Ammonium thiocyanate
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Space-filling model of the ammonium cation
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Space-filling model of the thiocyanate anion
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Identifiers
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ChemSpider
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ECHA InfoCard
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100.015.614
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EC Number
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RTECS number
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UNII
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UN number
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3077
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InChI=1S/CHNS.H3N/c2-1-3;/h3H;1H3
Y
Key: SOIFLUNRINLCBN-UHFFFAOYSA-N
Y
InChI=1/CHNS.H3N/c2-1-3;/h3H;1H3
Key: SOIFLUNRINLCBN-UHFFFAOYAF
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Properties
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[NH
4
][SCN]
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Molar mass
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76.122 g/mol
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Appearance
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Colorless
hygroscopic
crystalline solid
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Density
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1.305 g/cm
3
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Melting point
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149.5 °C (301.1 °F; 422.6 K)
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Boiling point
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170 °C (338 °F; 443 K) (decomposes)
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128 g/(100 mL) (0 °C)
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Solubility
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soluble in liquid
ammonia
,
alcohol
,
acetone
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?48.1·10
?6
cm
3
/mol
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Hazards
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GHS
labelling
:
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![GHS07: Exclamation mark](//upload.wikimedia.org/wikipedia/commons/thumb/c/c3/GHS-pictogram-exclam.svg/50px-GHS-pictogram-exclam.svg.png)
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Warning
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H302
,
H312
,
H332
,
H410
,
H412
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P261
,
P264
,
P270
,
P271
,
P273
,
P280
,
P301+P312
,
P302+P352
,
P304+P312
,
P304+P340
,
P312
,
P322
,
P330
,
P363
,
P391
,
P501
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NFPA 704
(fire diamond)
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Safety data sheet
(SDS)
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External MSDS
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Related compounds
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Ammonium cyanate
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Related compounds
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Ammonium cyanide
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Except where otherwise noted, data are given for materials in their
standard state
(at 25 °C [77 °F], 100 kPa).
|
Chemical compound
Ammonium thiocyanate
is an
inorganic compound
with the formula
[NH
4
]
+
[SCN]
?
. It is an
ammonium
salt
of
thiocyanic acid
. It consists of ammonium
cations
[NH
4
]
+
and
thiocyanate
anions
[SCN]
?
.
Uses
[
edit
]
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
(important for the production of hafnium-free
zircalloy
for use in nuclear
fuel cladding
), 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
.
[1]
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
[
edit
]
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
:
- CS
2
+ 2 NH
3
(aq) → [NH
2
?CS
2
]
?
[NH
4
]
+
→ [NH
4
]
+
[SCN]
?
+ H
2
S
Reactions
[
edit
]
Ammonium thiocyanate is stable in air; however, upon heating it
isomerizes
to
thiourea
:
![](//upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Gleichgewicht_Ammoniumthiocyanat_Thioharnstoff.svg/400px-Gleichgewicht_Ammoniumthiocyanat_Thioharnstoff.svg.png)
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
.
[NH
4
]
+
[SCN]
?
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
?
+ Fe
3+
→ [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.
References
[
edit
]
- ^
John David Chappell (1997).
Before the Bomb: How America Approached the End of the Pacific War
. University Press of Kentucky. pp. 91?92.
ISBN
978-0-8131-7052-7
.
- A. F. Wells,
Structural Inorganic Chemistry
, 5th ed., Oxford University Press, Oxford, UK, 1984.
ISBN
978-0198553700
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Inorganic salts
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Organic salts
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