Performance of the structure

1. Oxidation
Contact with organic matter can burn and explode, and give off toxic and irritating nitrogen peroxide and nitrogen oxide gas.

2. Easy deliquescence
It is oxidized to sodium nitrate in the air. This product is one of the food additives of acute toxicity, intake of large doses of sodium nitrite, can make hemoglobin into methemoglobin and lose the ability to transport oxygen, resulting in hypoxia of the body, until death.

3. High moisture absorption
Oxidation in the air under normal temperature is very slow, heating to 320℃ above the decomposition of nitrogen, oxygen, nitric oxide, and finally produce sodium oxide. Easy to burn and explode in contact with organic matter. The crystalline sodium nitrite has a transformation point between 160 ~ 162℃, at which time the physical properties such as expansibility, conductivity, specific heat and piezoelectric properties all change. Soluble in water and liquid ammonia, its aqueous solution is alkaline (PH = 9). Slightly soluble in anhydrous ethanol, methanol, ether. Dew in the air slowly oxidized to sodium nitrate. Heating to 320 ℃ above the decomposition of oxygen, nitric oxide, the final formation of sodium oxide. Easy to burn and explode in contact with organic matter. Poisonous!

4. Easy to water absorption
It should be kept in a dry, airtight container where nitrite is easily oxidized by oxygen in the air. NaNO2 solutions are unstable and cannot be stored for long periods of time. NaNO2 forms a weak acid when it encounters an acid and produces a brown gas called N2O3. Sodium nitrite is toxic and cannot be tasted with the mouth.

5. NaNO2
Different inorganic acids or carboxylic acids will produce HNO2. In most organic synthesis, NaNO2 is involved in the reaction in the form of unstable HNO2, and the reaction involving HNO2 is usually very complex, because N2O3, ON+ and so ON exist in the solution. A range of compounds, including NOX and RNH2, can undergo diazotization and nitroso reactions.
Reactions with ammonia and related substances under normal circumstances, NaNO2's HCl solution can react with ammonia quickly, and most of them can react quantitatively. For primary amines, the reaction produces diazo ion intermediates, which then eliminate one molecule of N2 to form carbocation, and further react with electrophiles (eq. 1~3).
However, when there are multiple nucleophilic functional groups in the molecule, the diazo group formed may continue to react (equation 2)[4]. Under the action of NaNO2, the primary amine first forms diazo salt, and then has a ring closing reaction with the secondary amine.
The central carbon of c-nitrosated alkanes generally does not undergo nitrosation unless there is an acyl group, aryl group, carbonyl group, carboxyl group, nitro group, cyano group, imino group, or phenyl group. Generally, the products are nitrosamines or oxime, and the adjacent carbon of nitro group generates oxime (equation 3) under the action of NaNO2 [5]. Formula 4 shows that nitrification occurs at the carbon atom, and the product is nitrosamine [6].
Nitroso compounds can be obtained by nitrosating phenol with the HCl solution of NaNO2. For example, phenol generally produces 4-nitroso phenol, while a small number of 2-substituted isomers (about 10%) are present, while 2-naphthol produces 1-nitro-2-naphthol. If NaNO2 was used to interact with NaOH before acetic acid was added, nitroso group (equation 5) could be directly introduced into the aromatic ring [7].
In addition to nitrosation of carbon atoms, n-nitrosation NaNO2 can also cause nitrosation of nitrogen atoms. Under heating conditions, the product can be stripped of a molecule of nitrogen and converted into ester compounds (equation 6)[8].
Under the action of catalyst, NaNO2 can oxidize primary alcohol, secondary alcohol and other compounds into corresponding aldehydes and ketones (equation 7)[9].
In addition to the oxidation reaction, NaNO2 can also participate in the reduction reaction, such as the conversion of nitrite into nitrate, so as to achieve the reduction of some compounds.

6. Stability: stability

7. Forbidden compounds: strong reducing agent, active metal powder, strong acid, ammonium salt, combustible powder or cyanide

8. Condition to avoid contact: exposure to heat

9. Polymerization hazard: no polymerization

Decomposition product: nitrogen oxide