Basic Organic Chemistry Notes

Organic vs Inorganic Compounds

  • Definition: Organic compounds are primarily composed of carbon atoms, while inorganic compounds consist of other elements.
  • Characteristics:
  • Organic Compounds: Derived from living organisms, contain carbon, typically have lower boiling points, often non-polar, and can be volatile.
  • Inorganic Compounds: Mainly obtained from non-living sources, may contain metals and other elements, usually have higher boiling points, and can be ionic.

Nomenclature of Organic Compounds

  • Stem: Indicates the number of carbon atoms in the longest chain. Common prefixes include:
  • 1 carbon: meth-
  • 2 carbons: eth-
  • 3 carbons: prop-
  • 4 carbons: but-
  • 5 carbons: pent-
  • 6 carbons: hex-
  • 7 carbons: hept-
  • 8 carbons: oct-
  • 9 carbons: non-
  • 10 carbons: dec-
  • Functional Groups: The suffix identifies the functional group (e.g., -ol for alcohols).
  • Substituents: Add prefix + -yl (e.g., methyl, ethyl) for side chains.
  • Side chains are numbered based on their position on the main carbon chain.

Isomerism

  • Definition: Isomers are compounds with the same molecular formula but different structural arrangements.
  • Types of Isomers:
  • Structural Isomers: Different connections of atoms.
  • Stereoisomers: Same connections but different spatial arrangements (includes geometric and optical isomers).

Special Nature of Carbon

  • Tetravalence: Carbon can form four strong covalent bonds due to its four unpaired valence electrons.
  • Catenation: Carbon can bond with itself to form chains, branched structures, and rings.
  • Multiple Bonds: Carbon can form double or triple bonds, enhancing its versatility (sp2 for double bonds, sp3 for single bonds).

Bonding and Molecular Structures

  • Types of Bonds:
  • Sigma (σ) and Pi (π) Bonds: Sigma bonds are single bonds, and pi bonds are found in double/triple bonds.
  • Molecular Formulas: Indicates the number of each atom in a molecule.
  • Empirical Formulas: Shows the simplest ratio of atoms.
  • Example: Empirical formula of a compound with C: 35.8%, H: 4.5%, O: 59.7% is C4H6O5.

Structural Representation of Organic Molecules

  • Displayed Formula: Shows all bonds as lines, indicating the arrangement of atoms within the compound visually.
  • Skeletal Formula: Simplified drawing with carbon skeleton and functional groups, omitting hydrogen where implicit.

Hydrocarbons

  • Classification:
  • Saturated: Alkanes (only single bonds).
  • Unsaturated: Alkenes (at least one double bond), Alkynes (at least one triple bond).
  • Aromatic: Compounds containing one or more benzene rings.

Naming Alkanes

  • Identify the longest continuous carbon chain for proper naming and number from the end closest to a substituent.
  • Use prefixes to indicate substituents and their positions on the base carbon chain (e.g., 2-methylbutane).

Conclusion

  • Understanding these principles is essential to mastering the basics of organic chemistry, including identifying and naming various organic compounds, recognizing isomerism, and understanding how molecular structures relate to chemical properties and reactions.