Ammonia → Caprolactam

Further, as the preferred embodiments of the present invention, cyclohexanone and cyclododecanone are simultaneously oximated as a mixture and the resulting mixture containing cyclohexanone oxime or a salt thereof and cyclododecanone oxime or a salt thereof is subjected to Beckmann rearrangement in the presence of sulfuric acid or fuming sulfuric acid, and then the resulting mixture is neutralized with ammonia gas or aqueous ammonia to obtain a lactam mixture mainly containing ε-caprolactam, ω-dodecanelactam and ammonium sulfate. Subsequently, the lactam mixture is extracted with an organic solvent which is immiscible with water, or the lactam mixture is allowed to stand to cause phase separation of a lactam oil layer mainly containing ε-caprolactam and ω-dodecanelactam, and an aqueous layer mainly containing ammonium sulfate and the above lactam oil layer is extracted with an organic solvent which is immiscible with water to obtain an extract containing lactam components such as ε-caprolactam and ω-dodecanelactam. Further, the extract is then reverse extracted with water to transfer ε-caprolactam into an aqueous layer, while ω-dodecanelactam remains in the organic solvent layer to separate ε-caprolactam and ω-dodecanelactam. Thereafter, each of the aqueous layer containing ε-caprolactam and the organic solvent layer containing ω-dodecanelactam is purified by using the conventional method such as distillation and others to obtain ε-caprolactam and ω-dodecanelactam simultaneously, which method is called as "colactamization method". In the present invention, by processing with anion exchange resin before reverse extracting the above "lactam mixture or the organic solvent extract of the lactam oil layer" with water, ε-caprolactam which is transferred into an aqueous layer in the subsequently carried out extraction with water can be effectively separated from ω-dodecanelactam which remains in the organic solvent layer.

ORD record

ord-4319e1eb404d4bf199e4bee7f61a9a63

Source dataset

uspto-grants-1995_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05440032