Orgo Exam 3

Front 1

What reaction does this picture show?

Back 1

SN2

Front 2

A group that is lost during nucleophilic substitution or elimination. Typically a halide. The less basic, the better

Back 2

Leaving group

Front 3

Rate of SN2 reaction

Back 3

Bimolecular, second order.

Rate = k[reactant][nucleophile]

Front 4

What happens during a SN2 reaction?

Back 4

Inversion of stereochemistry at site of backside attack, nucleophile attacks from opposite side of leaving group.

Front 5

What type of reactant works best in the SN2 reaction?

Back 5

Methyl and primary carbons, because of steric hindrence.

Front 6

Measure of a Lewis base to perform a substitution.

Back 6

Nucleophilicity

More basic = more nucleophilic for the same atom. The smaller the atom the better because of steric effects.

Front 7

What type of solvants are used in a SN2 reaction?

Back 7

Polar aprotic solvents: polar enough to dissolve the substrate and nucleophile but do not participate in hydrogen bonding with the nucleophile. Sometimes a salt. No H bonding in an aprotic solvant, but Hs can be present.

Front 8

What type of solvant is used in an SN1 reaction?

Back 8

Polar protic, something with an H

Front 9

What is created in an SN1 reaction?

Back 9

A racemic mixture, but more of the product with the opposite stereochemistry

Front 10

What reactant preserves stereochemistry?

Back 10

OTs

Front 11

What reactant inverts stereochemistry?

Back 11

SOCl

Front 12

What kind of reaction happens with a hydrogen halide and alcohol?

Back 12

Substitution

Front 13

What kind of reactants are used in an SN1 reaction?

Back 13

Tertiary and secondary carbons

Front 14

Why are sulfonates good surrogates for alkyl halides?

Back 14

Sulfonates don't need to protonate, OH is therefore a worse leaving group than sulfonic acid, making sulfonate have an advantage in substitution reactions.

Front 15

Is there rearrangement in E1 reactions?

Back 15

Yes

Front 16

Are there rearrangements in E2 reactions?

Back 16

No, no carbocation formed

Front 17

What happens in an E1 reaction?

Back 17

Alkenes are formed, sp2 hybridized carbons. Alkenes have shorter bond lengths than sp3 carbons. No stereoisomers. Works best with 2° and 3° carbons

Front 18

What solvents are used in an E1 reaction?

Back 18

Strong acids, heat

R-OH and H2SO4

Front 19

What is the nomenclature for an alkene with higher ranked groups on the same side?

Back 19

Z

Front 20

What is the nomenclature for an alkene with higher ranked groups on opposite sides?

Back 20

E

Front 21

What happens during an E2 reaction?

Back 21

Dehydrohalogenation of alkyl halides

An alkyl halide becomes an alkene

Front 22

What are the starting materials and solvants used in an E2 reaction?

Back 22

Alkyl halides carried out in a strong base. Works best with 2° and 3° carbons. Can work with 1° if (CH3)3OK is used.

Front 23

Why is regioselectivity and stereoselectivity important in E2 reactions?

Back 23

To react, axial halides and anti hydrogen's react faster, because of less steric hindrence. Products favor trans and more substituted.

Front 24

What is the rate of an E2 reaction?

Back 24

Second order

Rate = k[Alkylhalide][Base]

Front 25

What types of products are created in E1 and E2 reactions?

Back 25

Zaitev products

Front 26

What happens in a Markovnikov Addition reaction?

Back 26

A cation is formed in breaking the double bond of an alkene.

Front 27

In a Markovnikov reaction, where does the nucleophile attack?

Back 27

The more substituted carbon

Front 28

What is used to catalyze the hydration of alkenes?

Back 28

Strong acid, H2SO4

Front 29

What reactants and solvents are used in the electrophilic addition of HX to alkenes?

Back 29

A strong acid (HBr, HCl) and acetic acid

Front 30

What are the reactants and catalysts in ether synthesis?

Back 30

An alkene, HxCxOH, and H2SO4 as the catalyst.

Front 31

What solvents are used in oxymercuration and demercuration?

Back 31

Hg(OAc)2, THF-H2O

NaBH4, OH-

Front 32

What happens in an oxymercuration/demercuration reaction?

Back 32

A mercury cation intermediate is formed, and there is Markovnikov Addition of H and OH across a double bond.

Front 33

How are alkenes named?

Back 33

Front 34

Stability of alkenes

Back 34

Energy difference gets bigger between trans and cis the larger the group attached. Trans more stable.

For cycloalkenes: small and medium rings are more stable as cis, reduced steric strain

Front 35

What is the temperature of a dehydrohalogenation reaction?

