Ch. 5 - ChiralityWorksheetSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Another exception to the rule, these are compounds that remain achiral even though they have chiral centers!

Concept #1: Defining meso compounds.

  • Meso compounds have an internal line of symmetry (TEST 1), meaning they are actually achiral.
  • Follow the 2n – 1 rule. 

Concept #2: The 3 rules of meso compounds. 

A compound will be meso if it meets the following 3 criteria:

  1. It has 2 or more chiral centers.
  2. It is atomically symmetrical, meaning that is symmetrical in connectivity, not shape.   
  3. An even number of chiral centers have opposite configuration to each other (i.e. if one is R, the other is S). 

Is the following molecule meso and therefore achiral?

Example #1: Which of the following molecules are meso, and therefore achiral?

Is the following molecule meso and therefore achiral?

Example #2: Which of the following molecules are meso, and therefore achiral?