Chapter 5 - Carbonyls and Alcohols Flashcards
(117 cards)
1
Q
Acetal structure
A
2
Q
Hemiacetal structure
A
3
Q
Ketal structure
A
4
Q
Hemiketal structure
A
5
Q
Acid halide structure
A
6
Q
Acid anhydride structure
A
7
Q
Amide structure
A
8
Q
Imide structure
A
9
Q
Lactone structure
A
10
Q
Lactam structure
A
11
Q
Describe the signal present for a hydroxyl group on 1H NMR
A
broad peak between 1 and 5 ppm
12
Q
Describe the general reactivity of alcohols
A
They are not good nucleophiles, but they can be deprotonated and converted into an alkoxide under basic conditions.
13
Q
Describe the general reactivity of aldehydes and ketones
A
They are reactive with most nucleophiles , but not by a traditional nucleophilic substitution mechanism. The reactivity occurs mainly at the electrophilic carbonyl center, often forming a tetrahedral intermediate.
14
Q
Out of ketals, hemiketals, acetals, and hemiacetals, which can be formed and removed under acidic conditions?
A
acetals and ketals
15
Q
Out of ketals, hemiketals, acetals, and hemiacetals, which can be formed only under basic conditions, but removed under any conditions?
A
hemiacetals and hemiketals
16
Q
What are the 4 steps in an acid-catalyzed mechanism?
A
1) protonate (making the leaving group a better leaving group)
2) break bond (leaving group leaves)
3) make bond (nucleophile attacks carbocation)
4) deprotonate (molecule returns to natural state)
17
Q
What are the 4 steps in a base-catalyzed mechanism?
A
1) deprotonate (make a strong nucleophile)
2) make bond (nucleophile attacks), break bond (leaving group leaves)
3) protonate (molecule returns to neutral state)
18
Q
What charge do intermediates carry in an acid-catalyzed mechanism?
A
positive
19
Q
What charge do intermediates carry in a base-catalyzed reaction?
A
negative
20
Q
The addition of an alcohol to an aldehyde under acidic conditions yields what?
A
an acetal
21
Q
The addition of an alcohol to a ketone under basic conditions yields what?
A
a hemiketal
22
Q
What reactant is needed to form a ketal or acetal protecting group?
A
a 1,2-diol (OHCH2CH2OH) under acidic conditions
23
Q
What is produced when an ester is reacted with a strong base in water?
A
Saponification: forms a carboxylate (deprotonated carboxylic acid) + alcohol
24
Q
What is produced when an ester is reacted with an acid in water?
A
Ester hydrolysis: carboxylic acid + alcohol
25
What is formed when a methyl ketone is reacted with I2 and strong base and water?
Iodoform reaction: carboxylate (deprotonated carboxylic acid) + I3CH (iodoform)
26
What is formed when an aldehyde is reacted with potassium permanganate (KMnO4) in strong base and water?
Oxidation: carboxylic acid
27
What is formed when a primary alcohol is reacted with potassium dichromate (K2Cr2O7) and acid in water?
Oxidation: carboxylic acid
28
What is formed when a secondary amide is reacted with a strong acid at high temperature?
Amide hydrolysis: carboxylic acid + RNH3+
29
What is formed when a nitrile is reacted with a strong acid at high temperature?
Nitrile hydrolysis: carboxylic acid + NH4+
30
What is formed when a carboxylic acid is reacted with thionyl chloride (SOCl2)?
acid halide
31
What is formed when a carboxylic acid is reacted with an alcohol and acid in high temperature?
transesterification: ester
32
What is formed when a carboxylic acid is treated with high temperature?
Condensation reaction: acid anhydride
33
What is formed when a carboxylic acid is reacted with 1) LiAlH4 (lithium aluminum hydride), 2) NH4Cl (ammonium chloride)?
primary alcohol
34
Why are esters more reactive than ketones/aldehydes?
They have an alkoxy (OR) leaving group.
35
What is formed when an ester is reacted with alcohol at high temperature under acidic conditions?
Transesterification: new ester with an alkoxy group from the alcohol
36
What is formed when a cyclic ketone is reacted with peroxyacids (RCO3H) (commonly mcpba)?
