Organic II - Ether, Epoxides and Thioethers

Question 1

Give formula for an ether.

Answer 1

R-O-R’

Question 2

Are ethers symmetrical or unsymmetrical?

Answer 2

Both.

Question 3

What is the structure and polarity of ethers? (hybridization, molecular geometry, angle and polarity)

Answer 3

O is sp3 hybridized, bent molecular geometry, C-O-C 110 degrees and polar C-O bond

Question 4

Boiling point of ethers are similar to _______.

Answer 4

alkanes

Question 5

Can ethers hydrogen bond with other molecules?

Answer 5

No

Question 6

Ethers have a lower b.p than ________.

Answer 6

alcohols

Question 7

Ether molecules can H bond with ______ & ________ molecules.

Answer 7

water; alcohol

Question 8

Why are ethers used as solvents?

Answer 8

They can dissolve n.p and polar substances and are unreactive with strong bases.

Question 9

-OCH3 is named as…

Answer 9

methoxy

Question 10

Give the epoxide formula.

Answer 10

CH2-O-CH2

Question 11

Define heterocyclic.

Answer 11

O is part of the ring

Question 12

Oxetane is…

Answer 12

O + 3 C ring (forms a square)

Question 13

Dioxane is…

Answer 13

2 O + 4 C (hexagon)

Question 14

Furan is…

Answer 14

O + 4 C with 2 double bonds (dicyclopentene)

Question 15

Pyran is…

Answer 15

O + 5 C with 2 double bonds (dicyclohexene)

Question 16

Name all the heterocycles.

Answer 16

epoxide, oxetane, furan, pyran, dioxane

Question 17

Another name for oxirane is…

Answer 17

1,2-epoxyethane

Question 18

What method does the preparation of ether use?

Answer 18

Williamson ether synthesis

Question 19

What are two common products of nucleophilic substitution?

Answer 19

Alcohols and ethers

Question 20

Can unsymmetrical ethers be synthesized two different ways?

Answer 20

Yes.

Question 21

Which path is preferred in Williamson ether synthesis?

Answer 21

Alkoxide attack less hindered alkyl halide.

Question 22

Why are phenoxide ions easily produced?

Answer 22

The alcohol proton is acidic.

Question 23

Phenyl halides or tosylates can’t be used in Williamson ether synthesis because…

Answer 23

They are poor substrates.

Question 24

MCPBA with a double bond usually forms…

Answer 24

an epoxide

Question 25

Formation of the chlorohydrin involves what? (reactant, intermediate, product)

Answer 25

alkene, chloronium ion, chlorohydrin enantiomers

Question 26

What are the reactants of the formation of chlorohydrin?

Answer 26

Cl2 and H2O

Question 27

What are the reactants of the displacement of chlorohydrin?

Answer 27

Base like OH-

Question 28

What does the displacement of chlorohydrin produce?

Answer 28

Epoxide, H2O and Cl- ion

Question 29

In base-catalyzed opening of epoxide, the base attacks the __________ carbon.

Answer 29

less substituted

Question 30

Opening an epoxide ring with HCl, Cl- attacks the ___________ carbon.

Answer 30

more substituted

Question 31

Define regioselectivity.

Answer 31

Ring opening of an epoxide with either a strong nucleophile or an acid (HZ)

Question 32

When opening an epoxide with a strong nucleophile, it attacks the ____ substituted carbon.

Answer 32

less

Question 33

When opening an epoxide with an acid, it attacks the ____ substituted carbon.

Answer 33

more

Question 34

Grignards and organolithiums open an epoxide ring by attacking the _____ hindered carbon.

Answer 34

less

Question 35

A primary alcohol reacting with H2SO4 and heat produces...

Answer 35

An ether and H2O

Question 36

Does a secondary alcohol (alkane) reacting with H2SO4 and heat produce an ether?

Answer 36

No. (Alkene with H2O)

Question 37

How to convert a poor leaving group to a good one on ethers?

Answer 37

Reaction with strong acids (ex. HBr and HI)

Question 38

What happens to the C-O bond of ethers reacting with HBr or HI?

Answer 38

C-O bonds are cleaved & 2 alkyl halides are formed.

Question 39

A branched structure (tertiary C-O bond) goes through _____ mechanism when cleaved.

Answer 39

SN1

Question 40

CH3-OH bond goes through ___ mechanism when cleaved.

Answer 40

SN2

Question 41

Phenyl ether cleavage produces what?

Answer 41

Phenol and an alkyl halide

Question 42

Give the standard formula for thioethers.

Answer 42

R-S-R'

Question 43

Name CH3-S-CH3.

Answer 43

Dimethyl sulfide

Question 44

Are thioethers easily synthesized by the Williamson ether synthesis?

Answer 44

Yes.

Question 45

_________ ion is used as the nucleophile in the synthesis of thioethers.

Answer 45

Thiolate