Chemistry 212 --- Things-To-Study
Chapter 19: Carboxylic Acids

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Nomenclature
Trivial and IUPAC names for (a) saturated monoacids up to C4, (b) for unsaturated monoacids (C3 only), (c) for aromatic monoacids (benzoic and salicylic acid). The "carboxylic acid" nomenclature for cyclic alkane. Trivial and IUPAC names (a) for diacids (up to C6) and (b) for unsaturated diacids (C4 only).

Structural and Physical Properties
C=O and C-O bond length in -COOH group.
Effect of OH group on carbonyl basicity and of CO group on OH acidity. H-Bonding in cyclic dimers.
H-NMR: H-COOH, H₃C-COOH, H₃C-H₂C-COOH.
IR: C=O and OH stretches.

Acidic and Basic Character of Carboxylic Acids
Acidity: Nomenclature of salts. Magnitude of pKa values of carboxylic acids and alcohols. Trends as a function of alpha substituent variation.
Basicity: Always protonate at the carbonyl-O. The pKa of the conjugate acid is -6!

Syntheses of Carboxylic Acids
Method 1: Oxidation (CrO₃, KMnO₄, HNO₃) of primary alcohols and of aldehydes.
Method 2: Carbonation of Organometallic Reagents: Chlorides to Acids. Mechanism.
Method 3: Hydrolysis of Nitriles. Mechanism.

Synthesis of Carboxylic Acid Derivatives via Addition-Elimination
Recall: Nucleophiles add to As & Ks and hydrates, hemiacetals, acetals ... are formed. In these cases, the reagent H-Nuc adds such that Nuc adds to C(O) and H adds to O(C).
Acid derivatives RCOL differ as they contain a leaving group at carbonyl-C!
Addition-Elimination Mechanism via the tetrahedralintermediate occurs.
Know the key steps of the prototypical acid- and base-catalyzed Add./Elim. mechanisms.
(1) Alkanoyl Halides
Preparation of Acylhalide -COX from -COOH with Thionyl Chloride SOCl₂ or PBr₃.
In detail with mechanism for SOCl₂.
(2) Anhydrides
Method 1: Preparation of cyclic anhydrides via condenation
Method 2: General preparation of anhydrides using acylhalides
(3) Esters
Method 1: Mechanism of acid catalyzed ester formation from acid and alcohol.
Method 2: Methylesters via diazomethane
(4) Amides and Lactames
Different reactivities of amines with carboxylic acids depending on T. Preparation via condensation.

Important Reactions of Carboxylic Acids
(1) LAH reduction of Carboxylic Acids to Primary Alcohols (LiAlD₄ yields -CD₂-OH)
(2) Hell-Volhard-Zelinsky reaction with mechanism
(3) Hunsdieker Reaction with mechanism

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