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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
Q

1, 2 cis diol

A

came from OsO4!

26
Q

Rules of E2

A

carbocation rearrangement possible
3, 2, benzylic allylic faster than primary
Zaitsev product

27
Q

SOCl2

A

converts alcohol to halide.

Sn2, inversion

28
Q

PBr3

A

Converts alcohol to halide. Sn2, inversion

29
Q

TsCl, pyr

A

converts alcohols to OTs. No inversion.

30
Q

TMSCl

A

Makes OTMS, protecting group. Remove with H2SO4

31
Q

KH

A

Makes OH into O-

32
Q

Primary alcohol from methyl halide

A

H20, heat

33
Q

Primary alcohol from epoxide

A
  1. MeMgBr

2. H30+

34
Q

Primary alcohol from ether

A

HI, H20

35
Q

PCC

A

mild ox. alcohol to aldehyde or ketone

Same result as swern, CrO3 without water!

36
Q

Jones

A

strong ox. chromic acid.
primary alcohol to carboxyl
secondary alcohol to ketone

37
Q

CrO3, H20

A

same as Jones, KMnO4

38
Q

secondary alcohols from secondary alkyl halides

A

h20, heat. or NaOH, DMF

39
Q

secondary alcohols from aldehyde

A
  1. MeMgBr 2. H30+
40
Q

secondary alcohols from alkenes

A
  1. Hg(OAc)2 2. NaBH4
41
Q

secondary alcohols to carbocations

A

H2SO4

42
Q

tertiary alcohol from ketone

A
  1. EtMgBr 2. H30 +
43
Q

tertiary alcohol from alkene on tertiary carbon

A
  1. Hg(OAc)2 2. NaBH4
44
Q

R-OH + Strong base

A

alkoxide formation! R-O-

Use for williamson ether synthesis

45
Q

Cleaving ethers

A

add HI or HBr. Sn2

makes more substituted alcohol, less subbed alkyl halide

46
Q

See: KH, DB alkyl halide

A

Claisen Rearrangement?

47
Q

Ether from 2o alkyl iodide

A

MeOH, Sn1

48
Q

Ether from 2o alkyl bromide

A

NaOMe, DMF Sn2

49
Q

Ether from 2o alcohol

A

KH, MeI

Williams

50
Q

Ether from alkene

A
  1. Hg(OAc)2, MeOH

2. NaBH4

51
Q

Ether to 2o Alcohol

A

HBr

52
Q

Epoxide from alkene

A

mCPBA

53
Q

epoxides from OH adjacent to X

A

NaOH, H20

54
Q

H2N-NH2, KOH, heat

A

Wolff Kishner!

converts ketone/aldehyde to alkane

55
Q

3 ways to reduce carbonyls to alkanes

A

Zn, HCl (Clemmenson reduction)
H2N-NH2, KOH heat (Wolff-Kishner)
H2, Pd/C (If R group is ARYL only!!!)

56
Q

See PPh3

A

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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