esterification products. He noticed that not only the number but the position of double bonds is involved in oxidation susceptibility. For instance, linolenic acid with two bis-allylic positions (at the carbons no. 11 and 14 between the double bonds Δ9, Δ12 and Δ15) is more prone to autoxidation than linoleic acid exhibiting one bis-allylic position (at C-11 between Δ9 and Δ12). Therefore, Knothe introduced alternative indices termed allylic position and bis-allylic position equivalents (APE and BAPE), which can be calculated directly from the integration resultas of chromatographic analysis. Iodine values of various oils and fats Iodine value helps to classify oils according to the degree of unsaturation into drying oils, having IV > 150 (i.e. linseed, tung), semi-drying oils IV : 125 – 150 ( soybean, sunflower) and non-drying oils with IV < 125 (canola, olive, coconut). The IV ranges of several common oils and fats is provided by the table below. Related methods of analysis Acid number Amine value Argentation chromatography Bromine number Epoxy value Hydroxyl value Peroxide value Saponification value Notes The interaction between mercuric chloride and iodine chloride is supposed to produce the active agent of halogenation, the ICl as follows : HgCl2 + I2 → HgClI + ICl Chloroform is replaced in modern protocols by less hazardous and more available solvents such as cyclohexane and 2,2,4-trimethylpentane (ASTM D5768). References Analytical chemistry Dimensionless numbers of chemistry Number