CAS Number: 1762-95-4
EC Number: 217-175-6
Chemical formula: NH4SCN
Molar mass: 76.122 g/mol
IUPAC Name:: azanium;thiocyanate
Ammonium thiocyanate is an inorganic compound with the formula NH4SCN. It is the salt of the ammonium cation and the thiocyanate anion.
Ammonium thiocyanate is used in the manufacture of herbicides, thiourea, and transparent artificial resins; in matches; as a stabilizing agent in photography; in various rustproofing compositions; as an adjuvant in textile dyeing and printing; as a tracer in oil fields; in the separation of hafnium from zirconium, and in titrimetric analyses.
In May 1945, USAAF General Victor E. Betrandias advanced a proposal to his superior General Arnold to use of ammonium thiocyanate to reduce rice crops in Japan as part of the bombing raids on their country.
Ammonium thiocyanate can also be used to determine the iron content in soft drinks by colorimetry.
Ammonium thiocyanate may also be used to separate quinidine, from liquors, after the isolation of quinine from the neutral, aqueous, sulphate solution.
The salt is added to the hot solution and the gummy solid that forms is strained off from the liquid.
The solid is then refluxed with methanol, which dissolves most of the impurities, leaving the quinidine thiocyanate as a crystalline solid of 90 - 95% purity.
Following separation, (usually by centrifuge) the solid may then be further purified to pharmaceutical quality.
(Quinidine is used for the treatment of heart arrhythmia and therefore has considerable value.)
Ammonium thiocyanate is made by the reaction of carbon disulfide with aqueous ammonia. Ammonium dithiocarbamate is formed as an intermediate in this reaction, which upon heating, decomposes to ammonium thiocyanate and hydrogen sulfide:
CS2 + 2 NH3(aq) → NH2C(=S)SNH4 → NH4SCN + H2S
Ammonium thiocyanate is stable in air; however, upon heating it isomerizes to thiourea:
The equilibrium mixtures at 150 °C and 180 °C contain 30.3% and 25.3% (by weight) thiourea, respectively.
When heated at 200 °C, the dry powder decomposes to ammonia, hydrogen sulfide, and carbon disulfide, leaving a residue of guanidinium thiocyanate.
NH4SCN is weakly acidic due to the ammonium ion; it reacts with alkali hydroxides, such as sodium hydroxide or potassium hydroxide to form sodium thiocyanate or potassium thiocyanate, along with water and ammonia.
The thiocyanate anion, specifically, reacts with ferric salts to form a deep-red ferric thiocyanate complex:
6 SCN− + Fe3+ → [Fe(SCN)6]3−
Ammonium thiocyanate reacts with several metal ions including copper, silver, zinc, lead, and mercury, forming their thiocyanate precipitates, which may be extracted into organic solvents.
Appearance: Colorless hygroscopic crystalline solid
Density: 1.305 g/cm3
Melting point: 149.5 °C (301.1 °F; 422.6 K)
Boiling point: 170 °C (338 °F; 443 K) (decomposes)
Solubility in water: 128 g/100 mL (0 °C)
Solubility: soluble in liquid ammonia, alcohol, acetone
Magnetic susceptibility (χ): -48.1·10−6 cm3/mol
Appearance (Colour): White
Appearance (Form): Crystalline hygroscopic compund
Solubility (Turbidity) 10% aq. solution: Clear
Solubility (Colour) 10% aq. solution: Colourless
Assay: min. 99%
pH (5% aq. solution): 4.5 - 6.0
Thiocyanates can be used in different applications in the textile and fibre industry, in agriculture, in metal and steel industry and in construction.
In a number of applications ammonium thiocyanate can be used for various printing, dyeing and finishing operations, in the photographic industry as an acceleration in fixing baths, as well as agriculture, to stabilize various herbicides.
A colourless, soluble crystalline compound, NH4NCS.
Ammonium thiocyanate is made by the action of hydrogen cyanide on ammonium sulphide or from ammonia and carbon disulphide in ethanol.