Baeyer-Villiger reaction: lactone
37
What is formed when an acid anhydride is reacted with water?
Hydrolysis: 2 carboxylic acids
38
Why are acid halides the most reactive of all the carbonyl groups?
They have the best leaving group.
39
What functional group makes up the peptide bond?
amide
40
What is formed when an amide is reacted with LiALH4 (lithium aluminum hydride)?
Reduction: amine
41
What functional group forms the hydrogen bond in base pairing of DNA and RNA?
amide
42
Carbonyl reactions can be categorized into what 3 categories?
- attack at carbonyl carbon
- deprotonation of alpha proton
- oxidation/reduction
43
What are the 2 categories of reactions in which a nucleophile attackes the electrophilic carbonyl carbon?
- substitution (leaving group)
- addition (no leaving group)
44
What determines a carbonyl's leaving group strength?
the pKa of its conjugate acid (good leaving groups have better stronger conjugate acids with low pKas)
45
decreasing order of reactivity for acid anhydride, acid halide, amide, ester
acid halide \> acid anhydride \> ester \> amide
46
What forms in the deprotonation of alpha protons?
enolates
47
Enolate and Enol structures
48
What are tautomers?
structural isomers that very in position of a pi bond and a hydrogen
49
Keto-enol tautomerization
50
carbonyl carbanion structure
51
When a carbonyl carbanion is reacted with an alkyl halide, what happens?
The carbanion acts as a nucleophile to perform nucleophilic substitution, forming a new C-C bond and a longer ketone.
52
What two bonding changes increase oxidation state?
- gain of bonds to oxygen
- loss of bonds to hydrogen
53
What two bonding changes decrease oxidation state?
- loss of bonds to oxygen
- gain of bonds to hydrogen
54
What is required for a carbon to be oxidized?
It must be bonded to oxygen and at least on hydrogen.
55
How is oxidation state determined for each carbon in a molecule?
Electronegativity is analyzed.
Bonds to hydrogen give a negative to carbon and a positive to hydrogen. Bonds to oxygen give a positive to carbon and a negative to oxygen.
56
Oxidizing agents are rich in what element?
oxygen
57
Reducing agents are rich in what element?
hydrogen
58
What results from the oxidation of a primary alcohol?
aldehyde ► carboxylic acid
59
What results from the oxidation of an aldehyde?
carboxylic acid
60
What results from the reduction of a carboxylic acid?
primary alcohol
61
What results from the oxidation of a secondary alcohol?
ketone
62
What results from the oxidation of a tertiary alcohol?
nothing, it cannot be oxidized
63
What results from the reduction of a ketone?
secondary alcohol
64
What is formed from the reaction of a primary alcohol with PCC (Collin's reagent)?
Oxidation: aldehyde
65
What is formed from the reaction of a secondary alcohol with potassium permanganate (KMnO4) and base?
Oxidation: ketone
66
What is formed when an ester is reacted with 1) LiAlH4 (lithium aluminum hydride), 2) NH4Cl?
primary alcohol
67
Which is more reactive: LiAlH4 or NaBH4?
LiAlH4
68
What carbonyl compounds can NaBH4 reduce?
only aldehydes and ketones
69
What carbonyl compounds can LiAlH4 reduce?
all carbonyl compounds
70
What is formed by the reaction of an aldehyde/ketone with HCl/Zn(Hg)?
Clemmensen reduction: alkane
\*must be acidic conditions
71
What is formed by the reaction of an aldehyde/ketone with 1) HS(CH2)2SH, 2) Raney Ni
an alkane
72
73
What is formed by the reaction of an ester with NaBH4?
nothing, they do not react.
74
What does the term hydride indicate?
hydrogen has a negative oxidation state
75
What forms when an aldehyde reacts with a grignard nucleophile?
secondary alcohol
76
What forms when a ketone reacts with a Grignard nucleophile?
tertiary alcohol
77
What forms when carbonyls with a leaving group (esters, acid anhydrides, acid halides) reacts with a Grignard nucleophile?
tertiary alcohol (grignard adds twice)
78
What is the best solvent for grignard reagents and why?
anhydrous ether solvent because grignard reagents are strong bases, so no protic hydrogens should be present
79
What forms when carbon dioxide is reacted with a Grignard nucleophile?
carboxylic acid
80
Describe an aldol condensation mechanism from start to finish
- ketone/aldehydes's alpha hydrogen is deprotonated
- resulting carbanion attacks a second carbonyl compound, forming a hydroxy carbonyl compound
- hydroxy carbonyl undergoes elimination under basic conditions to yield an α,β-unsaturated carbonyl
81
When a ketone is asymmetric, what determines which side's alpha hydrogen will be deprotonated in basic conditions?
