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CH341—Organic Chemistry I > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

explain what is necessary for hydrogenation of alkenes/alkynes

A

H2
a catalyst
solvent
heat
pressure

2 equiv. if taking alkyne to alkane

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2
Q

hydrogenation is (reduction/oxidation)

A

reduction

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3
Q

heterogenous hydrogenation catalysts

A

Pd, Pt, Ni

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4
Q

Wilkinson’s catalyst:
- formula
- type of catalyst

A

Rh(PPH3)3Cl
homogeneous hydrogenation catalyst

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5
Q

homogeneous hydrogenation catalyst

A

Wilkinson’s

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6
Q

hydrogenation with a metal catalyst is (anti/syn)

A

syn

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7
Q

How to accomplish cis partial hydrogenation of alkyne?

A

Lindlar’s catalyst
P-2 catalyst

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8
Q

Lindlar’s catalyst:
- formula
- use

A

Pd/CaCO3 + quinoline
used to hydrogenate alkyne to cis alkene

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9
Q

P-2 catalyst:
- formula
- use

A

Ni2B
used to hydrogenate alkyne to cis alkene

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10
Q

How to accomplish trans partial hydrogenation of alkyne?

A

metal ammonia —Li, Na, or K + NH3 or RNH2

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11
Q

what is dissolving metal reduction?

A

partial hydrogenation of alkyne to give trans alkene

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12
Q

temp needed for dissolving metal reduction

A

cold

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13
Q

hydrogenation using radical mechanism

A

dissolving metal reduction; metal has one electron; attacks twice

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14
Q

sodium borohydride reduction —solvents

A

water
alcohol
ethers

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15
Q

LAH reduction —solvents you cannot use

A

water
alcohols
(reacts explosively)

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16
Q

carbene structure

A
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17
Q

carbene acts as (Nu/El)

A

either one!

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18
Q

3 methods of carbene addition

A

1) diazomethane
2) SImmons-Smith
3) Alpha elimination

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19
Q

Diazomethane reagent

A
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20
Q

diazomethane conditions required

A

heat or light

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21
Q

problems with diazomethane

A

very explosive & toxic
carbene can also insert into C-H bonds

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22
Q

Simmons-Smith reagent

A

ICH2ZnI

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23
Q

“figure 8” transition state

A

Simmons-Smith

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24
Q

Alpha elimination reagent

A

haloform (CHX3)
OH-

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25
Q

gives cyclopropane with 2 halogens

A

alpha elimination carbene addition

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26
Q

carbene adds to ___ bond

A

double

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27
Q

byproduct of diazomethane reaction

A

N2

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28
Q

explain syn 1,2-dihydroxylation

A

addition of 2 OH across C=C bond to give diol

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29
Q

2 methods of syn 1,2-dihydroxylation

A

1) KMnO4 + OH- + H2O + cold
2) OsO4 + pyridine; NaHSO3 + H2O

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30
Q

KMnO4 in COLD

A

syn 1,2-dihydroxylation

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31
Q

KMnO4 in HEAT

A

oxidative cleavage of alkenes

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32
Q

syn 1,2-dihydroxylation TS & relationship to stereochem of product

A

5-membered ring structure - must be cis - therefore product is trans

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33
Q

problems with KMnO4 method of syn 1,2-dihydroxylation

A

lower yield
byproducts due to overoxidation in any heat

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34
Q

problems with OsO4 method of syn 1,2-dihydroxylation

A

extremely toxic, but yield is higher

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35
Q

in the syn 1,2-dihydroxylation reaction, a trans alkene gives _________; a cis alkene gives _________

A

trans: 2 enantiomers
cis: meso

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36
Q

2 methods of oxidative cleavage of alkenes

A

1) KMnO4 + OH- + heat
2) ozonolysis

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37
Q

different types of alkenes & products with KMnO4 oxidative cleavage

A

unsubstituted: gives carbonyl product + CO2

monosubstituted: gives carboxylic acid (when tx with H3O+)

disubstituted: gives ketone

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38
Q

different types of alkenes & products with ozonolysis

A

unsubstituted: gives formaldehyde

monosubstituted: gives aldehyde

disubstituted: gives ketone

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39
Q

more useful reagent for oxidative alkene cleavage

A

ozone

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40
Q

name of ozonolysis mechanism

A

1,3-dipolar cycloaddition

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41
Q

ozonolysis conditions

A

anhydrous

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42
Q

difference between KMnO4 and ozonolysis in oxidative cleavage of alkynes

A

there is none!

