Patent GB-1182273-A (GB)
Title: Process for Oxidising Olefines
IPC: C07C31/34
Filed: 1967-02-17
Abstract: 1,182,273. Oxidation of olefins. TEIJIN Ltd. 17 Feb., 1967 [17 Feb., 1966 (2); 11 March, 1966; 19 Oct., 1966; 13 Dec., 1966], No. 7747/67. Heading C2C.  Preparation of an alkylene chloro- or bromohydrin and/or an alkylene glycol having 2-4 carbon atoms which comprises oxidizing the corresponding aliphatic olefin by contact with a thallic salt in the presence of water and chlorine and/or bromine ions wherein the mole ratio of said halide ion or ions to thallium atom is at least 4. According to a further embodiment of the invention a salt of a redox metal capable of possessing different valences under the reaction conditions and oxidizable with molecular oxygen, e.g. cupric or ferric chloride or bromide, is introduced into the reaction system in the presence or absence of the olefin to reform the thallic salt from the thallons. The halohydrins are preferentially formed from room temperature to 180 C., particularly from 50 to 150 C., and may be isolated as such in conventional manner and, if desired, hydrolysed to the alkylene glycol in a separate step or, alternatively, the glycol may be formed in situ by carrying out the reaction at a temperature in the range 100 to 250 C. and particularly in the range 120 to 200 C. The preferred olefines which need not be more than 90% pure and should be desulphurized, include ethylene, propylene, butene-1, butene-2 and iso-butene and may be used in the liquid or gaseous state. The specified halide ions may be provided in the form of hydrogen halide, redox metal halide and/or halides of alkali or alkaline earth metals or of other specified metals which do not enter into the reaction. The process is ordinarily carried out at or above atmospheric pressure under neutral or acid conditions by dispersing the olefin in aqueous medium or in organic compounds miscible with water containing the reagents. Continuous or batchwise regeneration of the thallium (III) ion using redox metal ions in the higher valence state may be carried out concurrent with or subsequent to the oxidation of the olefine either by passing a mixture of olefine and molecular oxygen simultaneously into the reaction mixture containing thallium and redox metal ions: or by passing the olefin and then oxygen alternately through the reaction medium in the same or separate reaction vessels; by separating the organic products from the reaction medium and treating the residual liquors with redox metal ions and oxygen; or by separating the spent thallium salt, treating it with oxygen in the presence of redox metal ions, extracting the resulting thallium compound (e.g. HT1X 4 ) with a suitable solvent and recycling the aqueoua solution of thallic ions formed therefrom. Optimum reaction conditions and various modes of operation are established and demonstrated in the examples. The oxidation of ethylene to ethylene chloro- and bromohydrin, ethylene glycol, acetaldehyde and traces of chloroacetaldehyde and crotonaldehyde; propylene to propylene-1,2-glycol and acetone; butene-1 to butylene-1,2-glycol and methyl ketone; and iso-butene to 2-methyl-propylene- 1,2-glycol and iso-butyraldehyde is described. Comparative examples illustrate the course of the reaction when ions other than halide ions are present.