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 c 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 FormulaR-o-R where r is alkyl or ary Symmetrical or unsymmetrical Examples: CH3-O-CH3 〉O-CH > Chapter 14
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 sp hybridized Tetrahedral angle H H C 110 H H H H Chapter 14
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- Comparison of the boiling points of Ethers. Alkanes, and Alcohols of Similar Molecular Weights Compound Formula Mw bp(C) Dipole Moment (D) water HO 18 100 1.9 ethanol CH3CH,-OH 46 1.7 dimethyl ether CH:-0-CH 46 25 propane CH CH2CH3 0.1 月- butanol CHa CH, CH- CH2-OH 74 118 1.7 tetrahydrofuran 72 66 diethyl ether CHaCH20--CH CH 7 pentane CH3CH,CH CH,CH3 36 0.1 Note: The alcohols are hydrogen bonded, giving them much higher boiling points. The et hers have boil ing points that are closer to those of alkanes with similar molecular weights Chapter 14
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), R the lone pair of O—H electrons from ether forms a hydrogen R R bond with the-oh or NH hydrogen bond donor acceptor Chapter 14
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. =>
Solvent Properties Nonpolar solutes ether solvates cations: dissolve better in ether than in alcohol RL计 Ether has large dipole R moment, so polar R—O solutes also dissolve R—O4 · Ethers solvate cations RR (not well solvated) RR Ethers do not react with strong bases Chapter 14
Chapter 14 6 Solvent Properties • Nonpolar solutes dissolve better in ether than in alcohol. • Ether has large dipole moment, so polar solutes also dissolve. • Ethers solvate cations. • Ethers do not react with strong bases. =>
Ether Complexes R Grignard reagents O—R H—C—Mg—X R—O Electrophiles : 0-B-H R BH3·THF · Crown ethers > Chapter 14
Chapter 14 7 Ether Complexes • Grignard reagents • Electrophiles • Crown ethers O B H H H + _ BH3 THF =>
Common names of ethers Alkyl alkyl ether Current rule: alphabetical order Old rule: order of increasing complexity Symmetrical: use dialkyl, or just alky EXamples CH CH3-0-C--CH CH3 CH2-O-CH2CH3 CH diethyl ether or ethyl ether t-butyl methyl ether or Chapter 14 methyl t-butyl ether=>
Chapter 14 8 Common Names of Ethers • Alkyl alkyl ether • Current rule: alphabetical order • Old rule: order of increasing complexity • Symmetrical: use dialkyl, or just alkyl. • Examples: CH3 CH2 O CH2 CH3 diethyl ether or ethyl ether CH3 O C CH3 CH3 CH3 t-butyl methyl ether or methyl t-butyl ether =>
UPAC Names ·A| koxy alkane EXamples CH3 O-CH3 CH3-O—C-CH3 CH3 2-methyl-2-methoxypropane Methoxycyclohexane Chapter 14
Chapter 14 9 IUPAC Names • Alkoxy alkane • Examples: CH3 O C CH3 CH3 CH3 2-methyl-2-methoxypropane O CH3 Methoxycyclohexane =>
Cyclic Ethers Heterocyclic: oXygen is in ring Epoxides(oXiranes)H2 C-CH2 Oxetanes Furans (Oxolanes()) O O Pyrans ()(Xanes O) Dioxanes O Chapter 14 10
Chapter 14 10 Cyclic Ethers • Heterocyclic: oxygen is in ring. • Epoxides (oxiranes) H2C CH2 O • Oxetanes O • Furans (Oxolanes ) O O • Pyrans (Oxanes ) O O •Dioxanes O O =>