Potassium cyanate

Structural formula
General
Surname	Potassium cyanate
Molecular formula	KOCN
Brief description	white, odorless solid
External identifiers / databases
EC number	209-676-3
ECHA InfoCard	100,008,798
PubChem	11378442
Wikidata	Q416304
properties
Molar mass	81.12 g mol −1
Physical state	firmly
density	2.06 g cm −3 (20 ° C)
Melting point	314-316 ° C
boiling point	Decomposition at> 700 ° C
solubility	easily soluble in water (750 g l −1 at 20 ° C); practically insoluble in ethanol;
safety instructions
GHS hazard labeling from Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary Caution
H and P phrases	H: 302-319
	P: 305 + 351 + 338
Toxicological data	567 mg kg −1 ( LD 50 , rat , oral )
	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.

{\ displaystyle \ mathrm {2 \ KCN + \ O_ {2} \ longrightarrow \ 2 \ KOCN}}

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.

{\ displaystyle \ mathrm {2 \ CO (NH_ {2}) _ {2} + \ K_ {2} CO_ {3} \ longrightarrow}}

{\ displaystyle \ mathrm {2 \ KOCN + 2 \ NH_ {3} + \ CO_ {2} + \ H_ {2} O}}

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).

[chemdat-1] ↑ ^a ^b ^c ^d ^e ^f data sheet potassium cyanate (PDF) from Merck , accessed on January 19, 2011.

[Taschenbuch-2] 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).

[GESTIS-3] Entry on potassium cyanate in the GESTIS substance database of the IFA , accessed on July 4, 2016(JavaScript required) .

[CLP_100.008.798-4] 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 .

[5] AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .

[Zimdahl-6] 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).

[PSM-7] 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.

[Werkstoffkunde-8] Wolfgang Weißbach: Material science: structures, properties, testing . 2009, ISBN 978-3-8348-0739-7 ( page 163 in the Google book search).