22,_24_&_25_Introduction_to_organic_chemistry,_Alkane_&_Alkene_Lecture

Unit 4: Organic Chemistry Overview

• Chapter Titles:

  • Introduction to Organic Chemistry

  • Crude Oil

  • Alkanes

  • Alkenes

  • Alcohols

  • Carboxylic Acids

  • Esters

  • Synthetic Polymers

Chapter 22: Introduction to Organic Chemistry

• Definition: Study of organic compounds, including their structures, properties, compositions, reactions, and preparations.

• Organic Compounds: Covalent compounds primarily containing carbon, commonly derived from living organisms.

  • Characteristics:

    • Contains carbon and hydrogen, possibly oxygen, nitrogen, and chlorine.

    • Must have at least one carbon-carbon (C─C) or carbon-hydrogen (C─H) bond.

• Hydrocarbons: Simplest organic compounds consisting solely of carbon and hydrogen.

• Saturation Levels:

  • Saturated: Compounds with single bonds only.

  • Unsaturated: Compounds that contain double or triple bonds.

Chapter 23: Organic Compounds

• Types of Hydrocarbons:

  • Alkanes (CnH2n+2): Saturated hydrocarbons with only single bonds.

  • Alkenes (CnH2n): Unsaturated hydrocarbons containing one or more double bonds (C=C).

  • Alkynes (CnH2n−2): Unsaturated hydrocarbons with one or more triple bonds (C≡C).

  • Alcohols (CnH2n+1OH): Organic compounds containing hydroxyl group (−OH).

  • Carboxylic Acids (CnH2nO2): Containing carboxyl group (−COOH).

Chapter 24: Alkanes

• Homologous Series: Alkanes follow a pattern regarding molecular structure and properties:

  • General Formula: CnH2n+2 where n = number of carbon atoms.

  • Types of Bonds: Only single covalent bonds.

  • Reactions: Predominantly substitution reactions.

• Properties:

  • First four are gases; higher molecular weights lead to liquids and solids.

  • Increasing molecular size leads to higher boiling/melting points due to stronger intermolecular forces.

• Physical Properties Table:

  • Methane (CH4): Gas, -182°C melting, -162°C boiling.

  • Ethane (C2H6): Gas, -183°C melting, -89°C boiling.

  • Propane (C3H8): Gas, -188°C melting, -42°C boiling.

  • Butane (C4H10): Gas, -138°C melting, 0°C boiling.

  • Pentane (C5H12): Liquid, -130°C melting, 36°C boiling.

Chapter 25: Alkenes

• Definition: More reactive than alkanes due to presence of double carbon-carbon bond (C=C).

• Reactions: Alkenes participate in various reactions including:

  • Combustion: CH2=CH2 + 3O2 -> 2CO2 + 2H2O (ethene combustion).

  • Addition Reactions:

    • Halogenation (test for unsaturation): C2H4 + Br2 -> C2H4Br2.

    • Hydrogenation: C2H4 + H2 → C2H6 (turns ethene into ethane).

    • Hydration: C2H4 + H2O → C2H5OH (ethanol production).

Structural Isomerism

• Definition: Structural isomers have the same molecular formula but different structures. For example:

  • Butane and methylpropane both have C4H10 but different structural representations.

• Isomers of C5H12 include:

  • Pentane

  • 2-Methylbutane

  • 2,2-Dimethylbutane

Naming Organic Compounds

• IUPAC Nomenclature System:

  • Identify the longest carbon chain.

  • Identify functional groups.

  • Number carbons starting from the end closest to the functional group.

• **Examples:

  • Alkanes end in -ane (e.g., ethane).

  • Alkenes end in -ene (e.g., ethene).

  • Alcohols end in -ol (e.g., ethanol).

  • Carboxylic acids end in -oic acid (e.g., ethanoic acid).

Summary of Functional Groups

• Alkanes: CnH2n+2, none.

• Alkenes: CnH2n, C=C.

• Alcohols: CnH2n+1OH, −OH.

• Carboxylic Acids: CnH2nO2, −COOH.

Conclusion

• Understanding organic compounds, their structures, properties, and reactions is vital for real-world applications, such as combustion and synthetic reactions in industry.