| 摘要 |
<p>Crude caprolactam contg. acid, obtd. in the rearrangement of cyclohexanone oxime, is mixed with: (i) 0.8-2 equivs. of a base, the pH being adjusted to 4-11; (ii) 3-6 pts. wt. toluene, w.r.t. the caprolactam; and (iii) 2-10 pts. wt. water w.r.t. the organic cpds. This forms a toluene phase and a water phase, the latter consisting of two layers. Substantially all the organic impurities are in the upper aq. layer, which is sepd. The crude caprolactam pref. contains 1-2 moles H2SO4 or 0.05-5 moles boric acid, depending on whether the cyclohexanone oxime rearrangement has been performed in the liq. phase with oleum as catalyst or the vapour phase with boric acid as catalyst. Purificn. of caprolactam, derived from rearrangement in oleum, by extraction with benzene is known, but there is a problem of supplementary treatment of the aqs. phase contg. all the impurities. The division of the aqs. phase into two in the present process solves this problem, the upper aqs. layer being easily sepd., e.g. by a siphon.</p> |
