Patent GB-653348-A (GB)
Title: Catalytic hydrogenation process for the production of hexamethylenediamine
IPC: C07C209/48
Filed: 1948-05-21
Abstract: Hexamethylenediamine is obtained by catalytically hydrogenating 1 : 4-dicyanobutenes in one step, the process being effected by heating a mixture comprising a 1 : 4-dicyanobutene and hydrogen in the presence of a cobalt hydrogenation catalyst at 75 DEG  to 200 DEG  C. and preferably at 90 DEG  to 140 DEG  C.  The process may be effected at atmospheric pressure but a pressure in excess of 400 lbs. per square inch is preferred and especially pressures of 4000 to 9000 lbs. per square inch.  The process may be carried out batchwise or in a continuous or semi-continuous manner and is preferably effected in the presence of an inert solvent such as water or an aliphatic alcohol or ether such as dimethyl ether, dioxane and tetrahydrofurane or a hydrocarbon such as cyclohexane. The use of a large excess of hydrogen over the theoretical requirement is desirable.  Any cobalt hydrogenation catalyst may be used, e.g. pyrophoric or stabilized cobalt catalysts either in the massive state, in the form of pellets or on suitable supports such as kieselguhr, alumina, silica and magnesia.  The catalysts may be prepared by reducing with hydrogen cobalt compounds such as the carbonate, oxide or hydroxide either alone or deposited on suitable supports, or mixed with oxygenated compounds of other metals known to form hydrogenating oxides, e.g. copper and zinc, or by extracting with alkali wholly or in part the alkali-soluble component of an alloy of cobalt with an alkali-soluble metal, or by reducing a cobalt salt with sodium naphthalene. Stabilized cobalt catalysts may be prepared by exposure of pyrophoric cobalt to an oxidizing atmosphere at below 50 DEG  C.  In examples: (1) 1 : 4-dicyano-2-butene, methanol and finely-divided cobalt metal prepared by the alkali activation of a cobalt-aluminium alloy are charged into an oxygen-free autoclave which is then sealed, pressured with hydrogen and heated.  After reaction the products are rinsed out with methanol and the resulting solution filtered to remove catalyst. Water is then added and the products, which are separated by fractional distillation, comprise hexamethylene diamine with some hexamethyleneimine; (2) 1 : 4-dicyano-2-butene, methanol and metallic cobalt prepared by the hydrogen reduction of cobaltous oxide are heated under hydrogen pressure in a shaking autoclave.  When the temperature reaches 120 DEG  C. the autoclave is repressurized with hydrogen and the shaking continued.  The products are the same as in (1); (3) as in (2) using dioxane instead of methanol; (4) as in (2) but using a catalyst consisting of metallic cobalt and metallic copper, prepared by mixing cobaltosic oxide (CO3O4) with cuprous oxide, pelleting, sintering at 900 DEG  C., crushing to a powder and reducing in hydrogen; (5) as in (2) but using 1 : 4-dicyano-1-butene; (6) to (9) a vertical steel cylinder is charged with a layer of silica chips, cobalt catalyst prepared as in (2) and a zone of silica chips to serve as a preheating section for the incoming reactants. The tube is mounted in an electric furnace and a solution of 1 : 4-dicyano-2-butene in methanol together with an excess of hydrogen is passed down the tube.  The process is carried out continuously and the methanol solution passing out at the other end is fractionally distilled to yield the products as in (1); in example (8) some e -aminocapronitrile is obtained; (10) as in (6) but using 1 : 4-dicyano-1-butene in methanol solution, the latter being passed upward through the catalyst bed co-currently with the hydrogen. Specification 653,347 is referred to.