《有机化学》课程PPT教学课件（Official PPT of Organic Chemistry, 7th Edition, L. G. Wade, Jr.Pearson Education）Chapter 14 Ethers, Epoxides, and Sulfides

R Organic Chemistry,7th Edition H O—R L.G.Wade,Jr. H-C-Mg-X H R—O④ R Chapter 14 Ethers,Epoxides,and Sulfides Copyright 2010 Pearson Education,Inc

Chapter 14 Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. Ethers, Epoxides, and Sulfides

Ethers Formula is R-O-R',where R and R' are alkyl or aryl. Symmetrical or unsymmetrical CH3-O-CH3 O-CH3 Chapter 14 2

Chapter 14 2 Ethers • Formula is R—O—R  where R and R are alkyl or aryl. • Symmetrical or unsymmetrical CH3 O CH3 O CH3

Structure and Polarity 。( Oxygen is sp3 hybridized. 。Bent molecular geometry. 。 C-O-C angles is 110° 。Polar C-O bonds. H ·Dipole moment of 1.3D. Chapter 14 3

Chapter 14 3 Structure and Polarity • Oxygen is sp3 hybridized. • Bent molecular geometry. • C—O—C angles is 110°. • Polar C—O bonds. • Dipole moment of 1.3 D

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 H2O 18 100 ethanol CH3CH2一OH 46 78 dimethyl ether CH3-O一CH3 46 -25 1.3 propane CH3CH2CH3 44 -42 n-butanol CH3CH2CH2CH2-OH 74 118 1.7 tetrahydrofuran 72 66 1.6 diethyl ether CH3CH2一O-CH2CH 35 1.2 pentane CH3CH2CH2CH2CH3 72 36 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 2010 Pearson Prentice Hall,Inc Chapter 14

Chapter 14 4 Boiling Points Similar to alkanes of comparable molecular weight

Hydrogen Bond Acceptor Alcohol Ether Alcohol ether hydrogen bond no hydrogen bond hydrogen bond donor acceptor no donor acceptor donor acceptor Copyright 2010 Pearson Prentice Hall,Inc. Ethers cannot hydrogen-bond with other ether molecules. Molecules that cannot hydrogen-bond intermolecularly have a lower boiling point. Ether molecules can hydrogen-bond with water and alcohol molecules. Chapter 14 5

Chapter 14 5 Hydrogen Bond Acceptor • Ethers cannot hydrogen-bond with other ether molecules. • Molecules that cannot hydrogen-bond intermolecularly have a lower boiling point. • Ether molecules can hydrogen-bond with water and alcohol molecules

Solvation of lons with Ether ether solvates cations: alcohol solvates cations and anions: R (not well solvated) R O-R Copyright2010 Pearson Prentice Hall,Inc. An ionic substance such as lithium iodide is moderately soluble in ethers because the small lithium cation is strongly solvated by the ether's lone pairs of electrons. Unlike alcohols,ether cannot serve as hydrogen- bond donors,so they do not solvate small anions well. Chapter 14 6

Chapter 14 6 Solvation of Ions with Ether • An ionic substance such as lithium iodide is moderately soluble in ethers because the small lithium cation is strongly solvated by the ether’s lone pairs of electrons. • Unlike alcohols, ether cannot serve as hydrogen￾bond donors, so they do not solvate small anions well

Ether Complexes R Grignard reagents:Complexation of O—R H an ether with a Grignard reagent stabilizes the reagent and helps H-C一Mg-X keep it in solution. H RO④ R H Electrophiles:The ethers )B-H nonbonding electrons stabilize the H borane (BH3). BH3·THF Chapter 14 7

Chapter 14 7 Ether Complexes • Grignard reagents: Complexation of an ether with a Grignard reagent stabilizes the reagent and helps keep it in solution. • Electrophiles: The ethers nonbonding electrons stabilize the borane (BH3). O B H H H + _ BH3 THF

Crown Ether Complexes 12-crown-4 15-crown-5 18-crown-6 18-crown-6 EPM of 18-crown-6 solvates Lit solvates Na solvates K with K+solvated Copyright2010 Pearson Prentice Hall,Inc. Crown ethers can complex metal cations inside the ring. The size of the cation will determine the size of the ring needed. Complexation by crown ethers often allows polar inorganic salts to dissolve in nonpolar organic solvents. Chapter 14 8

Chapter 14 8 Crown Ether Complexes • Crown ethers can complex metal cations inside the ring. • The size of the cation will determine the size of the ring needed. • Complexation by crown ethers often allows polar inorganic salts to dissolve in nonpolar organic solvents

Common Names of Ethers Name the two alkyl groups attached to the oxygen and add the word ether. Name the groups in alphabetical order Symmetrical:Use dialkyl or just alkyl. CH3 CH3CH2-O-CH2CH3 CH3-O-C-CH3 CH3 diethyl ether or t-butyl methyl ether or ethyl ether Chapter 14 methyl t-butyl ether s

Chapter 14 9 Common Names of Ethers • Name the two alkyl groups attached to the oxygen and add the word ether. • Name the groups in alphabetical order • Symmetrical: Use dialkyl or just alkyl. diethyl ether or ethyl ether t-butyl methyl ether or methyl t-butyl ether CH3CH2 O CH2CH3 CH3 O C CH3 CH3 CH3

IUPAC Names The more complex alkyl group is the alkane name.The small group (with the oxygen) becomes an "alkoxy"group. CH3 O-CH3 CH3-O-C-CH3 CH3 2-methyl-2-methoxypropane Methoxycyclohexane Chapter 14 10

Chapter 14 10 IUPAC Names • The more complex alkyl group is the alkane name. The small group (with the oxygen) becomes an “alkoxy” group. 2-methyl-2-methoxypropane Methoxycyclohexane CH3 O C CH3 CH3 CH3 O CH3