SPS 202 Heterocyclic and Biomolecules Chemistry: Dicarboxylic Acids Lecture Quiz

Dicarboxylic Acids

• Dicarboxylic acids are organic compounds containing two carboxylic acid (-CO2H) functional groups.
• Their general molecular formula is HO2C-RCO2H, where R can be an aliphatic or aromatic.
• Examples include oxalic, malonic, and isophthalic acids.
• Aspartic and glutamic acids, which are amino acids, are also dicarboxylic acids.

Naming of Dicarboxylic Acids

• Dicarboxylic acids are named by adding the suffix "dioic" acid to the name of the carbon chain that contains both carboxyl groups.
• Aliphatic dicarboxylic acids with a cycloalkane ring are named by giving the name of the ring and adding the suffix -dicarboxylic acid.
• Numbers are used to show the location of the carboxyl groups on the ring.
• Aromatic dicarboxylic acids are named by adding the words dicarboxylic acid to "benzene".

Physical Properties

• Dicarboxylic acids are colorless and odorless crystalline substances at room temperature.
• They have higher melting points than those of monocarboxylic acids containing the same number of carbon atoms.
• This is due to the existence of stronger hydrogen bonding between the diacid molecules.

Reactions of Dicarboxylic Acids

• Thermal reactivity: reactions depend on the chain length separating the carboxyl groups.
• Ring formation is usually favored if a 5- or 6-membered ring can be formed.
• Diacids with carboxylic groups at positions 1 and 6 or 7 when heated, decarboxylate to form cyclic ketones.
• Diacids with short carbon chains when heated, decompose to form carbon dioxide and a monocarboxylic acid.
• Reactions with amines: dicarboxylic acids react twice with ammonia or primary amine to form cyclic imides.
• Condensation reactions: esters of most dicarboxylic acids, except propanedioic esters, undergo an intramolecular Claisen condensation to form a 5- or 6-membered cyclic β-keto esters.
• Polymerization reactions: diacids are used for the production of high-performance polymers (polyesters, polyamides), anti-corrosives, etc.

Malonic Ester Synthesis

• Malonic ester synthesis is a method for preparing substituted carboxylic acids.
• The base used in malonic ester reactions is the ethoxide anion.
• The enolate anion of diethyl malonate is a nucleophile and reacts by an SN2 pathway with methyl and primary haloalkanes, α-haloketones, and α-haloesters.

Keto Acids and Esters

• Keto acids (also called oxo acids) are organic compounds that contain a carboxylic acid and ketone functional groups.
• Examples of keto acids include pyruvic, acetoacetic, and levulinic acids.
• Keto acids are classified into α-keto acids, β-keto acids, and γ-keto acids based on the position of the ketone group.

Types of Keto Acids

• α-keto acids have the keto group adjacent to the carboxylic acid.
• Examples of α-keto acids include pyruvic and oxaloacetic acids.
• β-keto acids have the ketone group at the second carbon from the carboxylic acid.
• Examples of β-keto acids include acetoacetic acid.
• γ-keto acids have the ketone group at the third carbon from the carboxylic acid.
• Examples of γ-keto acids include levulinic acid.

Claisen Condensation

• Claisen condensation is a carbonyl condensation reaction between two esters in the presence of a strong base to form a β-keto ester.
• The reaction takes place only in nonaqueous bases such as sodium ethoxide.
• Claisen condensation is the main method for preparing β-keto esters.