Ch. 6 - Thermodynamics and KineticsWorksheetSee 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

The Hammond-Postulate more accurately describes what transition states look like.

 

Paraphrased version: 

  • “Transition states most closely resemble the species with the highest energy”

Concept #1: Defining the Hammond Postulate.

  • Early transition state = Resembles reagents
  • Late transition state = Resembles products 

Example #1: Using radical chlorination to explain the Hammond Postulate. 

Example #2: Using radical bromination to explain the Hammond Postulate. 

Additional Problems
The reaction coordinate diagram below is an example of the application of Hammond postulate to carbocation formation in an SN1 reaction. Based on the reaction coordinate diagram below, which of the following statements is FALSE? A. The relative stabilities of the carbocation decreases in the following order: 3o > 2o > 1o B. The transition state shifts towards the reactant with increasing carbocation stability. C. The transition state become more stable as the reaction becomes less endothermic. D. The most stable transition state resembles the product more than any other transition state.
(c) Does the structure of the transition state more closely resemble reactants or products? Why? 
The reaction coordinate diagram below is an example of the application of Hammond postulate to carbocation formation in an SN1 reaction. Based on the reaction coordinate diagram below, which of the following statements is FALSE?   A. The relative stabilities of the carbocation decreases in the following order: 3 o > 2o >1o B. The transition state shifts towards the reactant with increasing carbocation stability. C. The transition state become more stable as the reaction becomes less endothermic. D. The most stable transition state resembles the product more than any other transition state.    
True of False: According to Hammond's postulate, an endergonic reaction's transition state resembles the reactants more than the products.
By applying Hammond’s postulate to the potential energy diagram for this reaction, we can say that: A. the structure of 2 is more carbocation-like than 4 B. the structure of 2 is less carbocation-like than 4 C. the structure of 2 resembles 1 more than it resembles 3 D. the structure of 4 resembles 5 more than it resembles 3 
Consider the following reaction: (g) Draw the transition state of this process, and identify its location on the energy diagram.
Consider the following reaction: (h) Is the transition state closer in structure to the reactants or products? Explain.