Lecture 4: functional groups

Question 1

What is a heteroatom?

Answer 1

Any atom that is not C or H

Question 2

Is a carbonyl group a nucleophile or an electrophile?

Answer 2

1. C atom is electrophile
2. O atom is nucleophile

Question 3

What is a conjugated diene?

Answer 3

2 double bonds separated by a single bond

Question 4

Why is a molecule more stable when there is resonance?

Answer 4

1. When p orbitals overlap, electron clouds in the pi bonds are spread over more atoms
2. This reduces the overall energy of the molecule, thus increasing stability.

Question 5

What kind of resonance structures are more stable?

Answer 5

1. Structures with more covalent bonds
2. Structures with fewer formal charges
3. Structures with the negative charges placed on the more electronegative atom
4. Structures that dont violate the octet rule

Question 6

What groups exert an electron donating inductive effect?

Answer 6

alkyl groups

Question 7

What groups exert an electron withdrawing inductive effect?

Answer 7

1. Halogens
2. -OH, -OR
3. -NH2, -NHR, -NR2, -NH3+
4. -CF3
5. -NO2
6. -CN

Question 8

Fill in the blank:
For there to be a resonance effect, the participating atoms must be ________.

Answer 8

Planar

Question 9

What kind of atoms are compatible with each other for resonance effect?

Answer 9

Atoms in the same period

Question 10

Why is the electron donating resonance effect of Cl not as significant as its electron withdrawing inductive effect?

Answer 10

Because Cl and C are not compatible in size, so the resonance effect is not as strong

Question 11

Why are alkyl groups attached to a benzene ring electron donating?

Answer 11

Due to hyperconjugation

Question 12

What happens during hyperconjugation?

Answer 12

There is overlap between the C-H molecular orbital and the p orbitals of the benzene ring

Question 13

Why is the keto form more predominant than the enol form?

Answer 13

1. Because the oxy-acid of the enol form is more acidic than the carbon acid of the keto form.
2. The weaker acid is more stable because the proton is held more strongly.