Verfahren zur Herstellung von Lactamen durch Umlagerung cyclischer Ketoxime

A process for the production of lactams by the catalytic rearrangement of cycloalkanone oximes in the presence of supported or unsupported solid acidic catalysts at 210 DEG to 450 DEG C. is characterized by contacting the oxime in the liquid state with the heated catalyst. The catalyst may be fluidized by the vaporized oxime and/or an inert gas, e.g. nitrogen or water vapour. Cycloalkanone oximes specified are those containing 5 to 12 carbon atoms, e.g. cyclopentanone oxime, methyl cyclopentanone oxime, cyclohexanone oxime, methylcyclohexanone oxime, cyclo-octanone oxime and cyclododecanone oxime; these may be used in the anhydrous state or may contain up to about 15% wt. of water, i.e. the amount present when the oxime is prepared from a ketone and a hydroxylamine salt. Catalysts specified are phosphoric acid, anhydrous boric acid (i.e. boron oxide), boric acid, or alkali metal hydrogen sulphates, e.g. lithium, sodium or potassium hydrogen sulphates or mixtures thereof. These may be suported on suitable carriers, for example oxides of those elements of Group III and IV of the Periodic Table having an atomic weight greater than 25, e.g. alumina, bayerite, corundum, silica gel, diatomaceous earth, tin dioxide and titanium dioxide; pumice, activated charcoal and zinc oxide may also be used as carriers. The process may be carried out at subatmospheric, atmospheric, or superatmospheric pressures. The product may be purified by distillation under reduced pressure, where necessary with the addition of oleum, followed by treatment with potassium permanganate, filtration, and further distillation. Specific examples relate to the preparation of caprolactam, methylcaprolactam and caprylolactam.