Hammond Postulate Practice Problems
Deuterium (D) is the hydrogen isotope of mass number 2. Deuterium shows almost identical chemistry to that of hydrogen, except that C−D bond is slightly stronger than the C−H bond by 5.0 kJ/mol, so that when a C−D bond is broken in a rate-limiting step, the reaction rate tends to be slower (as opposed to a C−H bond), an effect called a kinetic isotope effect.
When the chlorination of methane was compared to that of propane, experimental results showed that methane has a much larger isotope effect than propane. Consider the thermodynamics of the chlorination of methane and the chlorination of propane and explain this phenomenon using the Hammond postulate.
Illustrate the representation of the transition state for both the forward and reverse reactions
Determine the most likely transition state for the given conversion. Explain your response.
Which of the given electrophilic addition reactions would you expect to be more selective toward the carbocation formation? Explain your answer.
Determine whether the transition state structures for the given coordinate diagrams are greater in similarity to the reactant's structure or the product's structure.
Cyclopentene undergoes the following light-promoted reaction in the presence of a small amount of bromine.
(i) Write the structure of the rate-limiting transition state.
(ii) Determine which intermediate most closely resembles the rate-limiting transition state based on Hammond's postulate.