Editing Fatty acid (section)

===Hydrogenation and hardening===
[[Hydrogenation]] of unsaturated fatty acids is widely practiced. Typical conditions involve 2.0–3.0 MPa of H{{sub|2}} pressure, 150&nbsp;°C, and nickel supported on silica as a catalyst. This treatment affords saturated fatty acids. The extent of hydrogenation is indicated by the [[iodine number]]. Hydrogenated fatty acids are less prone toward [[rancidification]]. Since the saturated fatty acids are [[melting point|higher melting]] than the unsaturated precursors, the process is called hardening. Related technology is used to convert vegetable oils into [[margarine]]. The hydrogenation of triglycerides (vs fatty acids) is advantageous because the carboxylic acids degrade the nickel catalysts, affording nickel soaps. During partial hydrogenation, unsaturated fatty acids can be isomerized from ''cis'' to ''trans'' configuration.<ref name="Ullmann Fatty Acids"/>

More forcing hydrogenation, i.e. using higher pressures of H{{sub|2}} and higher temperatures, converts fatty acids into [[fatty alcohol]]s. Fatty alcohols are, however, more easily produced from simpler fatty acid [[ester]]s, like the [[fatty acid methyl ester]]s ("FAME"s).