Organic Chemistry,6th Edition L.G.Wade,Jr. Chapter 14 Ethers,Epoxides, and Sulfides Jo Blackburn Richland College,Dallas,TX Dallas County Community College District ©2006，Prentice Hall
Chapter 14 Ethers, Epoxides, and Sulfides Jo Blackburn Richland College, Dallas, TX Dallas County Community College District © 2006, Prentice Hall Organic Chemistry, 6th Edition L. G. Wade, Jr
Introduction Formula R-O-R'where R and R'are alkyl or aryl. Symmetrical or unsymmetrical 。Examples: CH3-O-CH3 )-CH3 => Chapter 14 2
Chapter 14 2 Introduction • Formula R-O-R where R and R are 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 Copyright 2005 Pearson Prentice Hall,Inc. H => 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 14-1 Comparison of the Boiling Points of Ethers,Alkanes, and Alcohols of Similar Molecular Weights Compound Formula MW bp (C) Dipole Moment(D) water H20 18 100 1.9 ethanol CH3CH2-OH 46 78 1.7 dimethyl ether CH3一O-CH3 46 -25 1.3 propane CH3CH2CH3 44 -42 0.1 n-butanol CH3CH2CH2CH2一OH 74 118 1.7 tetrahydrofuran 72 66 1.6 diethyl ether CH3CH2-O-CH2CH3 74 35 1.2 pentane CH3CH2CH2CH2CH3 72 6 0.1 Note:The alcohols are hydrogen bonded.giving them much higher boiling points.The ethers have boiling points that are closer to those of alkanes with similar molecular weights. Copyright 2005 Pearson Prentice Hall,Inc. => 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 hydrogen bond bond with the -OH or -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. =>