w-Aminoundecanoic acid is the precursor of nylon 11. The starting material is either the natural product castor oil - the glycerol ester of ricinoleic acid - or ricinoleic acid itself. Glycerol triricinolate is first transesterified with methanol to the methyl ester and then pyrolytically cleaved at about 300 "C into a C, aldehyde and the methyl ester of undecenoic acid: