More reduced – more H Can be more oxidized – store more energy Less readily available due to insolubility – require more reactions

Triglycerides Esterification – condensation molecule of water is released as OH group of glycerol condenses w tih COOH of fatty acid

Saturated Tetrahedral Packed closely High London dispersion forces High melting point

Unsaturated One or more double C=C bonds, so one of more 120 trigonal planar Lower melting points Melting point increases with increase molar mass

Iodine number Grams of iodine reacting with 100g of fat Measure of unsaturation (1 mol I2 reacts with each mol of C=C) 100g LA 1mol LA 2mol I2 254g I2 We would expect C17H35COOH if totally saturated. 4 Hydrogens fewer – 2 H removed for each C=C Therefore, 2 C=C’s 280g LA 1mol LA 1mol I2 1 mol Linoleic acid  2 mol of C=C  2 mol I2 181 g I2  Iodine number 181

Lower I2 number – more saturated fats What is the iodine number of a saturated fat?

Hydrolytic rancidity Favored by lots of water present, presence of lipase (sometimes present due to bacteria), high temperatures, extreme pH

Oxidative rancidity At C=C in unsaturated fats Accelerated by light, enzymes, or metal ions

Phospholipids Glycerol +2 fatty acids & phosphate group

Saponification

Saponification can occur in oil paintings over time, causing visible damage and deformation. Oil paints are composed of pigment molecules suspended in an oil binding medium. Heavy metal salts are often used as pigment molecules, such as in lead white, red lead, and zinc white.  If those heavy metal salts react with free fatty acids in the oil medium, metal soaps may form in a paint layer that can then migrate outward to the painting's surface

Steroids Table 34