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Organic Chemistry by Brown, Iverson, Anslyn, Foote | Mayya's Study Guide | Chapter 11

Chapter 11: Ethers, Epoxides, and Sulfides


Table of contents of main topics:

  • Nomenclature of ethers

  • Preparation of ethers

  • Reactions of ethers

  • Silyl Ethers as protecting groups

  • Synthesis of epoxides

  • Reactions of epoxides

  • Sulfides

  • Summary of the chapter reactions


Nomenclature of ethers


IUPAC Name

  1. Select the longest continuous carbon chain that has OR as a substituent and number from the carbon closest to the OR group (OH has priority over OR).

  2. Name the ether substituent (OR) with a number identifying carbon it is attached to followed by ...oxy ether

Common Name:

  1. Identify the two R groups attached to the oxygen

  2. Arrange R groups in alphabetical order and end the name with "ether"

  3. If two of the same R groups are attached, then use prefix di


Preparation of Ethers


Williamson Ether Synthesis

Williamson ether synthesis is a reaction that converts alcohols into ethers (C-O-C). In the first step, alcohol is deprotonated using a strong base such as NaH. The alkoxide ion that is created is a strong nucleophile and can attack primary alkyl halides and tosylates in an SN2 reaction. The O- attacks the carbon the leaving group is attached to and the leaving group leaves.

Note: If the alkyl halide or tosylate is not primary, E2 will happen instead of SN2.


Williamson Ether Synthesis
Williamson Ether Synthesis

How to predict the reactants of Williamson Ether Synthesis when product is given
How to predict the reactants of Williamson Ether Synthesis when product is given


Acid Catalyzed Dehydration of Alcohols


2 alcohols can come together to form an ether with H2SO4 and heat.

Acid Catalyzed Dehydration of Alcohols
Acid Catalyzed Dehydration of Alcohols

Acid Catalyzed Addition of Alcohols To Alkenes


Reagent: ROH with an acid catalyst

Product: Turn double bond into single bond and add OR to the most substituted carbon from the double bond. Rearrangements are possible


Acid Catalyzed Addition of Alcohols To Alkenes
Acid Catalyzed Addition of Alcohols To Alkenes

Reactions of Ethers


Acid Catalyzed Cleavage By Concentration HX

Reagent: HX (X=Br or I)

Product: Break the bonds between oxygen and the two carbons it is attached to. Attach X to each carbon broken off.

Cleavage Of Ethers By HBr or HI
Cleavage Of Ethers By HBr or HI

In the mechanism for this reaction, first oxygen gets protonated to become a better leaving group. X- can then attack carbon that has OHR+ group and the bond between oxygen and carbon breaks giving us the first product. This process repeats again with OH getting protonated to become a better leaving group and then X attacking the carbon that the OH2+ is attached to, and OH2+ leaving.


Silyl Ethers as Protecting Groups

Alcohol groups are transformed into silyl ethers in synthesis problems where alcohols need to be protected.


Silyl Ethers as Protecting Groups
Silyl Ethers as Protecting Groups

Synthesis of Epoxides


Internal Nucleophilic Substitution in Halohydrins

Reagent: alkene with 1.Cl2 (or Br2), H2O 2.NaOH, H2O

Product: Turn double bond into single and attach two carbons from the double bond to an oxygen, making a triangle (epoxide)

Oxidation of Alkenes with Peroxycarboxylic Acids

Reagent: RCO3H (peroxyacid)

Product: Turn double bond into single and attach two carbons from the double bond to an oxygen, making a triangle (epoxide)

Oxidation of Alkenes with Peroxycarboxylic Acids
Oxidation of Alkenes with Peroxycarboxylic Acids

Sharpless Asymmetric Epoxidation


Sharpless Asymmetric Epoxidation
Sharpless Asymmetric Epoxidation

Reactions of Epoxides

Epoxides with Acids

Examples of Acids: HCl, HCN, H3O+, ROH2+....


Epoxides with Bases


Mayya's Trick story : Imagine epoxide has a birthday and base comes with no present since it has no hydrogens to give. Epoxide is so upset, it makes base attack the least substituted carbon.


Reaction of Epoxide with Lithium Aluminum Hydride

Reagent: 1. LiAlH4 2.H2O

Product: Get rid of the epoxide and add OH to the MOST substituted carbon from the epoxide carbons.

Reaction of Epoxide with Lithium Aluminum Hydride
Reaction of Epoxide with Lithium Aluminum Hydride

Sulfides


reactions of sulfides
reactions of sulfides

Ether And Epoxide Reaction Cheat Sheet for Organic Chemistry by Brown, Iverson, Anslyn, Foote
Ether And Epoxide Reaction Cheat Sheet for Organic Chemistry by Brown, Iverson, Anslyn, Foote

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