Derivatization of methyl 9-hydroxyoctadec-12-ynoate (1) was done to obtain the industrially important fatty compounds. Methyl 9-hydroxyoctadec-12-ynoate (1) was subjected to mesylation and demesylation reactions in which an unknown compound, methyl 9-ethoxyoctadee-12-ynoate (VII), was furnished in good yield, in addition to an inseparable mixture of enynoic esters. In another set of reactions, methyl 9-hydroxyoctadec-12-ynoate (I) was oxidized with trimethyl chlorochromate wherein the resulting methyl 9-oxooctadec-12-ynoate (II) was subjected to three condensation reactions-with 1,2-ethanedithiol, ethylene glycol, and P -mercaptoethanol, separately-to yield diethyl 9,9-ethylenedisulfide octadec-12-ynoate (III), 9,9-ethylene-dioxyoctadec- 12-ynoate (IV), and 9-oxathiolaneoctadec-12-ynoate (V), respectively, in excellent yields. Their structures have been established using infrared (IR) spectroscopy, H-1 nuclear magnetic resonance (NMR) spectroscopy, C-13 NMR spectroscopy, and mass spectral studies.