Nomenclature_of_organic_compounds_L3 (4)

Nomenclature of Organic Compounds

  • Introduction to organic compound nomenclature.

  • Examples demonstrate various molecular structures.

Alkanes

  • Define alkanes: saturated hydrocarbons with single bonds only.

Rules for Naming Alkanes

  1. Identify the Longest Continuous Carbon Chain

    • Determines the base name of the alkane.

  2. Number the Carbon Chain

    • Start numbering from the end closest to a substituent to give lowest numbers to substituents.

    • If two substituents are equidistant, prioritize based on alphabetical order.

  3. Identify and Name Alkyl Substituents

    • Named by substituting -ane with -yl (e.g., methane to methyl).

    • Use prefixes for multiple identical substituents: di- (2), tri- (3), tetra- (4), etc.

  4. Assign Numbers to the Substituents

    • Place the position number before each substituent name. Use commas and dashes for clear separation.

Examples of Simple Unbranched Alkanes

  • Molecular and Structural Formulas:

    • Methane: C₁H₄ - CH₄

    • Ethane: C₂H₆ - CH₃CH₃

    • Propane: C₃H₈ - CH₃CH₂CH₃

    • Butane: C₄H₁₀ - CH₃CH₂CH₂CH₃

    • Pentane: C₅H₁₂ - CH₃(CH₂)₃CH₃

    • Hexane: C₆H₁₄ - CH₃(CH₂)₄CH₃

    • Heptane: C₇H₁₆ - CH₃(CH₂)₅CH₃

    • Octane: C₈H₁₈ - CH₃(CH₂)₆CH₃

    • Nonane: C₉H₂₀ - CH₃(CH₂)₇CH₃

    • Decane: C₁₀H₂₂ - CH₃(CH₂)₈CH₃

Alkyl Groups

  • Definition: Substituent derived from an alkane by removal of a hydrogen atom. Represented as R-.

  • Named by changing -ane to -yl.

  • Common Alkyl Groups:

    • Methyl: -CH₃

    • Ethyl: -CH₂CH₃

    • Propyl: -CH₂CH₂CH₃

    • Butyl: -CH₂CH₂CH₂CH₃

    • Isobutyl: -CH(CH₃)₂

Naming Branched Alkanes

  • Must identify substituents and analyze structure for alphabetical arrangement before numbering.

General Rules in Worksheet Examples

  • Naming alkanes includes drawing their structure accurately, incorporating elements such as:

    • Carbon bonding (single-bonded)

    • Substituent placement (indexing)

Alkenes

  • Introduction to alkenes: Unsaturated hydrocarbons containing at least one double bond.

Rules for Naming Alkenes

  1. Identify the Parent Hydrocarbon

    • Longest carbon chain including the double bond; use suffix -ene.

  2. Number the Chain

    • Start from the nearest end to the double bond.

  3. Write the Full Name

    • Number substituents based on their positions; indicate double bond location.

Alkynes

  • Introduction to alkynes: Unsaturated hydrocarbons with at least one triple bond.

Rules for Naming Alkynes

  1. Identify the Parent Chain

    • Like alkenes, the longest chain needs to include the triple bond.

  2. Identify Substituents

  3. Number the Parent Chain

    • Ensure the lowest locant for the triple bond.

  4. Alphabetize Substituents

Functional Groups Nomenclature

  • Developing a systematic approach in recognizing longest chains containing functional groups to provide the lowest numbers in specific categories:

    • Alkenes: -ene

    • Alkynes: -yne

    • Alcohols: -ol

    • Aldehydes: -al

    • Ketones: -one

    • Carboxylic Acids: -oic acid

Specialized Naming: Alcohols, Aldehydes, and Esters

  • Alcohols and Carboxylic Acids: Identify functional groups and apply respective suffixes.

  • Esters: Naming based on alkyl part and carboxylate part; typically expressed as alkyl carboxylate. Example: Ethyl Ethanoate.

Practice and Application

  • Various worksheets requiring structural formulation and naming based on given IUPAC rules across alkanes, alkenes, alkynes, and functional groups. Discussions emphasized tricky areas such as presence of chains, double/triple bonds and substituent interactions.