Fatty alcohol
Fatty alcohols are aliphatic, long chain, monovalent, primary alcohols. Said hydrocarbon radicals are straight-chain containing from 6 to 22 carbon atoms and can also be mono-or polyunsaturated.
Fatty alcohols found in natural waxes, bound as carboxylic acid esters, such as wool wax or spermaceti and wax alcohols are often called. Such alcohols typically contain an even number of C- atoms, which may also be at 36 or more carbon atoms.
Fatty alcohols are produced in the chemical industry, for example, by reduction of fatty acids or petrochemicals. Fatty alcohols may be used directly as a nonionic surfactant and for the preparation of various other surfactants.
Structure
The table shows examples of fatty alcohols. The nomenclature corresponds to the nomenclature of alkanes, complemented by the suffix- ol for the additional available alcohol group. Often their trivial names are used (see in brackets).
Production
Fatty alcohols can be prepared by reduction and hydrolysis of waxes, such as spermaceti with elemental sodium produce ( Bouveault Blanc reaction). The first technical presentation was conducted in 1928 by the Hydrierwerken in Rodleben. This method has no technical meaning more for the extraction of fatty alcohols.
As a rule, fatty alcohols from renewable raw materials, produced for example by hydrogenation of fatty acids derived from vegetable oils (see oleochemicals ). The typical carboxylic acids carboxy group (-COOH) is transferred to the typical alcohol hydroxy group (-OH ). The carbon atom of the -COOH group is retained as - CH2 -OH. For example, cetyl alcohol is obtained (C16) as a product of palmitic acid from palm oil or coconut oil and stearyl (C18 ) stearic acid.
Fatty alcohols can be prepared in cobalt and rhodium catalysts of olefins and carbon monoxide by hydroformylation ( oxo synthesis ). The resulting aldehydes are converted by hydrogenation into alcohols. The so obtained alcohols are also called oxo alcohols and can also be branched and odd by this synthetic route.
Fatty alcohols with even-numbered carbon chains can be prepared by reaction of ethylene with triethylaluminum. In the first step is prepared from aluminum metal, hydrogen and triethylaluminium as an intermediate diethylaluminum that further reacts with ethylene to triethylaluminum. About two-thirds of triethylaluminum formed are back to the starting reaction (1) is returned, a third is used for the build-up reaction.
The distribution of the chain length of which corresponds to a Poisson distribution that is optimized by a suitable choice of the process parameters for the range of 10 to 16 carbons. In the oxidation of the complex with oxygen and subsequent hydrolysis with sulfuric acid and water form identical to natural Ziegler alcohols, also called Alfols, which are used as fatty alcohol sulfates or by ethoxylation and sulfation as alkyl ether sulfates in personal care products, detergents and cleaning agents.
Use
Fatty alcohols such as stearyl alcohol and cetyl alcohol are used as nonionic surfactants and can be used as a basis for many creams and ointments used. You are not miscible with water, but can be converted by reaction with sulfuric acid in fatty alcohol sulfates, which are of great importance as anionic surfactants in detergents. By ethoxylation fatty alcohol ethoxylates as nonionic surfactants can be obtained, which are used in personal care products.