Cyanide

Forms

The salt S of this ion are extremely toxic, just as the Acide which is associated for them: the Hydrocyanic acid . In the language running, one often uses the term cyanide to indicate cyanide of Potassium KCN.

The ferrocyanides (or hexacyanoferrates II) Fe (CN) ₆^{4 -}, on the other hand, is practically inoffensive. Ferrocyanides of Calcium, Sodium and Potassium are food additive (anti-binders) respectively referred E 538, E 535 and E 536.

The potassium ferrocyanide is authorized for the joining of the Vin S white or rosy presenting iron excesses for a setting in bottles because of its capacity to be made precipitate metals (iron and copper in particular) responsible for breakages. This treatment is at the origin of the creation of the national diploma of enology in 1955 because the public authorities then estimated that it was necessary to train qualified and responsible technicians to carry out the operation. The removal of iron of the red wines by joining with the potassium ferrocyanide is prohibited because it is impossible to control the absence of iron residues (dissolved or in suspension) in the wine because of coloring of the wine related to the presence of Anthocyane S.

Historically, joining with the potassium ferrocyanide of the wines presenting of the residual Sucre S was practiced and made it possible to reduce the content of the wine of micronutrients usable by the Levure S persons in charge of spontaneous refermentations.

The ferr' i' cyanides (or hexacyanoferrates III) Fe (CN) ₆^3- also have a low toxicity.

Source and use

In nature

The cyanides can be produced by Bactérie S, Moisissure S and Algue S and are contained in many food and plants. In the plants, the cyanides are normally related to molecules of Sucre in the form of glycosides cyanogens and are used for the plants like defense against the Herbivore S. the roots of the Manioc or the linseeds contain glucosides cyanogens and, often, they should be treated before consumption (in general by prolonged boiling). The fruit cores, like the Cherry S and the Apricot S, often contain cyanides or glycosides cyanogens. The pips of Pomme also contain some. The bitter Amande S which one makes almond oil contain also a glycoside cyanogen, the Amygdaline. Many enzymes hydrogenases contain ligands cyanided on their active sites.

According to the Canadian Agency of inspection of food, the glycoside cyanogen contained in these almonds becomes toxic lorqu' it is transformed into hydrocyanic acid in the body. The lethal cyanide amount ranges between 0,5 and 3,0 Mg. by kg. body weight.

Chemistry

The cyanide is an anion which is often met in chemistry.

Chemistry of coordination

The cyanide is regarded as the most powerful ligand for much of metals of transition. The great affinity of metals for cyanide can be allotted to its negative charge and its capacity to enter a connection p.

Some complexes:

the octocyanures ^4- (M= Mo, W) which have a dodecahedral form;
the hexacyanures ^3- (M = Ti, V, Cr, mn, Fe, Co), which have an octahedral form;
the tétracyanures ^2- (M = Ni, Pd, Pt), which have a plane square form;
the dicyanures ^- (M = Cu, Ag, With), which have a linear form.

The pigment Prussian blue dark blue , used like dyeing, is a cyanided complex of iron. The Prussian blue can produce cyanide of Hydrogène by action of the Acide S.

Organic synthesis (see nitriles)

Very nucleophilic, the cyanide is easily introduced into molecules by displacement of the corresponding halogen. The organic cyanides, in general, are called nitriles. Thus, CH₃CN can be called methyl cyanide but, normally, one speaks about Acétonitrile. In organic chemistry, the cyanide is used to increase the length of the organic chains at the same time as the introduction of other functions:

X-ray + CN^- - > RCN + X^- (nucleophilic Substitution) followed

RCN + 2:00 ₂O - > RCOOH + NH₃ (Hydrolysis), or
RCN + 0.5 LiAlH₄ + (second stage) 2:00 ₂O - > RCH₂NH₂ + 0.5 LiAl (OH) ₄ (under Backward flow in ether, followed addition of H₂O)

An alternative method to introduce cyanide is the hydrocyanatation where the hydrogen cyanide reacts with a alkene. A metal catalyst is necessary.

A phenomenon little to occur if the transmutation of the cyinure (subtances hyperproteic of cyanide) and dicyanure is cataclysée mutually and molléculairement between the two subtances.

Others

the cyanides are used as insecticides in the boats and rat poisons.
the Professors Ernst T. Krebs Senior and Junior had proposed the intravenous amygdalin administration in carcinological Chimiothérapie. Indeed, it delivers cyanide under the action of beta-glycosidase specifically expressed by certain tumoral fabrics. Amygdalin IV however was not the proof of its effectiveness.
the cyanide is used in the mining extraction and industry to extract the Or and the money to replace the mercury.
It is also used to carry out the electrodeposition (electrolysis) of certain metals (money, gold, cadmium, copper, mercury,…)
Released by the Zyklon B, the Cyanure of hydrogen was used by the Nazi S during the Second world war like poison in the gas chambers.

Safety

Toxicity

The cyanide is fixed on the iron atoms contained in the Hémoglobine and the Cytochrome P450. This last is responsible for the transport and the use of the Oxygène in the respiratory Chaîne mitochondriale. It is to be announced that, if the cyanide fixing on hemoglobin moves the curve of saturation of hemoglobin towards the left and decreases by this fact the oxygen extraction by fabrics, this mechanism is modest in death by intoxication with cyanide.

It is particularly frightening in the form of Cyanure of hydrogen, compound volatile and very poison, which attacks directly the Poumon S. This gas is formed in particular when the cyanides are acidified (in solution or by the gastric juices after ingestion). It is usable for its properties anoxiantes like Chemical weapon.

The intoxication with cyanide can simply occur at the time of the ingestion of some Plante S (Cassave, Manioc…)

The combustion of certain polymers (Polyurethane S) involved intoxications with cyanide and the use even of cyanide salts in Métallurgie increased the risk by it. It is allowed that, in many fires, in particular “Feux of beds” (people smoking with the bed, falling asleep, the cigarette causing a slow combustion of the covers), smoke can contain much cyanides, which explains why one rather frequently finds victims died by intoxication before being burned.

Antidotes

The following antidotes exist:

Nitrite of amyl associated with the Nitrite of sodium and the Thiosulfate of sodium;
the Hydroxocobalamine, which collects cyanide to lead to the Vitamine B12, atoxic and excreted by the urines.
salts of Cobalt

It is necessary to react quickly and, in the event of respiratory stop, to make breathe oxygen and to in no case to practice stops it with mouth because there is a risk of intoxication to the expiry. Under the action of heat the cyanide does not represent any danger.

Nomenclature

Cyanide of sodium:

number CASE: 151-50-8
toxicological card INRS: FT111

Cyanide potassium:

number CASE: 143-33-9
toxicological card INRS: FT111

History

Heinrich Himmler (1900-1945) would have committed suicide by absorbing a cyanide capsule.
Magda Goebbels (1901-1945) killed his/her six children and committed suicide using cyanide bulbs.
Raspoutine (1869-1916) poisoned with difficulty with cyanide because one does not know if it had had recourse to the Mithridatisation or if the cyanide had reacted with the sugar of the cake where it had been placed.

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