Class Three

Question 1

is there a net change in the number of pi or sigma bonds in nucleophilic sub.

Answer 1

no. one sigma bond is broken & another is formed

Question 2

SN2 reaction

Answer 2

bond forming and bond breaking occurs simultaneously

involves two molecules

Question 3

product of an SN2 reaction

Answer 3

inverted product (at the carbon being attacked by the nucleophile)

Question 4

what type of attack occurs in SN2

Answer 4

backside attack

Question 5

SN2 rate of reaction

Answer 5

bimolecular - depends on the concentrations of the nucleophile & electrophile

Question 6

bulkiness - SN2

Answer 6

less substituted substrates react faster than more substituted ones in SN2

Question 7

why are protic solvents avoided for SN2

Answer 7

hydrogen bonding solvents → strongly solvate the nucleophile & hinders backside attack

Question 8

what happens in an SN1 reaction

Answer 8

a carbocation forms

Question 9

order of carbocation stability

Answer 9

tertiary carbocations are more stable than primary ones

Question 10

SN1 reactions occur in..

Answer 10

2 steps

Question 11

steps of SN1 reactions

Answer 11

leaving groups dissociates

racemization occurs: nucleophile attacks equally on either side of the carbocation

Question 12

rate limiting step - SN1

Answer 12

leaving group dissociating

Question 13

SN1 reaction

Answer 13

unimolecular - only depend on electrophile concentration

Question 14

how to speed up an SN1 reaction

Answer 14

more substituted carbocation = more stable intermediate = speed up

Question 15

why are protic solvents used for SN1

Answer 15

protic solvents = alcohol or water

stabilizes the forming carbocation & acts like the nucleophile in a solvolysis reaction

Question 16

water as solvent SN1

Answer 16

produces an alchohol product

Question 17

alcoholic solvent SN1

Answer 17

produces an ether product

Question 18

oxidation of an alcohol =

Answer 18

formation of a carbonyl

Question 19

what is a carbonyl

Answer 19

carbon double bonded to oxygen

Question 20

primary alcohols are oxidized to..

Answer 20

aldehydes

Question 21

secondary alcohols are oxidized to..

Answer 21

ketones

Question 22

tertiary alcohols are oxidized into..

Answer 22

no reaction

Question 23

why are the alpha protons acidic

Answer 23

the electrons left behind upon deprotonation can delocalize into the pi system

Question 24

enolate ions are..

Answer 24

negatively charged and nucleophilic

Question 25

when is a proton acidic

Answer 25

when it has a very high positive charge

Question 26

what is an enol

Answer 26

alkene + alcohol

Question 27

how is a ketone converted to an enol

Answer 27

deprotonation of an alpha-carbon and of the carboxyl oxygen

Question 28

what are tautomers

Answer 28

two molecules - interconvertible constitutional isomers in equilibrium

Question 29

characteristics of a strong reducing agent

Answer 29

easily loses electrons have lots of hydrogens attached to other elements with low electronegativity

Question 30

Grignard reagent

Answer 30

alkyl halide + magnesium

Question 31

carbonyl + Grignard reagent →

Answer 31

alcohol

Question 32

how to protect alcohols

Answer 32

transform them into mesylates & tosylates

Question 33

in SN1 reactions, ___ alcohols are favoured

Answer 33

tertiary

Question 34

in SN2 reactions, ___ alcohols are favoured

Answer 34

primary

Question 35

why do alcohols get protected

Answer 35

to prevent them as acting as an acid or nucleophile

Question 36

what is a mesyl

Answer 36

CH₃=SO₃^- protection of alcohol

Question 37

what is a tosyl

Answer 37

CH₃C₆H₄-SO₃^- protection of alcohol

Question 38

why is a base required when protecting alcohols

Answer 38

neutralizes the HCl and pull it out of solution as a salt

Question 39

mesylate and tosylate are ___ leaving groups

Answer 39

good hydroxyl is bad and can be converted into these

Question 40

difference between acetals and hemiacetals

Answer 40

acetals have 2 OR groups and hemiacetals have an OR and a OH group

Question 41

when do acetals form

Answer 41

when aldehydes/ketones react with alcohol in the presence of acid

Question 42

how to turn hemiacetal → acetal

Answer 42

remove a molecule of water

Question 43

how is a cyanohydrin formed

Answer 43

aldehydes/ketones reacting with HCN → cyanohydrin

Question 44

amine general structure

Answer 44

R-NH₂

Question 45

alkyl vs aryl amines

Answer 45

alkyl: N is bonded to an sp³ hybridized carbon aryl: N is bonded to an sp² hybridized carbon of an aromatic ring

Question 46

primary/sec/tert/quart amines

Answer 46

of R groups on the N

Question 47

molecular geometry of an alkyl amine is..

