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Organic Chemistry 2 > Ch 12. Alcohol (ROH) reactions > Flashcards

Ch 12. Alcohol (ROH) reactions Flashcards

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1
Q

What is the suffix for an alcohol when it is the priority functional group?

A

-ol

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2
Q

What is the name when an alcohol is substituent of a molecule?

A

hydroxyl-

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3
Q

A higher pKa value indicates…

A

lower acidity

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4
Q

pKa of alcohol (roughly)

A

~15

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5
Q

How does an alcohol behave frequently in a reaction?

A

As a Nucleophile, because of the two lone pairs on the oxygen.

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6
Q
A

When doing these sorts of reaction, you want to use a really strong base, like NaH, because using the weaker NaOH will result in a molecule with a similar pKa, and you want to favor the formation of a weak acid.

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7
Q

What are the qualities of a Sn2 reaction?

A

-Good Leaving Group
-Less Hindered carbon
-Concerted mechanism because the carbon is accessible

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8
Q

What are the qualities of an Sn1 reaction?

A

-Good Leaving group
-A hindered carbon does not allow for a concerted mechanism
- Goes through carbocation intermediate

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9
Q

What kind of reaction is this? And what are the products?

A
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10
Q

What kind of reaction is this? And what are the products?

A
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11
Q

What do you use for an Addition reaction?

A

Since it is a hydration reaction on an alkene, use a dilute acid.
H3O+

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12
Q

Are rearrangements possible in Addition reactions, and if so, what kind?

A

Carbocation rearrangements are possible
(3>2>1)

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13
Q

What reagents do you use for an oxymercuration-demercuration reaction?

A

This is an alkene reaction
1. Hg(OAc)2, H2O
2. NaBH4

The second step gets rid of the mercury

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14
Q

What are the pros and cons of oxymercuration-demercuration?

A

Pros:
-Does not go through carbocation
-No rearrangements

Cons:
-Dangerous!

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15
Q

What kind of reactions are oxymercuration-demercuration and addition?

A

Markovnikov reactions

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16
Q

Review: What are Markovnikov reactions?

A

When a protic acid (HX) adds onto an alkene,
-The hydrogen attaches to the carbon with more hydrogens
-The halide attaches itself to the carbon atom with more carbons

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17
Q

What reagents are needed for a Hydroboration-oxidation reaction?

A

An alkene is needed

  1. BH3, THF
  2. H2O2, NaOH
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18
Q

What kind of reaction is Hydroboration-oxidation?

A

Anti-Markovnikov

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19
Q

Review: What is an Anti-Markovnikov reaction?

A

describes the regiochemistry where the substituent is bonded to a less substituted carbon, rather than the more substituted carbon

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20
Q

What does “syn” mean in chemistry?

A

On the same face, with the same stereochemistry (2 wedges or 2 dashed)

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21
Q

What product would result from an alkene being reacted with Potassium Permanganate (KMnO4) (cold, dilute)

A

A syn 1,2-diol + enantiomer

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22
Q

What product would result from an alkene being reacted with OsO4 and H2SO4?

A

A syn 1,2-diol +enantiomer

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23
Q

What product would result from an alkene reaching with
1)RCO3H
2) H3O+

A

An anti 1,2-diol + enantiomer

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24
Q

What type of molecule is used to make an organometallic?

A

A transition metal such as Lithium or Magnesium

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24
Q

What is an anti-diol?

A

An anti-diol is an alcohol with it’s two OH groups having different stereochemistry (1 wedge, one dash) and it’s enantiomer

24
Q

What are the steps of making an tertiary alcohol from a terminal alkyne?

A
  1. NaNH2 (to make an Acetylide)
  2. Acetone
  3. H3O+
25
Q

How do you make Organomagnesium?
(R-Mg-X)

A

Start with an alkyl halide (Br, Cl, I) and react it with the transition metal of choice with ether.

26
Q

Are organometallics true ionic molecules?

A

No. They are carbon nucleophiles that generate a delta(-)

26
Q

How do you make organolithium?
(R-Li)

A

Start with an alkyl halide (Br, Cl, I), react it with two moles of Lithium (divalent) with hexanes

two moles are used because one is to make the carbon lithium bond, and one is to balance out the anion

27
Q

Why are hexanes/ethers used in organometallic synthesis?

A

So absolutely no water gets in the reaction! The RM can behave as a strong base, which can turn into an alkane if exposed to water (dead end).

28
Q

What reagents can be used to make an ether from a Carbonyl?

