Caprolactam

Overview

ε-Caprolactam

The ring-shaped starting molecule for nylon 6.

Caprolactam contains a cyclic amide in a seven-membered ring. Hydrolytic ring-opening polymerisation gives nylon 6, with six carbons in each repeat unit. Upstream, cyclohexanone can be converted through its oxime into caprolactam by a Beckmann rearrangement. That ring expansion is distinct from the ring-opening polymerisation which follows.

Identifiers

Formula

C6H11NO

Functional group

Cyclic amide (lactam)

Molar mass

113.16 g/mol

Also known as

epsilon-caprolactam, ε-caprolactam

Properties

Melting Point

69.3 °C

Boiling Point

270 °C

Relative density (water = 1)

Specific gravity: 1.02 at 75 °C/4 °C (liq)

Water solubility

In water, 5.25X10+6 mg/l @ 25 °C.

Related compounds

• Amides

  The ring-shaped starting molecule for nylon 6.

References

1. Polyamides: nylon 6 and nylon 6,6Chemical Industry Education Centre, University of York
2. New technology to manufacture caprolactam: oxime formation and Beckmann rearrangementSumitomo Chemical
3. PubChem: CaprolactamNational Center for Biotechnology Information

   Identity retrieved 2026-09-08; matched against the record's isomeric structure. Unspecified stereochemistry remains unspecified.

4. Hazardous Substances Data Bank (HSDB): Caprolactam — melting pointHazardous Substances Data Bank (HSDB)

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7768#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Lide, D.R. (ed.). CRC Handbook of Chemistry and Physics. 79th ed. Boca Raton, FL: CRC Press Inc., 1998-1999., p. 3-16

5. Hazardous Substances Data Bank (HSDB): Caprolactam — boiling pointHazardous Substances Data Bank (HSDB)

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7768#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Lide, D.R. (ed.). CRC Handbook of Chemistry and Physics. 79th ed. Boca Raton, FL: CRC Press Inc., 1998-1999., p. 3-16

6. Hazardous Substances Data Bank (HSDB): Caprolactam — densityHazardous Substances Data Bank (HSDB)

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7768#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Budavari, S. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 1996., p. 287

7. Hazardous Substances Data Bank (HSDB): Caprolactam — solubilityHazardous Substances Data Bank (HSDB)

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/7768#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Loewengart G; pp. 36-52 in Proc Symp Ind Approach Chem Risk Assess: Caprolactam Relat Compd Case Study, Arlington, VA: Marriott-Crystal Gateway (1984)