Potassium cyanate
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Potassium cyanate | |||||||||||||||
Molecular formula | KOCN | |||||||||||||||
Brief description |
white, odorless solid |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 81.12 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
2.06 g cm −3 (20 ° C) |
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Melting point |
314-316 ° C |
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boiling point |
Decomposition at> 700 ° C |
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solubility |
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safety instructions | ||||||||||||||||
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Toxicological data | ||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Potassium cyanate is the potassium salt of cyanic acid and isocyanic acid - a distinction cannot be made because the anion represents a mesomeric system and the anions of both acids are therefore identical. However, since the lengths of the bonds between carbon and nitrogen and between carbon and oxygen correspond more to double bonds than to a single and a triple bond , the term potassium isocyanate would be more justified; but it is unusual.
Manufacturing
Potassium cyanate is produced industrially by introducing air into a potassium cyanide melt.
The oxidation of potassium cyanide can also be achieved with other oxidizing agents such as manganese dioxide , lead (IV) oxide , potassium dichromate or potassium permanganate . In the laboratory, it can be made by melting urea and potassium carbonate together.
properties
Potassium cyanate forms colorless, needle-shaped crystals. It is odorless in its pure state; Technical products can have a faint odor, partly caused by hydrocyanic acid , which results from the production-related contamination with potassium cyanide . The melting point is around 315 ° C. At room temperature it has a density of approx. 2.056 g / cm 3 . It is very soluble in water (750 g of potassium cyanate dissolve per liter). The salt is insoluble in alcohol. When heated to temperatures above 700 ° C, it breaks down into potassium cyanide and oxygen . It hydrolyzes slowly in aqueous solution, producing ammonium carbonate , among other things .
use
Potassium cyanate was used as a herbicide in the US in the late 1940s because of its toxicity to many plants. However, it was never used on a large scale. In Germany, Austria and Switzerland, no plant protection product containing this active ingredient is approved. Today it is used for the surface hardening of metals and in the synthesis of organic compounds such as urea derivatives and carbamates ( e.g. hydantoin or semicarbazide ).
safety instructions
Potassium cyanate is slightly hazardous to water and harmful to health. When heated to over 700 ° C, the highly toxic potassium cyanide is formed .
Individual evidence
- ↑ a b c d e f data sheet potassium cyanate (PDF) from Merck , accessed on January 19, 2011.
- ^ A b c d Karl-Heinz Lautenschläger, Werner Schröter, Andrea Wanninger: Taschenbuch der Chemie . 2005, ISBN 978-3-8171-1760-4 ( page 596 in the Google book search).
- ↑ a b c Entry on potassium cyanate in the GESTIS substance database of the IFA , accessed on July 4, 2016(JavaScript required) .
- ↑ Entry on Potassium cyanate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .
- ^ Robert L. Zimdahl: A History of Weed Science in the United States . 2010, ISBN 978-0-12-381495-1 ( page 109 in the Google book search).
- ^ Directorate-General for Health and Food Safety of the European Commission: EU pesticide database ; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 12, 2016.
- ↑ Wolfgang Weißbach: Material science: structures, properties, testing . 2009, ISBN 978-3-8348-0739-7 ( page 163 in the Google book search).