chapter11

chapter11 - 11-11-1Organic Organic...

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Unformatted text preview: 11-11-1Organic Organic ChemistryChemistryWilliam H. BrownWilliam H. BrownChristopher S. FooteChristopher S. FooteBrent L. IversonBrent L. Iverson11-11-2Ethers & Ethers & EpoxidesEpoxidesChapter 11Chapter 1111-11-3StructureStructureThe functional group of an ether is an oxygen atom bonded to two carbon atomsin dialkyl ethers, oxygen is sp3hybridized with bond angles of approximately 109.5. in dimethyl ether, the C-O-C bond angle is 110.3HHOHCHHHC11-11-4StructureStructurein other ethers, the ether oxygen is bonded to an sp2hybridized carbonin ethyl vinyl ether, for example, the ether oxygen is bonded to one sp3hybridized carbon and one sp2hybridized carbonCH3CH2-O-CH=CH2Ethoxyethene(Ethyl vinyl ether)11-11-5Nomenclature: ethersNomenclature: ethersIUPAC: the longest carbon chain is the parent name the OR group as an alkoxy substituentCommon names: name the groups bonded to oxygen in alphabetical order followed by the word etherether2-Methoxy-2-methylpropane(tert-Butyl methyl ether)Ethoxyethane(Diethyl ether)CH3CH3CH3CH2OCH2CH3CH3OCCH3trans-2-Ethoxy-cyclohexanolOCH2CH3OH11-11-6Nomenclature: ethersNomenclature: ethersAlthough cyclic ethers have IUPAC names, their common names are more widely usedIUPAC: prefix ox-ox-shows oxygen in the ringthe suffixes -iraneirane, -etaneetane, -olaneolane, and -aneaneshow three, four, five, and six atoms in a saturated ringOxirane(Ethylene oxide)Oxolane(Tetrahydrofuran)Oxane(Tetrahydropyran)1,4-DioxaneOO123OOOOOxetane11-11-7Physical PropertiesPhysical PropertiesAlthough ethers are polar compounds, only weak dipole-dipole attractive forces exist between their molecules in the pure liquid state11-11-8Physical PropertiesPhysical PropertiesBoiling points of ethers are lower than alcohols of comparable MWclose to those of hydrocarbons of comparable MW Ethers are hydrogen bond acceptorsthey are more soluble in H2O than are hydrocarbons11-11-9Preparation of EthersPreparation of EthersWilliamson ether synthesis:Williamson ether synthesis:SN2 displacement of halide, tosylate, or mesylate by alkoxide ion2-Methoxypropane(Isopropyl methyl ether)Iodomethane(Methyl iodide)Sodiumisopropoxide++CH3CH3CH3ICH3CHO-Na+CH3CHOCH3Na+I-SN211-11-1010Preparation of EthersPreparation of Ethersyields are highest with methyl and 1 halides, lower with 2 halides (competing -elimination)reaction fails with 3 halides (-elimination only)CH3CH3CH3CO- K+CH3BrSN2CH3CH3CH3COCH3K+Br-++Potassiumtert-butoxideBromomethane(Methyl bromide)2-Methoxy-2-methylpropane(tert-Butyl methyl ether)CH3CH3CH3CBrCH3O-Na+E2CH3CH3C=CH2CH3OHNa+Br-+++2-Bromo-2-methylpropaneSodiummethoxide2-Methylpropene11-11-1111Preparation of EthersPreparation of EthersAcid-catalyzed dehydration of alcoholsdiethyl ether and several other ethers are made on an industrial scale this waya specific example of an SN2 reaction in which a poor leaving group (OH-) is converted to a better one (H2O)2CH3CH2OHH2SO4140 CCH3CH2OCH2CH3H2O+EthanolDiethyl ether11-...
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chapter11 - 11-11-1Organic Organic...

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