Rate constants were determined for the thermal dimerization of methyl 9-trans, 11-trans-octade-cadienoate at 230, 250, 270 and 290°C.
The activation energy of this reaction was also determined is 22.5 kcal/mol.
Furthermore, an attempt was made to see whether the octadecenoate would react with methyl octadecenoate (oleate and elaidate) to form addition compounds. When an equimolar mixture of the octadecadienoate and methyl oleate was heated, the octadecadienoate was dimerized but did not form scarcely any addition compound with oleate. Therefore, the oleate has little dienophlilic activity. Similar results were obtained when an equimolar mixture of the octadecadienoate and methyl elaidate was heated. In this latter case, however, the amount of cis, trans-conjugated octadecadienoate increased. This suggests that, in heat treatment in the presence of methyl elaidate, the trans, trans-conjugated octadecadienoate undergoes geometrical isomerization besides dimerization.