University:
The University Of Western Ontario
Course:
2223B | Organic Chemistry of Biological Molecules
Academic year:

2023
Views:

62

Pages:

2
Author:

Cole M

Carboxylic Acid Derivatives Nomenclature & Properties of Acyl Halides & Acid Anhydrides: Hydrogen bonding is stronger than that of dipole-dipole interactions and therefore acyl halides typically have lower boiling points than carboxylic acids Acyl halides are very reactive Acid anhydrides can be thought of as being derived from carboxylic acids as well Carboxylic acids also have higher boiling points due to their hydrogen bonding capability Both acid anhydrides and acyl halides can’t be differentiated based on solubilities due to the fact that they are both extremely reactive Nomenclature & Properties of Esters: An Ester has the following structure: RCOOR’ To name, you must figure out what the carboxylic acid side of the ester would be and then name the alkyl portion of the estern (R’ in this case) Nomenclature & Properties of Amides: These are Nitrogenous groups attached to a carbonyl In order to name, you just find the name of the carboxylic acid and stick “-amide” on the end of it Reactivity of Carboxylic Acid Derivatives: Two competing effects that determine the reactivity of a carboxylic acid derivative: Induction, which results in withdrawing electron density from the carbon of the carbonyl, increases reactivity of that particular carboxylic acid derivative Resonance decreases reactivity of that particular carboxylic acid (donating electron density) Chlorine and carbon are in different periods of the periodic table, and therefore their pi orbitals don’t overlap too well, meaning resonance stabilization doesn’t contribute all that much to the overall picture of the molecule Oxygen and carbon are on the same period of the periodic table, and therefore their pi orbitals do overlap, meaning that resonance stabilization does contribute more to the overall picture of the molecule The order of reactivity for carboxylic acid derivatives: 1. Acyl Halides 2. Anhydrides 3. Esters 4. Amides Nucleophilic Acyl Substitution: Nucleophile attacks, forms the tetrahedral intermediate, and then the halide group leaves, forming the nucleophilic substituted product Acid-Catalyzed Ester Hydrolysis: This is basically the opposite of Fischer Esterification, by increasing the [H2O] Acid & Base-Catalyzed Hydrolysis of Amides: So we know that amides aren’t that reactive, but under harsh conditions (such as pH shift or heat), you can get them to convert back to carboxylic acids If using Base, you need to use heat in the first step with the base and then acid in the second in order to protonate the carbonate anion Beta-Lactam Antibiotics: Lactam is an amide in a ring (beta because it comes after the beta carbon) The nitrogen is not planar due to the ring forcing it to not be in a flat conformation, therefore decreasing the resonance stabilization of the molecule (making it more reactive) However, the alcohol attacks the carbonyl closest to the one by the N in the ring Extra Notes: Longer the chain on the carboxylic acid, the more stable it is A cofactor is a non-protein chemical compound bound to an enzyme to assist in catalysis A coenzyme is a specific type of cofactor that carries chemical groups between enzymes, like methyl groups A holoenzyme describes the complex of an enzyme that has its cofactor bound and is considered ‘complete’ An apoenzyme is the protein without any extra things attached to it, such as a cofactor