Patent GB-743210-A (GB)
IPC: C08F4/32
Abstract: 743,210. Hydroxy hydroperoxides. DISTILLERS CO., Ltd. March 4, 1954 [March 28, 1953], No. 8624/53. Class 2 (3). The invention comprises hydroxy hydroperoxides of the formula wherein R 1  may be hydrogen, an alkyl radical or an alicyclic hydrocarbon radical and R 2'  R 3  and R 4  are alkyl radicals or alicyclic hydrocarbon radicals and Ar is an aromatic group which may be a benzene or alkyl substituted benzene nucleus, or a naphthalene, anthracene or phenanthrene nucleus or an alkyl substituted derivative thereof. The hydroxy hydroperoxides of the above formula are produced by a process which comprises reacting in the liquid phase at elevated temperatures with molecular oxygen a mono-carbinol of the formula wherein R 1 , R 2 , R 3  and R 4  and Ar are as defined above. The groups and are attached to non-adjoining carbon atoms in one or two benzene rings of the aromatic nucleus so that no ortho positions are substituted. Alkyl radicals mentioned include from methyl up to secondary butyl and alicyclic hydrocarbon radicals mentioned include cyclopentyl and cyclohexyl. The oxidation may be carried out in the presence of either liquids which may be inert to the action of the molecular oxygen and/or hydroperoxide produced, e.g. water or liquids which are oxidizable themselves and which dissolve the mono carbinols. Commercial oxygen or gaseous mixtures, e.g. air, and mixtures containing ozone, may be used as may be super-atmospheric pressures. Oxidation catalysts may be employed such as cobalt, manganese and copper compounds. The oxidation may be initiated by the addition of compounds liberating free radicals such as suitable peroxides or hydroperoxides or azo compounds known to furnish free radicals at the reaction temperatures. The process is preferably carried out in the presence of basic material to prevent accumulation of acids in the reaction mixture, e.g. the oxides, hydroxides, carbonates or bicarbonates of the alkali or alkaline earth metals or salts of those metals with weak organic or inorganic acids. Ammonia or amines may also be added. The desired products may be separated from the reaction mixture by fractional distillation or by extraction with water, aqueous alcohol, or aqueous alkali, e.g. aqueous sodium hydroxide solution, when salts are formed. The free hydroxy hydroperoxides may be recovered by extraction of the alkaline solution with water-immiscible solvents or by neutralization or acidification. Part of the product only may be extracted and the remaining oxidation mixture, preferably after addition of fresh mono-carbinol, may be subjected to further oxidation. The oxidation may be carried out batchwise or continuously. A continuous process may be carried out starting from the aromatic hydrocarbon from which the monocarbinol is prepared by oxidation with molecular oxygen to obtain a mixture of the monohydroperoxide with some monocarbinol and hydroxy hydroperoxide in unreacted aromatic hydrocarbon. The oxidation mixture is extracted with aqueous alkali metal hydroxide solution to remove the hydroxy hydroperoxide and dihydroperoxide and free hydroxy hydroperoxide is recovered from the solution after the addition of an acid such as carbon dioxide. The mixture remaining comprising unreacted hydrocarbon, monohydroperoxide and monocarbinol is then reduced, e.g. with sodium sulphite or hydrogen in the presence e.g. of Raney nickel whereby the monohydroperoxide is reduced to monocarbinol. The solution of mono-carbinol is then recycled, preferably after the addition of further aromatic hydrocarbon starting material to the oxidation stage. In examples m-(2-hydroxy-2-propyl)-α,α-dimethyl benzyl hydroperoxide is obtained by hydrogenating m-di-iso-propyl benzene mono-hydroperoxide to obtain m-isopropyl phenyl dimethyl carbinol, and oxydizing the latter with oxygen in the presence of calcium hydroxide and 2-azobis-isobutyronitrile. The oxidation product is then diluted with benzene and the sodium salt of the hydroxyhydroperoxide is separated partly by extraction with and partly by precipitation with aqueous sodium hydroxide, the sodium salt obtained being converted to free hydroxy hydroperoxide by treatment with solid carbon dioxide (1); p-(2-hydroxy-2-propyl)α,α- dimethyl benzyl hydroperoxide is similarly prepared from p-isopropyl phenyl dimethyl carbinol (2) ; and p - (2 - hydroxv - butyl) - α,α - dimethylbenzyl hydroperoxide is similarly prepared from p-isopropyl phenyl ethyl methyl carbinol, the latter being obtained in turn by Grignard reaction from p-bromo-isopropylbenzene and ethyl methyl ketone. By treatment of the hydroxy hydroperoxide products with acidic catalysts such as mineral acids, e.g. sulphuric acid, acid treated mineral earths such as fuller's earth, hydrogen ion exchange material and Friedel-Craft's catalysts such as aluminium trichloride and boron trifluoride the corresponding phenolalcohols and ketones such as acetone or aldehydes such as acetaldehyde are produced. The monocarbinol starting materials in general may be produced by catalytic hydrogenation or chemical reduction of the corresponding monohydroperoxides or may be separated from the products obtained by oxidation with molecular oxygen of the corresponding hydrocarbons.