Back 35

Very high

Front 36

"The most branched alkene will form"

Back 36

Zaitsev's Rule

Front 37

Has to do with which product is easier to make. Is related to either energetic pathway or stability of product. 'Preference' to product made.

Back 37

Stereoselection

Front 38

What is this reaction?

Back 38

E1: Dehydration of alcohols

Front 39

What reactions are these?

Back 39

E2: Dehydrohalogenation of alkyl halides

Front 40

What do stereoelectronic effects have to do with the E2 reaction?

Back 40

Axial halides and anti halogens react faster

Front 41

What reaction do 2° alkyl halides go through with a strong base?

Back 41

Elimination: E2

Front 42

1° alkyl halides only go through substitution unless:

Back 42

A bulky base, KOC(CH3)3, is used

Front 43

What type of reaction do 2° alkyl halides go through with weakly basic nucleophiles?

Back 43

Substitution, SN1

Front 44

What type of reactions do 3° alkyl halides go through with strong bases?

Back 44

E2

Front 45

What type of reactions do 3° alkyl halides go through in the absence of anionic nucleophiles?

Back 45

SN1/E1

Front 46

Rate of reaction for electrophilic addition of HX to alkenes

Back 46

Front 47

What mechanism is this?

Back 47

Electrophilic addition of HX to alkenes

Front 48

What kind of reaction is this?

Back 48

Acid catalyzed hydration of alkenes

Front 49

What mechanism is this?

Back 49

Acid catalyzed hydration of alkenes

Front 50

What reaction is this?

Back 50

Acid catalyzed ether synthesis from alkenes

Front 51

A system at equilibrium adjusts so as to minimize any stress applied to it

Back 51

Le Châtelier's

Front 52

What rection is this?

Back 52

Halogenation of alkenes to form vicinal dihalides. Stereospecific reaction, anti addition. Only works with bromine and chlorine

Front 53

What mechanism is this?

Back 53

Halogenation of alkenes to form vicinal dihalides

Front 54

What reaction is shown here?

Back 54

Halogenation of alkenes in the presence of water to make vicinal halohydrins with OH on the Markovnikov position

Front 55

What mechanism is shown?

Back 55

Halogenation of alkenes in the presence of water

Front 56

What products are made in the halogenation of alkenes reaction?

Back 56

Trans with the second group on the backside and the enantiomer.

Front 57

What reaction is shown here?

Back 57

Hydroboration oxidation

Front 58

What kind of reaction is hydroboration oxidation?

Back 58

Anti Markovnikov

Front 59

What reactants and solvents are used in a hydroboration oxidation reaction?

Back 59

An alkene, a strong base (OH-), H2O2, and a compound with B and H.

Front 60

Hydroboration oxidation mechanism

Back 60

Front 61

What is the stereospecific product in hydroboration oxidation?

Back 61

Syn

Front 62

What reactions are shown here?

Back 62

Hydrogenation of alkenes with the same substituent ( in this case H2)

Front 63

Based on starting materials, which product will be made

Back 63

Stereoselection

Front 64

What compound would have the highest heat of hydrogenation?

Back 64

The least stable

Front 65

What products are made in a hydrogenation reaction?

Back 65

The syn product and enantiomer if chirality centers are made

Front 66

What reaction is shown here?

Back 66

Preparation of vicinal diols by OsO4 dihydroxylation

Front 67

What reactions are shown here?

Back 67

Alkene epoxidation. Enantiomers are made

Front 68

What mechanism is this?

Back 68

Hydroboration

Front 69

What mechanism is this?

Back 69

Oxidation

Front 70

What reactant is needed in a hydrogenation reaction?

Back 70

A metal, Pt, Pd, Ni, or Rh

Front 71

What products are favored in an E2 reaction?

Back 71

Trans and more substituted

Front 72

What reactants and catalysts are used in the preparation of vicinal diols by OsO4 dihydroxylation?

Back 72

(CH3)3COOH, OsO4 (cat), tertbutanol, -OH

Front 73

Are intermediates formed in the SN2 and E2 reactions?

Back 73

No, no rearrangement possible. Called a concerted reaction

Front 74

What are the best nucleophiles?

Back 74

Iodides and sulfides. Sulfides the best because they are conjugate bases of strong acids.

Front 75

What way to retrosynthesis arrows face?

Back 75

Towards starting materials

Front 76

Memorize

Back 76

Front 77

What reagents are used in an ozonolysis of alkene reaction?

Back 77

Ozone (O3) and H20 or Me2S

Front 78

What happens when H2O is a reagents in the ozonolysis reaction?

