Overview
The lecture provided an introduction to organic chemistry nomenclature, focusing on naming conventions for alkanes, functional groups, substituents, and the application of numbering rules.
Naming Organic Compounds
- Organic compounds are named systematically based on the IUPAC (International Union of Pure and Applied Chemistry) rules.
- The longest continuous carbon chain in the molecule determines the base name (parent hydrocarbon).
- Side groups attached to the main chain are called substituents and are indicated with prefixes.
- Common prefixes for alkyl groups are methyl (CH₃-), ethyl (C₂H₅-), propyl (C₃H₇-), etc.
Numbering and Substituent Position
- Carbon atoms in the main chain are numbered to give substituents the lowest possible numbers (lowest sum rule).
- If multiple substituents are present, their positions and names are given in alphabetical order.
- Di-, tri-, and tetra- are used as prefixes for multiple identical substituents (e.g., dimethyl, trimethyl).
Halides and Functional Groups
- Halogen substituents are named as prefixes: fluoro (F), chloro (Cl), bromo (Br), iodo (I).
- Functional groups like carbonyl (C=O) change the suffix or prefix of the compound's name.
- Additional groups may be referenced as "-o" or "-yl" depending on their attachment.
Rules and Order of Naming
- Rule number five emphasizes using alphabetical order when listing different substituents.
- The positions of all substituents are clearly indicated by numbers.
- Numbers are separated by commas; numbers and names are separated by hyphens.
Example Names
- "3-ethyl-2-methylpentane" indicates an ethyl group at carbon 3 and a methyl group at carbon 2 of pentane.
- "5-propyl-3,3-dimethylheptane" has a propyl group at carbon 5 and two methyl groups at carbon 3 of heptane.
Key Terms & Definitions
- Substituent — An atom or group attached to the main carbon chain, modifying its structure.
- Parent Hydrocarbon — The longest carbon chain forming the base of the compound's name.
- Alkyl group — A hydrocarbon substituent derived from alkanes.
- IUPAC Nomenclature — International set of rules for naming organic compounds.
- Halide — A substituent derived from halogen atoms (F, Cl, Br, I).
Action Items / Next Steps
- Review the rules for numbering and naming organic compounds.
- Practice naming examples with various substituents following IUPAC rules.