University:
Kentucky State University
Course:
CHE 302 | Organic Chemistry II
Academic year:

2024
Views:

173

Pages:

12
Author:

hekeldigzjbz

Pharmaceutical organic chemistry “Ethers and Epoxides” Lecture 6 Ethers and Epoxides Names of Ethers Names and Properties of Ethers • Simple ethers are named by identifying the two organic substituents and adding the word ether (Common naming) • How is IUPAC naming? • If other functional groups are present, the ether part is considered an alkoxy substituent Physical Properties of Ethers • R–O–R ~ tetrahedral bond angle • Oxygen is sp3-hybridized • Oxygen atom gives ethers a slight dipole moment • The boiling point of ethers is comparable to the alkanes but much lower than that of alcohols of comparable molecular mass despite the polarity of the C-O bond. • Ether molecules are miscible in water. This is attributed to the fact that like alcohol, the oxygen atom of ether can also form hydrogen bonds with a water molecule The Williamson Ether Synthesis • Reaction of metal alkoxides and primary alkyl halides • Best method for the preparation of ethers • Alkoxides prepared by reaction of an alcohol with a strong base such as sodium hydride, NaH Silver Oxide-Catalyzed Ether Formation • Reaction of alcohols with Ag2O directly with alkyl halide forms ether in one step • Glucose reacts with excess iodomethane in the presence of Ag2O to generate a pentaether Alkoxymercuration of Alkenes • React alkene with an alcohol and mercuric acetate or trifluoroacetate • Demercuration with NaBH4 yields an ether • Overall Markovnikov addition of alcohol to alkene Reactions of Ethers: Acidic Cleavage • Ethers are generally unreactive • Strong acid will cleave an ether at elevated temperature • HI, HBr produce an alkyl halide from less hindered component by SN2 (tertiary ethers undergo SN1) Reactions of Ethers: Acidic Cleavage • Ethers are generally unreactive • Strong acid will cleave an ether at elevated temperature • HI, HBr produce an alkyl halide from less hindered component by SN2 (tertiary ethers undergo SN1) Cyclic Ethers: Epoxides • Cyclic ethers behave like acyclic ethers, except if ring is 3-membered • Dioxane and tetrahydrofuran are used as solvents

Ethers and Epoxides

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