Alcohols, including higher fatty alcohols, are compounds consisting of a hydroxyl group and a carbon chain. These include natural and synthetic alcohols, primary and secondary alcohols, linear and branched alcohols, saturated and unsaturated alcohols, as well as those with even and odd amounts of carbon atoms.
Fatty alcohols contain from 10 to 18 carbon atoms in the chain. In the case of natural alcohols, the number of carbon atoms is even, while synthetic alcohols may contain even and odd numbers of carbon atoms. Despite their surface and interphase activity, they are not considered to be surfactants. They are mainly used as raw materials for the production of surfactants. Fatty alcohols include mainly lauryl, cetyl, stearyl and oleyl alcohol. Their form at room temperature depends on the length of the carbon chain. For this reason, some of them (myristyl, cetyl, stearyl alcohol) are in the wax form, available on the market as flakes or pastilles.
Alcohols may be of oleochemical or petrochemical origin. The method of obtaining oleochemical raw materials involves the hydrolytic separation of vegetable or animal fat. The oil is heated to 300 °C with concentrated sodium hydroxide solution. The alcohol produced in this reaction is distilled together with the water from the sodium saponified fatty acids produced in the process. Another method is the reduction of oils with metallic sodium in the presence of alcohol as a source of hydrogen (e.g. butanol). In the case of petrochemical raw materials, in the first stage, basic ingredients such as ethylene and paraffin are obtained from crude oil or natural gas and then processed into higher fatty alcohols.
Reactions of alcohols and their derivatives
Higher fatty alcohols undergo the same reactions as other primary and secondary alcohols. Considering their industrial importance, they are mainly subjected to reactions such as:
Esterification – in order to obtain esters of waxy and oil consistency;
Sulphation, as a result of which alkyl sulphates and alkyl ether sulphates (anionic surfactants) are obtained;
Polyoxyethylation, which results in the production of non-ionic surfactants;
Halogenation, i.e. substitution of an alcohol hydroxide group with halogen, e.g. chlorine, iodine, used for the synthesis of alkyl halides;
Dehydration, which makes it possible to obtain an unsaturated compound from alcohol;
Oxidation, which, depending on the structure of alcohols, produces aldehydes or ketones, and then organic acids.
Applications of alcohols
Fatty alcohols are mainly used in the cosmetic industry as non-ionic surfactants. In formulations, they serve as emulsion stabilizers (both oil in water and water in oil), additives improving the consistency of cosmetics, emollients (these are preparations that moisturize the skin indirectly by creating a film that prevents water evaporation), as well as detergents.
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