Hydrocyan
| Structural formula | |||||||
|---|---|---|---|---|---|---|---|
| <math>
\ mathrm {H} \! - \! \ mathrm {C} \! \ equiv \! \ mathrm {N} </math> | |||||||
| General | |||||||
| name | hydrocyan | ||||||
| other names | prussic acid | ||||||
| sum formula | H C N | ||||||
| CAS number | 74-90-8 | ||||||
| short description | after bitter almonds smelling liquid | ||||||
| characteristics | |||||||
| mol mass | 27.02 g mol | ||||||
| state of aggregation | liquid | ||||||
| density | 0.687 g/cm ³ | ||||||
| melting point | -13.3 °C | ||||||
| boiling point | 25.7 °C | ||||||
| steam pressure | 830 h Pa | ||||||
| solubility | in water in each relationship | ||||||
| of safety references | |||||||
| of Gefahrensymbole | |||||||
| |||||||
| R and S-sentences | of R: 12-26-50/53 S: 1/2 7/9 16, 36/37 38 45 60 61 | ||||||
| MAK | 10 ml/m 3 = 11 mg/m 3 | ||||||
| deadly dose (humans) | 1-2 mg/kg | ||||||
| so farpossible and common, SI-UNITs are used. If not differently notes, the indicated data apply with standard conditions. | |||||||
Hydrocyan (prussic acid), sum formula HCN, is a colorless to easily yellowish, combustible and water-soluble liquid with a characteristic, unpleasant bitter almond smell. „The bitter almond smell “of almondsand sits down to other cores together from the pleasant smell of Benzaldehyd and the rather unpleasant smell of prussic acid. The smell is to be compared also with Marzipan. Originally a zyanogenes Glykosid, amygdaloside , is present in the almond cores,under the influence to a Hydroxynitrillyase ( an enzyme) or acids into prussic acid, Benzaldehyd and glucose disintegrates. Only about 20 50% of humans is - due to their genetic assessment - able to notice the smell. The name prussic acid agitatesof the production from Eisenhexacyanoferrat (citizen of Berlin blue) ago, a very steady pigment with blue color.
Prussic acid is also the title of a detective story of Agatha Christie. The expenditure for original appeared 1945 under the title „savingssounds cyanides “.
Table of contents |
The boiling point is to characteristics the melting point with approximately 26 °C with approximately -13 °C.
The salts of prussic acid are called cyanides. Prussic acid is an extremely weak acid, which is already driven by carbonic acid from its salts. As PCs becomesusually 9.31, occasionally also 9.21 or 9.04 indicated.Cyanide, salts of prussic acid (potassium cyanide) work with the hydrolysis strongly basic/alkalinely. Hydrochloric acid in the human stomach sets therefore from cyanides hydrocyan free.
Prussic acid is both easily inflammable andin each relationship water-solubly. With a fire with presence of prussic acid is recommended not to delete and prussic acid controlled burn down let if necessary with water.
A mixture from air and hydrocyan gas is highly explosive within the range of 5,4-46,6 volume %!
Pure one water-free prussic acid can polymerize spontaneously, particularly in presence of small quantities of basic materials. This reaction is strongly exothermic!
In water prussic acid dissoziert to a small part:
<math> \ mathrm {HCN + H_2O \ rightarrow H_3O^+_ {(aq)} + CN^-_ {(aq)}}< /math>
poison effects
prussic acid as well as allCyanides are high poisonous. Prussic acid evaporates with normal air temperature; a poisoning can take place therefore easily via inhalation (inhalational). An absorption over the skin is possible, it becomes by manual labor (which is connected with sweat) favours, there prussic acid onehigh water solubility possesses.
The primary poison effect exists Oxidase in the Mitochondrien in the formation of a complex with the iron III Zentralion of the Cytochrom -. By inactivating this enzyme the Zellatmung does not come to succumbing, the cell can the oxygen any longeruse for power production. Contrary to the landläufigen opinion a light red colouring of the skin is a typical sign of a poisoning with cyanides: The venous blood is enriched still with oxygen, since the oxygen could not be used by the cells.
ThoseConnection of the cyanide at Fe-II-ions is comparatively small. Inactivating hemoglobin by connection of the Fe-II-ion plays therefore with poisonings a subordinated role.
Not an not underestimating portion of humans can not notice the smell of prussic acid and should appropriatePrecautionary measures while handling prussic acid meet.
deadly employment of prussic acid
- the deadly effect of prussic acid was used in the National Socialist extermination camps, in order to murder humans in large number. (Comparisons cyclone B, Gaskammer, Holocaust).
