Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

organic sem 2 > 4b > Flashcards

4b Flashcards

1
Q

how can C=O be made

A

oxidation of alcohols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

partial oxidation of a primary alcohol

A

aldehyde
- 2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

full oxidation of a primary alcohol

A

carboxylic acid

-2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

from a carboxylic acid to an aldehyde

A

reduction
+ 2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

aldehyde to a primary alcohol

A

reduction
-2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

oxidation of a secondary alcohol

A

forms a ketone

nothing but a ketone
- 2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is used as an oxidation agent to go from a primary alcohol to a aldehyde

A

PCC (pyridinum chlorochromate)
PDC (pyridinium dichromate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how come using PCC AND PDC stops oxidation at an aldehyde

A

bc they are mild oxidation agents
they cannot fully oxidise the primary alcohol to a carboxylic acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what oxidising agent is used to fully oxidise a primary alcohol into a carboxylic acid

A

KMnO4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is used to oxidise a secondary alcohol info a ketone

A

KMnO4
(CrO3 + H+ )
Na2Cr2O7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how many electrons are lost in the oxidation from a primary alcohol to a carboxylic acid

A

4!!

2 to get an aldehyde,, then 2 more to get a carboxylic acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is jones oxidation

A

from a primary alcohol to a carboxylic acid using CrO3 and H2SO4 + H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the intermediate in a jones oxidation

A

the aldehyde is an intermediate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

in a jones oxidation reaction,, are all functional groups oxidised

A

yes!! other primary alcohols or aldehydes will also be oxidised!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

jones oxidation with a secondary alcohol

A

secondary alcohol + CrO3 + H2SO4 + H2O

gives a ketone!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

can ketones be oxidised

A

nope!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

can phenols be oxidised

A

nope!!

there is no H’s on the alpha carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is MnO2

A

a mild oxidising agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what can MnO2 oxidise

A

prim alcohols to aldehydes

aldehydes to carboxylic acids

secondary to ketones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

is C=O electrophilic or nucleophilic

A

electrophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what reactions occur at the C=O

A

acid base reactions
oxidation reduction reactions
additions (reversible or irreversible)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what reactions can occur on the alpha C next to the C=O

A

acid base reactions to form enolates

enolate reactions can then occur as they act as a nucleophile (O- near a CC double bond)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what’s an enolate

A

C=C — O-
act as nucs

formed by acid base reactions of an alpha C next to a C=O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what shape is C=O

A

trigonal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

name a reducing agent

A

HBr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

alkene + HBr

A

1,2 addition reaction.

= attacks H
then Br attacks CC+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

ketone + HBr

A

O attacks the H

then Br attacks the C
lone pair on O can kick off the Br to form a ketone again (as the ketone is more stable)

intermediate can’t be isolated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

if the nucleophile attacking the C=O is a good leaving group,, what can occur

A

the lone pairs on O can kick off the nuc as it’s a good LG.

addition occurs,, then elimination occurs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what’s special abojt the O on C=O

A

it’s weakly basic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

as the O on C=O is weakly basic,, hat can it interact with

A

a bronsted acid
a lewis acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

bronsted acid

A

donated H

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

lewis acid

A

accepts e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

when the O on C=O acts as a base and attacks an electrophile (H+) what then happens

A

the O will be +.
resonance can now occur and make the C more +.

gives the aldehyde// ketone conjugate acid CC+ character

this reaction is also reversible (the O attacking a H+ // electrophile)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what’s a gem diol

A

when 2 OH are bonded to the same C.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what is another way of explaining a gem diol

A

it’s a ketone or aldehyde hydrate.

36
Q

how do we form a ketone hydrate // gemdiol

A

O attacks a H+
H2O attacks the C
de protonate the H2O using H2O
u now have a gemdiol

R, R, OH, OH

this rea is reversible + the OH can grab a H,, lone pair of other OH can kick off the water, H on OH can be attacked by water + removed to give a ketone

37
Q

what reaction gives a gem diol

A

a 1-2 addition of water

38
Q

H2O + H2O gives (rev reaction)

A

OH -
H3O+

39
Q

at low ph there is a bunch of

A

H3O
high con

40
Q

at high ph there is a bunch of

A

OH -
high conc

41
Q

when is OH- a good leaving group

A

in strongly basic conditions
high pH!!
aka lots of OH around it

42
Q

what could favour certain products from forming

A

the bond angles!!
double bond but 60* when it wants to be 120* isn’t favoured!!

60* when it’s meant to be 109.5 is more favoured!!

43
Q

in 1-2 addition reactions with C=O,, how does the nuc attack

A

at 107*
burgi dunitz trajectory

44
Q

what can decrease the rate of a 1-2 addition

A

steric hinderance to do burgi dunitz trajectory.

this is why aldehydes are more reactive than ketones. (H vs R group)

45
Q

are 1-2 additions reversible

A

they can be!!
both irreversible + reversible

46
Q

where does the nuc attack the C in C=O

A

at 107*
in the pi**
🦋 shape

the O then attacks an electrophile

47
Q

what is between the C=O bond

A

nothing!!
there is a node —— that way.

