Organic Chemistry,5th Edition L.G.Wade,Jr. Chapter 14 Ethers,Epoxides, and Sulfides Jo Blackburn Richland College,Dallas,TX Dallas County Community College District ©2003，Prentice Hall
Chapter 14 Ethers, Epoxides, and Sulfides Jo Blackburn Richland College, Dallas, TX Dallas County Community College District © 2003, Prentice Hall Organic Chemistry, 5th Edition L. G. Wade, Jr
Introduction Formula R-O-R where R is alkyl or aryl. Symmetrical or unsymmetrical ● Examples: CH3-O-CH3 )-CH3 => Chapter 14 2
Chapter 14 2 Introduction • Formula R-O-R where R is alkyl or aryl. • Symmetrical or unsymmetrical • Examples: O CH3 CH3 O CH3 O =>
Structure and Polarity Bent molecular geometry Oxygen is sp3 hybridized ·Tetrahedral angle Chapter 14 3 =>
Chapter 14 3 Structure and Polarity • Bent molecular geometry • Oxygen is sp3 hybridized • Tetrahedral angle =>
Boiling Points Similar to alkanes of comparable molecular weight. TABLE 14-I Comparison of the Boiling Points of Ethers,Alkanes,and Alcohols of Similar Molecular Weights Compound Forula MW bp°C) Dipole Moment (D) water HO 18 100 1.9 ethanol CHCH2一OH 46 78 1.7 dimethyl ether CH3—OCH 46 -25 1.3 propane CHCH2CH 44 -42 0.1 n-butanol CH,CH2CHCH2一OH 74 118 1.7 tetrahydrofuran 72 66 1.6 diethyl ether CHCH2O一CHCH 74 35 1.2 pentane CH CHCHCHCH 72 36 0.1 Note:The alcohols are hydrogen bonded,giving them much higher boiling points.The ethers have boil- ing points that are closer to those of alkanes with similar molecular weights. Chapter 14 4
Chapter 14 4 Boiling Points Similar to alkanes of comparable molecular weight
Hydrogen Bond Acceptor Ethers cannot H-bond to each other. Alcohol ether ·In the presence of -OH or-NH (donor), the lone pair of electrons from ether forms a hydrogen bond with the -OH or hydrogen bond -NH. donor acceptor Chapter 14 5
Chapter 14 5 Hydrogen Bond Acceptor • Ethers cannot H-bond to each other. • In the presence of -OH or -NH (donor), the lone pair of electrons from ether forms a hydrogen bond with the -OH or -NH. =>