Everything about Hydroxylamine totally explained
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Hydroxylamine is a reactive chemical with
formula NH
2OH. It can be considered a hybrid of
ammonia and
water due to parallels it shares with each. At room temperature pure NH
2OH is ordinarily a white, unstable
crystalline,
hygroscopic compound; however it's almost always encountered as an aqueous solution.
Hydroxylamine tends to be
explosive, and the nature of the hazard isn't entirely understood. At least two factories dealing in hydroxylamine have been destroyed since 1999 with loss of life. It is known, however, that ferrous and ferric
iron salts accelerate the decomposition of 50% NH
2OH solutions. Hydroxylamine and its derivatives are more safely handled in the form of
salts.
NH
2OH is an intermediate in biological
nitrification. The oxidation of NH
3 is mediated by
hydroxylamine oxidoreductase (HAO).
Production
NH
2OH can be synthesized via several routes:
Raschig synthesis:
Aqueous
ammonium nitrite is reduced by HSO
4−/SO
2 at 0°C to yield a hydroxylamido-N,N-disulfate anion, which can be hydrolyzed to give (NH
3OH)
2SO
4.
» :NH
4NO
2 + 2SO
2 + NH
3 + H
2O → [NH
4]
2[N(OH)(OSO
2)
2]
» :[NH
4]
+2[N(OH)(OSO
2)
2]
2− + H
2O → [NH
4][NH(OH)(OSO
2)] + [NH
4][HSO
4]
» :2[NH
4]
+[NH(OH)(OSO
2)]
− + 2H
2O → [NH
3(OH)]
2[SO
4] + [NH
4]
2[SO
4]
Solid
NH2OH can be collected by treatment with liquid ammonia.
Ammonium sulfate is insoluble in liquid ammonia and is removed by filtration; the liquid
ammonia is evaporated to give the desired product.
» : NH
2OH (Zn/HCl) → NH
3
: R-NHOH (Zn/HCl) → R-NH
2
Uses
Hydroxylamine and its salts are commonly used as reducing agents in a myriad of organic and inorganic reactions. They can also act as antioxidants for fatty acids.
Some non-chemical uses include removal of hair from animal hides and photography developing solutions.
The nitrate salt,
hydroxylammonium nitrate, is being researched as a rocket propellant, both in water solution as a
monopropellant and in its solid form as a
solid propellant.
This has also been used in the past by biologists to introduce random mutations by switching base pairs from A to G, or from C to T. This is to probe functional areas of genes to elucidate what happens if their functions are broken. Nowadays other mutagens are used. Hydroxylamine can also be used to highly selectively cleave
asparaginyl-
glycine peptide bonds in peptides and proteins. It also bonds to and permanently disables (poisons)
heme-containing enzymes. It is used as an irreversible inhibitor of the
oxygen-evolving complex of photosynthesis on account of its similar structure to water.
In the semiconductor industry, hydroxylamine is often a component in the "resist stripper" which removes photoresist after lithography.
Safety
Hydroxylamine may explode on heating. It is an irritant to the respiratory tract, skin, eyes, and other mucous membranes. It may be absorbed through the skin, is harmful if swallowed, and is a possible mutagen.
Further Information
Get more info on 'Hydroxylamine'.
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