Exam 4: The Study of Chemical Reactions

Write the structures of all of the monobromination products of 1,1,3,3-tetramethylcyclobutane.

Will the sign of ΔS° in the combustion of propane be positive, negative or zero?

________ is the study of reaction rates.

Does one expect ΔS° in a propagation step of the free-radical chlorination of methane to be greater than zero, less than zero, or approximately equal to zero? Briefly explain your choice.

Consider the elementary step in the solvolysis of isopropyl chloride shown below and write the rate equation for this step. (CH₃)₂CHCl → (CH₃)₂CH⁺ + Cl^-

When the free radical halogenation of methylpropane is done with chlorine, the major product is 1-chloro-2-methylpropane, but if bromine is used, the major product is 2-bromo-2-methylpropane. Explain the difference in the regiochemistry of these reactions.

Of the two C-H bonds shown, which has the smaller bond dissociation energy? Explain your choice. (CH₃)₂CH-H vs. CH₃CH₂-H

If stronger bonds are formed and weaker bonds are broken, then the reaction is ________.

Predict the major monobromination product in the following reaction. (CH₃)₃CCH₂CH₃ + Br₂

Which H atom in the molecule shown will be most readily abstracted by a bromine radical?

What reactive species is produced in the initiation step of the free radical chlorination of 2,2-dimethylpropane?

Use the Hammond Postulate to explain why free radical brominations are more selective than free radical chlorinations.

How do alkyl substituents stabilize a carbocationic center to which they are attached?

Given the chlorination of acetone shown below, choose the correct rate law. CH₃COCH₃ + Cl₂ → CH₃COCH₂Cl + HCl

Free radical bromination of pentane results in poor yields of 1-bromopentane, while cyclopentane can be readily brominated under similar conditions to yield bromocyclopentane. Offer an explanation.

If a reaction is exothermic, then ________.

Predict the major monobromination product in the following reaction.

Consider the three-step mechanism for the reaction of A through intermediates B and C to produce D shown below. A → B E_a = 15 kcal/mol, ΔH° = 13 kcal/mol B → C E_a = 10 kcal/mol, ΔH° = -6 kcal/mol C → D E_a = 2 kcal/mol, ΔH° = -20 kcal/mol What's the enthalpy difference between reactant A and intermediate C?

Remove an H+ from the following structure to create the most reactive (least stable) carbanion.

For the reaction A + B → C + D, ΔG° = -5.00 kcal/mol. What is the corresponding equilibrium constant at R = 1.987 cal/mol∙K.