Quiz 1

Question 1

-OH group=

Answer 1

alcohol

Question 2

Ph-OH =

Phenol ring+ OH

Answer 2

hydroxyl group

Question 3

Bc of ——- alcohols have higher bp

Answer 3

hydrogen bonding

Question 4

Alkoxide

Answer 4

conjugate base of an alcohol w/ a negative O

Question 5

Alcohols are more acidic than amines +alkanes but less acidic than ——-

Answer 5

hydrogen halides

Question 6

What kind of bases are needed to deprotonate an alcohol?

Answer 6

N-,C-,H-

strong bases, unless its a hydroxyl group

Question 7

What are the three stabilizing effects for alkoxides

Answer 7

1. resonance
2. induction
3. solvation/steric hinderence

Question 8

True or False?

A weaker, well stabilized base will have more steric hinderence to protect it from solvent effects

Answer 8

False, less steric hinderence allows the solvent to stabilize a charge creating a weaker base and stronger acid

Question 9

If you want to prepare an alcohol via substitution what kind of substrate must it be?

Answer 9

Primary or tertiary

secondary = elimination

Question 10

What are the three addition reactions that can be used to prepare alcohols?

Answer 10

1. Acid cataylized hydration
2. Oxymercuration demurcuration
3. Hydroboration oxidation

Question 11

Oxidation

Answer 11

increases the number of electrons, increases the number of bonds between C and an electronegative atom

Question 12

Reduction

Answer 12

decreases the number of electrons, decreases the number of bonds between C and an electronegative atom

Question 13

name the three reduction agents for reducing ketones/aldehydes to alcohols

Answer 13

1. Hydrogenation of an alkene with a metal catalyst
2. NaBH4 (mild reagent)
3. LiAlH4 (strong reagent)

Question 14

Why isnt hydrogenation of alkene used often for reduction of alcohols?

Answer 14

Bc it requires harsh conditions

Question 15

What are the mechanistic steps for using NaBH4 as a reducing agent?

Answer 15

1. nuc attack by hydride source
2. proton transfer from solvent to O- for neutralization

Question 16

What are the mechanistic steps for using LiAlH4 as a reducing agent?

Answer 16

1. add LiAlH4 as a hydride source for nuc attack
2. add solvent separately to LiAlH4 for neutralization/ proton transfer step

Question 17

LiAlH4 and NaBH4 react — with C=O bonds

Answer 17

selectivley

Question 18

Mechanistic steps for reduction of an ester using LiAlH4

Answer 18

• need 2 eq. of hydride
  1. nuc attack by hydride source
  2. loss of leaving group by other O group to reform C=O bond
  3. nuc attack by hydride source
  4. proton transfer/ neutralization

Question 19

Grignard reagent

Answer 19

R-Mg-X
- prepared by reaction of Mg + alkyl halide

Question 20

What is special about the C-Mg bond in the grignard reagent?

Answer 20

it can be deemed an ionic bond where the C has a partial negative charge, giving it nucleophilic qualities

Question 21

Why would you have to protect an alcohol?

Answer 21

Bc if it is used with a grignard reagent the reagent would react with itself and not the C=O bond

Question 22

What is an example of a protecting group?

Answer 22

TMSCl

Question 23

What are the three steps for protection of alcohols?

Answer 23

1. replace proton on unwated alcohol with protecting group
2. Proceed with reaction of the grignard agent+ substrate
3. deprotecting alcohol and regenerate proton

Question 24

examples of deprotecting agents

Answer 24

1. TBAF/F-
2. H3O+

Question 25

What kind of reactions can a tertiary alcohol undergo?

Answer 25

SN1 reaction w/ HX as the reagent

Question 26

What kind of reactions can a secondary alcohol undergo?

Answer 26

- SN2 by converting OH` to OTMS and using a strong nuc only - SN2 by using PBr3 or SOCl2 - elimination by strong base

Question 27

What kind of reactions can a primary alcohol undergo?

Answer 27

- SN2 by treatment w/ HBr - SN2 by conversion of OH to OTMS and using a good nuc only - SN2 by SOCl2 and PBr3

Question 28

What is the one step featured in all of the substiutuon reactions with alcohols?

Answer 28

Turning the OH group into a better leaving group

Question 29

explain an E1 reaction w/ an alcohol

Answer 29

1. youll need acidic conditions + heat 2. tertiary alcohol to prevent re-arrangements

Question 30

explain and E2 reaction w/ an alcohol

Answer 30

1. a strong base must be used (ex: TBuOK) 2. E2 does not have rearrangements

Question 31

What are two oxidixing reagents for oxidation of an alcohol?

Answer 31

PCC and Chromic acid | PCC = mild Chromic= strong

Question 32

If a primary alcohol is oxidzized with chromic acid what is the product?

Answer 32

carboxylic acid

Question 33

How many oxidations can a secondary alcohol go through?

Answer 33

only one bc it has one hydrogen

Question 34

What is the product of a tertiary alcohol reacted with chromic acid?

Answer 34

none, tertiary alcohols cannot be oxidized, they have no hydrogens

Question 35

IUPAC naming of Ethers

Answer 35

choosing the longest R group of the ether to be the parent chain and naming the shorter one as an oxy substituent | recall that ethers are low on the priority list

Question 36

Why do ethers not have a high bp?

Answer 36

bc they have no hydrogen bonding like alcohols

Question 37

Why are ethers often used as organic solvents?

Answer 37

Bc/ they are not very reactive and have low bp

Question 38

Williamson Ether synthesis

Answer 38

- Sn2 like process - Proton transfer to create alkoxide intermediate and then nuc attack where alkoxide acts as the nucleophile - Alkoxide key intermediate - can only be done with primary or secondary alkyl halides

Question 39

Alkoxymercuration demercuration

Answer 39

- very similar to the alkene rxn of the same name - ROH group added via markovnikov addition instead of OH