Patent GB-459920-A (GB)
Title: Improvements in or relating to the production of oxygenated organic compounds
IPC: C07B35/04
Filed: 1935-07-15
Abstract: Oxygenated organic compounds are obtained by treating an aromatic hydrocarbon in the vapour phase with not more than an equimolecular proportion of oxygen under a pressure of at least 10 atm.  The temperature may be 200--400 DEG  C. and the reaction may be effected in a closed vessel or in a system through which the mixture flows. An inert gas may be present.  An oxidation catalyst may optionally be used, and this may be a solid catalyst, e.g. vanadium pentoxide, or a gaseous catalyst, e.g. hydroquinone.  The process may be effected in stages, with or without intermediate separation of the products and with addition of oxygen between the stages.  Generally, the products are separated by condensation, and unchanged hydrocarbon is revaporized, preferably by heat-exchange with fresh products, and returned to the reaction; phenol, however, may be separated from benzene without condensing the latter by passing the mixture over hot caustic soda.  In the examples: (1) a mixture containing benzene 75--80 and air 25--20 per cent by volume is passed at 365--375 DEG C. and 50 atm. pressure and at a space velocity above 10 through a reaction zone void of catalyst; the products include phenol, quinone, hydroquinone, formaldehyde and maleic acid, and unspecified aliphatic acids and aldehydes; (2) a mixture of benzene vapour and air containing benzene and oxygen in the molecular ratio 5 : 1 is passed at 373 DEG  C. and 50 atm. pressure and at a specified rate through an empty stainless steel tube; phenol is the principal product; (3) a mixture of toluene vapour and air containing toluene and oxygen in the molecular ratio 30 : 1 is heated in an autoclave to 337 DEG  C., the initial pressure being 35 atm.; the products include benzyl alcohol, benzaldehyde benzoic acid, and 2 : 4-dihydroxytoluene; (4) a mixture of ethylbenzene vapour and air containing ethylbenzene and oxygen in the molecular ratio 40 : 3 is heated in an autoclave to 322 DEG  C., the initial pressure being 27,5 atm.; the products include benzaldehyde, acetophenone, 2 : 4-dihydroxyethylbenzene, phenylmethylcarbinol, and benzoic acid; (5) a mixture of toluene and oxygen in the molecular ratio 26 : 1 is passed through a reaction zone at 340--350 DEG  C. and a pressure above 20 atm., whereby benzyl alcohol is formed; the latter is condensed, and the residue, after adjustment of the toluene: oxygen ratio to 15 : 1, is passed through a second reaction zone at 330-340 DEG  C. and a pressure above 20 atm., whereby benzaldehyde is formed; the latter is condensed, and the residue, after adjustment of the toluene: oxygen ratio to 5 : 1, is passed through a third reaction zone at 275-300 DEG  C. and a pressure above 20 atm., whereby benzoic acid is formed.  Reference is made also to (a) the production of phenol by passing a mixture of benzene vapour and air containing benzene and oxygen in a molecular ratio of at least 5 : 1 at 300--400 DEG  C. and under a pressure of at least 10 atm. through a reaction zone void of catalyst; (b) the production of benzaldehyde by passing a mixture of ethylbenzene vapour and air containing ethylbenzene and oxygen in a molecular ratio of at least 10 : 1 at 300--350 DEG  C. and at a pressure of at least 20 atm. and at a space velocity of at least 20 through a reaction zone void of catalyst; (c) the production of benzaldehyde by passing a mixture containing toluene vapour 75--80 and air 25--20 per cent by volume at 320--340 DEG  C. and a pressure of at least 20 atm. and at a space velocity above 20 through a reaction zone void of catalyst; (d) the production of benzyl alcohol by passing a mixture containing toluene vapour about 84 and air about 16 per cent by volume at 340--350 DEG  C. and a pressure of at least 20 atm. and at a space velocity above 20 through a reaction zone void of catalyst; and (e) the production of benzoic acid by passing a mixture containing toluene vapour about 50 and air about 50 per cent by volume at 275--300 DEG  C. and a pressure above 20 atm. and at a space velocity of 4--20 through a reaction zone void of catalyst. Results are given also of experiments on the production of phenol by heating various benzene-oxygen mixtures in an autoclave to 312 DEG C. under a benzene partial pressure of 20 atm.  Other specified hydrocarbons which may be treated are xylenes, trimethylbenzenes, cumene and cymene. Specifications 122,167 and 189,091, [both in Class 2 (iii)], are referred to.