What is the chemical name of CO



Carbon monoxide (also Carbon monoxide, common short name: Carbon monoxide) is a chemical compound made of carbon and oxygen and belongs to the group of carbon oxides along with carbon dioxide and carbon trioxide.

Carbon monoxide is a colorless, odorless and tasteless gas. It arises from the incomplete oxidation of carbonaceous substances. This happens, for example, when these substances are burned, if there is not enough oxygen available or if the combustion takes place at high temperatures (see also: Boudouard equilibrium). Carbon monoxide itself is flammable and burns with a blue flame together with oxygen to form carbon dioxide.

Surname

In the German standard DIN 32640 "Chemical elements and simple inorganic compounds - names and symbols" from December 1986, only the spellings "carbon monoxide" and "carbon monoxide" are recommended with "oo", because according to the IUPAC rules for the nomenclature of inorganic chemistry End vowels of leading Greek numerals cannot be omitted.

In contrast, the 1990 edition of the IUPAC nomenclature only mentions the spellings “carbon monoxide” and “carbon monoxide”; when using the multiplicative prefixes, it says: “The final vowels of the multiplicative prefixes are not omitted unless there are compelling linguistic ones Reasons before. Monoxide is one such exception ”.[2]

Chemical properties

The molecular structure can best be described using molecular orbital theory. The length of the bond (111 pm) indicates that it is a partial triple bond. The molecule has a low dipole moment (0.12 D) and is often represented as follows (mesomerism):

It should be noted that the octet rule in the two structural formulas on the right is not adhered to.

Although carbon monoxide is formed from the elements in an exothermic reaction, it is thermodynamically unstable with regard to the decomposition into carbon and carbon dioxide. Although this decomposition reaction is almost immeasurably slow at room temperature - CO is metastable - it plays a major role at higher temperatures. In iron production (blast furnace process), for example, the equilibrium between CO on the one hand and C + CO, which is quickly established at higher temperatures, is used2 on the other hand (Boudouard equilibrium).

Carbon monoxide is a good and inexpensive reducing agent and is used in this function in a variety of ways. The oxidizing power of CO, on the other hand, is only weak.

Carbon monoxide is a very good ligand for metal complexation. For this reason, numerous metal carbonyls are known. The extreme toxicity (see below) is also due to this property. Carbon monoxide is one of the strong field ligands and is isoelectronic with dinitrogen (N.2) as well as the ions cyanide (CN) and nitrosyl (NO+). A strong metal-ligand bond is created through the development of synergetically strengthening back and forth bonds. CO is a strong σ donor and π acceptor.

At 1073 kJ / mol, carbon monoxide has the strongest bond of an uncharged molecule.

toxicity

Carbon monoxide is a dangerous breath poison and can lead to carbon monoxide intoxication. It binds when it is z. B. enters the bloodstream with tobacco smoke, about 210 times more of the red blood pigment hemoglobin than oxygen. This means that if carbon monoxide is present in a concentration ratio of 1: 210 to oxygen (this corresponds to about 0.1 percent carbon monoxide in the air), over time 50% of the hemoglobin in the blood is blocked by CO. With 1.28% carbon monoxide in the air, death occurs within 1-2 minutes.[3][4] Carbon monoxide blocks the binding sites of oxygen by entering into a stronger coordinative bond with the central ion (iron, here bivalent) of the heme group in hemoglobin and myoglobin (complex formation reaction). This blocks the transport of oxygen in the blood or muscles, which can lead to death from suffocation. However, this binding is made more difficult by the structure of the hemoglobin compared to the actual oxygen carrier heme embedded in the hemoglobin: the affinity of CO to bind to isolated heme is 26,000 times stronger than that of oxygen. If the oxygen transport were not the task of hemoglobin, even small amounts of carbon monoxide, which is also produced in some processes in the body, would be fatal. Collman et al. formulated the thesis that carbon monoxide, which is bound to the sixth coordination point of the heme due to the arrangement of its lone pair of electrons at C at an angle of 180 °, is quasi bent by "distal effects" and thus the binding reaction becomes more difficult. [5]

By binding the CO to hemoglobin, pulse oximeters are fooled and incorrectly indicate high rates of oxygen saturation. The outward signs of carbon monoxide poisoning are cherry-red mucous membranes. According to more recent studies with a high number of cases (231 patients), this clinical sign is seldom encountered, especially in milder forms of intoxication.[6] The color is a result of the deep red hemoglobin carbon monoxide charge transfer complexes. Furthermore, the dead spots (livores) that appear on the corpse after death can typically also be colored bright red by this very mechanism and thus give an indication of carbon monoxide poisoning.