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43
Q

internal alkyne gives 2 ___________ upon oxidative cleavage

A

carboxylic acids

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44
Q

alkyne + KMnO4 + heat + neutral conditions –>

A

diketone

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45
Q

diketone formation TS

A

tetrahydroxy

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46
Q

reagents used to turn alkene into an alkyne

A

X2
2 mol NaNH2

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47
Q

double dehydrohalogenation involved in…

A

synthesis of alkyne from alkene by elimination

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48
Q

steps in synthesis of alkyne from alkene

A

alkene + X2 –> vicinal dihalide
+ 2 mol NaNH2 –> alkyne + 2 NH3 + 2 NaX

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49
Q

steps in synthesis of acetylene

A

geminal dihalide + 3 mol NaNH2 –> acetylide ion
+ acid –> acetylene

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50
Q

used to deprotonate acetylene

A

NaNH2

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51
Q

3 methods of polymerization

A

1) cationic
2) radical
3) anionic (rare)

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52
Q

3 steps for any method of polymerization

A

1) chain initiation
2) chain propagation
3) chain termination

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53
Q

explain cationic polymerization

A

acid (lewis or bronsted) + alkene –> C+

another alkene attacks C+

chain continues

conjugate base takes H+ from C+ and alkene forms at end of chain

54
Q

explain radical polymerization

A

radical initiator: peroxide ROOR + heat/light –> 2RO-, homolytic cleavage

pi bond attacks radical, giving stabilized radical on C

Next pi bond attacks this radical and so on

chain terminates as an RO- attacks the C radical; RO ends up on both ends of chain

55
Q

explain anionic polymerization

A

ester/nitrile (e- withdrawing group)

base catalyzed

anion attacks another substrate to give chain

56
Q

super glue is an example of which kind of polymerization

A

anionic

57
Q

“metathesis”

A

“change positions”

58
Q

explain olefin metathesis

A

2 alkenes are cleaved and recombined

59
Q

metathesis catalysts

A

Schrock & Grubbs

60
Q

3 types of metathesis

A

1) cross metathesis
2) ring-closing metathesis
3) ring-opening metathesis

61
Q

type of metathesis involved in polymerization

A

ring opening method

62
Q

glycol

A

1,2-diol

63
Q

how to form a Grignard?

A

RX + Mg in ether –> R-Mg-X

64
Q

Grignard structure

A

RMgX

65
Q

Grignard acts as a (C+/C-)

A

carbanion (Nu)

66
Q

explain Grignard reaction

A

Grignard attacks backside of carbonyl

R of Grignard adds to carbon, giving (-) O

acid protonates O to give OH

67
Q

Grignard rxn with acid chlorides and esters

A

2 equiv Grignard required

R adds twice

68
Q

synthesis rxn for organolithiums

A

RX + 2 Li in Et2O, hexane, etc –> RLi

69
Q

structure of organolithium

A

RLi

70
Q

organolithium acts as (C+/C-)

A

carbanion

71
Q

explain organolithium rxn

A

RLi attacks carbonyl

R attaches to carbon and carbonyl –> alcohol

72
Q

explan organolithium rxn with acid chloride and ester

A

reacts twice just like Grignard

73
Q

long name for Gilman reagent

A

Lithium dialkylcuprate

74
Q

formation of Gilman rxn

A

R RLi + CuI –> R-CuLi-R

75
Q

how is Gilman written

A

(R)2CuI

76
Q

how to get from alkyl halide to Gilman reagent?

A

1) 2 Li
2) CuI

77
Q

Gilman rxn with acid chlorides

A

R replaces X on starting material, giving Ketone, not alcohol

78
Q

Gilman rxn with ester

A

none bitch!

79
Q

Gilman reagents can undergo ____ reactions with alkyl halides

A

SN2

80
Q

2 reagents for reduction of carbonyl & strength/use

A

NaBH4 – weak – ketones, aldehydes, acid chlorides

LAH – strong – ketones, aldehydes, acid chlorides, esters, carboxylic acids

81
Q

explain hydride reduction of carbonyl

A

hydride attacks carbonyl

carbonyl becomes alcohol

if there is an acid chloride or an ester, that bitch gets kicked off and an alcohol is made (with LAH)

82
Q

what is special about raney ni

A

reduces carbonyls, alkenes and alkynes in SM

83
Q

6 methods of alcohol oxidation –> carbonyl

A

1) NaOCl + HOAc
2) NaOCl + TEMPO
3) Chromic acid (Jones reagent)
4) Pyridinium chlorochromate (PCC)
5) Swern oxidation
6) Dess-Martin Periodinate (DMP)

84
Q

alcohol that cannot be oxidized

A

tertiary!!! bitch

85
Q

TEMPO structure

A
86
Q

what does TEMPO do to bleach

A

makes it a milk

87
Q

VERY strong oxidizer of alcohols

A

Jones reagent (chromic acid)

88
Q

2 ways to write Jones reagent (plus other condition in the stuff)

A

CrO3 + H2SO4

Na2Cr2O7 + H2SO4

89
Q

3 methods of oxidizing alcohols that do the same damn thing

A

PCC
Swern
DMP

90
Q

components of Swern reagent

A
  1. DMSO + (COCl)2 + -60°C
  2. Et3N
91
Q

why is Swern better than PCC

A

less toxic for the environment and doesnt cause fucking CANCER like PCC does

92
Q

DMP reagent structure

A

yeah memorize that. Bitch.