48
Q

asymmetric ketones can give what

A

enantiomers due to different stereogenic centres

49
Q

what is a cyanohydrin

A

R, R, OH, CN

50
Q

what process makes a cyanohydrin

A

1-2 addition using NaCN + H2O

51
Q

steps in the 1-2 addition to make cyanohydrin addition

A

CN- attacks the C
e- go to the O
O attacks H2O H
cyanohydrin is made
this is reversible!!

52
Q

cyanohydrin to ketone

A

1-2 elimination
lone pair on OH kick off CN
OH is now +
base removes the H from OH
ketone is formed

53
Q

alcohol to aldehyde

A

MnO2

54
Q

secondary alcohol to ketone

A

MnO2

55
Q

cyclo hexane + alcohol to aldehyde

A

PCC
PDC

56
Q

ketone to cyanohydrin

A

NaCN
H2O
MeOH

57
Q

what is equilibrium influenced by

A

influenced by factors that determine reactant and + product stability

58
Q

what makes a C=O more stable

A

if it’s more substituted

59
Q

are ketones or aldehydes more stable

A

ketones!!
more substituted C=O
more steric hinderance of burgi dunitz trajectory

60
Q

is ketone addition or aldehyde addition more favoured

A

aldehyde addition is more favoured
less hinderance of burgi dunitz trajectory.
less stable C=O as less substituted

61
Q

what substituents on the C=O favour addition

A

EWG
make the C more +
gem diol derivative is favoured

62
Q

C=O and a EDG

A

C=O is less electrophilic
gem diol derivatives are not favoured
addition is less favoured

63
Q

C=O and large substituents

A

addition isn’t favoured
gem diol derivatives aren’t favoured

64
Q

stability of the C=O usually dictates what stability

A

reactant stability.

ketone + aldehyde stability

65
Q

what dictates product stability

A

the steric hinderance.
ketones -> 2 R groups,, close together than before, tetrahedral in shape when gem diols are formed : less stable. the gemdiol is favoured less than the ketone.

ketone addition product is less favoured than the aldehyde addition product.

66
Q

aldehydes in terms of pro and rea stability

A

rea = less stable
pro = more stable

67
Q

ketones in terms of pro and rea stability

A

rea = more stable
pro = less stable

68
Q

ketone hydration under acidic conditions to form gem diols or ketone hydrates

A

use H3O+ (acidic conditions)
protonate the C=O
H2O attacks the C
H2O is deprotonated
all reversible reactions

69
Q

hydration of ketones under basic conditions

A

use of OH
OH attacks the C and e- move to the O
O attacks H20 Hydrogen (its protonated)
gem diol is made. with OH-

reversible reaction

70
Q

what’s a hemiacetal

A

R H OR OH
from an aldehyde

use of alcohol

71
Q

what’s a hemiketal

A

R R OH OR

ketone + alcohol to hemiketal

72
Q

hemiacetal synthesis

A

aldehyde O attacks the H
alcohol attacks the C
H on alcohol bonded is deprotonated by alcohol

hemiacetal is made!!

73
Q

hemiketal synthesis

A

ketone O attacks the H
alcohol attacks the C
alcohol H is deprotonated by alcohol
hemiketal is made!!

74
Q

are cyclic hemiketal and hemiacetal more stable than acyclic ones

A

yes!!!

cyclic ones will be favoured over the reactant.

the reactant will be favoured if the product is an acyclic hemiacetal or hemiketal!!

75
Q

what is an acetal

A

R H
OR OR

76
Q

how is an acetal made

A

aldehyde + H3O+ + alcohols + H20

77
Q

acetal synthesis mechanism

A

aldehyde O attacks H3O+
alcohol attacks C
e- move up to O
water deprotonates alcohol
OH on hemiacetal attacks H3O+ H
lone pair on alcohol kicks of the water
alcohol attacks the C (O is stabilised)
alcohol is deprotonated
acetal is formed

78
Q

how is the back reaction of acetal synthesis made

A

presence of excess H2O and a catalyst

79
Q

what’s a ketal

A

like an acetal but with 2 RS

R R
OR OR

80
Q

what’s the ketal mechanism

A

same as the acetal mechanism

excess alcohol + H

81
Q

how is the back reaction of ketal synthesis obtained

A

excess H2O
acid catalyst

82
Q

what is glucose

A

hydroxyaldehyde
6 membered cyclic hemiacetal

83
Q

what is ribose

A

5 membered cyclic hemiacetal

84
Q

maltose

A

glucose + glucose

85
Q

cellulose

A

polymer of glucose bridged by acetal bridges

86
Q

key points of the jones reaction

A

prim alcohol to carboxylic acid.
CrO3 + H2SO4 –> CHROMIC ACID ( Cr OH OH =o =o )
O: attacks Cr
=o forms o-
water removed, alcohol forms, deprotonation, aldehyde forms

water attacks,, hydrated aldehyde forms,, CrO3 + H2SO4 must be used again to get the carboxylic acid.

87
Q

1 electron movement for MnO2

A

weak oxidising agent
benzyllic and allylic alcohols to aldehydes

O: attacks Mn and O on Mn attacks H
deprotonation makes O neutral
1 e- movement from alpha H and =O to form OH
other e- from =O goes to Mn. forms a radical on alpha C.
radical and O - Mn electrons form a double bond + other e- goes to Mn

organic sem 2 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions