Nitrites

The nitrite is an ion of formula NO -1 . The anion is angular, being isoelectronic with O 3. Nitrites are salts or esters of nitrous acid (HNO 2 ). They are salts of a weak acid in contact with strong acids such as sulfuric acid , unstable nitrous acid is released, which in acid solution is in equilibrium with the nitrosonium ion (NO + ). It is involved in various electrophilic substitution reactions and in synthesis reactions of diazo dyes.

Summary

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  • 1 Natural State
  • 2 Physical properties
  • 3 Determination
  • 4 Health effects
  • 5 How to remove nitrites from your water
  • 6 Applications
  • 7 Source
  • 8 External link

Natural state

In nature, nitrites are formed by biological oxidation of amines and ammonia , or by reduction of nitrate under anaerobic conditions.

In industry they can be obtained by dissolving N 2 O 3 in basic solutions.

In the case of salts of a weak acid in contact with strong acids such as sulfuric acid, unstable nitrous acid is released, which in acid solution is in equilibrium with the nitrosonium ion (NO + ). It is involved in various electrophilic substitution reactions and in synthesis reactions of diazo dyes.

Physical properties

  • Chemical name: Nitrite
  • Regulatory name: Nitrite
  • Molecular formula: NO -1
  • Molecular weight: 46 g / mol

Determination

The nitrite present in the water is determined by diazotization with sulfanilamide and coupling with N- (1-naphthyl) -ethylenediamine hydrochloride, to form a high intensity azo dye that is measured spectrophotometrically at a wavelength of 540nm. This reaction, proposed by Griess, has its place in the history of Chemistry due to the fact that it was the first identification reaction in which an organic reagent was used, since until then only inorganic reagents were used. It is also analyzed by adding Zambelli reagent and measuring it spectrophotometrically at 450nm.

Health effects

Nitrite is toxic (2 g can kill a person), being able to bind to hemoglobin in the blood, in a similar way as it does to meat myoglobin, forming methemoglobin, a compound that is no longer capable of transporting oxygen. This poisoning can be fatal, and in fact several fatal cases are known from ingestion of sausages with very high amounts of nitrites, produced locally by a poor mixing of the additive with the other ingredients during its manufacture. To avoid this, you can use previously mixed nitrite with salt. In many countries, this must be done and the EC regulations include this requirement. Children are much more susceptible than adults to this poisoning, due to its lower amount of hemoglobin, and in the case of the very young,

The most obvious symptom of methemoglobinemia is the appearance of a bluish tint to the skin, particularly around the eyes and mouth. If discovered quickly, this disease can be successfully treated with an injection of methylene blue, which transforms methemoglobin back to hemoglobin. The disease is extremely serious if left untreated: death occurs when 70 percent of the body’s hemoglobin has been converted to methemoglobin. A relationship has been shown to exist between infant deaths from methemoglobinemia and high levels of nitrate in water.

How to remove nitrites from your water

An easy solution to remove nitrites from your water is by oxidizing them to nitrates (as we said earlier, nitrates are much less toxic than nitrites). This can be accomplished by injecting ozone into the water . Ozone is a highly oxidizing chemical that will oxidize all nitrites to nitrates, thereby eliminating the toxicity caused by nitrites.

Applications

Nitrites are part of many salt formulations for Acecin or salting meats (E249 = potassium nitrite; E250 = sodium nitrite ). It is due to their ability to maintain a desired reddish color in the raw material since they react with the myoglobin of the meat. However, the concentration should be low since there are suspicions that favor the development of cancer. Furthermore, due to their interaction with hemoglobin, they are toxic. Nitrites are starting products in the synthesis of various chemical compounds, especially diazo compounds. Its medical application is as an antidote in case of potassium cyanide poisonings , causing vasodilation and is also antispasmodic.

 

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