Chapter 20: The Chemistry of Carboxylic Acids

How do you (common) name carboxylic acids?

add the suffix -ic and the word acid to the end

draw acetic acid

draw benzoic acid

draw methylmalonic acid

What are carboxylic acids with two carboxy groups called?

dicarboxylic acids

Name this structure: HCO₂H

Common: formic acid

IUPAC: methanoic acid

Name this structure: CH₃CO₂H

Common: acetic acid

IUPAC: ethanoic acid

Name this structure: CH₃CH₂CO₂H

Common: propionic acid

IUPAC: propanoic acid

How do you (IUPAC) name carboxylic acids?

drop the final e from the hydrocarbon name and add the suffix -oic acid

Give the common and IUPAC name of this structure.

Common: p-bromobenzoic acid

IUPAC: 4-bromobenzoic acid

What is the priority of substituents when naming carboxylic acids with more than one functional group?

carboxylic acid > aldehyde > ketone > —OH > —SH

Carboxylic acids have (higher/lower) boiling points than alcohols/aldehydes/ketones with similar molecular masses.

higher

Why do carboxylic acids have generally higher boiling points?

hydrogen bonding and dimer formation

What is the IR spectroscopy of carboxylic acid?

C=O at 1710 cm^-1
and
O—H at 2400 - 3600 cm^-1 (veryyy broad)

What is the ¹H NMR spectroscopy of carboxylic acid?

α-protons at 2.0 - 2.5 ppm
O—H proton at 10 - 13 ppm (exchanges with D₂O)

What is the ¹³C NMR spectroscopy of carboxylic acid?

160 - 180 ppm

Why does the carbonyl C of carboxylic acid have a lower chemical shift than aldehydes/ketones?

shielding effects of nonbonding electron pairs on the carboxylate O (OH group)

Conjugate bases of carboxylic acids are called…

carboxylate ions

What are the factors influencing acidic strength of carboxylic acids?

• resonance

• polar effect

How does resonance influence acidic strength of carboxylic acids?

it stabilizes the conjugate base

How does the polar effect influence acidic strength of carboxylic acids?

the carbonyl group (C=O) stabilizes the carboxylate charge because it is EN

Halogen substitution of alkyl groups connected to carboxylic acids (increases/decreases) acidity.

increases

Sulfonic acids are much (stronger/weaker) than carboxylic acids.

stronger

Why are sulfonic acids stronger than carboxylic acids?

high oxidation state of S (expanded octet)

Sulfonic acids are useful as ____ in organic solvents.

acid catalysts

Why are sulfonic acids useful as acid catalysts in organic solvents?

they are more soluble than more inorganic acids

Moderately-sized carboxylic acids are (soluble/insoluble) in water.

insoluble

Although moderately-sized carboxylic acids are insoluble in water, what about them is soluble in water?

their alkali metal salts

The carbonyl oxygen is weakly (acidic/basic).

basic

What reagent is used in oxidation of an aldehyde or a primary alcohol to a carboxylic acid?

H₂CrO₄, H₂O
or
CrO₃, H₂SO₄
or
Na₂Cr₂O₇, H₂SO₄

What reagent is used in oxidation of an alkyl benzene to a carboxylic acid?

KMnO₄, ^-OH

H₃O⁺

draw the mechanism for turning a Grignard reagent into a carboxylic acid

What reagent is needed for turning a Grignard reagent into a carboxylic acid?

CO₂, THF

H₃O⁺