CH4: Alcohols and Ethers

Question 1

3 membered ring ether called

Answer 1

Oxirane

Question 2

4 membered ring ether called

Answer 2

Oxetane

Question 3

Ether vs alcohol vs hydrocarbon BP, Solubility

Answer 3

BP: HC=Ether

Question 4

Acid-catalyzed hydration

Answer 4

An alkene + water with HA leads to an alcohol.

Alkene + H2O 1) HA

There is a carbocation intermediate which may rearrange. Markovnikov addition.
Everything is in equilibrium.

Not a stereoselective reaction, leads to a racemic mixture.

Question 5

Alcohols from alkenes

Answer 5

1) Acid-catalyzed hydration
2) Oxymercuration-demercuration
3) Hydroboration-oxidation

Question 6

Oxymercuration-demercuration

Answer 6

Water + Alkene with 1) Hg(Oac)2/THF 2) NaBH4/NaOH.

Not a stereoselective reaction, markovnikov addition.

Question 7

Hydroboration-oxidation

Answer 7

1) BH3/THF 2) H2O2, NaOH

Antimarkovnikov. Syn addition.

Question 8

How to make an alkoxide

Answer 8

Alcohol and strong base ex. NaNH2

Question 9

Can organometallic reagents be used with alcohols

Answer 9

NO! They will react and form alkoxides

Question 10

Alkyl halides from alcohols

Answer 10

1) Hydrogen halides
2) PBr3
3) SOCl2

Question 11

Hydrogen halides and alcohol

Answer 11

Reactivity: HI>HBr>HCl>HF
Alcohol: Only 3, 2, allylic, and benzyllic

SN1 rxn
SN2 rxn can take place with 1

Question 12

Lewis-acid catalyst and 1+2 alcohols

Answer 12

ZnCL3 or FeCL3 etc can be used with primary and secondary alcohols to form alkyl halides

Question 13

SOCl2 + PBr3

Answer 13

These convert primary and secondary alcohols into alkyl halides with no rearrangement via the SN2 rxn. They make OH- a good L.G.

SOCl2 is done with pyridine/imadazole to mop HCl

Question 14

Tosylates, mesylates and trifylates

Answer 14

Create good L.G.
Put on to create an ester. When it is attacked via SN2 it inverts, when it is originally put on it doesn’t invert. This is done with Ts/Tf/Ms + Cl

Question 15

What is special about trifylate

Answer 15

It can cause vinylic carbons to go through SN1

Question 16

3 ways to make ethers

Answer 16

1) Intermolecular dehydration
2) Williamson ether
3) Alkoxymercuration-demercuration

Question 17

Intermolecular dehydration

Answer 17

2 symmetrical alcohols and 2 moles of acid ex. 2HBr cleaves an ether via SN2

It must be done at a lower temp so that elim doesn’t occur. It is also only done with primary alcohols.

Question 18

Williamson ether synthesis

Answer 18

Can be done with 2 unsymmetrical ethers. Alkoxide attacks a primary alkyl halide via SN2.

To form the alkoxide we can use NaNH2 etc.

Must be a good L.G. on the primary alkyl halide ex Br or I

Question 19

Alkoxymercuration-demercuration

Answer 19

1) Hg(OAC)2, R-OH 2) NaBH4, NaOH

Alcohol gets used instead of water forming an ether.

Question 20

T-butyl ethers

Answer 20

T-butyl ethers are good protecting groups for primary alcohols against organometallic reagants

1) H2SO4 2) CH2=C(CH3)2

They are removed with dilute acid H3O+/H2O

Question 21

Silyl ether protecting group

Answer 21

Protecting group against organometallic

Primary alcohol + TBDMSCl…must have imidazole or pyrimidine in DMF.

Removed with TBAF or Bu4N+F-

Question 22

TBDMSCl

TBAF

Answer 22

Silyl ether protecting group

Removal of the group (Bu4N+F-)

Question 23

Ether cleavage

Answer 23

Acyclic ethers are typically unreactive, however, with 2 moles of strong acid they are cleaved via SN2

Question 24

Epoxide

Answer 24

3 membered ring

Question 25

How to make an epoxide

Answer 25

Alkene + Peroxy acid ex. MMPP leads to a syn addition

Question 26

MMPP

Answer 26

Epoxide former (peroxy acid)

Question 27

Cis vs trans epoxidation

Answer 27

Cis leads to 1 product

Trans leads to 2 product (enantiomers)

Question 28

Acid vs catalyzed epoxide ring opening

Answer 28

Acid-More sub= Trans diol
Lots of eq bullshit

Base-Less sub=Ether, alcohol via SN2
1) Opening 2) Protonation

Question 29

Epoxides

Answer 29

LOOK UP STEROSELECTIVITY