《有机化学》课程PPT教学课件（Official PPT of Organic Chemistry 6th LG Wade by Prentice Hall，L. G. Wade, Jr.）Chapter 25 Lipids

Organic Chemistry,6th Edition L.G.Wade,Jr. Chapter 25 Lipids Jo Blackburn Richland College,Dallas,TX Dallas County Community College District ©2006，Prentice Hall

Chapter 25 Lipids Jo Blackburn Richland College, Dallas, TX Dallas County Community College District © 2006, Prentice Hall Organic Chemistry, 6th Edition L. G. Wade, Jr

Introduction Classified by solubility,not structure. Can be extracted from cells by nonpolar organic solvents. Complex lipids are easily hydrolyzed. >Waxes >Triglycerides 。 Simple lipids are not easily hydrolyzed. >Steroids >Prostaglandins >Terpenes Chapter 25 => 2

Chapter 25 2 Introduction • Classified by solubility, not structure. • Can be extracted from cells by nonpolar organic solvents. • Complex lipids are easily hydrolyzed. ➢Waxes ➢Triglycerides • Simple lipids are not easily hydrolyzed. ➢Steroids ➢Prostaglandins ➢Terpenes =>

Examples of Lipids Examples of complex lipids Examples of simple lipids 0 CH2-O-C-(CH2)16CH3 - H3 d-o8cwa HO tristearin,a fat cholesterol,a steroid CH3(CH2)15-O-C-(CH2)14CH3 spermaceti(cetyl palmitate),a wax a-pinene,a terpene 三> Copyright2005 Pearson Prentice Hall,Inc. 3

Chapter 25 3 Examples of Lipids =>

Waxes Esters of long-chain fatty acids with long-chain alcohols. Spermaceti is found in the head of the sperm whale and is probably used to control buoyancy. Most natural waxes are protective coats for plants'leaves,insects'exoskeletons, mammals'fur,and birds'feathers. 二> Chapter 25

Chapter 25 4 Waxes • Esters of long-chain fatty acids with long-chain alcohols. • Spermaceti is found in the head of the sperm whale and is probably used to control buoyancy. • Most natural waxes are protective coats for plants’ leaves, insects’ exoskeletons, mammals’ fur, and birds’ feathers. =>

Triglycerides Fatty acid esters of glycerol. ·Fats >Solid at room temperature >Most are derived from mammals 。Oils >Liquid at room temperature >Most are derived from plants or cold- blooded animals. => Chapter 25 5

Chapter 25 5 Triglycerides • Fatty acid esters of glycerol. • Fats ➢Solid at room temperature ➢Most are derived from mammals • Oils ➢Liquid at room temperature ➢Most are derived from plants or cold￾blooded animals. =>

Fatty Acids Unbranched carboxylic acids with 12-20 carbons. Most contain an even number of carbons because they are built from acetic acid units. Melting points increase with increasing molecular weights. Unsaturation greatly lowers the melting point. => Chapter 25 6

Chapter 25 6 Fatty Acids • Unbranched carboxylic acids with 12-20 carbons. • Most contain an even number of carbons because they are built from acetic acid units. • Melting points increase with increasing molecular weights. • Unsaturation greatly lowers the melting point. =>

Melting Points A cis double bond bends the molecule so it cannot pack efficiently. A trans double bond has less effect. COOH COOH stearic acid,mp 70C oleic acid.mp 4C > Chapter 25 7

Chapter 25 7 Melting Points • A cis double bond bends the molecule so it cannot pack efficiently. • A trans double bond has less effect. =>

Fats and Oils Most fats have saturated fatty acids. Most oils have unsaturated fatty acids. CH,-0-C CHO( CH2-0一C tristearin,mp 72C CH2O CH一0 triolein,mp-4C Chapter 25

Chapter 25 8 Fats and Oils • Most fats have saturated fatty acids. • Most oils have unsaturated fatty acids. =>

Saponification ·“Soap-making' ● Base-catalyzed hydrolysis of ester linkages in fats and oils. 0 CH2-OH 0(CHCH CH-OH 0 CH-0-C-(CH)1CH: CH2-OH +3 NaOH 0 CH2-O-C-(CH2)16CH3 +3Na*O-C-(CH2)16CH3 => Chapter 25 A soap 9

Chapter 25 9 Saponification • “Soap-making” • Base-catalyzed hydrolysis of ester linkages in fats and oils. CH O C O (CH2 )16CH3 CH2 O C O (CH2 )16CH3 CH2 O C O (CH2)16CH3 + 3 NaOH CH2 CH CH2 OH OH OH + 3 Na+ - O C O (CH2 )16CH3 A soap =>

Soap Structure Ionic head CO boundary of water into structure Hydrocarbon tail => Chapter 25 10

Chapter 25 10 Soap Structure =>