Back 78

Oxidative conditions, carboxylic acid formed

Front 79

What reagents are used in the Simmons-Smith (or cyclopropanation) reaction?

Back 79

CH2I2 and ZnCu and diethyl ether

Front 80

What reaction is shown?

Back 80

Ozonolysis of alkenes

Front 81

What happens when zinc is a reagent in ozonolysis?

Back 81

The second step is reductive, an aldehyde and formaldehyde are made

Front 82

What reaction is shown?

Back 82

Simmons-Smith Reaction

Front 83

What products are made in a Simmons-Simon Reaction?

Back 83

Carbenoid, syn addition

Front 84

What are the properties of alkynes?

Back 84

Pretty acidic

Linear, short bond lengths

Low water solubility

Similar bpts to alkanes

Front 85

What happens to alkynes in the presence of water and amide ions?

Back 85

They can be protonated. This is useful in making long chains through the SN2 mechanism.

Front 86

What happens in reactions with alkynes and secondary or tertiary carbons?

Back 86

E2

Front 87

Mechanism of E2 using alkynes

Back 87

Front 88

What reaction is shown?

Back 88

Formation of alkynes via elimination

Front 89

What reagents are used in the formation of alkynes via elimination?

Back 89

NaNH2, NH3, H2O

Front 90

What reaction is shown below?

Back 90

Hydrogenation of alkynes

Front 91

What reagents create alkenes from alkynes during hydrogenation?

Back 91

H2 and Lindlar Pd

Front 92

What reaction is shown?

Back 92

Addition of hydrogen halides to alkynes. Reaction can occur again to make a alkane with geminal dihalides.

Front 93

What mechanism is shown?

Back 93

Addition of hydrogen halide to alkyne. Markovnikov reaction

Front 94

What reaction is shown here?

Back 94

Hydration of alkynes

Front 95

What products are created in the hydration of alkynes?

Back 95

Ketones

Front 96

What reagents are used in the hydration of alkynes when ketones are formed?

Back 96

Water, acid, and mercury

Front 97

What reaction is shown?

Back 97

Addition of dihalogen to alkynes. Markovnikov reaction

Front 98

What reaction is shown here?

Back 98

Ozonolysis of alkynes. Ketones also made during demercuration.

Front 99

Back 99

Memorize

Front 100

Stability of alkyl radicals

Back 100

Front 101

How are radicals formed?

Back 101

Homolytic cleavage (homolysis)

Front 102

What mechanism is this?

Back 102

Methane chlorination

Front 103

What mechanism is shown?

Back 103

Halogenation of higher alkanes

Front 104

What happens in a free radical HX addition to alkenes and alkynes with and without peroxides?

Back 104

No peroxides, X adds in the Markovnikov position. With peroxides, X adds to anti Markovnikov position

Front 105

Mechanism of free radical addition of HX to alkenes and alkynes with peroxides

Back 105

Front 106

What product is made when an alkyne reacts with HX in free radical addition?

Back 106

Front 107

What reagents are used to hydrogenate alkynes using free radicals?

Back 107

Na, NH3. Metal ammonia reduction

Front 108

Mechanism for Na-ammonia reduction

Back 108

Front 109

What reaction is shown here?

Back 109

SN1 of allylic halides

Front 110

What mechanism is this?

Back 110

SN1 of allylic halides

Front 111

What reaction is shown here?

Back 111

SN2 of allylic halides

Front 112

What reagents are used in an SN1 of allylic halides reaction?

Back 112

H2O and Na2CO3, or alcohol for ether synthesis

Front 113

What reaction is shown here?

Back 113

Allylic free radical halogenation

Front 114

What mechanism is shown here?

Back 114

Allylic free radical halogenation mechanism

Front 115

What is the stability of dienes?

Back 115

Conjugated > isolated > cumulated

Front 116

How are sigma bonds affected my pi bonds?

Back 116

They become shorter

Front 117

What reaction is shown here?

Back 117

Addition of HX to conjugated dienes. If cold temps, no rearrangements occur

Front 118

What reaction is shown?

Back 118

Halogen addition to conjugated dienes. Leads to mixture but 1,4 dominating

Front 119

What reaction is shown?

Back 119

The Diels-Alder reaction

Front 120

How is the Diels-Alder reaction both stereospecific and stereoselecive?

Back 120

If a trans groups on the dienophile, groups off cyclohexane have opposite stereochemistry. If cis groups on the dienophile, same stereochemistry and Endo preferred.

Front 121

What reaction is shown here?

Back 121

Intramolecular Diels-Alder reaction

Front 122

The Cope and Claisen Rearrangement

Back 122