All Topics  
Potassium cyanide

 

 
   Email Print
   Bookmark   Link
 

 

Potassium cyanide
 
 
  Topics Potassium cyanide Topic Home

Potassium cyanide is an inorganic compound
Inorganic compound

Traditionally, inorganic compounds are considered to be of a mineral, not biological, origin. Complementarily, most organic compounds are traditionally viewed as being of biological origin....
 with the formula
Chemical formula

A chemical formula is a way of expressing information about the atoms that constitute a particular chemical compound, and how the relationship between those atoms changes in chemical reactions....
 KCN. This colorless crystalline compound, similar in appearance to sugar
Sugar

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many other sources....
, is highly soluble in water. The vast majority of KCN is used in gold mining
Gold mining

Gold mining consists of the processes and techniques employed in the resource extraction of gold from the ground. There are several techniques by which gold may be extracted from the Earth....
 followed by use in organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
, and electroplating. Smaller applications include jewelry for chemical gilding
Gilding

Gilding is the technique of applying a thin layer of gold to a surface. Gilding is performed through a mechanical process, known as leafing, or using one of many chemical processes....
 and buffing.

KCN is highly toxic. Due to hydrolysis
Hydrolysis

Hydrolysis is a chemical reaction during which one or more water are split into hydrogen and hydroxide ions which may go on to participate in further reactions....
, the moist solid emits small amounts of hydrogen cyanide
Hydrogen cyanide

Hydrogen cyanide is a chemical compound with chemical formula HCN. A solution of hydrogen cyanide in water is called hydrocyanic acid. Hydrogen cyanide is a colorless, extremely poisonous, and highly volatility liquid that boiling slightly above room temperature at 26 Celsius ....
, which smells like bitter almonds (not everyone can smell it — the ability thereof is due to a genetic trait).






Discussion
Ask a question about 'Potassium cyanide'
Start a new discussion about 'Potassium cyanide'
Answer questions from other users
Full Discussion Forum



Encyclopedia


Potassium cyanide is an inorganic compound
Inorganic compound

Traditionally, inorganic compounds are considered to be of a mineral, not biological, origin. Complementarily, most organic compounds are traditionally viewed as being of biological origin....
 with the formula
Chemical formula

A chemical formula is a way of expressing information about the atoms that constitute a particular chemical compound, and how the relationship between those atoms changes in chemical reactions....
 KCN. This colorless crystalline compound, similar in appearance to sugar
Sugar

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many other sources....
, is highly soluble in water. The vast majority of KCN is used in gold mining
Gold mining

Gold mining consists of the processes and techniques employed in the resource extraction of gold from the ground. There are several techniques by which gold may be extracted from the Earth....
 followed by use in organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
, and electroplating. Smaller applications include jewelry for chemical gilding
Gilding

Gilding is the technique of applying a thin layer of gold to a surface. Gilding is performed through a mechanical process, known as leafing, or using one of many chemical processes....
 and buffing.

KCN is highly toxic. Due to hydrolysis
Hydrolysis

Hydrolysis is a chemical reaction during which one or more water are split into hydrogen and hydroxide ions which may go on to participate in further reactions....
, the moist solid emits small amounts of hydrogen cyanide
Hydrogen cyanide

Hydrogen cyanide is a chemical compound with chemical formula HCN. A solution of hydrogen cyanide in water is called hydrocyanic acid. Hydrogen cyanide is a colorless, extremely poisonous, and highly volatility liquid that boiling slightly above room temperature at 26 Celsius ....
, which smells like bitter almonds (not everyone can smell it — the ability thereof is due to a genetic trait). It is used by entomologists as a killing agent in collecting jars, as most insect
Insect

Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
s succumb within seconds, minimizing damage of even highly fragile specimens.

Production

KCN is produced by treating hydrogen cyanide
Hydrogen cyanide

Hydrogen cyanide is a chemical compound with chemical formula HCN. A solution of hydrogen cyanide in water is called hydrocyanic acid. Hydrogen cyanide is a colorless, extremely poisonous, and highly volatility liquid that boiling slightly above room temperature at 26 Celsius ....
 with potassium hydroxide.
HCN + KOH ? KCN + H2O
Approximately 50,000 tons are produced yearly.

