Chapter 19 Lipids CHEM 2124 – General Chemistry II Alfred State College Professor Bensley

Learning Objectives  Describe the general characteristics of lipids  Classify fatty acids and describe the relationship between melting point and the number of double bonds  Draw the structure of triacylglycerols and describe the difference between a fat and an oil  Draw the hydrolysis products of triacylglycerols (Saponification)

Lipids Lipids are biomolecules that are soluble in organic solvents and insoluble in water. A.Polarity B.Classification Scheme 1.Hydrolyzable Lipids I.Introduction to Lipids

Lipids 2.Nonhydrolyzable Lipids II. Fatty Acids A. General Structure nonpolar portion = hydrophobic polar portion = hydrophillic

Lipids As the number of double bonds in the fatty acid increases, the melting point decreases. B.Saturated vs. Unsaturated Fatty Acids C.Monounsaturated vs. Polyunsaturated Fatty Acids

E.Omega-3 Fatty Acids D.Trans fats vs. Cis fats Lipids

III.Triacylglycerols (Triglycerides) Triacylglycerols (triglycerides) are three esters formed from glycerol and three molecules of fatty acids Lipids

A.Simple vs. Mixed Triacylglycerols IV.Fats and Oils

Lipids

Soaps are metal salts of fatty acids prepared by basic hydrolysis (saponification) of a triacyl- glycerol polar head ionic end nonpolar tail nonpolar end V.Hydrolysis of Triacylglycerols (Soap Production)

Lipids C O C O C O CH 2 —O CH —O CH 2 —O H2OH2O CH 2 —OH CH —OH CH 2 —OH glycerol + C O R Na + − O 3 soap molecules 3 R R R + 3 NaOH