GB708593A - Improvements in the catalytic production of hydroquinone - Google Patents

Abstract

Hydroquinone is produced by the reaction of carbon monoxide and acetylene in the presence of water and/or an alcohol at an elevated temperature and superatmospheric pressure, e.g. at 80-150 DEG C., at a pressure exceeding 5 atmospheres, in the presence of a catalyst which comprises a salt of an ammonium or amino complex of a heavy metal with cobalt carbonyl hydride. The cation of the catalyst may be derived from ammonia or a primary amine and cadmium, zinc or copper, or a metal of the iron group, for example [Fe(NH3)6]++, [Fe(NH3)6]+++, [Co(NH3)6]++, [Ni(NH3)6]++, [Co(NH2.CH2.CH2.NH2)3]++, [Cd(NH3)2]++. In forming the catalysts, the complex cation replaces the hydrogen atoms of the equivalent number of molecules of cobalt carbonyl hydride, HCo(CO)4. In examples: (1) acetylene and carbon monoxide are reacted with ethanol in the presence of a complex salt of the formula [Fe(NH3)6] [Co(CO)4]2 to give hydroquinone, and, if desired, the complex ferrous ammonium cation might be replaced by complex ferrous cations with ethylene diamine, hexamethylene diamine or pyridine; (2) a mixture of ethanol, hydroquinone and the ferrous ammonium cobalt carbonyl compound of (1) are treated with carbon monoxide and acetylene under pressure at 90-100 DEG C. to give an increased amount of hydroquinone. Metal-amine complex salts of cobalt carbonyl hydride are prepared by introducing cobalt carbonyl into an aqueous solution of an alkali or alkaline earth metal hydroxide or an amino compound, e.g. by treating an aqueous solution or suspension of a cobalt salt oxide or hydroxide in the presence of ammonia or an amine at 50-250 DEG C. at superatmospheric pressure with carbon monoxide, and treating the resultant solution of a salt of cobalt carbonyl hydride with a complex amine salt of a heavy metal, or when there is already a sufficient excess of amine present, with the simple salt of a heavy metal. The preparation of the complex salts of cobalt carbonyl hydride with the iron complex of ethylene diamine of the formula [Fe(NH2.CH2.CH2.NH2)3] [Co(CO)4]2 the corresponding hexamethylene diamine compound of the formula [Fe(NH2(CH2)6NH2)3] [Co(CO)4]2 and the corresponding pyridine compound is described.ALSO:Salts of ammonium complexes of heavy metals with cobalt carbonyl hydride are prepared by introducing cobalt carbonyl into an aqueous solution of an alkali or alkaline earth metal hydroxide or an amino compound to form the corresponding salt of cobalt carbonyl hydride which is then treated with a complex heavy metal salt obtained by the action of ammonia on a solution of the ordinary mineral acid salt of the heavy metal to give by double decomposition the desired heavy metal complex ammonium salt of cobalt carbonyl hydride. These salts may also be obtained by treating an aqueous solution or suspension of a cobalt salt, oxide or hydroxde with carbon monoxide at 50-250 DEG C. in the presence of ammonia or an amine at superatmospheric pressure and treating the resulting solution of an ammonium or amine salt of cobalt carbonyl hydride with a complex ammonium salt of a heavy metal or, where the reaction mixture already contains a sufficient excess of ammonia, with a simple salt of a heavy metal. The above reactions are preferably carried out with the exclusion of air. Specified heavy metal complex cations are those derived from cadmium, zinc or copper or metals of the iron group such as [Fe(NH3)6]++, [Fe(NH3)6+++], [Co(NH3)6++, [Ni(NH3)6++ and [Cd(NH3)2]++. In an example the preparation of the compound of the formula [Fe(NH3)6] [Co(CO)4]2 is described.