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Description of key information

No classification is required for: Self-reactivity, pyrophoricity and selfheating. Amonium thiocyanate is not corrosive to metals. Contact with acids liberates very toxic gas.

Additional information

Self-reactivity:

based on testing by DSC with low scan rate 2°C/min (in DSC with high scan rate exothermal effect at 190°C; (Notox, 493859, 2010)

No exothermic decomposition of the test substance was observed at a temperature of < 175°C. According to this, it was considered to be a safe indication that the estimated SADT of the test substance is > 75°C.

Selfheating:

based on melting point <160°C, but UN N4 test was already performed and no selfheating (Notox, 493859, 2010)

Pyrophoricity:

Since exposure to air during the self heating test (UN N4) did not lead to ignition, then certainly exposure to air without heating will not lead to ignition. Also experience with handling the substance indicates that it does not spontaneously ignite when exposed to air.

Corrosion to metals:

According to the criteria in the UN Standard methods, ammonium thiocyanate should be classified as non-corrosive to metals.

Reactivity of Thiocyanate Ions with Acid:

Multiple lines of evidence from literature support the fact that reaction of SCN with acids liberates toxic gases, supporting the need for EUH032 - Contact with acids liberates very toxic gas.

The reaction of solid ionic thiocyanates, such as KNCS and NH4NCS, with concentrated sulfuric acid to produce carbonyl sulfide, OCS, along with CO2, SO2 and traces of HCN (Glidewell G et al, 1984)

Additionally:

Nitric acid violently oxidized a thiocyanate solution [Bretherick 1979 p. 121]. Caution should be exercised in treating a thiocyanate with an oxidizing agent such as a peroxide or chlorate as such mixtures have been known to explode. Special Hazards of Combustion Products: Irritating oxides of sulfur and nitrogen may form in fire [USCG, 1999]. Carbonyl sulfide is produced in a violent reaction by the mixture of sulfuric acid and Sodium thiocyanate.

AMMONIUM THIOCYANATE can release ammonia vapors if mixed with a chemical base or with an acid.