Structure

In aqueous solution, KCN is dissociated into hydrated K+ ions and CN-
Cyanide

A cyanide is any chemical compound that contains the nitrile , which consists of a carbon atom chemical bond to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN-....
. As a solid, the salt crystallizes such that the cations and anions organize like Na+ and Cl- in NaCl. The cations and anions six-coordinate. Each K+ is linked to two pi-bonds of the CN- as well as two links each to C and N each. Since CN- is diatomic, the symmetry of the solid is lower than that in NaCl. The cyanide anions form sheets. The CN- ions rapidly rotate in the solid at ambient temperature such that the time averaged shape of the CN- ions is spherical.

Applications

In gold mining
Gold mining

Gold mining consists of the processes and techniques employed in the resource extraction of gold from the ground. There are several techniques by which gold may be extracted from the Earth....
, KCN and NaCN
Sodium cyanide

Sodium cyanide is the inorganic compound with the chemical formula NaCN. This highly toxic colourless salt is used mainly in gold mining but has other niche applications....
 form water-soluble salts from gold metal in the presence of air:
4 Au + 8 KCN + O2 + 2 H2O ? 4 K[Au(CN)2] + 4 KOH
Very few alternative methods exist for this extraction process.

KCN and the related NaCN are widely used in organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
 for the preparation of nitrile
Nitrile

A nitrile is any organic compound which has a -Carbon=Nitrogen functional group. The -C=N functional group is called a nitrile group....
s and carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s; illustrative in the Von Richter reaction
Von Richter reaction

The von Richter reaction is the chemical reaction of aromatic nitro compounds with potassium cyanide giving carboxylation ortho to the position of the former nitro group....
.

Toxicity

KCN can be detoxified most efficiently with hydrogen peroxide
Hydrogen peroxide

Hydrogen peroxide is a very pale blue liquid which appears colorless in a dilute solution, slightly more viscous than water. It is a weak acid....
 KCN + H2O2 ? KOCN
Cyanate

The cyanate ion is an anion consisting of one oxygen atom, one carbon atom, and one nitrogen atom, [OCN]-, in that order, and possesses 1 unit of negative electric charge, borne mainly by the nitrogen atom....
 + H2O

Cyanide
Cyanide

A cyanide is any chemical compound that contains the nitrile , which consists of a carbon atom chemical bond to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN-....
 is a potent inhibitor of cellular respiration
Cellular respiration

Cellular respiration is the set of the metabolism reactions and processes that take place in organisms' cell s to convert Energy from nutrients into adenosine triphosphate , and then release waste products....
, acting on mitochondrial cytochrome c oxidase
Cytochrome c oxidase

The enzyme cytochrome c oxidase or Complex IV is a large transmembrane protein complex found in bacteria and the mitochondrion.It is the last enzyme in the respiratory electron transport chain of mitochondria located in the mitochondrial membrane....
 and hence blocking oxidative phosphorylation
Oxidative phosphorylation

Oxidative phosphorylation is a metabolic pathway that uses energy released by the redox of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism....
. This prevents the body from oxidising food to produce useful energy. Lactic acidosis
Lactic acidosis

Lactic acidosis is a condition caused by the buildup of lactic acid in the body. It leads to acidification of the blood , and is considered a distinct form of metabolic acidosis....
 then occurs as a consequence of anaerobic metabolism. Initially, acute cyanide poisoning causes a red or ruddy complexion in the victim because the tissues are not able to use the oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
 in the blood. The effects of potassium and sodium cyanide
Sodium cyanide

Sodium cyanide is the inorganic compound with the chemical formula NaCN. This highly toxic colourless salt is used mainly in gold mining but has other niche applications....
 are identical. The person may die within two hours if not treated medically. During this period, convulsions may occur. Death occurs mainly by cardiac arrest
Cardiac arrest

A cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is the abrupt cessation of normal circulation of the blood due to failure of the heart to contract effectively during Systole ....
.

A number of prominent persons were killed or committed suicide using potassium cyanide, including members of the Nazi Party, WWII era British agents
Special Air Service

The Special Air Service is a special forces regiment within the British Army which has served as a model for the special forces of other countries....
 and various religious cults such as in Jonestown
Jonestown

Jonestown was the informal name for the "Peoples Temple Agricultural Project", an intentional community in northwestern Guyana formed by the Peoples Temple, a cult from California, United States, led by Jim Jones....
. Potassium cyanide (and other forms of cyanide) are a popular method of murder in fiction.

External links

  • (CICAD 61)
  • Institut national de recherche et de sécurité (1997). "". Fiche toxicologique n° 111, Paris:INRS, 6pp. (PDF file, in French)