GB628457A - Improvements in or relating to the oxidation of aliphatic hydrocarbons - Google Patents

Abstract

Fatty acids or fatty acid-containing mixtures are prepared by heating a normally liquid or solid aliphatic hydrocarbon with a persalt and an emulsion comprising water, an oleaginous material and an emulsifying agent, while passing through the reaction mass a gas containing oxygen and a percentage of water vapour therein, preferably 1-3 per cent by weight, at a temperature between 80 DEG and 150 DEG C., at which the hydrocarbon is in the liquid state. Hydrocarbons which may be so oxidized are fuel oils, lubricating oils, the paraffins, crude mineral wax, ozokerite, ceresine, crude mineral oils and fractions thereof. Generally, the persalt is mixed with the emulsion, which is then added to the heated liquefied hydrocarbon, preferably in small portions, and humidified air or oxygen is bubbled into the reaction mass with agitation. The oleaginous material used in the emulsion may be any animal or vegetable fat such as tallow, lard, stearin, cocoa fat or oil, fatty acids such as stearic or oleic acid, aliphatic hydrocarbons, or the fatty acid end products, the non-saponifiable products or the reaction end products of the present process, alone or in admixture with other hydrocarbons, fats or fatty acid. As emulsifying agent there may be used a soap. Suitable persalts are the permanganates, perborates, perchlorates, perchromates, persulphates, and peracetates of alkali-metals, or alkaline earth metals or other polyvalent metals, many of which are specified. To facilitate oxidation there may be added to the reaction mixture an oxidation catalyst, preferably of the drier type, for example metallic oxides, hydroxides and peroxides and inorganic or organic salts of metals including soaps, numerous examples being given. This catalyst may be added initially or portionwise or may be included in the emulsion. Generally, the emulsion comprises 2-10 per cent oleaginous material, 1-10 per cent water, 0.5-5 per cent sodium or potassium soap and 0.05-5 per cent each of the per-salt and oxidation catalyst, all weights based on the weight of the hydrocarbon. Aluminium apparatus is stated to have a catalytic effect on the reaction. The reaction products comprise mainly fatty acids together with minor amounts of partially or non-saponifiable matter and volatile by-products such as acids, aldehydes and ketones which are removed by the excess of gas during the reaction. The fatty acids are preferably recovered by cooling the liquid reaction mass to a temperature above the congealing point of the fatty acids and below that of the unsaponifiable material, the latter being separated off, for example, by filtration or centrifuging or the mass is settled and the middle layer of acids removed from the upper layer of congealed material and the bottom layer of catalyst. The fatty acids may be used in the preparation of soaps, reference being made to Specification 628,458, detergents, wetting agents, lubricating greases and emulsifiers, while the non-saponifiable material may be used as soap filler, as an antioxidant or as an additive in paints, varnishes or enamels, or it may be submitted to further oxidation. In a typical example, an emulsion comprising hot water, beef tallow acids, potassium permanganate and potassium stearate is added to molten paraffin wax and humidified air passed through the mixture with agitation so yielding a fatty acid-containing mixture of saponification value 196. The mixture is cooled to 42 DEG C., allowed to settle, and the middle layer containing the acids removed. Further examples are p given illustrating the oxidation of paraffin wax and also of yellow mineral oil.