From 650 °C to 750 °C, as the case of decomposition of potassium nitrate is, the system attains equilibrium. At 790 °C, a rapid decrease in volume is first observed, followed by a period of 15 minutes during which no volume changes occur. This is then followed by an increase in volume due primarily to the evolution of nitrogen, which is attributed to the decomposition of potassium nitrite.[4]

Potassium nitrite reacts at an extremely slow rate with a liquid ammonia solution of

cobaltic oxide, to form nitrogen and potassium hydroxide
.

Medical uses

Interest in a medical role for inorganic nitrite was first aroused because of the spectacular success of organic nitrites and related compounds in the treatment of

venesection and wrongly concluded that the pain must be due to elevated blood pressure. As a treatment for angina, the reduction of circulating blood by venesection was inconvenient. Therefore, he decided to try the effect on a patient of inhaling amyl nitrite, a recently synthesized compound and one that his colleague had shown lowered blood pressure in animals. Pain associated with an anginal attack disappeared rapidly, and the effect lasted for several minutes, generally long enough for the patient to recover by resting. For a time, amyl nitrite was the favored treatment for angina, but due to its volatility, it was replaced by chemically related compounds that had the same effect.[2]

The effect of potassium nitrite on the nervous system, brain, spinal cord, pulse, arterial blood pressure, and respiration of healthy human volunteers was noted, as was the variability between individuals. The most significant observation was that even a small dose of <0.5 grains (≈30 mg) given by mouth caused, at first, an increase in arterial blood pressure, followed by a moderate decrease. With larger doses, pronounced hypotension ensued. They also noted that potassium nitrite, however administered, had a profound effect on the appearance and oxygen-carrying capacity of the blood. They compared the biological action of potassium nitrite with that of amyl and ethyl nitrites and concluded that the similarity of action depends on the conversion of organic nitrites to nitrous acid. [2]

Solutions of acidified nitrite have been used successfully to generate NO and to induce

vasorelaxation in isolated blood vessel studies, and the same reaction mechanism has been proposed to explain the biological action of nitrite.[2]

Other uses

Potassium nitrite is used in the manufacturing of heat transfer salts. As

INS number
249).

Reactivity hazards

When reacting with acids, potassium nitrite forms toxic nitrous oxides. Fusion with ammonium salts results in effervescence and ignition. Reactions with reducing agents can result in fires and explosions.[8]

Storage requirements

Potassium nitrite is stored with other oxidizing agents but separated from flammables, combustibles,

cyanides, ammonium compounds, amides, and other nitrogenous salts in a cool, dry, well ventilated location.[8]

See also

External links

  1. ^ Santa Cruz Biotechnology. "Potassium Nitrite Materials and Safety Sheet". {{cite web}}: Missing or empty |url= (help)
  2. ^
    PMID 18427145
    .
  3. PMID 454677
    .
  4. doi:10.1021/ja01561a015
    .
  5. ^ UK Food Standards Agency: "Current EU approved additives and their E Numbers". Retrieved 2011-10-27.
  6. ^ US Food and Drug Administration: "Listing of Food Additives Status Part II". Food and Drug Administration. Retrieved 2011-10-27.
  7. ^ Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27.
  8. ^
    doi:10.1021/ed085p779. Archived from the original
    on 2012-06-22. Retrieved 2012-06-22.
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