Synthesis of ε-caprolactam from ε-caprolactone and ammonia in supercritical water

Hanae Ito, Junko Nishiyama, Tadafumi Adschiri, Kunio Arai

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8 Citations (Scopus)


Synthesis of ε-caprolactam from caprolactone with ammonia was carried out in supercritical water (SCW : T>374°C, P>22.1 MPa). A main reaction pathway for the formation of ε-caprolactam was elucidated on the basis of a series of reactions of 1) ε-caprolactcne, 2) hexanol + ammonia, 3) hexanoic acid + ammonia, and 4) hexanoic acid + hexanamide in SCW. The results clearly showed the following three steps of reactions for the formation of ε-caprolactam. The first step is the ring cleavage of ε-caprolactone to yield 6-hydroxyhexanoic acid. The second step is the dehydration between 6-hydroxyhexanoic acid and ammonia to form 6-hydroxyhexanamide. The final step is the intramolecular dehydration of 6-hydroxyhexanamide to produce ε-caprolactam. The effects of reaction temperature, water density, and ammonia concentration were also studied. At 380°C and 38 MPa (water density 0.5 g/cm3), the yield of ε-caprolactam from ε-caprolactone and ammonia at a ratio 1:5 increased with increasing reaction time and reached 79.2% in 60 min.

Original languageEnglish
Pages (from-to)679-684
Number of pages6
JournalKobunshi Ronbunshu
Issue number12
Publication statusPublished - 2001 Dec


  • Ammonia
  • Dehydration
  • Hydrolysis
  • Supercritical water
  • ε-caprolactam
  • ε-caprolactone


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