BMS1011 Wk2L1 Part B

Functional Groups Overview

• Discusses first groups of functional groups in organic chemistry, with a focus on alkanes, alkenes, alcohols, and amines.

Alkanes

• Definition: Saturated hydrocarbons, possessing single bonds.

• Structure:

  • Typically in linear chains, branched, or ring structures (cyclic alkanes).

  • Open-chain is referred to as aliphatic.

• Nomenclature:

  • Ends with '-ane' (e.g., methane, ethane).

  • Formulas:

    • General formula: C_nH_(2n+2) for alkanes; cyclic alkanes have two fewer hydrogens.

  • Bond angles are tetrahedral (109.5°).

• Visual Representation:

  • Lewis structures can be simplified to line drawings, representing hydrocarbons readily.

Alkenes

• Definition: Unsaturated hydrocarbons containing at least one double bond.

• Structure:

  • Presence of a double bond leads to sp² hybridization and a trigonal planar structure.

  • Bond angle is ~120°.

  • Configurations are locked due to p-orbital overlap preventing rotation around the double bond.

• Nomenclature:

  • Ends with '-ene' (e.g., ethene, propene).

Alkynes

• Definition: Unsaturated hydrocarbons with a triple bond.

• Structure:

  • Hybridization is sp, resulting in a linear configuration with a bond angle of 180°.

  • Two perpendicular p-orbitals engaged in pi bonding.

• Nomenclature:

  • Ends with '-yne' (e.g., ethyne, propyne).

Nomenclature Basics

• Structures generally follow:

  • Prefix: Indicates the number of carbon atoms.

  • Infix: Indicates the type of bond (single, double, triple).

  • Suffix: Indicates the functional group (e.g., -ane, -ene, -yne, -ol for alcohols, -amine for amines).

  • Important to identify the main chain of the molecule and longest carbon chain for naming purposes.

Alcohols

• Definition: Compounds with one or more hydroxyl (-OH) groups.

• Structure:

  • Introduces polarity to organic compounds, resulting in higher boiling points due to hydrogen bonding.

• Nomenclature:

  • Named with '-ol' (e.g., butanol). Position of -OH group is indicated (e.g., 1-butanol, 2-butanol).

  • Types of alcohols: Primary, secondary, tertiary based on the carbon bearing the -OH group.

  • Example: Primary alcohols have -OH on the end carbon, secondary on a carbon connected to two other carbons.

Amines

• Definition: Organic compounds that contain nitrogen, capable of forming multiple bonds.

• Structure:

  • Nitrogen forms three bonds and has a lone pair.

  • Similar hierarchy in naming as alcohols: primary (one carbon), secondary (two carbons), tertiary (three carbons).

• Nomenclature:

  • Named using the prefix 'N' to denote attached groups (e.g., N,N-dimethylamine).

• Chemical Behavior:

  • Basic substances; capable of forming hydrogen bonds impacting their boiling points.

  • Participate in acid-base reactions, transferring protons to form ammonium ions.

Conclusion

• The video delineates foundational classes of organic functional groups, preparing for more complex topics in organic chemistry.