Ammonium thiocyanate is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula NH₄SCN. It is the

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

of the

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

and the

thiocyanate Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrot ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

Uses

Ammonium thiocyanate is used in the manufacture of

herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page fo ...

thiourea Thiourea () is an organosulfur compound with the formula and the structure . It is structurally similar to urea (), except that the oxygen atom is replaced by a sulfur atom (as implied by the ''thio-'' prefix); however, the properties of urea a ...

, and transparent artificial

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

s; 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 Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri M ...

from

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...

(important for the production of hafnium-free

zircalloy Zirconium alloys are solid solutions of zirconium or other metals, a common subgroup having the trade mark Zircaloy. Zirconium has very low absorption cross-section of thermal neutrons, high hardness, ductility and corrosion resistance. One of the ...

for use in nuclear

fuel cladding Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoin ...

), and in titrimetric analyses. In May 1945,

USAAF The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

General A general officer is an Officer (armed forces), officer of highest military ranks, high rank in the army, armies, and in some nations' air forces, space forces, and marines or naval infantry. In some usages the term "general officer" refers t ...

Victor E. Betrandias advanced a proposal to his superior General Arnold to use of ammonium thiocyanate to reduce

rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...

crops in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

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.)

Preparation

Ammonium thiocyanate is made by the reaction of

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical n ...

with aqueous

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

Ammonium dithiocarbamate The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...

is formed as an intermediate in this reaction, which upon heating, decomposes to ammonium thiocyanate and

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...

: : CS₂ + 2 NH₃(aq) → NH₂C(=S)SNH₄ → NH₄SCN + H₂S

Reactions

Ammonium thiocyanate is stable in air; however, upon heating it isomerizes to

: :

Gleichgewicht Ammoniumthiocyanat Thioharnstoff

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

, leaving a residue of

guanidinium thiocyanate Guanidinium thiocyanate (GTC) or guanidinium isothiocyanate (GITC) is a chemical compound used as a general protein denaturant, being a chaotropic agent, although it is most commonly used as a nucleic acid protector in the extraction of DNA and ...

. NH₄SCN is weakly acidic due to the ammonium ion; it reacts with alkali hydroxides, such as

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...

to form

sodium thiocyanate Sodium thiocyanate (sometimes called sodium sulphocyanide) is the chemical compound with the formula NaSCN. This colorless deliquescent salt is one of the main sources of the thiocyanate anion. As such, it is used as a precursor for the synthes ...

potassium thiocyanate Potassium thiocyanate is the chemical compound with the molecular formula KSCN. It is an important salt of the thiocyanate anion, one of the pseudohalides. The compound has a low melting point relative to most other inorganic salts. Use in chem ...

, along with water and ammonia. The thiocyanate anion, specifically, reacts with ferric salts to form a deep-red ferric thiocyanate complex: : 6 SCN⁻ + Fe³⁺ → e(SCN)₆sup>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.

References

# A. F. Wells, ''Structural Inorganic Chemistry'', 5th ed., Oxford University Press, Oxford, UK, 1984. {{Ammonium salts Thiocyanates Ammonium compounds Chemical anti-agriculture weapons