93
Q

2° alcohol –> ketone oxidizing methods

A

6, all of them do this

94
Q

1° alcohol –> aldehyde oxidizing methods

A

NaOCl + TEMPO
Swern
DMP
PCC

95
Q

1° alcohol –> carboxylic acid oxidizing methods

A

NaOCl excess
Jones reagent

96
Q

3 methods to convert alcohol to alkyl halide

A

1) HX method
2) PBr3 method
3) SOCl2 method

97
Q

method to turn any ° alcohol into an alkyl halide

A

HX

98
Q

can only turn 1° or 2 ° alcohol into alkyl halide

A

PBr3 or SOCl2

99
Q

explain HX conversion of alcohol to alkyl halide

A

ROH + HX –> RX

100
Q

if converting alcohol to alkyl chloride, use ______ reagent

A

ZnCl2

101
Q

explain PBr3 rxn with alcohol

A

ROH + PBr3 –> RBr

inversion of stereochemistry!!

101
Q

explain PBr3 rxn with alcohol

A

ROH + PBr3 –> RX

inversion of stereochemistry!!

102
Q

explain SOCl2 rxn with alcohol

A

ROH + SOCl2 + pyridine –> RCl

inversion of stereochemistry IF you use pyridine!

103
Q

formation of sulfonate ester rxn

A

ROH + TsCl + pyridine –> ROTs

104
Q

alternatives to tosyl chloride

A

MsCl
TfCl

105
Q

why is sulfonate ester reaction really useful

A

converts OH to OTs, and that’s a bitchin’ leaving group!

substitution or elimination y’all! it’s seriously cool

106
Q

sulfonate ester rxn with NaOH gives…

A

an alcohol with a flipped stereochemistry (because SN2 backside attack)

107
Q

sulfonate ester rxn with NaBr gives…

A

alkyl halide

108
Q

sulfonate ester rxn with LAH gives…

A

alkane (basically taking off the alcohol altogther)

109
Q

sulfonate ester rxn with NaOCH3 gives…

A

ether

110
Q

what do you need for Williamson ether synth?

A

a 1° alkyl halide
an alcohol that’s been deprotonated

111
Q

steps to williamson ether synth

A

1) deprotonate alcohol with strong base (NaOH, NaH)

2) add 1° alkyl halide

boom! you have an ether

112
Q

how. tomake cyclic ethers???

A

intermolecular rxn with williamson ether synthesis —- alcohol on one end of a chain, alkyl halide on the other, they come together and smooch O

113
Q

reagent used for cleavage of ethers

A

HX, excess

114
Q

explain HX cleavage. ofethers

A

the ether is chopped in half at the oxygen. Where the oxygen was on each piece, there is now X

115
Q

HX cleavage of ether mechanism

A

ether O attacks H on HX

X- attacks less sub. C+; alcohol leaves, giving product #1

alcohol attacks H on HX again

protonated alcohol leaves; X- attacks C+, giving product #2

116
Q

2 methods to form epoxides

A

1) mCPBA (peroxyacid)

2) halohydrin + base

117
Q

when forming an epoxide it replaces a(n)…

A

alkene

118
Q

cis alkene + mCPBA –>

A

cis epoxide

119
Q

trans alkene + mCPBA –>

A

trans epoxide

120
Q

if we have 2 alkenes in a SM, and we use 1 equiv. mPBCA……

A

epoxide forms on the most sub. alkene

121
Q

reagents used in halohydrin method of epoxide formation

A
  1. Br2 + H2O
  2. NaOH + H2O
122
Q

steps in halohydrin/base formation of epoxide

A

1) halohydrin forms across alkene
2) base deprotonates OH, and O- attacks adjacent C (on itself!!), kicking off the Br and giving epoxide

123
Q

epoxide rxns are the addition of a (Nu/El)

A

nucleophile

124
Q

2 types of epoxide ring opening

A

acid-catalyzed

base-catalyzed

125
Q

how to get trans diol from epoxide

A

cis epoxide + H3O+ –> trans diol (enantiomers)

126
Q

difference between acid/base catalyzed ring opening of epoxides

A

acid: addition on the most sub. C

base: addition on the least sub C

127
Q

how to add carbons, or H, to epoxide rings?

A

carbons – use Grignard
hydrogens – use LAH

128
Q

pinacol

A

1,2-diol/glycol

129
Q

reagent used in pinoacol–>pinacolone rxn

A

H2SO4 in water

130
Q

pinacol –> pinacolone rxn

A

one OH attacks hydrogen on sulfuric acid

protonated alcohol leaves

methyl shift on C+; other OH makes double bond to C

OH is deprotonaed by water, giving ketone

CH341—Organic Chemistry I (9 decks)

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