Carboxylic Acids (Chapter 19)

Conjugation (i.e. π-electron delocalization) between the carbonyl group and the hydroxyl group sets the entire carboxylic acid domain in the same plane.

Planar The carbonyl group and the hydroxyl group are in the same plane due to π-electron delocalization across the two functional groups.

• Nucleophile: Addition to Carbonyl Carbon • Base: Deprotonation of Hydroxyl Hydrogen • Acid: Protonation of Carbonyl Oxygen The acidic protonation of the carbonyl oxygen is more favored than protonation of the hydroxyl oxygen. (The carbonyl oxygen will always be protonated before the hydroxyl oxygen.)

Stability of the (Carboxylic Acid’s) Conjugate Base The acidity of a carboxylic acid increases as the stability of its conjugate base increases. (Carboxylic acids with conjugate bases possessing a lower negative charge density are MORE STABLE than carboxylic acids with conjugate bases possessing a higher negative charge density.)

Deprotonated Form of Carboxylic Acid —COO– The carboxylate anion is the conjugate base of the carboxylic acid.

Increases Acidity The EWG stabilizes/delocalizes the negative charge of the carboxylate anion (through inductive effects), so the carboxylic acid is more prone to donating the H+ ion.

Decreases Acidity The EDG destabilizes/increases the negative charge of the carboxylate anion (through inductive effects), so the carboxylic acid is less prone to donating the H+ ion.

As the number of EWGs increases, the acidity of the carboxylic acid increases.

As the number of EDGs increases, the acidity of the carboxylic acid decreases.

As the distance to the EWG(s) decreases, the acidity of the carboxylic acid increases.

As the distance to the EDG(s) decreases, the acidity of the carboxylic acid decreases.

Protonation of the carbonyl Oxygen results in multiple cationic resonance structures (i.e. a greater delocalization of positive charge). Protonation of the carbonyl Oxygen results in a single cationic resonance structure (i.e. no delocalization of positive charge).

• Oxidation of 1° Alcohols OR Aldehydes • Organometallic Addition to CO2 • Hydrolysis of Nitriles • Synthesis of 2-Hydroxyl Carboxylic Acids

• —R (Akyl) • —OR (Ether) • —OCOR (Acyloxyl) • —OH (Hydroxyl) • —NHCOR (Amide) • —NR2 (Amine) • —NHR (Amine) • —NH2 (Amine) EDGs decrease the acidity of carboxylic acids.

• —X (Halide) • —COOH (Carboxylic Acid) • —COOR (Ester) • —COR (Ketone) • —CF3 (Trialkylfluoride) • —CN (Nitrile) • —SO3+H (Sulfonic Acid) • —NO2 (Nitro) • —NR3+ (Trialkylammonium) EWGs increase the acidity of carboxylic acids.

Jones Oxidation

Jones Oxidation

Na2Cr2O7, H2SO4 • CrO3, H2SO4 • HNO3 • KMnO4

Organometallic Addition to CO2 The addition of an organometallic to CO2 results in a carboxylic acid compound with one more carbon than the organometallic reagent.

Organometallic Addition to CO2 The addition of an organometallic to CO2 results in a carboxylic acid compound with one more carbon than the organometallic reagent.

• CO2 • H3O+

• Grignard Synthesis • Organometallic Addition to CO2 This Grignard-intermediated synthesis reaction can occur with any alkyl halide compound.

• Nitrile Synthesis • Nitrile Hydrolysis This nitrile-intermediated synthesis reaction can only occur with 2°/1°/0° alkyl halides.

• OH– Addition • Jones Oxidation This alcohol-intermediated synthesis reaction can ONLY occur with 1°/0° alkyl halides.