Laurolactam from Cyclododecane (Oximation with Hydroxylamine)

The process under analysis comprises four major sections: (1) Cyclododecane Oxidation; (2) Cyclododecanol Dehydrogenation; (3) Cyclododecanone Oximation; and (4) Oxime Rearrangement.

Cyclododecane Oxidation. Initially, fresh boric acid, recovered boric acid and fresh cyclododecane are mixed and fed to jacketed and agitated reactors. Cyclododecane is oxidized by air in the presence of a boric acid catalyst, yielding cyclododecanol. The oxidation is carried out in atmospheric pressure, at temperatures from 140 to 160°C. As the boric acid esterifies part of the cyclododecanol product, the effluent is sent to a mixer, where the boric esters are hydrolyzed. The mixture settles and the aqueous phase, containing boric acid, is removed. The oil phase is washed with caustic soda and directed to a settler for water removal. The mixture is passed through a water scrubber and is fed to a column where the unconverted cyclododecane is distilled from the oil phase under reduced pressure. In a second distillation heavy compounds and residues are removed from cyclododecanol.

Cyclododecanol Dehydrogenation. The cyclododecanol obtained is then dehydrogenated to cyclododecanone over a catalyst consisting of copper on alumina. The effluent is fed to a flash vessel for hydrogen release and is twice distilled, so light and heavy ends are removed.

Cyclododecanone Oximation. The purified cyclododecanone is then reacted with hydroxylamine sulfate in oximation reactors, where the cyclic ketone is converted to cyclododecanone oxime by condensation. This reaction takes place in hydrocumene, used as solvent, under agitation. Ammonia is added to the reactors for pH control. The mixture is fed to a settler, and the oil phase is sent to next step, where oxime is extracted with sulfuric acid from hydrocumene.

Oxime Rearrangement. The solution of a cyclododecanone oxime sulfate adduct in sulfuric acid is then fed to jacketed agitated reactors. Under low pH and elevated temperatures, the cyclododecanone oxime is converted to Laurolactam via a Beckmann rearrangement. The reaction product is washed and neutralized by caustic soda in the presence of hydrocumene, in order to favor the subsequent settling. The purpose is to remove both residual catalyst, salts and acid entrained in the organic phase. After three distillation columns, which separate lights, hydrocumene and heavies, Laurolactam is obtained.