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The nitrite ion has the chemical formula NO − 2. Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. [1] The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.
Nitrogen cycle. Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite.Nitrification is an important step in the nitrogen cycle in soil.The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria.
[12] [13] Complete nitrification, the conversion of ammonia to nitrate in a single step known as comammox, has an energy yield (∆G°′) of −349 kJ mol −1 NH 3, while the energy yields for the ammonia-oxidation and nitrite-oxidation steps of the observed two-step reaction are −275 kJ mol −1 NH 3, and −74 kJ mol −1 NO 2 − ...
Nitrite oxidoreductase (NOR or NXR) is an enzyme involved in nitrification.It is the last step in the process of aerobic ammonia oxidation, which is carried out by two groups of nitrifying bacteria: ammonia oxidizers such as Nitrosospira, Nitrosomonas, and Nitrosococcus convert ammonia to nitrite, while nitrite oxidizers such as Nitrobacter and Nitrospira oxidize nitrite to nitrate.
Sodium nitrite acts as an antioxidant in a mechanism similar to the one responsible for the coloring effect. [19] Nitrite reacts with heme proteins and metal ions, neutralizing free radicals by nitric oxide (one of its byproducts). [19] Neutralization of these free radicals terminates the cycle of lipid oxidation that leads to rancidity. [19]
These include methods that can destroy nitrogen compounds, such as chemical and electrochemical methods, and those that selectively transfer nitrate to a concentrated waste stream, such as ion exchange or reverse osmosis. Chemical removal of nitrate can occur through advanced oxidation processes, although it may produce hazardous byproducts. [38]
Nitrosation is typically performed with nitrous acid, formed from acidification of a sodium nitrite solution. Nitrous acid is unstable, and high yields require a rapid reaction rate. NO + synthon transfer is catalyzed by a strong nucleophile, such as (in order of increasing efficacy) chloride, bromide, thiocyanate, or thiourea.
Name Formula Nitroxide: O=N − or NO −: Nitrite: O=N−O − or NO − 2: Nitrate: O 2 N−O − or NO − 3: Peroxynitrite: O=N−O−O − or NO − 3 ...