01 CHEM2008 Intro. to Organic Chemistry (2) (2) (1)

Organic Chemistry Overview

  • Organic Chemistry involves the study of carbon compounds, excluding oxides of carbon, carbonates, and hydrogen carbonates.

Specific Objectives

  • Define the following key terms:
      - Organic Compound: Compounds primarily made of carbon atoms.
      - Homologous Series: A series of compounds with similar properties and a consistent structural formula.
      - Functional Group: A specific group of atoms within a molecule that determines characteristic reactions.
      - General Formula: A simplified expression that defines the composition of a compound in a homologous series.
      - Structural Formula: A representation of a molecule that shows its atoms and how they are connected.
      - Molecular Formula: A formula that shows the number and type of atoms in a molecule.

Key Concepts in Organic Chemistry

  • Hydrocarbon: A compound consisting solely of hydrogen and carbon.
  • Cyclic Compounds: Compounds where carbon atoms are arranged in a closed ring.
  • Writing general and molecular formulae for various organic compounds:
      - Alkanes, Alkenes, Alkynes, Alcohols, Aldehydes, Ketones, Carboxylic Acids, Esters.
  • Draw structural formulae for isomers of the above compounds.
  • Naming conventions using the IUPAC system.

Homologous Series Characteristics

  1. General Molecular Formula: All members share a common formula (e.g., Alkanes: CnH2n+2).
  2. Incremental Difference: Each successive member differs by a -CH2 group.
  3. Similar Chemical Properties: Members exhibit comparable reactivity.
  4. Gradual Change in Physical Properties: As the number of carbon atoms increases, properties like melting point, boiling point, and density increase, while water solubility decreases.
  5. Preparation Methods: General methods can synthesize any member of the series.

General Molecular Formula of Common Functional Groups

  • Alkanes: CnH2n+2
  • Alkenes: CnH2n (double bond >C=C<)
  • Alkynes: CnH2n-2
  • Alcohols: CnH2n+1OH (-OH)
  • Carboxylic Acids: CnH2n+1COOH (-COOH)
  • Esters: CnH2n+1COOCnH2n+1 (-COO)
  • Aldehydes: CnH2n+1CHO (-CHO)
  • Ketones: CnH2nCO (>C=O)

Molecular and Structural Formulae

  • Molecular Formula: Represents the total number of each type of atom (e.g., C4H10 for butane, C6H14 for hexane).
  • Structural Formula: Shows connectivity and bonding between atoms. Types include:
      - Displayed Formula: All bonds are explicitly shown.
      - Condensed Formula: Bonds are implied, focusing on atom arrangement.

General Formula in Hydrocarbons

  • Hydrocarbons consist of carbon and hydrogen only. In cyclic compounds, carbon atoms form a ring.

Isomerism

  • Isomerism: Different compounds with the same molecular formula but distinct structural arrangements.
  • Example of isomers for C4H10, C5H12, and an exercise to draw isomers for C6H14.

IUPAC Naming System for Alkanes

  1. Identify the longest carbon chain (parent alkane).
  2. Number the chain to minimize numbers assigned to substituents.
  3. List substituents alphabetically before the parent alkane name, including a number for each.
  4. Use prefixes (di-, tri-, tetra-) for multiple substituents.
  5. Use commas between numbers and dashes between numbers and letters.

IUPAC Naming Guidelines for Various Hydrocarbons

  • Alkenes: Change suffix from 'ane' to 'ene', ensuring the double bond has the lowest number.
  • Alkynes: Change suffix from 'ane' to 'yne', indicating the position of the triple bond.
  • Alcohols: Change suffix from 'e' to 'ol', indicating the –OH group position.
  • Carboxylic Acids: Replace 'e' with 'oic acid', with the carboxyl group always at position 1.
  • Aldehydes: Change 'e' to 'al', with the carbonyl group at position 1.
  • Ketones: Change 'e' to 'one', assigning the lowest number to the carbonyl carbon.
  • Esters: General formula is represented as CnH2n+1 COO CnH2n+1.

Advanced Naming Rules

  • Handle multiple bonds with specific numbering for prioritization.
  • Ensure that both double and triple bonds are considered for the lowest numbers, maintaining the correct suffix rules.

Structural Isomerism

  • Watch video links for examples regarding isomerism, IUPAC nomenclature practice, and cycloalkenes.