Aliphatic compound
Aliphatic hydrocarbons (Greek ἄλειφαρ aleiphar greasy ' ) are organic chemical compounds which are composed of carbon and hydrogen and non-aromatic. Thus, they are a subset of the hydrocarbons. IUPAC are aliphatic compounds " acyclic or cyclic saturated or unsaturated carbon compounds, excluding aromatic compounds ". The simplest group of aliphatic hydrocarbons are the saturated alkanes; continue to include also saturated cycloalkanes and unsaturated hydrocarbons of alkenes and alkynes to the group of aliphatic compounds.
Like all pure hydrocarbons are aliphatic hydrocarbons nonpolar lipophilic compounds (not water soluble). Since the IUPAC definition aliphatic compounds are compared with the aromatic carbon compounds and therefore defined by a negation, this means, conversely, that all organic compounds that are not aromatic, are aliphatic. Classification of organic compounds in aliphatic and aromatic compounds is carried out by the aromaticity. The so-called alicyclic compounds form a subgroup of the aliphatics and feature - similar to the aromatics - by annular chains, but are distinguished by the aromaticity of the aromatics.
Exemplary aliphatic compounds
The main fabric groups of aliphatic compounds according to the above definition are the following:
- N-, iso-and cyclo -alkanes (saturated hydrocarbons)
- N-, iso-and cyclo - alkenes and alkynes (unsaturated hydrocarbons).
Important examples of low molecular weight aliphatic compounds can be found in the table below ( arranged in order of increasing number of carbon atoms):
( The part here mitaufgeführte CAS Registry Number is a registered trademark of the American Chemical Society).
Aliphatic compounds in spectroscopy
Aliphatic CH stretching vibrations of non-conjugated CH- blocks in a molecule have the IR spectrum in the range of 3000-2750 cm -1 characteristic peaks. In contrast, the peaks are located at CH- conjugated building blocks beyond the 3000 cm -1 line.
In the 1H NMR spectrum, most aliphatic peaks are in the range of 1-2 ppm. Higher values up to about 5 ppm are obtained in neighboring electron-withdrawing groups.
Aliphatic compounds in the petrochemical industry
Main source of production of aliphatic compounds is the oil. The most important method of preparation is the steam cracking of oil to be cracked at the inter alia, ethane, LPG, naphtha and gas oil, or other suitable hydrocarbons. The gas phase of the steam cracker products containing aliphatic basic chemicals ethylene, propylene, C4 - section (mainly butene, iso- butene and 1,3- butadiene ) and isoprene.
- Of ethylene: Polyethylene - for example by Ziegler- Natta process approximately 21% of total ethylene production in LDPE
- About 13 % as LLDPE
- Approximately 23% HDPE
- Poly- α -olefins as lubricant
- Comonomers for polyethylene
- Polypropylene - for example, by the Ziegler- Natta process ( about 57 % of the total propylene production )
- Monomers and co- monomers ( butene- derived products in the production of plastics )
- Isobutene - as a monomer for copolymerization with isoprene
- 1,3-butadiene - monomer or co- monomer for polymerization to elastomers