Alcohols General Nomenclature Ethers General Nomenclature Synthesizing Alcohols
- Slides: 16
Alcohols: General Nomenclature
Ethers: General Nomenclature
Synthesizing Alcohols from Alkenes • We’ve Looked at Several OH Synthesis Reactions in Ch. 8 Ø Acid-Catalyzed Hydration (Markovnikov) Ø H 3 O+/H 2 O OR warm, dilute H 2 SO 4, H 2 O Ø Oxymercuration/Demercuration (Markovnikov) Ø 1. Hg(OAc)2 THF/H 2 O 2. Na. BH 4, Na. OH Ø Hydroboration/Oxidation (Anti-Markovnikov) Ø 1. BH 3 : THF 2. H 2 O 2, Na. OH • Now Let’s Consider Some Reactions of Alcohols
Reactions of Alcohols • Lone Pairs on Alcohols: Lewis Bases, Nucleophiles • Note Bond Polarizations: C, H are d+ and O is d¯ • Alcohol Carbon Not Particularly Electrophilic (HO¯ Bad LG) • Protonation of Alcohol H 2 O; Good Leaving Group
Reactions of Alcohols • Protonation of Alcohol H 2 O; Good Leaving Group • Presence of Good Leaving Group Makes COH Electrophilic • OH 2+ More Electron Withdrawing than OH; More Polarized • Can Observe SN 1 or SN 2 Reactions (Depends on Alcohol Class)
Reactions of Alcohols • Protonation of Alcohol H 2 O; Good Leaving Group • Another Alcohol Moleculae Can React, Get Protonated Ether • Subsequent Deprotonation Ether Product (Symmetric Here) • Reaction is CONDENSATION of Two Alcohols
Converting Alcohols into Alkyl Halides
HX Reactions with Alcohols (3°, 2°)
HX Reactions with Alcohols (1°, Me. OH) • As Seen Previously, Protonation Makes Good Leaving Group • Presence of Nucleophile (Br) Allows for Substitution Reaction • Can also Add Lewis Acid to Help (esp. Zn. Cl 2 w/ Cl¯)
Alcohol Reactions w/ PBr 3, SOCl 2 • P and S Atoms are Electrophilic Sites, O acts as Nucleophile • Low Temperatures w/ PBr 3 Prevent C Skeleton Rearrangement • PBr 3 Reaction Choice Reagent for 1°, 2° OH 1°, 2° Br • SOCl 2 Good Reagent for 1°, 2° OH 1°, 2° Cl • Reaction Usually Run with Added Amine Base (Consume HCl) • SOCl 2 Reactions Also Typically Don’t Involve Rearrangements • Will Later See SOCl 2 Replaces OH of Carboxylic Acid with Cl
Williamson Synthesis of Ethers Unsymmetrical Ethers From RONa + Halide, Sulfonate, etc. • Utility of this Reaction is Much Greater Than Condensation: Ø Works with 1° and 2° Halides, Sulfonates, etc. Ø Still Exclusively Alkenes with 3° Alkyl Groups Ø Lower Temperatures Favor Substitution over Elimination Ø SN 2 Conditions Apply Prefer Unhindered Substrate
Ether Reactions w/ Strong Acids • Ethers Can be Protonated by Strong Acids (Oxonium Ions) • w/ 2 Equivalents of Acid (HX), Cleaved to 2 Eq. Alkyl Halide Ø Protonation, SN 2, Protonation, SN 2
Ether Cleavage by HBr: Mechanism • Two Equivalents of Ethyl bromide Produced (+ H 2 O)
Synthesis of Epoxides • Three-Membered Oxygen Containing Ring; Use Peroxy Acid
Epoxide Opening: Acid-Catalyzed • Epoxides Are Reactive to Opening Due to Ring Strain • After Protonation, Opening is SN 2 Like Reaction (Anti) • “Desire” to Relieve Ring Strain Good Electrophiles
Epoxide Opening: Base-Catalyzed • Epoxides Are Ethers That Can be Attacked by Bases • Reactivity is Due to Ring Strain (Increases Electrophilicity) • As in Acid Case, Opening is an SN 2 Reaction • Can Open With Strong Base, Hydroxide and Alkoxide Usual
- Alcohols phenols thiols and ethers
- Nomenclature of ethers
- Ethers naming
- Alkoxide leaving group
- Alcohols nomenclature
- Naming alkyl halides
- Cis-2 3-dimethyloxirane
- Ethers naming
- Epoxide plus grignard
- How to make ether from alcohol
- Acidic cleavage of ethers
- Alkyl alkanoate
- Ethers boiling point
- Ether naming
- Synthesizing images of humans in unseen poses
- Synthesizing mind example
- Synthesizing information allows a reader to