Chapter 15 Flashcards
What are the conditions that lead to kinetic control?
cold - low energy
Why is a kinetically controlled reaction irreversible?
product distribution is guided by relative differences in activation energy.
What are the conditions that lead to thermodynamic control?
heat - high energy
Why are thermodynamically controlled reactions reversible?
product distribution is guided by the relative stability of the products.
Why is the 1,2-addition product formed faster at all temperatures?
The intermediate that gives rise to the 1,2-addition product is a more stable 2* carbocation (more of the positive charge is on the secondary carbon in the transition state.)
Why doesn’t the 1,2-addition undergo reverse reaction under cold conditions?
the reverse reaction has a high activation energy, which is not overcome by many of the collisions occurring at a low energy state.
Why is the 1,4-addition product more stable?
It contains an internal alkene, whereas the 1,2-addition contains a terminal alkene.
Why does increasing the heat cause the 1,4-addition to predominate?
Increased energy of collisions provides enough energy to induce the reverse reaction of the 1,2-product. The 1,4-addition occurs and is more stable and therefore higher in concentration (does not undergo reverse reaction as easily.)
