Hydroxylamine

Structural formula
Wedges to clarify the geometry
General
Surname	Hydroxylamine
other names	Oxyammonia
Molecular formula	NH 2 OH (hydroxylamine)
Brief description	hygroscopic, odorless and colorless platelets or needles
External identifiers / databases
CAS number 7803-49-8 (hydroxylamine) EC number 232-259-2 ECHA InfoCard 100.029.327 PubChem 787 Wikidata Q259997
properties
Molar mass	33.03 g · mol -1 (hydroxylamine)
Physical state	firmly
density	1.22 g cm −3 (14 ° C)
Melting point	33 ° C (hydroxylamine) 151 ° C (hydroxylamine hydrochloride ) 159 ° C (hydroxylamine hydrochloride) (decomposition)
boiling point	58 ° C (29 mbar)
Vapor pressure	29.33 h Pa (57 ° C, hydroxylamine)
pK s value	8.20 (NH 3 OH + / NH 2 OH) 13.70 (NH 2 OH / NHOH - )
solubility	soluble in water (560 g / l for hydroxylamine) and ethanol very soluble in water, soluble in methanol insoluble in benzene and chloroform
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 290-302-315-317-318-335-351-373-400 P: 273-280-302 + 352-304 + 340-305 + 351 + 338-308 + 313
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Hydroxylamine is a colorless, crystalline inorganic chemical compound that was first synthesized by Cornelis Adriaan Lobry van Troostenburg de Bruyn .

synthesis

Hydroxylamine can be produced by reducing higher oxidation levels of nitrogen ( NO , NO ₂ ^- , NO ₃ ^- ) with hydrogen , sulphurous acid or electric current . Technically, it is produced by introducing a mixture of nitrogen monoxide and hydrogen into a sulfuric acid suspension of a catalyst ( palladium or platinum ) on activated carbon ; the yield is 90%.

${\displaystyle \mathrm {2\,NO+3\,H_{2}\rightarrow 2\,NH_{2}OH} }$

Another technical method is the introduction of sulfur dioxide into a solution of ammonium nitrite in sulfuric acid at 0 to 5 ° C. This produces diammonium hydroxylamine bis (sulfonate) N (SO ₃ NH ₄ ) ₂ OH, which slowly splits into hydroxylamine and hydrogen sulfate at 100 ° C. With this method, too, the yield is about 90%.

Another technical method is the electrochemical reduction of nitric acid in 50% sulfuric acid.

${\displaystyle \mathrm {HNO_{3}+6\,H^{+}+6\,e^{-}\rightarrow NH_{2}OH+2\,H_{2}O} }$

Responsiveness

Hydroxylamine can be stored for a few weeks if air is excluded. In an aqueous solution it is quite stable in the absence of air. In the presence of atmospheric oxygen, hydroxylamine decomposes very quickly both as a pure substance and in solution; above 70 ° C the decomposition occurs explosively. But even concentrated solutions can explode violently, as accidents in Japan and the USA have shown.

${\displaystyle \mathrm {3\,NH_{2}OH\rightarrow NH_{3}+N_{2}+3\,H_{2}O} }$

Because of its instability, hydroxylamine is mostly converted into its salts (e.g. hydroxylamine hydrochloride , hydroxylammonium sulfate ).

The relatively high melting and boiling temperatures of hydroxylamine can be carried to a H-bridge formation , on the other hand by the partial tautomerization to the amine oxide , the ionic charge carrying explained. In addition, hydroxylamine easily acts as an ampholyte .

Mutagenic effect

Hydroxylamine converts cytosine to uracil through hydrolysis . In contrast to cytosine, uracil pairs with adenine, so that the base pair CG converts to TA after two replications . However, since uracil does not appear in DNA , such errors are easily identified and corrected.

use

Most of the industrially produced hydroxylamine is converted to oximes with aldehydes or ketones . 97% of the world's annual production of hydroxylamine is used to obtain cyclohexanone oxime from cyclohexanone , which is converted into polyamide 6 via caprolactam (see Beckmann rearrangement ). It is also used in the Neber rearrangement .

Individual evidence

1. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 464.
2. ↑ ^{a b c} Entry on hydroxylamine. In: Römpp Online . Georg Thieme Verlag, accessed on May 4, 2014.
3. ↑ ^{a b c d e f g} Entry on hydroxylamine, aqueous solution in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
4. ↑ ^{a b c d e} David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Properties of the Elements and Inorganic Compounds, pp. 4-66.
5. ^ The Merck Index . An Encyclopaedia of Chemicals, Drugs and Biologicals . 14th edition, 2006, p. 837, ISBN 978-0-911910-00-1 .
6. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .
7. ↑ Data sheet Hydroxylamine hydrochloride, 97% from Acros, accessed on September 26, 2011.
8. ↑ Entry on hydroxylamines (> 55% in aqueous solution) in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on September 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
9. ↑ M. Binnewies et alii: Allgemeine und Anorganische Chemie . 2nd Edition. Spectrum, 2010, ISBN 3-8274-2533-6 . P. 484.
10. ↑ Explosion in Ojima, Japan .
11. ^ Explosion near Allentown, Pennsylvania, USA .

Web links

Commons : Hydroxylamines  - Collection of pictures, videos, and audio files

• International Chemical Safety Card