Carboxylic acid Flashcards
1
Q
What is the functional group of a carboxylic acid?
A
carboxyl group (carbonyl group + hydroxyl group)
2
Q
What is the general formula for an aliphatic carboxylic acid?
A
RCOOH
3
Q
How do you name a carboxylic acid?
A
derived from the parent alkane by dropping the suffix -e and adding -oic acid
4
Q
Why do you not need to give the carboxyl group a number?
A
Because it is understood to be carbon 1 because it is the highest priority functional group
5
Q
How do you name a dicarboxylic acid?
A
Named as a -dioic acid and the longest chain contains both carboxyl carbons
6
Q
Describe the polarity of carboxyl group (2 components)
A
- polar hydrophilic carboxyl group (incease solubility)
2. nonpolar hydrophobic hydrocarbonchain (decrease solubility)
7
Q
Why do carboxylic acids have high boiling points?
A
Because they are associated by hydrogen bonding into dimers
8
Q
Explain the increased acidity of carboxylic acids
A
- charge delocalization through resonance in a carboxylate anion relative to an alkoxide ion
- the electron-withdrawing inductive effect of the carbonyl group
9
Q
pKa tells you the acidity of what?
A
The hydrogen atom in the molecule
10
Q
pH tells you the acidity of what?
A
The solution
11
Q
Write the equilibrium formula for acid HA with water
A
HA + H2O A- + H3O
12
Q
Write the equilibrium formula for acid HA with water
A
HA + H2O A- + H3O
13
Q
Why can all molecules be considered amphoteric?
A
Because they can always be protonated/deprotonated by a stronger acid/base
14
Q
The pH of a solution depends on what two things?
A
- The concentration of the solution
2. The acid in question
15
Q
Write the acidity constant Ka for the equilibrium reaction of an acid with water
A
Ka = [H3O][A-]/[AH}
16
Q
What is the logarithmic form of the acidity constant?
A
pKa = -logKa
17
Q
A stronger acid has a lower pKa or a higher pKa?
A
the lower the pKa the higher the Ka and the stronger the acid
18
Q
Rearrange the expression for Ka to show that pKa is the pH at which an acid is exactly half dissociated
A
- Ka = [H3O][A-]/[AH]
- [H3O] = Ka * [AH]/[A-]
- pH = pKa - log [AH]/[A-]
19
Q
At pH above the pKa, how does an acid exist?
A
Acid exists as A- in water and will be fairly soluble
20
Q
At pH below the pKa, how does an acid exist?
A
Acid exists mostly as AH in water and will be less soluble
21
Q
How are pKa and stability of conjugate base related?
A
More stable conjugate base has a higher Ka becuase they give up a proton more, and therefore have a lower pKa.
22
Q
How are pKa and stability of conjugate base related?
A
More stable conjugate base has a higher Ka becuase they give up a proton more, and therefore have a lower pKa.
23
Q
Explain the increased acidity of carboxylic acids compared to alcohols (2 components)
A
- charge delocalization through resonance in a carboxylate anion relative to an alkoxide ion
- electron withdrawing inductive effect of the carbonyl group
24
Q
What are three ways to prepare a carboxylic acid?
A
- Oxidation of primary alcohols and aldehydes
- Treating a grignard reagent with carbon dioxide
- Treating a nitrile with water
25
Explain the problem with the reduction of carboxylic acids
Only LiAlH4 will reduce them. This means you can reduce other functional groups without worrying about carboxyl group.
26
Define fischer esterification
Prepration of an ester by treating a carboxylic acid with an alcohol in the presence of an acid catalyst such as a sulfuric acid
27
What is a powerful reagent for Fischer esterification and what product does it yield?
DIazomethane (CH2N2) gives a methyl ester in high yield.
28
How do you prepare an acid chloride from a carboxyl group?
Treatment with thionyl chloride
29
What is decarboxylation
Loss of CO2
30
What carboxylic acids undergo decarboxylation
1. All carboxylic acids to some extent with enough heat
| 2. Carboxylic acids with a (second) carbonyl group Beta to the carboxyl group undergo undergo mild heating.
31
What is the IUPAC name of HCOOH
Methanoic acid
32
What is the common name of HCOOH
Formic acid
33
What is the IUPAC name of CH3COOH
Ethanoic acid
34
What is the common name of CH3COOH
Acetic acid
35
What is the IUPAC name of CH3CH2COOH
Propanoic acid
36
What is the common name of CH3CH2COOH
Propionic acid
37
What is the IUPAC name of CH3(CH2)2COOH
Butanoic acid
38
What is the common name of CH3(CH2)2COOH
Butyric acid
39
What is the IUPAC name of CH3(CH2)3COOH
Pentanoic acid
40
What is the common name of CH3(CH2)3COOH
Valeric acid
41
What is the common name of CH3(CH2)3COOH
Valeric acid
42
What is the IUPAC name for salicylic acid?
o-hydroxybenzoic acid
43
Electron-donating groups are what type of directing groups in EAS?
