Patent GB-770299-A (GB)
Title: Improvements in and relating to the production of amines
Inventor: DENT WALTER THEODORE
Filed: 1954-03-05
Abstract: A process for the production of amines of the general formula <FORM:0770299/IV(b)/1> where R is a cycloaliphatic radical, or a radical having a structure <FORM:0770299/IV(b)/2> wherein R1 and R11 are alkyl, aryl or aralkyl groups, comprises the steps of coupling diphenylamine with a benzene diazonium salt whereby p-phenylaminoazobenzene which has the structure <FORM:0770299/IV(b)/3> is produced, and subsequently catalytically hydrogenating this compound in the presence of a cycloaliphatic ketone or a ketone R1COR11 whereby there is produced a mixture of amines having the structures <FORM:0770299/IV(b)/4> <FORM:0770299/IV(b)/5> The diphenylamin  employed may contain alkyl or alkoxy groups in one or both of the benzene rings ortho or meta to the NH group and the benzene diazonium salt may be substituted. Hydrogenation catalysts specified comprise copper or a metal selected from Group VIII of the Periodic System, e.g. copper chromite, finely-divided nickel or platinum or platinum oxide. Chlorine-containing organic compounds may be removed from the intermediate amino azo compound by solvent extraction or by contacting a solution with an anion exchange resin.  In examples: 4-isopropylamino diphenylamine and N-isopropyl aniline are obtained by diazotizing aniline dissolved in methanol and hydrochloric acid and coupling the product with diphenylamine dissolved in methanol and hydrochloric acid, separating p-phenylene aminoazobenzene hydrochloride, mixing the product with ammonia, dissolving the free base in acetone and after treating the solution with an anion exchange resin, passing the p-phenyl-aminoazo benzene dissolved in acetone with hydrogen over a copper chromite catalyst at elevated temperature and pressure and fractionating the products (1); in a similar process treatment with ether instead of anion-exchange resin is employed (2); 4-sec.-butylaminodiphenylamine and N-sec.-butylaniline are obtained in a similar process using aniline, diphenylamine and methyl ethyl ketone and a platinum-on-charcoal hydrogenation catalyst (3); 4-cyclohexylaminodiphenylamine is obtained by hydrogenating p-phenylaminoazobenzene, produced as in (1), in cyclohexanone solution using a platinum-on-charcoal catalyst (4); 4 - isopropylaminodiphenylamine is produced by a process similar to (1) in which an excess of the diazonium salt is employed and recycled (5); 3 : 31-dimethyl-4 - sec. - butylaminodiphenylamine is obtained in a process similar to (3) using 3 : 31-dimethyldiphenylamine as starting material (6); and in similar processes diphenylamine and p-toluidine (7), m-toluidine (8) and p-anisidine (9) are employed instead of aniline to obtain 4-sec.-butylamino-diphenylamine.  The products of the invention may be used in stabilizing compounds liable to peroxide formation, e.g. petrols, aldehydes, ethers, esters of unsaturated carboxylic acids and unsaturated hydrocarbons or mixtures thereof.ALSO:Petrols are stabilized with amines having the structure <FORM:0770299/III/1> wherein R is a cycloaliphatic radical or a radical -CH(R1)(R11) where R1 and R11 are alkyl, aryl or aralkyl groups (see Group IV(b))