Ester Nomenclature

This page focuses on the nomenclature of esters, which are important derivatives of carboxylic acids. It explains how ester names are derived from their parent alcohol and carboxylic acid components.

Vocabulary: IUPAC (International Union of Pure and Applied Chemistry) - the organization that develops the official system for naming chemical compounds.

The naming convention for esters is described:

1. The first part of the name comes from the alkyl group of the alcohol
2. The second part is derived from the carboxylate group of the acid

Example: Several examples of ester naming are provided, including:

• Methyl ethanoate
• 1-methylethyl methanoate (isopropyl formate)
• Benzyl 2-methylpropanoate (benzyl isobutyrate)
• Phenyl benzoate
• Methyl cyclopentanecarboxylate
• Methyl 2-phenylethanoate (methyl phenylacetate)
• Cyclohexyl methanoate (cyclohexyl formate)

These examples illustrate both IUPAC and common names for various esters.

Cyclic Esters (Lactones)

This page introduces cyclic esters, known as lactones. It explains how lactones are named in the IUPAC system.

Definition: A lactone is a cyclic ester formed by the intramolecular reaction of a hydroxy acid.

The naming convention for lactones is described:

• Add the term "lactone" to the end of the name of the parent hydroxycarboxylic acid

Example: The formation of 4-hydroxybutanoic acid lactone from 4-hydroxybutanoic acid is shown, demonstrating the intramolecular esterification process.

Amides of Carboxylic Acids

This page covers the formation and properties of amides, another important class of carboxylic acid derivatives. It explains how amides are formed from carboxylic acids and amines (or ammonia).

Definition: An amide is a compound formed by the reaction between a carboxylic acid and an amine or ammonia.

The formation of amides is described:

1. The amine and carboxylic acid react to form a salt
2. Heating drives off water, producing the amide

Highlight: Amides are much less basic than their parent amines due to delocalization of the nitrogen's lone pair onto the carbonyl oxygen.

The page also discusses the protonation of amides in strong acid conditions, noting that the oxygen is typically protonated first rather than the nitrogen.

Vocabulary: Conjugation - the interaction of p-orbitals in a molecule, leading to delocalization of electrons.

The structural characteristics of amides are explained:

• The nitrogen is sp² hybridized with a planar arrangement of bonds
• Bond angles around the nitrogen are close to 120°
• The C-N bond has partial double bond character with a rotational barrier of 18 kcal/mol

Example: The structure of formamide is shown to illustrate these bond angles and the planar arrangement.

Types of Amides

This page continues the discussion of amides, focusing on the classification of different types of amides based on their substitution patterns.

Three types of amides are described:

1. Primary amides (R-CO-NH₂)

   Definition: Primary amides have only one carbon atom bound to the nitrogen.

2. Secondary amides (R-CO-NHR')

   Definition: Secondary amides, also called N-substituted amides, have two carbon atoms bound to the nitrogen.

3. Tertiary amides (R-CO-NR₂)

   Definition: Tertiary amides, also called N,N-disubstituted amides, have three carbon atoms bound to the nitrogen.

The page includes structural diagrams for each type of amide to illustrate the differences in substitution.

Nomenclature of Amides

This page covers the nomenclature of amides, explaining how to name these carboxylic acid derivatives according to IUPAC rules.

For primary amides:

1. Identify the acid part of the molecule
2. Remove the "-oic acid" suffix
3. Add "-amide" to the end

Example: CH₃-CO-NH₂ is named ethanamide

For secondary and tertiary amides:

• Treat alkyl groups on the nitrogen as substituents
• Use the prefix "N-" to indicate attachment to nitrogen

Example: CH₃-CO-NH-CH₂CH₃ is named N-ethylethanamide

Example: H-CO-N(CH₃)₂ is named N,N-dimethylmethanamide

The page also introduces cyclic amides, known as lactams:

Definition: Lactams are cyclic amides produced from amino acids, where the amino and carboxylic acid groups react to form an amide linkage.

Example: The formation of 4-aminobutanoic acid lactam from 4-aminobutanoic acid is shown.

Lactams are named by adding "lactam" to the IUPAC name of the parent amino acid.

Nitriles of Carboxylic Acids

This page introduces nitriles, another class of carboxylic acid derivatives. It explains their structure, relationship to carboxylic acids, and key properties.

Definition: Nitriles contain the cyano group (-C≡N) and can be hydrolyzed to carboxylic acids or produced by dehydration of primary amides.

Key points about nitriles:

• They lack a carbonyl group but are still classified as carboxylic acid derivatives
• Both the carbon and nitrogen atoms are sp hybridized
• The C≡N bond angle is 180°

Example: The structure of acetonitrile (CH₃-C≡N) is shown.

The page compares the structure of nitriles to alkynes:

• Similar triple bond structure
• Nitrogen has a lone pair instead of a bond to hydrogen

Highlight: The lone pair on the nitrogen is contained in an sp orbital, making it less available for bonding compared to an amine.

This comprehensive overview of nitriles completes the discussion of major carboxylic acid derivatives, providing students with a solid foundation in this important area of organic chemistry.

Carboxylic Acid Derivatives Overview

This page introduces the main types of carboxylic acid derivatives, including esters, amides, nitriles, acid halides, and anhydrides. It explains that these compounds can be converted to carboxylic acids through hydrolysis reactions. The general structures of each derivative type are shown.

Definition: Carboxylic acid derivatives are compounds that can be converted to carboxylic acids via simple acidic or basic hydrolysis.

Example: The reaction between ethanol and ethanoic acid to form ethyl ethanoate (an ester) is provided as an example of ester formation.

Highlight: The most important acid derivatives covered are esters, amides, and nitriles, though acid halides and anhydrides are also mentioned as activated forms of carboxylic acids.