Large-scale synthesis of methyl cis-9, trans-11-octadecadienoate from methyl ricinoleate

The conjugated linoleic acid methyl cis-9,trans-11-octadecadienoate has been prepared on a large scale from methyl ricinoleate. Methyl ricinoleate was purified from castor esters by a partition method. It was converted to the mesylate, which was reacted with a base (1,8-diazabicyclo[5,4,0]-undec-7-ene) to give a product that contained 66% of the desired ester. Two urea crystallizations produced a product containing 83% methyl cis-9,trans-11-octadecadienoate, the identity of which was confirmed by gas chromatography linked to mass spectrometry and by Fourier transform infrared spectroscopy. The remaining impurities were methyl cis-9,cis-11- and cis-9-,trans-12-octadecadienoate.