Classification and Nomenclature of Organic Compounds

2. Aromatic compounds

Aromatic compounds contain one or more planar rings that exhibit increased stability due to resonance. The most famous example is benzene, which is represented as a hexagonal ring with single and double bonds:

C 6 H 6 (benzene)

Here is a simplified view:

3. Heterocyclic compounds

Heterocyclic compounds have rings that contain at least one atom other than carbon, such as nitrogen, oxygen, or sulfur. An example of this is pyridine, which includes a nitrogen atom in the ring:

C 5 H 5 N (pyridine)

The ring structure can be represented as follows:

4. Functional groups

Functional groups define specific chemical properties of organic molecules. Each functional group confers specific reactivity patterns. Some common functional groups include:

• Alcohol: Hydroxyl group represented by -OH. Example: CH 3 CH 2 OH (ethanol).
• Aldehyde: The carbonyl group is characteristic of CHO. Example: CH 3 CHO (acetaldehyde).
• Ketone: Contains a carbonyl group CO bonded to two carbon atoms. Example: CH 3 COCH 3 (acetone).
• Carboxylic Acid: Contains carboxyl group -COOH. Example: CH 3 COOH (acetic acid).

Here is a view of the carboxylic functional group connection:

Nomenclature of organic compounds

Accurate naming of organic compounds gives information about their structure. The International Union of Pure and Applied Chemistry (IUPAC) sets the rules for systematic nomenclature, allowing consistent naming of known compounds and new discoveries.

1. Basic principles of IUPAC nomenclature

• Identify the longest continuous chain of carbon atoms: This chain determines the parent name of the compound.
• Number the carbon atoms in the longest chain: start at the end closest to the highest priority substituent or functional group.
• Identify and name functional groups: use prefixes and suffixes according to their level of priority.
• Assign positions to functional groups and substituents: These numbers indicate the exact position on the carbon chain.
• Compile the names by listing the groups alphabetically: Write the location of each substitute name before it.

For example, a compound with the structural formula:

CH 3 -CH 2 -CH(OH)-CH 2 -CH 3

It is named 2-pentanol because the longest chain has five carbons, and the –OH group is on the second carbon.

2. Naming of substituents and functional groups

Substituents are considered to be atoms or groups attached to the carbon chain other than hydrogen. Functional groups determine which class the molecule belongs to.

Common substitutions

• Methyl: _{-CH 3}
• Ethyl: -C 2 H 5
• Propyl: -C 3 H 7

Functional group

• Alcohol: contains the suffix -ol
• Aldehyde: contains the suffix -al
• Ketones: have the suffix -one
• Carboxylic acids: contain the suffix -oic acid

In nomenclature, functional groups other than alkenes are placed after the parent name, while prefixes are used to indicate the presence of other substituents that are not part of the main chain.

Consider the following example: CH 3 CH(Br)CH 2 OH. Following the IUPAC rules gives the name: 2-bromo-1-propanol, which shows the bromine substituent at C-2 and the hydroxyl group at C-1 along the three-carbon chain.

Conclusion

Classifying and naming organic compounds makes it easier to understand their structures and properties. With scientific naming conventions, such as those developed by IUPAC, chemists can effectively express complex molecular structures, communicate functional group behavior, and explore the vast variety of organic chemical reactions and compounds.

Through further study and practice, gaining proficiency in the classification and nomenclature of organic compounds opens the door to deeper exploration of organic chemistry and its applications in a variety of scientific fields.