| 摘要 |
o -Laurolactam is continuously produced by Beckmann rearrangement of cyclododecanone oxime with sulphuric acid or oleum in the liquid phase in the following stages:-(a) mixing a solution of the oxime in a solvent which is not miscible with sulphuric or oleum, in an extraction stage, with concentrated sulphuric acid or oleum at 0 DEG to 60 DEG C. while extracting the heat introduced and that generated by combination of the oxime with sulphuric acid, (b) separating the liquid, oxime-containing. solvent-free sulphuric acid phase from the oxime-free solvent phase; (c) transferring the oxime-sulphuric acid phase into the rearrangement stage and rearranging the oxime into the lactam at 60 DEG to 140 DEG C.; (d) transferring the lactam-sulphuric acid phase to the hydrolysis stage with simultaneous addition of water and a solvent for the extraction of the laurolactam resulting from the hydrolysis of the lactam-sulphuric acid phase; (e) separating the lactam-containing solvent phase from the phase of dilute sulphuric acid free from lactam; and (f) washing the lactam-containing solvent phase and working it up by fractional distillation. The preferred solvents for stage (a) are cycloaliphatic hydrocarbons, particularly hydrocumene. The same solvent may be used in steps (a) and (d) and the solvent from step (a) may be supplied to step (d). Alternatively, separate solvent cycles may be used in steps (a) and (d) and different solvents may be used. Preferred solvents for step (d) are cycloaliphatic hydrocarbons, particularly cyclododecane and p - diisopropylcyclohexane. Cyclododecanone and aliphatic or aromatic hydrocarbons may also be used. |