- Steric hindrance: less substituted side will be the kinetic product (lower Eact of transition state)
- Greater stability: more substituted side will be thermodynamic product (more negative ΔGrxn)
82
In an aldol condensation, which product will be favored if reacted with a strong, bulky base and low temperatures?
kinetic
83
In an aldol condensation, which product will be favored when reacted with a strong, small base and high temperatures
thermodynamic
84
In the fourth step of glycolysis, what enzyme breaks a six-carbon β-hydroxyketone into two three-carbon fragments (DHAP and G3P)?
aldolase
85
How does the Claisen condensation differ from an aldol condensation?
An ester is used rather than a ketone or aldehyde. Since it has a leaving group, it is a substitution reaction rather than an addition reaction.
86
What reaction is involved in fatty acid synthesis between thioesters?
claisen condensation
87
What is the general result of transesterification?
conversion of one ester into another by exchanging the alkoxy group, in either acidic or basic conditions
88
What is the result of saponification of triglycerides?
They are broken down into glycerol and fatty acids
89
What reaction is responsible for the conversion of fatty acids and glycerol into fatty acids?
transesterification
90
What is the general result of the Wittig reaction?
It converts a carbonyl into an alkene using phophonium ylide
91
What is the general result of a pinacol rearrangement?
conversion of a vicinal diol into a ketone by alkyl migration, which converts a tertiary carbocation into a resonance stabilized carbocation, in acid
92
What is the general result of an iodoform reaction?
methyl ketone reacts with iodine (I2) in the presence of a strong base, producing a carboxylate and iodoform
93
What are the results of an iodoform test if it is positive?
It will be a yellow precipitate, meaning the reactant was a methyl ketone.
94
What is the general result of the Wolff-Kishner reduction?
conversion of a ketone/aldehyde into an alkane using 1) hydrazine, 2) aqueous hydroxide
\*must be basic conditions
95
Hydrazine structure
96
PCC structure
97
What is a typical protecting group of ketones?
ketals
98
What is a typical protecting group of aldehydes?
acetals
99
What is a typical protecting group of alcohols?
silyl ether
100
What is the pKa of alpha protons in the middle of acetoacetic ester/malonic ester?
~11
101
acetoacetic ester structure
102
Malonic ester structure
103
When a β-ketoacid is heated, what results?
Decarboxylation: carbon dioxide + tautomerized enol/ketone
104
Is anabolism reductive or oxidative? Does it build up or break down a moledule?
reductive, build-up
105
Is catabolism reductive or oxidative? Does it build up or breakdown a molecule?
oxidative, breakdown
106
Where do reductions normally take place physiologically? What is one exception?
in the cytoplasm, with the exception of glycolysis
107
What are the two most common biological reducing agents?
NADH, FADH2
108
What are the two most common biological oxidizing agents?
NAD+, FAD
109
What is FADH2's biochemical role?
hydrogenation of pi bonds
110
What is acetal coenzyme A's biochemical role?
transfer of an acetyl group to a biological species
111
What is formed from the reaction of an alcohol with SOCl2 (thionyl chloride)?
alkyl halide (X = Cl)
112
What is formed from the reaction of alcohol with PBR3?
alkyle halide (X = Br)
113
What is a possibility when malonic ester is reacted with a reactant that has two nucleophilic sites?
it may cyclize
114
Where do oxidations normally take place physiologically?
in the mitochondrial matrix
115
acetate structure
116
What is formed when a carboxylic acid is reacted with SOCl2 (thionyl chloride)?
acid chloride
117
What is formed when an aldehyde is reacted with peroxyacids (or mcpba)?
Baeyer-Villiger reaction: carboxylic acid