Ortho and para directing
44
Electron-withdrawing groups are what type of directing group in EAS?
Meta directing
45
What is the common name for HOOCCOOH
Oxalic acid (2 carbon dioic acid)
46
What is the common name for HOOC(CH2)COOH
Malonic acid (3 carbon dioic acid)
47
What is the common name for HOOC(CH2)2COOH
Succinic acid (4 carbon dioic acid)
48
What is the common name for HOOC(CH2)3COOH
Glutaric acid (5 carbon dioic acid)
49
What is the common name for HOOC(CH2)4COOH
Adipic acid (6 carbon dioic acid)
50
What is the common name for a carboxylic acid with a 12-carbon chain?
lauric acid
51
What is the common name for a carboxylic acid with a 14-carbon chain?
myristic acid
52
What is the common name for a carboxylic acid with a 16-carbon chain?
palmitic acid
53
What is the common name for a carboxylic acid with a 18-carbon chain?
stearic acid
54
How do you name an acid chloride?
-ic acid replaced by -yl chloride
55
How do you name an amide?
-ic/-oic acid replaced by -amide
56
How do you name an ester?
1. -ic acid replaced by -ate
| 2. precede name by alkyl or aryl group bonded to oxygen (R')
57
How do you name an anhydride?
acid replaced by anhydride
58
How do you name the salt of a carboxylic acid?
1. Replace the -ic/-oic acid with -ate
| 2. Precede name by name of counterion
59
How do you name an anhydride if the acyl groups are different?
List the groups in alphabetical order
60
What is an acyl group?
R-CO -
61
What are the five most important carboxylic acid derivatives?
1. acid halides
2. acid anhydrides
3. esters
4. amides
5. nitriles
62
What are acid halides?
Acyl group bonded to a halogen
63
What are acid anhydrides?
Two acyl groups bonded to an O atom
64
What are esters?
Acyl group bonded to an -OR group
65
What are amides?
Acyl group bonded to an N atom
66
What are nitriles?
A cyano group bonded to a carbon
67
What are lactones?
Cyclic esters in which the acyl carbon and O atom are part of the ring
68
What are lactams?
cyclic amides in which the acyl carbon and the N atom are part of the ring
69
What are imides?
Two acyl groups attached to the same N atom
70
How do you name an lactone??
1. IUPAC: Count number of carbons from carboxyl carbon to the carbon that is bonded to Sp3 oxygen, drop -ic acid and name it -olide
2. Common name: count carbons the same way, drop -ic acid and name it -olactone, indicate substitutions with greek letters.
71
How do you name an lactone??
1. IUPAC: Count number of carbons from carboxyl carbon to the carbon that is bonded to Sp3 oxygen (count around the ring), drop -ic acid and name it -olide
2. Common name: count carbons the same way, drop -ic acid and name it -olactone, indicate substitutions with greek letters.
72
How do you name a lactam?
IUPAC: Count number of carbons from carboxyl carbon to the carbon that is bonded to N (count around the ring) drop -ic acid and name it -lactam
73
How do you name an imide?
Similar to an anhydride; name acyl group as a carboxylic acid derivative; drop -ic/-oic acid and add amide.(alphabetical order if different) and
74
How do you indicate substitutions on an amide?
Indicate substitutions on N-atom in the name by preceding the group with N (i.e. N-methyl)
75
Rank Carboxylic acid, acid halides, acid anhydrides, esters, amides and nitriles by their solubility from least soluble to most soluble
1. Ester
2. Nitrile
3. Amide
4. Carboxylic acid
5. Acid halides and acid anhydrides react with water (hydrolysis)
76
Rank Carboxylic acid, acid halides, acid anhydrides, esters, amides and nitriles by their solubility from least soluble to most soluble
1. Ester
2. Nitrile
3. Amide
4. Carboxylic acid
5. Acid halides and acid anhydrides react with water (hydrolysis)
77
Rank Carboxylic acid, acid halides, acid anhydrides, esters, amides and nitriles by their boiling point from least to highest boiling
1. Nitrile
* *2. Ester (similar to hydrocarbons)
3. Acid halide
4. Anhydride
* *5. Carboxylic acid (above 10 carbons are solid at room temp)
* *6. Amide
78
Rank Carboxylic acid, acid halides, acid anhydrides, esters, amides and nitriles by their boiling point from least to highest boiling
1. Nitrile
* *2. Ester (similar to hydrocarbons)
3. Acid halide
4. Anhydride
* *5. Carboxylic acid (above 10 carbons are solid at room temp)
* *6. Amide
79
What are the two steps in nucleophilic acyl substitution?
