POISON CHEMISTRY - CYANIDE COMPOUNDS
Cyanide is a fast-acting, bitter-tasting poison, and one of the deadliest known. Its compounds have famously been utilised in suicide pills over the years.
H I S T O R Y
Cyanide has been used for centuries as a poison, but was
first identified in 1782 by the Swedish chemist Scheele;
in fact, it’s thought Scheele’s death may have been
contributed to by cyanide exposure.
During WWI, the French attempted to use hydrocyanic
acid, then cyanogen chloride, in chemical warfare. In WWII,
The Nazis used hydrogen cyanide in the form of Zyklon B
to kill millions in their concentration camps.
Hydrogen cyanide gas has previously been used for pest
control, which sometimes led to accidental deaths. Today,
cyanides are still used in the mining of gold and silver, and
in organic synthesis reactions.
T R E A T M E N T
HCN KCN NaCN
HYDROGEN
CYANIDE
POTASSIUM
CYANIDE
SODIUM
CYANIDE
O
RAPID BREATHING &
HEART RATE
H2NOC
H
R N
N O
AMYL NITRITE
(Note: KCN and NaCN both get converted to HCN by stomach acid)
Na
H
MEDIAN LETHAL DOSE: 3-8mg/kg
O R A L - VA R I E S D E P E N D I N G O N F O R M O F C YA N I D E A D M I N I S T E R E D
N
N
+
-
O
N
O
CONH2
N
O
NH
O
S
O- Na+
S
O
P O
O-
O
Na+ -O
N
HO
O
SODIUM NITRITE
(HCN ONLY)
CONH2
SODIUM
THIOSULFATE
Co+
H2NOC
HO
VITAMIN B12a
The most prevalent antidotes are nitrites, which convert haemoglobin
into methemoglobin, which then removes cyanide from cytochrome
oxidase. Thiosulfate helps convert cyanide to thiocyanate so it can
be excreted. Cobalt ions also form a stable complex with cyanide.
Sample added to
5% NaOH solution
NAUSEA &
VOMITING
CONH2
D E T E C T I O N
E F F E C T S
DIZZINESS &
HEADACHE
N
O
H2NOC
Transferred to solution
of 5% FeSO 4 & 1% FeCl3
Adding hydrochloric
acid solution gives
prussian blue.
LOW BLOOD
PRESSURE
60˚C
1:6 HCl:H2O
LOSS OF
CONSCIOUSNESS
RESPIRATORY
FAILURE
CONVULSIONS
& DEATH
Cyanide inhibits the cytochrome oxidase enzyme, preventing the
body’s cells from using oxygen. HCN smells of bitter almonds, but
only ~40% of people have the genetic ability to smell it. Many fruit
seeds also contain small amounts of cyanide-containing compounds.
C
HEAT
1 MIN
10 MINS
10-15 MINS
A common test for cyanide in the early 20th Century formed prussian
blue, an iron-cyanide complex, in the presence of cyanide ions.
There are several other chemical tests, including portable cardbased tests, and instrumental methods can also be used.
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