Answer 47

pyramidal

Question 48

amines behave as..

Answer 48

BL bases or nucleophiles (bc of the lone pair of electrons)

Question 49

a weak base is..

Answer 49

a good leaving group

Question 50

keto and enol tautomers are _____ isomers

Answer 50

structural

Question 51

which is more stable - keto or enol

Answer 51

keto

Question 52

how to make a reaction with a weak nucleophile

Answer 52

by making the electrophile more electron deficient (add acid)

Question 53

what is a hydride reaction

Answer 53

either fewer bonds to O or more bonds to H

Question 54

Grignard reagents are ___ nucleophiles

Answer 54

strong

Question 55

what is a common trait of hemiacetals and acetals

Answer 55

one carbon bonded to two Os

Question 56

how many alcohols needed to make an acetal

Answer 56

2

Question 57

can you reverse from an acetal to the original ketone/aldehyde

Answer 57

yes

Question 58

alcohol + aldehyde/ketone =

Answer 58

acetal

Question 59

aldehyde/ketone + primary amine =

Answer 59

imine

Question 60

aldehyde/ketone + secondary amine =

Answer 60

enamine

Question 61

what is an aldol condensation

Answer 61

enolate anion of one carbonyl + carbonyl group of another carbonyl compound

Question 62

aldol condensations requires a ____ base

Answer 62

strong

Question 63

kinetic vs thermodynamic control

Answer 63

thermodynamic: will remove protons from the more sterically crowed carbon kinetic: will remove protons from the less crowded carbon (not enough energy)

Question 64

what is a β-hydroxy carbonyl

Answer 64

hydroxyl group bonded to the beta carbon of an aldehyde/ketone

Question 65

what is a retro-aldol reaction

Answer 65

β-hydroxy carbonyl decomposes into a aldehyde/ketone + a carbonyl compound

Question 66

why can carboxylic acids form strong H bonds

Answer 66

contains an H bond donor (acidic proton) and an H bond acceptor (e on O)

Question 67

carboxylic acids can be recused into..

Answer 67

primary alcohols

Question 68

CAs can be reduced with ____ but not \_\_\_\_

Answer 68

LiAlH₄ but not NaBH₄

Question 69

why are CAs that have carbonyl groups beta to the carboxylate unstable

Answer 69

they are subject to decarboxylation (loss of CO₂)

Question 70

carboxylic acid derivatives (4)

Answer 70

acid halide, acid anhydride, ester and amide

Question 71

characteristic of an elimination reaction

Answer 71

2 sigma bonds break and 1 pi bond forms (opposite from addition reaction)

Question 72

esterification

Answer 72

carboxylic acid + alcohol in the presence of acid (catalyst)

Question 73

acid & base catalyzed ester hydrolysis

Answer 73

both involve nucleophilic addition and elimination steps same products, different mechanisms

Question 74

saponification is an example of..

Answer 74

base-mediated ester hydrolysis

Question 75

saponification reaction

Answer 75

tricylglyceride (in the presence of base) → glycerol + fatty acids

Question 76

how are acid halides made

Answer 76

carboxylic acid + PX₃ (some halogen)

Question 77

how are acid anhydrides made

Answer 77

condensation of 2 CAs with the loss of water OR CA + acid halide

Question 78

how are esters made

Answer 78

CA + alcohol

Question 79

how are amides made

Answer 79

from an acid halide, anhydride or ester + amine can NOT be made from CA directly (amides are very basic)

Question 80

reactivity of acid derivatives in nucleophilic addition/elimination reactions decreases with..

Answer 80

inching basicity of the leaving group

Question 81

order of reactivity in nucleophilic addition/elimination reactions

Answer 81

acid chlorides \> acid anhydrides \> esters \> amides

Question 82

aldol condensation products

Answer 82

beta-hydroxyl carbonyl OR alpha-beta unsaturated carbonyl

Question 83

aldol reaction starting

Answer 83

nucleophilic enolate reacts with aldehyde/ketone

Question 84

activate our electrophile =

Answer 84

protonation

Question 85

activate our nucleophile =

Answer 85

deprotonation