Butane (C 4 H 10 ) - an organic compound, a hydrocarbon of the alkanes class. In chemistry, the name is used primarily to denote n- butane. A mixture of n- butane and its isobutane isomer, CH (CH 3 ) 3, has the same name. The name comes from the root “but-” (the French name for butyric acid is acide butyrique , from other Greek. Βούτῡρον , oil [3] ) and the suffix “-an” (belonging to alkanes). Inhalation of butane causes respiratory dysfunction. It is contained in natural gas , it is formed during the cracking of petroleum products , in the separation of associated petroleum gas , "fat" natural gas . As a representative of hydrocarbon gases, it is flammable and explosive, low toxic, has a specific characteristic odor, and has narcotic properties. By the degree of exposure to the body, gas belongs to substances of the 4th hazard class (low hazard) according to GOST 12.1.007-76 [4] . Harmful effect on the nervous system [5] .
| Butane | |
|---|---|
 | |
  | |
| Are common | |
| Chem. formula | C 4 H 10 |
| Physical properties | |
| Molar mass | 58.12 g / mol |
| Density | 0.6010 (at 0 ° C) g / cm³ |
| Ionization energy | |
| Thermal properties | |
| T. melt. | −138.4 ° C |
| T. bale. | −0.5 ° C |
| T. aux. | and |
| T. svpl. | 372 ° C |
| Etc. blast | |
| Steam pressure | |
| Chemical properties | |
| Solubility in water | 6.1 mg in 100 ml |
| Classification | |
| Reg. CAS number | 106-97-8 |
| PubChem | |
| Reg. EINECS number | |
| Smiles | |
| Inchi | |
| Codex Alimentarius | |
| RTECS | |
| Chebi | |
| UN number | |
| ChemSpider | |
| Security | |
| MPC | 300 mg / m³ |
| Toxicity |  four one one |
Content
Isomerism
Bhutan has two isomers :
| title | formula | structural formula | melting point, ° С | boiling point, ° С |
|---|---|---|---|---|
| n- butane | CH 3 –CH 2 –CH 2 –CH 3 | −138.3 | −0.5 | |
| isobutane | CH (CH 3 ) 3 | −159.6 | −11.7 |
Physical Properties
- Butane is a colorless combustible gas with a specific odor, easily liquefied from −0.5 ° C at normal pressure, freezes at −138 ° C; at elevated pressure and ordinary temperature - volatile liquid. Critical temperature +152 ° C, critical pressure 3,797 MPa.
- Solubility in water - 6.1 mg per 100 ml (for n- butane, at 20 ° C), it is much better soluble in organic solvents [6] ). It can form an azeotropic mixture with water at a temperature of about 100 ° C and a pressure of 10 atm.
- The density of the liquid phase is 580 kg / m³ [7]
- The density of the gas phase under normal conditions is 2.703 kg / m³.
- The heat of combustion is 45.8 MJ / kg (2657 MJ / mol (see [8] ).
Finding and Receiving
- Contained in gas condensate and petroleum gas (up to 12%). It is a product of catalytic and hydrocatalytic cracking of petroleum fractions. The laboratory can be obtained by the Würz reaction :
Desulfurization (demercaptanization) of butane fraction
The straight-run butane fraction must be purified from sulfur compounds, which are mainly represented by methyl and ethyl mercaptans . The method for purifying the butane fraction from mercaptans consists in the alkaline extraction of mercaptans from the hydrocarbon fraction and the subsequent alkali regeneration in the presence of homogeneous or heterogeneous catalysts with atmospheric oxygen with the release of disulfide oil.
Application and reactions
When free-radical chlorination forms a mixture of 1-chloro and 2-chlorobutane. Their ratio is well explained by the difference in the strength of C – H bonds at positions 1 and 2 (425 and 411 kJ / mol).
When completely burned in air, it forms carbon dioxide and water. Butane is used in a mixture with propane in lighters, in gas cylinders in a liquefied state. The boiling point of butane is −0.5 ° C, much higher than that of propane (−42 ° C), therefore, in its pure form it can only be used in a warm climate. Sometimes “winter” and “summer” mixtures with different compositions are used (in summer butane up to 50%, in winter - not more than 15%). The heat of combustion of 1 kg is 45.7 MJ (12.72 kWh ).
With a lack of oxygen, soot , carbon monoxide or a mixture of them is formed:
DuPont has developed a method for producing maleic anhydride from n-butane by catalytic oxidation:
n- Butane - raw materials for the production of butylene , 1,3-butadiene , a component of high octane gasolines. High purity butane, and especially isobutane, can be used as a refrigerant in refrigeration units. The performance of such systems is slightly lower than that of freon ones , but butane is environmentally friendly, unlike freon refrigerants.
In the food industry, butane is registered as a food additive E943a , and isobutane - E943b , as a propellant .
Security
Highly flammable. Explosive limits of 1.4–9.3% in air by volume. MPC in the air of the working area - 300 mg / m³. With deep repeated inhalation, it causes hallucinations and is popular among drug addicts, it can also cause fatal choking.
See also
- Isobutane
- Cyclobutane
Notes
- ↑ 1 2 3 http://www.cdc.gov/niosh/npg/npgd0068.html
- ↑ 1 2 https://pubchem.ncbi.nlm.nih.gov/compound/butane#section=Flash-Point
- ↑ In turn, Dr. Greek βούτῡρον “butter” comes from βοῦς “cow, ox” and τυρός “cheese”.
- ↑ GOST 20448-90. Liquefied petroleum hydrocarbon gases for domestic consumption
- ↑ Gas chromatographic measurement of mass concentrations of hydrocarbons: methane, ethane, ethylene, propane, propylene, n- butane, alpha-butylene, isopentane in the air of the working area. Methodical instructions. MUK 4.1.1306-03 (APP. BY THE CHIEF STATE SANITARY DOCTOR OF THE RUSSIAN FEDERATION March 30, 2003)
- ↑ Chemical Encyclopedia T1, M. 1988, p. 331, Article “Bhutans”
- ↑ Physico-chemical properties of the propane-butane mixture
- ↑ Bhutan: chemical and physical properties (inaccessible link)
Literature
- Lvov M.D. Bhutan, hydrocarbon // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.