Elaidic acid (trans-9-octadenoic acid), C18H34O2, which crystallizes in plates, and which has a melting point of 46.5oC, is the trans-isomer of oleic acid.
How is elaidic acid made?
Elaidic acid is prepared from oleic acid by treatment with isomerizing agents.
0.3% selenium at 150oC - 220oC is the most effective.
An equilibrium mixture of 66% elaidic acid and 34% oleic acid forms.
How is the elaidic acid separated from the oleic acid?
Oleic acid is an oil with a melting point (or freezing point) of 4oC, while elaidic acid has a melting point of 46.5oC. So the two isomers can be separated by fractional crystallization.
