Carboxylic acid Flashcards
What is the functional group of a carboxylic acid?
carboxyl group (carbonyl group + hydroxyl group)
What is the general formula for an aliphatic carboxylic acid?
RCOOH
How do you name a carboxylic acid?
derived from the parent alkane by dropping the suffix -e and adding -oic acid
Why do you not need to give the carboxyl group a number?
Because it is understood to be carbon 1 because it is the highest priority functional group
How do you name a dicarboxylic acid?
Named as a -dioic acid and the longest chain contains both carboxyl carbons
Describe the polarity of carboxyl group (2 components)
- polar hydrophilic carboxyl group (incease solubility)
2. nonpolar hydrophobic hydrocarbonchain (decrease solubility)
Why do carboxylic acids have high boiling points?
Because they are associated by hydrogen bonding into dimers
Explain the increased acidity of carboxylic acids
- charge delocalization through resonance in a carboxylate anion relative to an alkoxide ion
- the electron-withdrawing inductive effect of the carbonyl group
pKa tells you the acidity of what?
The hydrogen atom in the molecule
pH tells you the acidity of what?
The solution
Write the equilibrium formula for acid HA with water
HA + H2O A- + H3O
Write the equilibrium formula for acid HA with water
HA + H2O A- + H3O
Why can all molecules be considered amphoteric?
Because they can always be protonated/deprotonated by a stronger acid/base
The pH of a solution depends on what two things?
- The concentration of the solution
2. The acid in question
Write the acidity constant Ka for the equilibrium reaction of an acid with water
Ka = [H3O][A-]/[AH}
What is the logarithmic form of the acidity constant?
pKa = -logKa
A stronger acid has a lower pKa or a higher pKa?
the lower the pKa the higher the Ka and the stronger the acid
Rearrange the expression for Ka to show that pKa is the pH at which an acid is exactly half dissociated
- Ka = [H3O][A-]/[AH]
- [H3O] = Ka * [AH]/[A-]
- pH = pKa - log [AH]/[A-]
At pH above the pKa, how does an acid exist?
Acid exists as A- in water and will be fairly soluble
At pH below the pKa, how does an acid exist?
Acid exists mostly as AH in water and will be less soluble
How are pKa and stability of conjugate base related?
More stable conjugate base has a higher Ka becuase they give up a proton more, and therefore have a lower pKa.
How are pKa and stability of conjugate base related?
More stable conjugate base has a higher Ka becuase they give up a proton more, and therefore have a lower pKa.
Explain the increased acidity of carboxylic acids compared to alcohols (2 components)
- charge delocalization through resonance in a carboxylate anion relative to an alkoxide ion
- electron withdrawing inductive effect of the carbonyl group
What are three ways to prepare a carboxylic acid?
- Oxidation of primary alcohols and aldehydes
- Treating a grignard reagent with carbon dioxide
- Treating a nitrile with water
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.
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
What is a powerful reagent for Fischer esterification and what product does it yield?
DIazomethane (CH2N2) gives a methyl ester in high yield.
How do you prepare an acid chloride from a carboxyl group?
Treatment with thionyl chloride
What is decarboxylation
Loss of CO2
What carboxylic acids undergo decarboxylation
- 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.
What is the IUPAC name of HCOOH
Methanoic acid
What is the common name of HCOOH
Formic acid
What is the IUPAC name of CH3COOH
Ethanoic acid
What is the common name of CH3COOH
Acetic acid
What is the IUPAC name of CH3CH2COOH
Propanoic acid
What is the common name of CH3CH2COOH
Propionic acid
What is the IUPAC name of CH3(CH2)2COOH
Butanoic acid
What is the common name of CH3(CH2)2COOH
Butyric acid
What is the IUPAC name of CH3(CH2)3COOH
Pentanoic acid
What is the common name of CH3(CH2)3COOH
Valeric acid
What is the common name of CH3(CH2)3COOH
Valeric acid
What is the IUPAC name for salicylic acid?
o-hydroxybenzoic acid
Electron-donating groups are what type of directing groups in EAS?
Ortho and para directing
Electron-withdrawing groups are what type of directing group in EAS?
Meta directing
What is the common name for HOOCCOOH
Oxalic acid (2 carbon dioic acid)
What is the common name for HOOC(CH2)COOH
Malonic acid (3 carbon dioic acid)
What is the common name for HOOC(CH2)2COOH
Succinic acid (4 carbon dioic acid)
What is the common name for HOOC(CH2)3COOH
Glutaric acid (5 carbon dioic acid)
What is the common name for HOOC(CH2)4COOH
Adipic acid (6 carbon dioic acid)
What is the common name for a carboxylic acid with a 12-carbon chain?
lauric acid
What is the common name for a carboxylic acid with a 14-carbon chain?
myristic acid
What is the common name for a carboxylic acid with a 16-carbon chain?
palmitic acid
What is the common name for a carboxylic acid with a 18-carbon chain?
stearic acid
How do you name an acid chloride?
-ic acid replaced by -yl chloride
How do you name an amide?
-ic/-oic acid replaced by -amide
How do you name an ester?
- -ic acid replaced by -ate
2. precede name by alkyl or aryl group bonded to oxygen (R’)
How do you name an anhydride?
acid replaced by anhydride
How do you name the salt of a carboxylic acid?
- Replace the -ic/-oic acid with -ate
2. Precede name by name of counterion
How do you name an anhydride if the acyl groups are different?
List the groups in alphabetical order
What is an acyl group?
R-CO -
What are the five most important carboxylic acid derivatives?
- acid halides
- acid anhydrides
- esters
- amides
- nitriles
What are acid halides?
Acyl group bonded to a halogen
What are acid anhydrides?
Two acyl groups bonded to an O atom
What are esters?
Acyl group bonded to an -OR group