Antimony (III) oxide

Structural formula
General
Surname	Antimony (III) oxide
other names	Antimony trioxide Diantimony trioxide Antimony white Antimony flower Antimony anhydride Senarmontit Valentinite White skewer gloss
Molecular formula	Sb 2 O 3
Brief description	white, odorless solid
External identifiers / databases
CAS number 1309-64-4 EC number 215-175-0 ECHA InfoCard 100,013,796 PubChem 14794 Wikidata Q409035
properties
Molar mass	291.50 g mol −1
Physical state	firmly
density	5.7 g cm −3 5.19 g cm −3 (cubic shape)
Melting point	655 ° C
boiling point	1425 ° C
solubility	practically insoluble in water (2.7 mg l −1 at 20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary Caution H and P phrases H: 351 P: 281
MAK	Switzerland: 0.1 mg m −3 (measured as inhalable dust , calculated as antimony)
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Antimony (III) oxide (also called antimony trioxide ) is an antimony compound with the empirical formula Sb ₂ O ₃ . It belongs to the oxide class .

Occurrence

Antimony (III) oxide occurs as a natural compound in the form of the minerals senarmontite and valentinite .

Extraction and presentation

Antimony trioxide is obtained technically by heating antimony trisulfide ( gray spit gloss , stibnite ) in the air ( roasting ) or by burning antimony .

The hydrolysis of antimony (III) chloride produces valentinite, which is metastable at room temperature and which gradually changes to senarmontite when treated with alkalis.

properties

Antimony (III) oxide

Physical Properties

Antimony (III) oxide shows thermochromic properties. When heated to temperatures well above 600 ° C, the compound turns yellow. The connection becomes reversibly white again when it cools down. The cause of the color change is a polymorphic , enantiotropic transformation from the white cubic crystal form ( senarmontite ) to a yellow orthorhombic crystal form ( valentinite ) at 606 ° C. The enthalpy of formation of the cubic form is Δ _f H = −720.5 kJ mol ⁻¹ , that of the orthorhombic form is Δ _f H = −708.5 kJ mol ⁻¹ , so that a transformation enthalpy of Δ _t for the polymorphic transformation H = 12 kJ mol ⁻¹ results.

Chemical properties

Antimony trioxide is a white crystalline powder that is insoluble in water but dissolves in concentrated acids and alkalis . Its structure corresponds to that of phosphorus trioxide . If it is heated to over 800 ° C, it absorbs more oxygen and binds antimony tetroxide . This represents a mixed oxide of antimony trioxide and antimony pentoxide . As the solubility in concentrated acids - whereby neutral salts or oxide salts are formed depending on the acid concentration - and in alkalis - whereby antimonites are formed - antimony trioxide is an amphoteric oxide.

use

Antimony trioxide is used partly as a pigment and in enamel production. In electroplating it is used to antimony other metals . It is also used as a catalyst for making PET . Together with a doping of tin as ATO ( antimony-tin-oxide ) for transparent-conductive coatings of glasses, e.g. for display technology and pigments for light and transparent antistatic coatings. When flame retardants such as decabromodiphenyl ether , antimony trioxide is used as a synergist.

Safety instructions / toxicology

The International Agency for Research on Cancer (IARC) has classified antimony trioxide as a potentially carcinogenic substance .

Antimony (III) oxide was included by the EU in 2016 in accordance with Regulation (EC) No. 1907/2006 (REACH) in the context of substance evaluation in the Community's ongoing action plan ( CoRAP ). The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. Antimony (III) oxide ingestion was caused by concerns about worker exposure , high (aggregated) tonnage, high risk characterization ratio (RCR), other exposure / risk-based concerns and widespread use as well as the suspected dangers of carcinogens Properties. The reassessment has been running since 2018 and is being carried out by Germany .

Individual evidence

1. ↑ Data sheet antimony (III) oxide (PDF) from Merck , accessed on April 24, 2010.
2. ↑ ^{a b c} 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. 4-48.
3. ↑ ^{a b} Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 593.
4. ↑ ^{a b c} Entry on antimony (III) oxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
5. ↑ Entry on Diantimony trioxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
6. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 1309-64-4 or antimony (III) oxide ), accessed on November 2, 2015.
7. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 91st – 100th, improved and greatly expanded edition. Walter de Gruyter, Berlin 1985, ISBN 3-11-007511-3 , p. 687.
8. ↑ Federal Environment Agency : Brominated flame retardants in electrical and electronic equipment: The flame retardant decabromodiphenyl ether (DecaBDE) can be replaced by more environmentally friendly alternatives ( Memento from June 26, 2013 in the Internet Archive ) (PDF file; 54 kB) , February 2007.
9. ↑ Federal Office of Public Health Switzerland (FOPH): Risk analysis: Antimony in food and ready meals that are prepared directly in PET trays. (PDF) August 23, 2007.
10. ↑ Antimony Trioxide Monograph IARC Volume 47, 1989
11. ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Diantimony trioxide , accessed on March 26, 2019.