Chapter 14: Ethers and Epoxides

Question 1

Ethers contain…

Answer 1

R-O-R
- can be waters or alcohols

Question 2

Three-membered cyclic ether is an…

Answer 2

epoxide

Question 3

What makes ethers useful solvents?

Answer 3

1) Good at dissolving both polar and non-polar molecules
2) Low chemical reactivity
3) Low BP (volatility) allows for easy removal through evaporation or distillation

Question 4

Crown ether functions (i.e KMnO4 oxidations)

Answer 4

Good solubility and stabilizing specific reagents others can’t
1) Gringard reagents (strongly basic and nucleophilic)
2) Electrophiles (Lewis acid)

Question 5

Williamson Ether Synthesis

Answer 5

SN2 run w/ alkoxide ion, alkyl halide, or tosylate
- works best when electrophilic substrate (R-X) is first degree

Question 6

Alkoxymercuration-Demercurration (Ether Synthesis)

Answer 6

• Treat alkene with mercury (II) acetate in presence of alcohol
• adds alkoxy group to Markovnikov position (after reducing NABH4)

Question 7

Condensation of alcohols (industrial) (Ether Synthesis)

Answer 7

• synthesis of small, symmetric ethers from primary alcohols

Question 8

Ether Rxn: Cleavage by strong acid at high temp

Answer 8

1) Sn2 or Sn1 rxn
- produces an alkyl halide and an alcohol
2) Second rxn converts alcohol to alkyl halide

Question 9

Ether Rxn: Autoxidation (peroxide formation)

Answer 9

1) slowly form organic peroxides upon exposure to oxygen from air

Question 10

Sulfides (Thioethers)

Answer 10

R-S-R
- formed via SN2 RXNS analogous to Williamson Ether Synthesis

Question 11

Silyl Ethers

Answer 11

R-O-SiR3

Question 12

Alkenes to Epoxide (Epoxide Synthesis)

Answer 12

peroxyacids (i.e MCPBA) used to convert alkenes into epoxides (one long step)

Question 13

Base-promoted cyclization of halohydrins

Answer 13

• X and OH add anti to one another
• treatment with base generates alkoxide ion adjacent to a Carbon and substrate cyclizes to form an epoxide (Sn2-like)

Question 14

Acid-catalyzed Epoxide Rxns

Answer 14

1) proton catalyzed ring opening using solvent withH2O or -OH or halide ion as nuc
2) After protonation, NUC: attacked more sub Carbon (greater partial positive charge) in an SN2 fashion

Question 15

Aq Acid (H3O+) Epoxide Rxn

Answer 15

: produces a trans glycol

Question 16

ROH, H+ Epoxide Rxn (i.e Ch3OH)

Answer 16

a) alcohol solvent => alkoxy group added on substrate

Question 17

Basic Conditions Epoxide Rxns

Answer 17

1) Nuc: attacks less sub epoxide carbon in SN2 rxn, leaving group is alkoxide ion
( i.e hydroxide, alkoxide, amine,and Gringard reagents can be used as solvents)