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O Chem 2 > Exam Unit 2 > Flashcards

Exam Unit 2 Flashcards

1
Q

NaBH4, workup

A

Aldehydes and ketones only. One reduction, except with ab unsaturated. Oxygen and “skip one” get protonated by acid component.

Will still deprotonate esters and carboxyls.

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2
Q

LiAlH4, workup

A

reduces all carbonyls. two reductions on esters and carboxyls.

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3
Q

Grignard formation

A

Add Mg, Et2OH to alkyl halide.

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4
Q

Grignards and Carbonyls, excess

A

adds once to C, once to O

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5
Q

grignards and carbonyls, H3O+ present

A

NR to carbonyl. Grignard loses MgX and is protonated.

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6
Q

POCl3, pyr

A

Dehydrates primary alcohols. E2

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7
Q

Acidity: Normal Alcohol

A

pKa 16

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8
Q

Acidity: Phenol

A

pKa10

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9
Q

Acidity: Carboxylic

A

pKa 5

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10
Q

Acidity

A

proportional to stability of conjugate base

More resonance, more acidity

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11
Q

Acidity: with EWG

A

activated rings are less acidic

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12
Q

Hydroboration

A
  1. BH3/THF 2. H2O2, NaOH aq.

Adds H and OH across DB, syn, non-Markovnikov

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13
Q

Oxymercuration

A

Hg(OAc)2, H2O

Adds H and OH across DB, anti, markovnikov.

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14
Q

Reduce ketones, aldehydes

A

NaBH4, H3O+ workup.

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15
Q

Reduce ketones, aldehydes, esters or amines

A

LiAlH4, H30+ work-up.

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16
Q

Grignard

A

RX+Mg gives RMGX

makes carbanion nucleophile. But incompatible with acidic protons, (pKa < 20) electrophiles.

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17
Q

Acidic Protons

A

OH, SH, NH, et cetera.

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18
Q

alpha, beta unsaturated carbonyl

A

DB adjacent to carbonyl.

With LiAlHa, only carbonyl is reduced. (Coordinates to O)
With NaBH4, single and double reductions.

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19
Q

peroxyacids

A

alkene attaches terminal oxygen, forms cyclic ether. (same stereochem as start.)

very electrophilic sources of O. mCPBA is our favorite.

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20
Q

mCPBA preferences

A

round 1: EDG > regular > EWG

round 2: if regular: constituents! the more, the merrier.

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21
Q

from epoxide: in acid

A

nucleophile chooses less hindered carbon, UNLESS TERTIARY!

sn2, except tertiary, then sn1

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22
Q

from epoxide, in base

A

nucleophile chooses less hindered carbon.

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23
Q

Williamson Ether Synthesis

A

adds R chain to OH in place of H.

NaH, RX

sn2: needs primary or secondary alcohol.

24
Q

1, 2 trans diol

A

came from an epoxide!

25
1, 2 cis diol
came from OsO4!
26
Rules of E2
carbocation rearrangement possible 3, 2, benzylic allylic faster than primary Zaitsev product
27
SOCl2
converts alcohol to halide. | Sn2, inversion
28
PBr3
Converts alcohol to halide. Sn2, inversion
29
TsCl, pyr
converts alcohols to OTs. No inversion.
30
TMSCl
Makes OTMS, protecting group. Remove with H2SO4
31
KH
Makes OH into O-
32
Primary alcohol from methyl halide
H20, heat
33
Primary alcohol from epoxide
1. MeMgBr | 2. H30+
34
Primary alcohol from ether
HI, H20
35
PCC
mild ox. alcohol to aldehyde or ketone Same result as swern, CrO3 without water!
36
Jones
strong ox. chromic acid. primary alcohol to carboxyl secondary alcohol to ketone
37
CrO3, H20
same as Jones, KMnO4
38
secondary alcohols from secondary alkyl halides
h20, heat. or NaOH, DMF
39
secondary alcohols from aldehyde
1. MeMgBr 2. H30+
40
secondary alcohols from alkenes
1. Hg(OAc)2 2. NaBH4
41
secondary alcohols to carbocations
H2SO4
42
tertiary alcohol from ketone
1. EtMgBr 2. H30 +
43
tertiary alcohol from alkene on tertiary carbon
1. Hg(OAc)2 2. NaBH4
44
R-OH + Strong base
alkoxide formation! R-O- Use for williamson ether synthesis
45
Cleaving ethers
add HI or HBr. Sn2 makes more substituted alcohol, less subbed alkyl halide
46
See: KH, DB alkyl halide
Claisen Rearrangement?
47
Ether from 2o alkyl iodide
MeOH, Sn1
48
Ether from 2o alkyl bromide
NaOMe, DMF Sn2
49
Ether from 2o alcohol
KH, MeI Williams
50
Ether from alkene
1. Hg(OAc)2, MeOH | 2. NaBH4
51
Ether to 2o Alcohol
HBr
52
Epoxide from alkene
mCPBA
53
epoxides from OH adjacent to X
NaOH, H20
54
H2N-NH2, KOH, heat
Wolff Kishner! converts ketone/aldehyde to alkane
55
3 ways to reduce carbonyls to alkanes
Zn, HCl (Clemmenson reduction) H2N-NH2, KOH heat (Wolff-Kishner) H2, Pd/C (If R group is ARYL only!!!)
56
See PPh3
Wittig! turns carbonyl into DB with R groups. | cis selective if R isn't stabilized by EWG (carbonyl)

O Chem 2 (5 decks)

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