On heating, it turns into its isomer thiourea, SC(NH2)2.
Ammonium thiocyanate solutions give a characteristic blood-red colour with iron(III) compounds and so are employed as a test for ferric iron.
Ammonium thiocyanate is used as a rapid fixative in photography and as an ingredient in making explosives.
The ammonium thiocyanate analytical waste generated during the colorimetric estimation of uranium in the PUREX process streams is chemically as well as radiologically toxic and poses difficulties for its safe disposal.
Treatment of this waste for reuse will reduce the inventory of such waste during the reprocessing.
The ammonium thiocyanate was regenerated by precipitating the metal ions present in the system using ammonia.
The quality of the regenerated ammonium thiocyanate was compared with the fresh reagent as well as the thiocyanate regenerated from a mixture of ammonium thiocyanate and standard uranium solution.
Ammonium thiocyanate is a colorless crystalline solid.
Ammonium thiocyanate is soluble in water.
The primary hazard is the threat posed to the environment.
Immediate steps should be taken to limit its spread to the environment.
Ammonium thiocyanate is used in chemical analysis, in photography, as a fertilizer, and for many other uses.
Ammonium thiocyanate is used in the following areas: building & construction work.
Release to the environment of Ammonium thiocyanate can occur from industrial use: in processing aids at industrial sites and in the production of articles.
Other release to the environment of Ammonium thiocyanate is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use as processing aid and indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters).
Ammonium thiocyanate is used in the following products: pH regulators and water treatment products.
Ammonium thiocyanate has an industrial use resulting in manufacture of another substance (use of intermediates).
Ammonium thiocyanate is used in the following areas: building & construction work.
Ammonium thiocyanate is used for the manufacture of: chemicals.
Release to the environment of this substance can occur from industrial use: in processing aids at industrial sites, in the production of articles and as an intermediate step in further manufacturing of another substance (use of intermediates).
Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use as processing aid and indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters).
Ammonium thiocyanate is an inorganic synergist that is not a plant protection product and is out of scope with respect of EU regulation 1107/2009.
It is relatively volatile and highly soluble in water.
It has a moderate mammalian toxicity and there is some risk of bioaccumulation.
It is a recognised irritant.
Ammonium thiocyanate is moderately toxic to fish but is relatively non-toxic to aquatic invertebrates.
These corrosion data are mainly based on results of general corrosion laboratory tests, carried out with pure chemicals and water solutions nearly saturated with air (the corrosion rate can be quite different if the solution is free from oxygen).
All concentrations are given in weight-% and the solvent is water if nothing else is shown.
The corrosion data apply to annealed materials with normal microstructure and clean surfaces, throughout.
We show that aqueous solutions of ammonium thiocyanate (NH4SCN) can be used to match the index of refraction of several transparent materials commonly used in experiments, while maintaining low viscosity and density compared to other common refractive index-matching liquids.
We present empirical models for estimating the index of refraction, density, and kinematic viscosity of these solutions as a function of temperature and concentration.
Finally, we summarize the chemical compatibility of ammonium thiocyanate with materials commonly used in apparatus.
Inorganic thiocyanates are used for a broad range of applications but mainly used as raw materials or auxiliaries in fiber production, for agricultural products, in photography, in the chemical industry and in construction chemicals.
The realization that thiocyanates play an important role in many biochemical processes in animals and humans has been increasingly exploited in the production of personal hygiene products and in the foodstuffs and pharmaceutical industries.
Thiocyanic acid, ammonium salt
Thiocyanic acid, ammonium salt (1:1)
Rhodanine, ammonium salt
(N H4) (S C N)
Ammonium thiocyanate, 98%, ACS reagent
Ammonium thiocyanate, 99+%, extra pure
Ammonium thiocyanate, ammonium thiosulfate solution
Ammonium thiocyanate, ACS reagent
Ammonium thiocyanate, 0.1N Standardized Solution
Ammonium thiocyanate, >26% in a non hazardous diluent