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Ochem 2 > Quiz 1 > Flashcards

Quiz 1 Flashcards

1
Q

-OH group=

A

alcohol

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2
Q

Ph-OH =

Phenol ring+ OH

A

hydroxyl group

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3
Q

Bc of ——- alcohols have higher bp

A

hydrogen bonding

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4
Q

Alkoxide

A

conjugate base of an alcohol w/ a negative O

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5
Q

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

A

hydrogen halides

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6
Q

What kind of bases are needed to deprotonate an alcohol?

A

N-,C-,H-

strong bases, unless its a hydroxyl group

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7
Q

What are the three stabilizing effects for alkoxides

A
  1. resonance
  2. induction
  3. solvation/steric hinderence
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8
Q

True or False?

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

A

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

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9
Q

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

A

Primary or tertiary

secondary = elimination

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10
Q

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

A
  1. Acid cataylized hydration
  2. Oxymercuration demurcuration
  3. Hydroboration oxidation
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11
Q

Oxidation

A

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

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12
Q

Reduction

A

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

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13
Q

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

A
  1. Hydrogenation of an alkene with a metal catalyst
  2. NaBH4 (mild reagent)
  3. LiAlH4 (strong reagent)
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14
Q

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

A

Bc it requires harsh conditions

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15
Q

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

A
  1. nuc attack by hydride source
  2. proton transfer from solvent to O- for neutralization
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16
Q

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

A
  1. add LiAlH4 as a hydride source for nuc attack
  2. add solvent separately to LiAlH4 for neutralization/ proton transfer step
17
Q

LiAlH4 and NaBH4 react — with C=O bonds

A

selectivley

18
Q

Mechanistic steps for reduction of an ester using LiAlH4

A
  • 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
19
Q

Grignard reagent

A

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

20
Q

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

A

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

21
Q

Why would you have to protect an alcohol?

A

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

22
Q

What is an example of a protecting group?

A

TMSCl

23
Q

What are the three steps for protection of alcohols?

A
  1. replace proton on unwated alcohol with protecting group
  2. Proceed with reaction of the grignard agent+ substrate
  3. deprotecting alcohol and regenerate proton
24
Q

examples of deprotecting agents

A
  1. TBAF/F-
  2. H3O+
25
Q

What kind of reactions can a tertiary alcohol undergo?

A

SN1 reaction w/ HX as the reagent

26
Q

What kind of reactions can a secondary alcohol undergo?

A
  • SN2 by converting OH` to OTMS and using a strong nuc only
  • SN2 by using PBr3 or SOCl2
  • elimination by strong base
27
Q

What kind of reactions can a primary alcohol undergo?

A
  • SN2 by treatment w/ HBr
  • SN2 by conversion of OH to OTMS and using a good nuc only
  • SN2 by SOCl2 and PBr3
28
Q

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

A

Turning the OH group into a better leaving group

29
Q

explain an E1 reaction w/ an alcohol

A
  1. youll need acidic conditions + heat
  2. tertiary alcohol to prevent re-arrangements
30
Q

explain and E2 reaction w/ an alcohol

A
  1. a strong base must be used (ex: TBuOK)
  2. E2 does not have rearrangements
31
Q

What are two oxidixing reagents for oxidation of an alcohol?

A

PCC and Chromic acid

PCC = mild Chromic= strong

32
Q

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

A

carboxylic acid

33
Q

How many oxidations can a secondary alcohol go through?

A

only one bc it has one hydrogen

34
Q

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

A

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

35
Q

IUPAC naming of Ethers

A

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

36
Q

Why do ethers not have a high bp?

A

bc they have no hydrogen bonding like alcohols

37
Q

Why are ethers often used as organic solvents?

A

Bc/ they are not very reactive and have low bp

38
Q

Williamson Ether synthesis

A
  • 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
39
Q

Alkoxymercuration demercuration

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

Ochem 2 (7 decks)

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