GB816200A - Process for the separation of diisopropyl benzene dihydroperoxides - Google Patents

Abstract

<PICT:0816200/IV (b)/1> Di - isopropylbenzene dihydroperoxide is separated from mixtures also containing diisopropyl benzene and its oxidation products by subjecting the mixture to the action of two solvents which move in counter-current and are only slightly mutually soluble, one being a non-alkaline, substantially neutral aqueous liquid containing 0-80 per cent methanol or ethanol and the other a liquid hydrocarbon. The dihydroperoxide dissolves preferentially in the aqueous layer and high recovery yields are obtained by suitable adjustment of the extraction temperature and the ratios of extracting liquid and washing liquid (the hydrocarbon) to the amount of material to be extracted. The washing liquid is preferably a saturated aliphatic or cycloaliphatic hydrocarbon of 5-7 carbon atoms, although aromatics, e.g. di-isopropyl benzene may be used, and is preferably present in a quantity approximately equivalent to that of the material to be extracted. If the extracting liquid contains no alcohol the weight ratio of it to the amount of material to be extracted may be 20 : 1 to 5 : 1, preferably 15 : 1 to 10 : 1 and the extracting temperature 50-100 DEG C., preferably 70-90 DEG C. When the extracting liquid contains 30-60 per cent methanol the weight ratio may be 10 : 1 to 1 : 1, preferably 5 : 1 to 2 : 1, and the extracting temperature 15-25 DEG C. The extraction may be carried out batchwise, e.g. in a system of fillers and separators or continuously, e.g. in an extraction column or in a rotating disc contactor, as shown in the Figure, where the mixture to be extracted enters a vessel 1 through line 5, the extracting aqueous liquid enters through 6 and leaves through 14 and the washing liquid (hydrocarbon) enters through 7 and leaves through 9. The solvents are distilled off in vessels 10 and 15 and are recycled through 11 and 17 and separator 16. The purified dihydro-peroxide is withdrawn through 21 and di-isopropyl benzene and its other oxidation products withdrawn through 13 for recycle to the oxidizer. In the examples: (1) an oxidation product of m-di-isopropyl benzene containing 52.5 per cent monohydroperoxide and 15.6 per cent dihydroperoxide is treated batchwise using 1 : 1 water : methanol and n-hexane at 20 DEG C.; (2) a similar oxidation product is treated continuously in an apparatus similar to that described with 1 : 1 water : methanol and n-hexane at 20 DEG C.; (3) a similar oxidation product is treated with water and m-diisopropyl benzene at 80 DEG C. to show that there is no peroxide decomposition during the extraction. Specifications 659,241, [Group VI], and 727,498 are referred to.