Patent GB-482954-A (GB)
Title: Improvements in the manufacture and production of oxidation products from mixtures containing paraffin waxes
Filed: 1936-10-07
Abstract: Crude products containing solid paraffin hydrocarbons are dissolved in liquid aromatic nitrohydrocarbons or mixtures containing them, and the solutions are cooled, whereupon solid paraffin hydrocarbons are deposited.  The hydrocarbons are separated, and may then be subjected again to similar treatment with the same solvent or another solvent of the type defined above.  Suitable starting materials are brown coal tars or coal- or tar-hydrogenation products containing paraffin wax.  In the examples, (1) dehydrated brown-coal tar is stirred with nitrobenzene at about 50 DEG  C., the mixture is cooled to 15 DEG C., and the deposited paraffin wax is filtered and freed from nitrobenzene by treatment with steam; (2) paraffin wax is recovered from brown-coal tar as in example 1, and then dissolved again in nitrobenzene, reprecipitated by cooling, filtered, and freed from nitrobenzene by distillation under reduced pressure. Other specified solvents are mixtures of nitrobenzene with chloronitrobenzenes; according to the Provisional Specification, dinitrobenzenes and chloronitrobenzenes may also be used.ALSO:Crude products containing solid paraffin hydrocarbons are dissolved in liquid aromatic nitrohydrocarbons or mixtures containing them, and the solutions are cooled; solid paraffin hydrocarbons are deposited, and these are separated and oxidized with nitrogenous oxidizing agents.  Suitable starting materials are brown coal tars or coal- or tar-hydrogenation products containing paraffin wax.  The solution and cooling treatment may be repeated, with the same solvent or another solvent of the type defined above, before the paraffin hydrocarbons are oxidized, and the solvent adhering to the hydrocarbons may be separated or may be allowed to remain.  The oxidation may be effected with nitric acid or nitrous gases, preferably at 50-100 DEG  C., and the oxidation product may be purified by washing it with water or by warming and, if desired, by treatment with alkaline reagents.  In the examples, (1) dehydrated brown-coal tar is stirred with nitrobenzene at about 50 DEG  C., the mixture is cooled to 15 DEG  C., and the deposited paraffin wax is filtered and then treated at about 80 DEG  C. with nitric acid of 45 per cent strength; the product separates into layers, one of which is a nitrobenzene solution of oxidation products, and this layer is separated, treated with water, and then freed from nitrobenzene by distillation, preferably under reduced pressure; the residual oxidation product is then worked up in known manner to yield fatty acids useful for making soaps; the oxidation product may include dicarboxylic acids as well as monocarboxylic acids; nitrobenzene may be separated from the paraffin wax, e.g. by treatment with steam, before the wax is oxidized, or alternatively additional nitrobenzene may be added; (2) paraffin wax is recovered from brown-coal tar as in example 1 and then dissolved again in nitrobenzene and reprecipitated by cooling; the wax is filtered, freed from nitrobenzene by distillation under reduced pressure, and then treated at 90 DEG  C. with nitric acid of 60 per cent strength; the layer of oxidation products is separated, heated to 120 DEG  C. to eliminate nitric acid, and worked up in known manner.  Other specified solvents for refining the paraffin wax are mixtures of nitrobenzene with chloronitrobenzenes; according to the Provisional Specification, dinitrobenzenes and chloronitrobenzenes may also be used.