1. A strong nucleophile adds directly to acyl carbon, breaking C=O pi bond and creating a tetrahedral addition intermediate (a weaker nucleophile can be catalyzed by acid)
2. Tetrahedral intermediate collapses by losing a leaving group and reforming the C-O pi bond.
80
Rank the leaving group ability of amides, esters, anhydrides and acid halides from best leaving group to worst
1. Acid halides
2. Anhydride
3. Ester
4. Amide
81
What are two factors influencing the relative reaction rates of the carboxylic acid derivatives to acyl substitution?
1. Relative leaving group ability
| 2. Relative resonance stabilization
82
How does resonance stabilization affect rate of acyl substitution?
If a molecule is more stabilized by resonance it is less likely to react (the partial positive charge is removed from the carbon).
83
Rank the relative resonance stabilization from least stabilized to best
1. Acid halide
2. Anhydride
3. Ester
4. Amide
84
Rank the relative resonance stabilization from least stabilized to best
1. Acid halide
2. Anhydride
3. Ester
4. Amide
85
What does catalysis refer to in carboxylic acid chemistry?
When converting between functional groups, acid halide and anhydride are reactive enough that common nucleophiles will react directly. But esters and amides require acid or base catalysis.
86
What is the theory behind base catalysis?
Base is used to increase nucleophilicity by converting a neutral nucleophile to an anionic nucleophile
87
What is the theory behind acid catalysis? (2 components)
Acid is used to (1) increase positive charge on carbonyl carbon by protonating carbonyl oxygen OR (2) used to protonate a leaving group to allow it to leave as a stable molecule
88
What is the theory behind acid catalysis? (2 components)
Acid is used to (1) increase positive charge on carbonyl carbon by protonating carbonyl oxygen OR (2) used to protonate a leaving group to allow it to leave as a stable molecule
89
What is the mechanism for Fischer esterification
1. Protonate carbonyl group
2. Make a new bond between carboxyl carbon and alcohol. Deprotonate alcohol
3. Protonate carboxyl group. Leave as stable water.
4. Deprotonate alcohol to restore original carbonyl group.
90
What is the mechanism for Fischer esterification
1. Protonate carbonyl group
2. Make a new bond between carboxyl carbon and alcohol. Deprotonate alcohol
3. Protonate carboxyl group. Leave as stable water.
4. Deprotonate alcohol to restore original carbonyl group.
91
What are four (4) carboxylic fatty acids?
1. Lauric (12)
2. Myristic (14)
3. Palmitic (16)
4. Stearic (18)
92
What are four oxidation reactions to prepare a carboxylic acid?
1. Oxidation of arene side chain
2. Oxidation of primary alcohols
3. Oxidation of aldehydes
4. Oxidative cleavage (tautomerization) of alkynes
93
How do you prepare a carboxylic acid by oxidation of arene side chain?
Hot KMnO4, H2O will oxidize all benzylic carbons with at least one hydrogen to carboxyl groups.
94
How do you prepare a carboxylic acid by oxidation of primary alcohols?
Chromic acid
95
How do you prepare a carboxylic acid by oxidation of aldehydes?
Tollen's reagent (Ag+ in NH4OH)
96
How do you prepare a carbxylic acid by oxidative cleavage?
Hg2+, H2SO4 or
1) BH3 2)H2O2, NaOH
97
What are two unique synthetic methods for a carboxylic acid and what is unique about them?
1. Hydrolysis of nitriles
2. Carboxylation of organometallic reagents
Both methods increase chain size by 1.
98
Explain the hydrolysis of nitriles method of preparing a carboxylic acid
1. Sn2 reaction of CN- with an alkyl halide
| 2. Nitrile is put with water; similar addition of water across triple bond and tautomerization. NH4+ leaves
99
Explain the carboxylation of organometallic reagents method of preparing a carboxylic acid
Grignard reagent is treated with CO2 and H3O+. Results in a carboxyl carbon being added to the alkyl group of grignard reagent.
100
Explain the carboxylation of organometallic reagents method of preparing a carboxylic acid
Grignard reagent is treated with CO2 and H3O+. Results in a carboxyl carbon being added to the alkyl group of grignard reagent.