A
  1. CH3MgBr (to make an alkoxide)
  2. Ethyl bromide (makes the ether)
29
Q

What molecule is this?

A

An Alkoxide

30
Q

What do reduction reactions do?

A

Make C-H bonds or remove C-O bonds

31
Q

What are two reagents that can be used to reduce a carbonyl?

A
  1. Sodium borohydride (NaBH4)
  2. Lithium aluminum hydride (LiAlH4/LAH)
32
Q

How do you use NaBH4 in a reaction?(alcohol synthesis)

A
  1. NaBH4 in an ether solution
  2. ROH, H2O, H3O+
33
Q

Aldehyde (R=O-H) + reduction reaction (NaBH4 or LAH) = ?

A

Primary ROH

34
Q

Ketone (R=O=R) + reduction reaction (NaBH4 or LAH) = ?

A

Secondary ROH

35
Q

ROCl or ROOR’ + 1. xs LAH 2. H3O+ =?

A

Primary Alcohol

36
Q

Carboxylic acid COOH + 1. xs LAH 2. H3O+ =?

A

Primary Alcohol

37
Q

What do oxidation reactions do?

A

Make C-O bonds

38
Q

In a STRONG oxidation reaction, what do Primary ROHs turn into?

A

A carboxylic acid (COOH)

39
Q

In a STRONG oxidation reaction, what do Secondary ROHs turn into?

A

A ketone (R2O)

40
Q

Name three STRONG oxidizers for ROH reactions

A
  1. Chromic acid reagent
  2. Potassium Permanganate (KMnO4)
  3. Bleach (NaOCl aq)
41
Q

How do you make chromic acid

A

CrO3 + H2SO4 (aq) –> H2CrO4

42
Q

In a STRONG oxidation reaction, what do Tertiary ROHs turn into?

A

Nothing! They are inert

43
Q

In a WEAK oxidation reaction, what do Tertiary ROHs turn into?

A

Nothing! they are inert

44
Q

In a WEAK oxidation reaction, what do Secondary ROHs turn into?

A

A ketone (R2CO)

45
Q

In a WEAK oxidation reaction, what do Primary ROHs turn into?

A

An Aldehyde (RCHO)

46
Q

What are the reagents for WEAK Oxidation reactions?

A
  1. PCC (Pyridinium chromate)
  2. Swern Oxidation: DMSO (COCl2), NEt3
  3. Dess Martin Periodinane (DMP)
47
Q

What will result in a reaction with ROH (weak nucleophile) and Na(metal)/ K (metal)/ NaH

A

An alkoxide (RO-)

48
Q

What reagents are needed for Williamson Ether Synthesis?

A

ROH + 1. Base 2. Unhindered R-X =
Ether (R-O-R)

49
Q

What do we use to make the OH in an alcohol into a good leaving group?

A

Tosylates (TsCl) (Tosylchlorides)

50
Q

What can we use on a TERTIARY ROH as an alternative to tosylates?

A

Lucas Reagent (HCl, ZnCl2)

51
Q

How can you turn a Primary/Secondary ROH to a Primary/Secondary RX

A
  • Phosphorus trihalide- PX3
  • Thionyl Chloride (SOCl2) (makes only Cl RX)
52
Q

How does Phosphorus trihalide (PX3) affect the stereochemistry of the OH group it reacts with?

A

Inversion of stereochemistry (Sn2 like)

53
Q

How does thionyl chloride affect the stereochemistry of the primary/secondary RCl it creates with an ETHER SOLVENT?

A

It retains it’s original stereochemistry
(intramolecular, ,creates a solvent sphere)

54
Q

How does thionyl chloride affect the stereochemistry of the primary/secondary RCl it creates with an PYRIDINE SOLVENT?

A

It inverts it’s original stereochemistry
(outside Cl adds on, no solvent sphere)

55
Q

How do you get an alkene from an ROH?

A

Elimination reaction

56
Q

What is a simple, one step way to get an alkene from an ROH?

A

ROH + strong acid (H2SO4, H3PO4)
(E1 mechanism)

57
Q

Fill in the blanks:

ROH+ 1.________ = R-OTs + 2. _______ = alkene

A
  1. TsCl, pyridine
  2. Base, heat
58
Q

What is Zaitsev’s rule?

A

The more substituted the alkene is, the more stable it is.

59
Q

What is the rate determining step in a reaction?

A

the formation of the carbocation

Organic Chemistry 2 (14 decks)

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