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29 Cards in this Set

  • Front
  • Back
What is the electron donor called?
What is the electron acceptor called?
The electrophile
Is a nucleophile an anion or a cation?
Anion, (negatively charged, so wants to give off the excess electrons)
Is an electrophile an anion or a cation?
Cation, (positively charged, so wants the negative charge to neutralize it)
Are full orbitals higher or lower in energy than empty orbitals?
Full orbitals are lower in energy than empty orbitals, (which is why they want to be filled)
Why is activation energy required in the transfer of electrons to orbitals?
When the electrons move into an empty orbital, they have to go up in energy and this is part of the activation energy
When atomic orbitals interact, how many new molecular orbitals are formed?
Two - one above and one below the old orbitals
When is the energy gain of interacting orbitals the greatest and when is it the least?
Greatest when the 2 orbitals are the same and least when the 2 orbitals are very far apart.
What are the relevant orbitals of the nucleophile called?
Highest occupied molecular orbitals, (HOMO), because electrons want to come from the highest state of energy
What are the relevant orbitals of the nucleophile called?
Lowest unoccupied molecular orbital, because electrons want to go to the lowest state of energy
Why do molecules attract each other?
1. Attraction of opposite charges
2. Overlap of high-energy filled orbitals with low-energy empty orbitals
How must molecules approach one another in order to react?
1. Enough energy to overcome the repulsion
2. The right orientation to use any attraction
What characteristic do the most common type of nucleophiles have?
A nonbonding lone pair of electrons, (usually on heteroatoms, such as O,N,S, or P).
Give an analogy to think of nucleophiles and electrophiles.
Nucleophiles are involved in real estate that costs a lot, such as "loan" pairs, (which is why they are in the negative)

Electrophiles are empty real estate, (empty orbitals), that cost less money, so the electrons want to move there.
When there are no lone pair electrons to supply high-energy nonbonding orbitals to donate electrons, what is the next best provider?
Lower-energy filled pie orbitals rather than the even lower-energy sigma bonds. For example, simple alkenes are weakly nucleophilie and react with strong electrophiles, such as bromine.
What is an acid in terms of electrophiles/nucleophiles?
- Protic acids can donate protons to nucleophiles
- Lewis acids can donate more complicated cations to nucleophiles
What part of a C=O bond does a nucleophile attack?
The "crotch" of the double bond
Where can nucleophiles donate electrons to and where can electrophiles put the electrons?
Nucleophiles may donate electrons from:
1. a lone pair
2. a pie bond
3. a sigma bond

Electrophiles may place electrons in:
1. an empty orbital
2. an anti-bonding orbital of a pie bond or even a sigma bond
What are some nucleophilic functional groups?
NH2 and OH, because they have nonbonding loan pairs
What are some electrophilic functional groups?
Carbonyl compounds and alkyl halides, because they have low-energy LUMOS, (pie bond for C=O and sigma bond for C-X, respectively)
If the starting materials had no overall charge, can the products?
No, so if we start with a neutral molecule and make a cation, we must make an anion too.
When a nucleophile arrow goes to the crotch of a carbonyl group, where does the subsequent arrow of the carbonyl group go?
It goes from the middle of the double bond to the top of the O
What is the leaving group?
Functional group on the electrophile that makes off with the electrons of the old sigma bond
What is heterolytic fission/heterolysis?
Leaving group takes both electrons from the old pie bond
What is homolytic fission?
When a sigma bond breaks on nucleophile, rather than moving to one of the atoms as in heterolysis, one electron can go in either direction. Both fragments have an unpaired electron and are known as radicals.
How is homolytic fission represented?
Fish hooks
What can push a mechanism?
A lone pair or an anion
What can pull a mechanism?
A cation, an empty orbital, or the breaking of a reactive weak pie bond or sigma bond
What are 3 guidelines for writing your own arrow-pushing mechanisms?
1. Decided whether to think in a push or pull manner
2. Mark lone pairs on the nucleophilic atom
3. Curly arrows always move in the same direction. They never meet head on.