SPS 202 Heterocyclic and Biomolecules Chemistry: Dicarboxylic Acids Lecture Quiz

Study Notes

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.

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".

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.

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 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 (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.

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 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.