Carbon monoxide is a photosynthetic poison and also damages the chlorophyll in plants.

Resilience of a person under the effect of CO

* For healthy adults there does not seem to be any danger with continuous exposure of 8 hours at concentrations below 50 ppm. Sick people could suffer from it even with less stress.
  • With a mild exposure of 70 to 100 ppm over a few hours, symptoms similar to colds appear: runny nose, headache, sore eyes and shortness of breath.
  • At medium exposure of 150 to 300 ppm, dizziness, drowsiness and nausea, even vomiting, develop.
  • Extreme exposure above 400 ppm: unconsciousness, brain damage and death.

Deafness is increased by up to 50% when exposed to CO.

 

Rescue in case of carbon monoxide intoxication

Carbon monoxide reacts strongly exothermically with air if an ignition spark is found. A spark in the light switch or the doorbell can therefore trigger an explosion. For the helper, this means that self-protection has absolute priority and the utmost caution is required. In particular, the risk of self-poisoning should also be taken into account. Self-contained breathing apparatus is usually necessary for rescue, which in most cases is carried out by the fire brigade.

Patients with carbon monoxide poisoning are generally intubated and ventilated with positive end-expiratory pressure (PEEP) and 100% oxygen by the ambulance service and emergency physician. Due to the significantly increased oxygen supply, carbon monoxide can be displaced by the hemoglobin. If available, hyperbaric oxygenation may be considered.[7][8]

Manufacturing

Carbon monoxide can be obtained from numerous starting materials such as B. natural gas, biogas, light petrol, heavy oils, coal and biomass can be produced, whereby synthesis gas, a mixture of carbon monoxide with hydrogen, is generated first, which is then cleaned and processed (synthesis gas, Fischer-Tropsch synthesis). It also escapes in large quantities as an air pollutant via exhaust gas emissions.

On a large scale (e.g. from coke), carbon monoxide can be produced under the influence of energy (combustion) as follows:

Carbon burns with oxygen in the presence of carbon dioxide to carbon monoxide.

The carbon dioxide is used to prevent the carbon from burning to carbon dioxide:

In the presence of sufficient oxygen, carbon burns to carbon dioxide.

In the laboratory, CO can be produced by decomposing formic acid:

The disintegration is caused by the dehydrating effect of concentrated sulfuric acid, which is added dropwise to the formic acid.

disposal

Since carbon monoxide is very poisonous, excess quantities must be collected with special absorbers or flamed with a flame device. Particular care should be taken with CO-air mixtures, as they can react very explosively.

use

Pure carbon monoxide is mainly used for the following applications:

References

  1. abcdefGH Entry for CAS no. 630-08-0 in the GESTIS substance database of the BGIA, accessed on December 12, 2007 (JavaScript required)
  2. IUPAC: Inorganic Chemistry Nomenclature. German edition of the recommendations 1990. VCH, Weinheim 1994, ISBN 3-527-25713-6, P. 76.
  3. http://www.lpm.uni-sb.de/chemie/kohlenstoffche/kohlenstoff/texte/Kohlenst06.htm
  4. Hu & Speizer: Environmental and Occupational Hazards. Carbon monoxide. In: Harrison's Principles of Internal Medicine, McGraw-Hill, New York City, 14th edition, page 2533
  5. James Collman et al: Nature of O2 and CO Binding to Metalloporphyrins and Heme Proteins, 1976
  6. Cevik AA et al. Interrelation between the PSS, CO-Hb levels and in-hospital clinical course of CO poisoning. Int J Clin Pract 2006; 60: 1558-1564 PMID 16918999
  7. Weaver et al .: Carbon monoxide poisoning: risk factors for cognitive sequelae and the role of hyperbaric oxygen. Am J Respir Crit Care Med. 2007; 176 (5): 491-7. PMID 17496229
  8. Weaver et al. Hyperbaric oxygen for acute carbon monoxide poisoning. N Engl J Med. 2002 Oct 3; 347 (14): 1057-1067. PMID 12362006

Safety data sheets

Safety data sheets for carbon monoxide from various manufacturers in alphabetical order:

literature

  • Hans Beyer, Wolfgang Walter: Organic Chemistry Textbook. S. Hirzel Verlag, Stuttgart - Leipzig 1998, 23rd revised. and updated edition, ISBN 3-7776-0808-4

Categories: Flammable Substance | Toxic substance | Carbon compound | Oxygen compound | gas