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chapter 18 > Chapter 19 > Flashcards

Chapter 19 Flashcards

1
Q

how are enolate anions formed

A

deprotenation of the alpha carbon

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2
Q

on an enolate anion where is the majority of the negative charge

A

on the oxygen

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3
Q

where do enolate anions react

A

they react at the carbon

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4
Q

which of the resonace structures gives the most contribution

A

the one with the negative charge on on the 0

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5
Q

are enolate anions electrophiles or nucleophiles

A

they are nucleophiles

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6
Q

what is the aldol reaction

A

enolate anion of an aldehyde or ketone to the carbonyl group of another molecule

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7
Q

what is the product of an aldol reaction

A

a beta hydroxy ketone or aldehyde

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8
Q

aldol products are easily dehydrated in to what

A

ab unstaurated aldehydes or ketones

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9
Q

if you have a beta hydroxy ketone and treat it with base what do you get

A

an alpha beta unsaturated aldehyde

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10
Q

are aldol reactions reversible

A

yes

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11
Q

what happens in a crossed aldol reactions

A

one molecule provides the enolate anion and the other provides a carbonyl group

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12
Q

can the reactants have alpha hydrogens in an crossed aldol reactoin

A

no

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13
Q

why cant reactants have alpha h have alpha hydrogens in crossed aldol reactions

A

it can not form enolate anion

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14
Q

what are the reactants for claisen condensaton

A

eto, na , h20 , hcl

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15
Q

what happens in claisen

A

the or comes off of one ester the 2 come together

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16
Q

what is the product of clasen

A

a beta keto ester

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17
Q

what is diekmann

A

it is intramolecular claisen

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18
Q

in diekmann what kind of molecule is needed

A

it needs 2 esters on the same molecule

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19
Q

how many carbons can be on a ring in diekmann

A

5 ring

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20
Q

what kind of rings can you form in an intramolecular aldol reaction

A

5 and 6

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21
Q

can you from a 7 memered ring for intramolecular aldol

A

no

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22
Q

what is a crossed claisen

A

if gives a mixture of 4 different beta keto esters

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23
Q

can ester form enolate anions

A

yes

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24
Q

if you have an ester and clasen reagents what will you get

A

you will get the the same ester with an enolate version attatched

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25
Q

2 esters plus claisen reactants gives

A

drop the r from one ester and combine them

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26
Q

how are enamines formed

A

2 amine the carbonyl group of aldehyde or ketone

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27
Q

clasen is the key route to what

A

ketones

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28
Q

what is the use of acetoacetic ester synthesis

A

it is useful for the preparation of mono and disubstituted acetones

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29
Q

What is another name for michael reaction

A

1-4 reaction

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30
Q

what is lda

A

it is a strong base

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31
Q

kinetic control

A

mixture is relative to the rates of formation

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32
Q

thermodynamic control

A

the compostion of the product mixture is determined by the stabilities of the products

33
Q

enol is a neutral or charged molecule

A

neutral

34
Q

enolate is a neutral or charged molecule

A

charged

35
Q

how do you form an enolate anion

A

base + ketone or aldehyde

36
Q

how do you form enol

A

acid the ketone or aldehyde

37
Q

why does the resonacne structure of enolate ion with negative o contrbute more

A

because the o is more electronegative

38
Q

what are the 2 reasons why reactions take place at the c and not the o on enolate

A

static hinderance on o

c=0 is stronger thn c-c

39
Q

aldol reactions take place between what 2 kinds of molecules

A

aldehydes or ketones

40
Q

what 2 things make up an aldol

A

aldehyde and ketone

41
Q

what is the product of an aldol reaction

A

beta hydroxy aldehyde or ketone

42
Q

do we get enantiomers or what kind of mixture in aldol reactons

A

racemic mixture , 2 enantionmers

43
Q

does the aldol reaction fo to compleion

A

no

44
Q

in a base aldol reaction the enolate serves ad the ..

A

nucleophile

45
Q

in an acid reaction of aldol the enol serves A

A

the nucleophile

46
Q

If you dehydrate an aldol product what do you get

A

a double bond in the alpha beta postions

47
Q

what is the product of a crossed aldol reaction

A

either an alpha or beta aldehyde or ketone

48
Q

what is the key to make sure that you have a good yield

A

make sure that it does not have alpha hydrogens

49
Q

what is nitro

A

it is an electron withdrawing group

50
Q

what is the pka of a nitro gorup

A

10

51
Q

in an intra molecular aldol reaction both nucleophiles or electrophiles are arpart of the same molecule

A

electrophiles

52
Q

what kind of rings do you from intramolecular reactions

A

5 and 6 no 7

53
Q

what are the reactants for claisen

A

na eto and hcl , h20

54
Q

what kind of reaction would u use to form a beta keto ester

A

claisen

55
Q

in a claisen condensation reaction what is the nucleophile

A

the enolate version

56
Q

describe in words what is going to happen during a claisen reaction

A

two esters are going to come together , but the r group is going to fall off of one

57
Q

what is the final product of a claisen reaction called

A

beta keto ester

58
Q

can you use a catalytic amount of base in a claisen reaction

A

no

59
Q

explain in words how a diekmann condensation reaction occurs

A

there are 2 esters in the same molecule , this forms into a cycilc molecule

60
Q

what is the only kind of ring that we can form in a diekmann condensation

A

5 ring

61
Q

what are the reagents fro dieckmann condensaiton

A

eto na, hcl and h20

62
Q

how are diekmann condensation and claisen condensation similar

A

in dieckmann both esters are on the same molecule . on claisen there are 2 molecules of the same ester

63
Q

can crossed claisen have alpha hydrogens

A

no it will form 4 beta esters

64
Q

describe in words crossed claisen is like

A

it is combining 2 different esters , the r group breaks off of one and they combine

65
Q

what kind of reactions to enamines undergo

A

sn2 reactions

66
Q

where do reactions take place in enamines

A

at the beta carbon

67
Q

what are the 3things that you use 1,2 addition

A

strong bases , organolithium compounds and grignards

68
Q

1,2 are reversible or not

A

not

69
Q

are 1,4 reversible or not

A

yes

70
Q

why is 1,4 more stable

A

because o f the c=0 bond

71
Q

is 1/2 under kinetic or thermodynamic control

A

kinetic

72
Q

is 1/4 under thermodynamic or kinetic control

A

thermodynamic

73
Q

gilman reagents give what kind of products 1,2 or 1,4

A

1,4

74
Q

organolithium and grignards give 1,2 or 1/4

A

1/2

75
Q

what does LDA stand for

A

lithium di isopropyl amide

76
Q

is lda a good or bad nuc

A

a bad nuc

77
Q

is LDA a good or bad base

A

a good base

78
Q

why is LDA a bad nuc

A

it is very hindered

chapter 18 (3 decks)

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