The Final Chapter.
No description yet. This curated deck is ready for daily study.
Card preview (7)
Are conjugated or isolated bonds stronger and why?
Conjugated bonds- b/c they have resonance stabilization.
Is a cumulated diene or an terminal alkyne stronger?
terminal alkyne - the cumulated diene has a lot of reactive pi bonding in once place.
What is the expected product in a reaction of a conjugated diene and HBr.
two products - 1,2 bromoalkene, and 1,4 bromoalkene.
Under normal conditions (40C) for addition to conjugated dienes, what is the predominant product?
the 1,4 - addition, internal alkene is more stable.
Under cold conditions (-80C) for addition to conjugated dienes, what is the predominant product?
the 1,2 - addition, b/c the internal carbocation is more stable (forms easier.)
In which reaction is NBS used as a source of Br2?
Free-radical allylic bromination. (reacts with HBr by-product to regenerate molecule of Br2.)
Tell me about the REAL reason why 1,3 - butadiene is more stable than a similar compound with isolated double bonds.
1,3 - butadiene has four pi-bonding electrons that reside in two energy conformations. The lowest energy conformation contains 2 of these electrons, and evenly disperses them within the pi-orbitals of all four sp2 - hybridized carbons. The second pair of electrons reside in a slightly higher energy conformation, which allows them to only hangout between C1-C2 and C3-C4. This is why these carbons have more pi-bonding character. The partial pi-bonding character about the C3-C4 bond lowers the energy of the planar conformation, making it a more stable molecule.