WLS-CHEM10021-Org-CompiledHandoutNotes-v2-2024

Introduction to Organic Chemistry

• Course: CHEM10021 Chemistry for Bioscientists

• Lecturer: Dr. Lu Shin Wong (l.s.wong@manchester.ac.uk)

• Location: Manchester Institute of Biotechnology (MIB) 2.014

Course Structure

• Feedback appreciated on material delivery

• Office hours available through email appointment

• Recommended Textbooks:

  • P. Y. Bruice, Organic Chemistry (Prentice Hall)

  • F. A. Carey, Organic Chemistry (McGraw-Hill)

  • M. A. Fox, J. A. Whitesell, Organic Chemistry (Bartlett and Jones)

• Course Plan includes:

  • Series of videos with practice questions

  • Live Q&A sessions

  • Written notes available on Blackboard

Key Concepts in Organic Chemistry

Structural Diagrams

• Importance of various representations of organic molecules

• Shape and geometry significantly affect chemical and physical properties:

  • Csp: Linear (X-C-X angle 180°)

  • Csp2: Trigonal (X-C-X angle 120°)

  • Csp3: Tetrahedral (X-C-X angle 109°)

Hybridisation of Carbon

• Consistent drawing conveys three-dimensional structure

• Necessary structural information without clutter

Acidity and Basicity

Concepts

• Dissociation of O-H bond creates an oxygen anion and a proton (H3O+)

• Dissociation constant Ka illustrates acidity

• Stabilization of anion enhances acidity

Equilibria & pKa System

• Formation of N-H bonds produces ammonium cation

• pKa = - log Ka; useful for wide ranges of acidity

Lewis Acidity and Basicity

• IUPAC definitions:

  • Electron-pair acceptor: Acid

  • Electron-pair donor: Base

Electron Delocalisation

Stability of Organic Molecules

• Replacing carbon with oxygen in a molecule increases acidity through anion stabilization.

• Carboxylate anions stabilize through resonance structures.

Resonance Structures

• Represented by curved arrows showing electron movement

• Stability increases with greater electron delocalisation

Benzene and Aromaticity

Properties of Benzene

• Molecular formula: C6H6

• Physical: Colorless liquid, boiling/melting points at 81°C/5°C

• Chemical: Reactivity shows substitution rather than addition

Huckel's Rule

• Aromatic compounds need cyclic, planar structures with (4n + 2) π-electrons

• Stability and reactions depend on electron count

Chirality and Isomerism

Definitions

• Chiral objects: Non-superimposable mirror images

• Enantiomers: Chiral compounds that are mirror images

• Diastereoisomers: Non-mirror image stereoisomers

Importance in Biochemistry

• Enantiomers show different physiological responses

• Amino acids and nucleic acids are stereospecific

Examination Skills Require:

1. Understanding molecular structures acting as Lewis acids or bases.

2. Drawing equilibria for acids and bases with dissociation constants.

3. Describing resonance and electron delocalisation concepts.

4. Identifying stable resonance forms and hybrid structures.

5. Analyzing stability impacts of resonance in carbonyl-containing groups.

6. Drawing and explaining conformational preferences in hydrocarbons.

7. Applying E/Z nomenclature for stereo isomers.

8. Identifying and defining properties of stereoisomers and chiral centers.