101
What reagents are used to convert a carboxylic acid into an ester?
Acid and R-OH
102
What reagents are used to convert a carboxylic acid into an acid chloride?
SOCl2
103
What reagents are used to convert a carboxylic acid into an amide?
NH3 (or a derivative)
104
What reagents are used to convert a carboxylic acid into an anhydride?
An acid chloride and carboxylic acid.
105
How do you predict the product of the reaction between an acid chloride and a carboxylic acid to form an anhydride?
Take both acyl groups and bond them to a common -O-.
106
Predict the product of an acid chloride reacting with water.
Cl is substituted for -OH.
107
How do you convert an acid chloride to an aldehyde?
LiAlH(Ot-Bu)3
108
How do you convert an acid chloride to an ester?
R-OH
109
How do you convert an acid chloride to an amide?
React with ammonia or primary/secondary amine (mono/disubstituted ammonia)
110
How do you convert an acid chloride to a ketone?
Organocuprate reagent
111
How do you convert an acid anhydride to a carboxylic acid?
Acid anhydrides react with water to form carboxylic acids.
112
How do you convert an acid anhydride to an ester?
Acid anhydride + R-OH ---> Ester and Carboxylic acid
113
Predict the product of an acid anhydride with an alcohol.
Break the bond between the two acyl groups; attach hydrogen to one of the oxygens (carboxylic acid product) and the alkyl group on the alcohol to the other acyl group (ester product).
114
How do you convert an acid anhydride to an amide?
Acid anhydrides react with primary and secondary amines to form amides.
115
Predict the products of an acid anhydride with an alcohol.
Break the bond between the two acyl groups; attach hydrogen to the carbon containing the oxygen (carboxylic acid product) and the alkoxy group from the alcohol to the other acyl group (ester product).
116
How do you convert an acid anhydride to an amide?
Acid anhydrides react with primary and secondary amines to form amides.
117
Predict the products of an acid anhydride with a primary or secondary amine.
Break the bond between the two acyl groups; attach amine minus one hydrogen to the carboxyl carbon (amide product) and form a salt with the protonated amine and the remaining carboxylate ion
118
How do you convert an acid anhydride to an ester?
Acid anhydride + R-OH --->(Pyridine) Ester and Carboxylic acid
119
Predict the products of an acid anhydride with a primary or secondary amine.
Break the bond between the two acyl groups; attach amine minus one hydrogen to the carboxyl carbon (amide product) and form a salt with the protonated amine and the remaining carboxylate ion
120
What is acid catalyzed hydrolysis of an ester?
Esters can be cleaved back into a carboxylic acid and an alcohol by reaction with water and a catalytic amount of acid.
121
Predict the products of an ester in acid catalyzed hydrolysis
The acyl alkyl group forms a carboxylic acid and the ester alkyl group forms an alcohol.
122
How do you prepare a tertiary alcohol from an ester?
Addition of grignard reagents converts esters to tertiary alcohols.
123
Predict the products of grignard addition to an ester
Alkyl group from grignard reagent adds twice to ester. The original ester -OR group is converted to an alcohol by addition of H.
124
How do you prepare a primary alcohol from an ester?
Esters can be converted to primary alcohols using LiAlH4
125
Predict the products of an ester in LiAlH4
1. Remove the carbonyl oxygen and convert -OR to -OH to get primary alcohol product.
2. Original ester -OR group is protonated to form additional alcohol product.
126
How do you prepare an amide from an ester? (2 methods)
1. Liquid ammonia at -70 degrees Celsius forms an amide and an alcohol.
2. aqueous ammonia at -10 degrees Celsius for one hour
127
Predict the products of an ester in liquid or aqueous ammonia
substitute -OR on ester for -NH2 and protonate the original ester -OR to form an alcohol.
128
Predict the products of an ester in liquid or aqueous ammonia
substitute -OR on ester for -NH2 and protonate the original ester -OR to form an alcohol.
129
How do you prepare an aldehyde from an ester?
Esters can be converted to aldehydes using diisobutylaluminum hydride (DIBAH).
130
Predict the products of an ester in DIBAH
substitute the -OR on ester for an H to form aldehyde product. protonate original ester -OR to form an alcohol product.
131
What is transesterification?
When one ester is converted into another by an exchange of alkoxy groups.
132
What are the reaction conditions for transesterification?
The most common method is a large excess of alcohol with an acid catalyst such as H2SO4.
133
Predict the products for RCOOR' + R''-OH
RCOOR'' + R'-OH (exchange alkoxy groups)
134
What is saponification of an ester?