- Inunite states of the USA prussic acid gas for the enforcement of the death penalty in the Gaskammer are used. According to assumptions the prussic acid concentrations used with it are with approx. 3.200 ppm. The death of the condemned one usually occurs within 4 to 10 minutes.In addition, depending upon physical condition should be possible up to 17 minutes.
prussic acid as weapons
as poisonous gas became prussic acid for the first time by the French army at the 1. July 1916 assigned. This employment did not only remain because of newerFilter in the gas masks of the German opponents ineffectively. Usefulness of prussic acid gas as agent proved as unsatisfactory, because the gas evaporated very rapidly. After this failure prussic acid gas was not continued to use as weapon.
antidote
Cyanide poisonings 4-Dimetyhlaminophenol (4-DMAP) is used as antidote. This converts Fe (II) into Fe (III), which to a Methämoglobin - education leads. The Methämoglobin binds the cyanide ions. Based on total hemoglobin a small quantity of Methämoglobin, around a large part of the cyanide is already sufficientto bind. The effect of this remedy depends however on the hemoglobin concentration in the blood . CAVE: With combustible gas inhalation it must be absolutely noted that e.g. by a carbon monoxide poisoning larger quantities hemoglobin are already bound and no more oxygen to transport can. This saveswith the treatment, which converts up to a 1/3 of hemoglobin, large dangers of respiratory Insuffiziens.Partly (!) causes less more.In the USA after an intoxication the Cyanokit in such a way specified is used. Since side effects are however disputed, is this emergency kitin Germany not yet approved. To note it is here however that a lifesaving promises chances on success only with 100%ig sober condition (also no remainder alcohol in the blood).
As the further measure ISO amyl nitrite is given for inhalation, which lowers the blood pressure andthus a slowing down of the poisoning causes; this measure should be used because of the danger of a possible blood pressure drop however only with caution.
Other remedies are:
- Natriumthiosulfat: It supplies the sulfur needed for the enzyme Rhodanid Synthetase, which for the transformationin Rhodanid one needs. Since many food contains hydrocyan in small concentrations, humans possess the enzyme Rhodanid Synthetase, which small quantities of prussic acid into the harmless material Rhodanid converts. Therefore poisonings with slight traces of prussic acid lead rarely to long-term damage.
- Hydroxycobalamin: Cobalt connection, which complex connection strong with cyanide ions is received.
natural occurrence
the cores of some stone fruit fruits (almond, in particular bitter almond, apricot, peach, cherry) and other Rosacen contain small quantities of prussic acid, this serveprobably as eating protection of the seeds. In the Tropics often as food used the tuber Maniok contains likewise as cyanogenes Glykosid bound prussic acid, which is removed by the processing before the consumption of the plant. Cyanogene plants are far common underthe higher plants and can set HCN free from cyanogenen Glykosiden with injury of the Pflanzengewebes by herbivores by Hydroxynitrillyasen ( a biocatalyst). It concerns poison plants naturally. Some examples of cyanogene plants are the tropical Goldtüpfelfarn Phlebodium aureum (a member of the Tüpfelfarngewächse) or the Brazilian Gummibaum Hevea brasiliensis.
cultural one occurrence
prussic acid is used in many processes in the industry and in the mining industry, for example for leaching out gold:
<math> \ mathrm {4 outer ones +8 HCN + O_2 + 4 OH^ \ rightarrow 4 [outer one (CN) _2] ^ - + 6 H_2O}< /math>
The gold solution is then reduced with zinc. (Ways of the better handling here not liquid prussic acid, but a cyanide solution is used.) this procedure leads, like also that alternativelyassigned mercury amalgam procedures, for the often catastrophic waters poisonings in the gold assisted areas of the third world.
Prussic acid becomes free with wrong control steps in the galvanic shop.
Prussic acid is also an important basic material for many products of organic chemistry. Usually becomesprussic acid at the place of its production processes immediately, since a transport of this dangerous material is avoided after possibility.
During burning nitrogenous polymers (plastics) prussic acid can develop to substantial extent. Also when smoking tobacco something prussic acid develops.
Production and use
for the production of prussic acid are three procedures of importance
- with the Ammonoxidation of methane (Andrussow procedure) a mixture from ammonia and methane with approximately 1,200 °C at a platinum net as catalyst are oxidized.
- With the Ammondehydrierung ofMethane (Degussa - BMA procedures) ammonia and methane are converted with the help of a catalyst to prussic acid and hydrogen.
- During the form amide splitting (BASF - procedures) one evaporates to form amide and one heats up strongly. Form amide splits thereby into prussic acid and water.
Prussic acid becomes in largeQuantities for the production of Adiponitril, an intermediate product of plastic production, uses. In addition prussic acid is added by means of a nickel catalyst at butadiene (Hydrocyanierung).
accidents in handling prussic acid
- 1947, the USA, Los Angeles:
During the aeration one from woodbuilt house for the fight against termites, which threatened to up-eat it, the hermetically blocked house exploded because of a too high concentration of prussic acid.
- 1995, Croatia, resort Lovran with Rijeka:
During the attempt to release a church from wood worms to a part steppedthe gas because of inappropriate sealing of the building out. The entire local centre thereupon in the night evacuates in the middle.
- 1998, the USA, Iowa:
After a pupil with potassium cyanide had killed itself, nine humans became ill from steams withdrawing from its body.
- 2006, Tschechien, Nymburg:
In a chemistry accident in Tschechien a larger quantity cyanide arrives into the Elbe.
proof
a classical procedure is the proof over the cyanide ions: An alkaline cyanide solution iron (II ) becomes - sulfate in the deficiency - solution admitted. Are Available, citizen of Berlin blue forms cyanide ions after acidifying. Caution: it escapes from prussic acid!
preventive measures
of Schutzhandschuhe, dust respirator, respiratory protection gas filter B.
storage
cool, under strict oxygen and humidity exclusion.
