Thermometric Titrations of Free Fatty Acids with Iodine Monochloride

✍ Scribed by J.A. Hatcher; J.A. Lynch; E.T. Lane

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 282 KB
• Volume: 47
• Category: Article
• ISSN: 0026-265X
• DOI: 10.1006/mchj.1993.1022

✦ Synopsis

Thermometric titrations of the three unsaturated fatty acids found in vegetable seed oils, i.e., oleic, linoleic, and linolenic, were performed using iodine monochloride as the titrant. The titration curves produced indicate unusually stable transition states consistent with formation of the charged transfer complexes observed by others. Values for titration end points were often high, indicating that reaction rates were determined by slow kinetics. Enthalpy changes were quite large and showed an approximate doubling in going from oleic, with its one double bond, to linoleic, with its two double bonds. The (\Delta H) for linolenic acid was, however, only 2.1 times that of oleic. This suggests that the slow reaction of linolenic's third double bond is perhaps the main reason for the long incubation time used in the classical Wijs method. C 1993 Academic Press, Inc.