Hydrolysis (ester -> carboxylic acid + alcohol) using water and NaOH (basic)
135
Predict the products of an ester in H2O/NaOH
The products are a carboxylate ion (carboxylic acid is deprotonated because of basic conditions) and an alcohol form from the ester -OR group.
136
Predict the products of an ester in H2O/NaOH
The products are a carboxylate ion (carboxylic acid is deprotonated because of basic conditions) and an alcohol form from the ester -OR group.
137
How do you prepare an amide from a nitrile?
Nitriles can be converted to amides when acid catalyzed by HCl at 40 degrees celsius.
138
How do you prepare a nitrile from a primary amide?
primary amides can be converted to nitriles by reaction by dehydration with thionyl chloride (SOCl2)
139
Predict the products of a primary amide in SOCl2
Replace CONH2 carbon of primary amide with CtriplebondN
140
How do you prepare an amine from an amide?
Amides can be converted to 1°, 2° or 3° amines using LiAlH4.
141
Predict the products of a primary, secondary or tertiary amine in LiAlH4
Remove the carbonyl oxygen.
142
What are the two types of hydrolysis of amides?
1. Hydrolysis under acidic conditions
| 2. Hydrolysis under basic conditions
143
What are the products when amides are hydrolyzed under acidic conditions (HCl)?
A carboxylic acid and an ammonium chloride.
144
What are the products when amides are hydrolyzed under alkaline conditions (OH-)?
Sodium carboxylate and ammonia.
145
What are the two types of hydrolysis of amides?
Both require severe conditions (heat):
1. Hydrolysis under acidic conditions
2. Hydrolysis under basic conditions
146
What are the products when amides are hydrolyzed under alkaline conditions (OH-)?
Sodium carboxylate and ammonia.
147
How can you form an imide?
A difunctional molecule containing an amide and a carboxylic acid can dehydrate to form an imide with heat.
148
Predict the product of a amide/carboxylic acid molecule forming an imide.
Remove hydroxyl and a hydrogen from the nitrogen and create a new bond between nitrogen and the other acyl carbon.
149
Predict the product of a amide/carboxylic acid molecule forming an imide.
Remove hydroxyl and a hydrogen from the nitrogen and create a new bond between nitrogen and the other acyl carbon.
150
What is the product of Claisen condensation?
A beta-ketoester.
151
What are the reactants and the reaction conditions for Claisen condensation?
Two molecules of an ester with a strong nonaqueous base like sodium ethoxide in ethanol.
152
Describe how the Claisen reaction works (3 steps)
1. A strong base removes an alpha-hydrogen from an ester to form an enolate ion which is a nucleophile for addition to an ester.
2. The -OR (alkoxy) of the ester leaves as a strong base then deprotonates the carbon tethered between carbonyl carbons forming a weak base (enolate ion) and an alcohol.
3. Mild acid is added to protonate enolate ion to give the beta-ketoester.
153
Distinguish between Amine, Amide, Imine, Imide
- ides are acyl group containing compounds:
1. Amine: Ammonia derivative
2. Amide: Carboxylic acid derivative, -OH replaced by -NH2
3. Imine: C=N
4. Imide: two acyl groups bound to nitrogen
154
Explain why the reaction of an acid chloride with ammonia to form an amide is spontaneous (2 components)
The acid chloride is a strong leaving group than the NH2 and the amide is more stable than the acid chloride because of resonance stabilization.
155
What are the reagents to halogenate an aromatic ring?
X2, FeX3
156
What are the reagents for friedal crafts acylation
RCOCl + AlCl3
157
Predict the products of an acid anhydride with a primary or secondary amine.
Break the bond between the two acyl groups; attach amine minus one hydrogen to the carboxyl carbon (amide product) and form a salt with the protonated amine and the remaining carboxylate ion
158
Explain why the reaction of an acid chloride with ammonia to form an amide is spontaneous/favorable (2 components)
The acid chloride is a strong leaving group than the NH2 and the amide is more stable than the acid chloride because of resonance stabilization.
159
What are the reagents for friedal crafts acylation
RCOCl + AlCl3
160
Explain why Thioesters are more reactive to nucleophilic acyl substitution than ordinary carboxylic esters
Weaker bases are better leaving groups and RS- (thiolate) is a weaker base than RO- (alkoxide)
161
Predict the product for benzoic acid with sodium bicarbonate.
Sodium benzoate and carbonic acid (strong acid makes weaker acid)
162
Predict the product for benzoic acid with sodium bicarbonate.
Sodium benzoate and carbonic acid (strong acid makes weaker acid)
