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chem > DAT Ochem Substitution and Elimination > Flashcards

DAT Ochem Substitution and Elimination Flashcards

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1
Q

an electron-rich species that tends to donate electron density

A

nucleophile

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2
Q

an electron-poor species or compound

A

electrophile

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3
Q

Nucleophile strength increases from…. on pd table

A

right to left

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4
Q

increase in nucleophilicity is due to decreasing

A

e/n

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5
Q

nucleophile strength increases down a group in what kind of solvent

A

polar protic

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6
Q

A larger
atomic radius results in

A

more reactive nucelophile

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7
Q

nucleophilicity decreases down a group in what kind of solvent

A

polar aprotic

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8
Q

In polar aprotic solvents, nucleophilicity parallels….

A

basicity

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9
Q

Basicity decreases

A

down a group

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10
Q

Both substitution and elimination reactions involve the

A

loss of LG

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11
Q

nucleophile attacks an electrophile and kicks out a leaving group… what kind of rxn

A

SN2

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12
Q

nucleophilic attack and loss of a leaving group occur in the same step.

A

concerted

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13
Q

rate law for sn2

A

k(nuc)(elec)

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14
Q

if a nucleophile attacks a chiral center, what happens to stereochemistry …. SN2

A

inverted

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15
Q

consists of separate steps and therefore is not concerted.

A

Sn1

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16
Q

first step of an SN1

A

carbocation intermediate formation via the loss of a leaving group.

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17
Q

what is the rate limiting step of an SN1 rxn

A

carbocation intermediate formation via the loss of a leaving group.

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18
Q

final step of SN1

A

nucleophilic attack of the carbocation.

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19
Q

SN1 can only occur with what kind of substrates

A

secondary and tertiary

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20
Q

rate law for SN1

A

k(electrophile)

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21
Q

Carbocations
can be stabilized by neighboring alkyl groups bonds via

A

hyperconjugation

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22
Q

what is the least stable carbocation rearrangement

A

vinyl

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23
Q

what is next to least stable carbocation rearrangement

A

phenyl

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24
Q

what is more stable carbocation, methyl or primary

A

primary

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25
Q

what is more stable methyl or phenyl

A

methyl

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26
Q

what is most stable carbocation arrangement

A

benzyl

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27
Q

what is next to most stable carbocation rearrangement

A

allyl

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28
Q

are SN1 reactions stereospecific

A

no

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29
Q

more substituted alkene,

A

zaitsev product

30
Q

less substituted alkene

A

hofman

31
Q

what product is favored if the base is large and sterically
hindered.

A

hofman

32
Q

what product is favored When a
non-sterically hindered base is used

A

zaitsev

33
Q

are E2 rxn concerted

A

yes

34
Q

E2 rate law

A

k(base)(substrate)

35
Q

In an E2 reaction, the leaving group and the beta proton must be

A

antiperiplanar

36
Q

For cyclohexane, E2 reactions only occur if the leaving group and beta proton are

A

on adjacent axial
positions and are anti-periplanar to one another:

37
Q

what version of alkene is preferred to be formed for an E2 rxn

A

E alkene

38
Q

If the substrate has only one proton on the relevant beta carbon, only… (e2)

A

stereoisomer is possible

39
Q

E1 rxn rate law

A

k(substrate)

40
Q

E1 reactions occur using what kind of bases

A

weak

41
Q

examples of weak bases

A

h2o or alcohol

42
Q

strong bases favor…

A

e2 rxns over e1

43
Q

Heat can be
added to the reaction to ensure that the

A

E1 product is favored over the SN1 product.

44
Q

elimination of alcohols requires the use of

A

concentrated acid and heat

45
Q

what is always the major product of an acid catalyzed dehydration reaction.

A

Zaitsev product

46
Q

If the alcohol is primary, what type of rxn will occur

A

e2

47
Q

The first step of acid catalyzed dehydration is…

A

protonation of the hydroxyl group to make it good lg

48
Q

does not occur with a tertiary substrate,

A

SN2

49
Q

what kind of rxns will a primary subs not work with

A

SN1, E1

50
Q

which are possible with a secondary substrate,

A

all 4 mechanism

51
Q

negatively charged molecule is

A

reactive, strong base/nucleophile

52
Q

If the molecule is neutral and unreactive, it is a

A

weak base/nucleophile

53
Q

A strong base/nucleophile will favor

A

SN2, E2

54
Q

a weak base/
nucleophile will favor

A

SN1, E1

55
Q

A sterically hindered molecule will almost
exclusively act as a

A

base

56
Q

A polar protic solvent favors

A

E2

57
Q

a polar aprotic solvent favors

A

SN2

58
Q

At low temperatures, what is more likely

A

nucleophile subsititution

59
Q

at high temps, what is more likely

A

elimination

60
Q

Br-, I-, Cl-, H2S, RS-, HS-

A

non basic nucelphile

61
Q

primary substrate, nonbasic nucleopuile

A

SN2

62
Q

secondary subs, polar aprotic solv, nonbasic nuc

A

SN2

63
Q

secondary subs, polar protic, nonbasic nuc

A

SN1

64
Q

tertiary subs, non basic nucleophile

A

SN1

65
Q

t-buOK, DBU, DBN,
Diisopropylethylamine,
Triethylamine, LDA, NaH

A

non nucleophilc base

66
Q

what kind of rxn is favored for all non nucleophilc bases

A

e2

67
Q

RO-: HO-, MeO-, EtO-

A

strong nuc, strong base

68
Q

strong nuc, strong base, primary OR secondary, polar aprotic

A

SN2

69
Q

strong nuc, strong base, primary OR secondary, polar protic

A

E2

70
Q

strong nuc, strong base, tertiary

A

E2 only

71
Q

ROH: HOH, MeOH,
EtOH

A

weak nuc, weak base

72
Q
A

chem (12 decks)

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