Lecture 4: functional groups Flashcards
What is a heteroatom?
Any atom that is not C or H
Is a carbonyl group a nucleophile or an electrophile?
- C atom is electrophile
- O atom is nucleophile
What is a conjugated diene?
2 double bonds separated by a single bond
Why is a molecule more stable when there is resonance?
- When p orbitals overlap, electron clouds in the pi bonds are spread over more atoms
- This reduces the overall energy of the molecule, thus increasing stability.
What kind of resonance structures are more stable?
- Structures with more covalent bonds
- Structures with fewer formal charges
- Structures with the negative charges placed on the more electronegative atom
- Structures that dont violate the octet rule
What groups exert an electron donating inductive effect?
alkyl groups
What groups exert an electron withdrawing inductive effect?
- Halogens
- -OH, -OR
- -NH2, -NHR, -NR2, -NH3+
- -CF3
- -NO2
- -CN
Fill in the blank:
For there to be a resonance effect, the participating atoms must be ________.
Planar
What kind of atoms are compatible with each other for resonance effect?
Atoms in the same period
Why is the electron donating resonance effect of Cl not as significant as its electron withdrawing inductive effect?
Because Cl and C are not compatible in size, so the resonance effect is not as strong
Why are alkyl groups attached to a benzene ring electron donating?
Due to hyperconjugation
What happens during hyperconjugation?
There is overlap between the C-H molecular orbital and the p orbitals of the benzene ring
Why is the keto form more predominant than the enol form?
- Because the oxy-acid of the enol form is more acidic than the carbon acid of the keto form.
- The weaker acid is more stable because the proton is held more strongly.
