EthersR-O-R or R-O-R′Nomenclature simple ethers are.pptVIP

* Ethers R-O-R or R-O-R′ Nomenclature: simple ethers are named: “alkyl alkyl ether” “dialkyl ether” if symmetric CH3 CH3 CH3CH2-O-CH2CH3 CH3CH-O-CHCH3 diethyl ether diisopropyl ether CH3-O-C(CH3)3 tert-butyl methyl ether (MTBE) If complex, the ether part is named as an “alkoxy” group: CH3-O- = methoxy CH3CH2-O- = ethoxy, etc. CH3-O-CH2CH2CH2-O-CH3 1,3-dimethoxypropane HO-CH2CH2-O-CH2CH3 2-ethoxyethanol Physical properties: oxygen is sp3 hybridized, bond angle ~ 109.5o ethers are polar; no hydrogen bonding mp/bp moderate water insoluble Diethyl ether = very important organic solvent, polar, water insoluble, bp = 35o. Very flammable forms explosive peroxides. Industrial synthesis for diethyl ether: 2 CH3CH2-OH + H2SO4, 140oC ? CH3CH2-O-CH2CH3 + H2O Not generally useful for syntheses of ethers in the lab: Only symmetric ethers can be made this way. Conditions are very compound specific ( at 180o ethanol would yield ethylene instead of the ether) Synthesis of ethers Williamson Synthesis. R-O-Na+ + R′-X ? R-O-R′ + NaX ?R′-X should be CH3 or 1o SN2 mechanism Mechanism for the Williamson Synthesis = SN2 R′-X should be CH3 or 1o R-OH + Na ? R-O-Na+ ? R-O-R′ R′-OH + HX ? R′-X (CH3)2CH-OH + Na ? (CH3)2CH-O-Na+ + ? CH3CH2CH2-O-CH(CH3)2 CH3CH2CH2-OH + HBr ? CH3CH2CH2-Br isopropyl n-propyl ether note: the alkyl halide is primary! ? CH3CH2CH2-OH + Na ? CH3CH2CH2-ONa + ? CH3CH2CH2-O-CH(CH3)2 (CH3)2CH-OH + HBr ? (CH3)2CH-Br 2o ? alkene The product of this attempted Williamson Synthesis using a secondary alkyl halide results not i