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.