Possible Exp. 6 Questions

Question 1

The center carbon in a carbonation is _______ hybridized.

Answer 1

sp2

Question 2

What is the geometry of the center carbon in a carbocation?

Answer 2

Trigonal planar

Question 3

What is the bond angle of the carbonation to its three substituents?

Answer 3

120 degrees

Question 4

What is the relative order of stability for carbocations?

Answer 4

Allylic>tertiary>secondary>primary>methyl

Question 5

Why is the allylic carbocation the most stable?

Answer 5

The positive charge can be delocalized through resonance

Question 6

Alkyl groups can help stabilize through _______ effects.

Answer 6

Inductive

Question 7

What is an inductive effect?

Answer 7

The donation of electron density via sigma bonds

Question 8

The more alkyl groups attached to the carbocation, the (more, less) stable it will be.

Answer 8

More

Question 9

Is the methyl carbocation believed to ever form?

Answer 9

No

Question 10

Why is the methyl carbocation believed to never form?

Answer 10

It is so unstable it cannot be isolated.

Question 11

What is the “super” allylic carbocation?

Answer 11

Triphenylmethyl carbocation

Question 12

Why is the triphenylmethyl carbocation so stable?

Answer 12

It has 10 resonance structures.

Question 13

In this experiment, ________ was first dissolved in _________.

Answer 13

Triphenylmethanol, acetic acid

Question 14

Acetic acid is a _______.

Answer 14

Good ionizing, polar protic solvent.

Question 15

Hydrobromic acid is a _______.

Answer 15

Strong acid and a nucleophile

Question 16

The intermediate carbocation in this experiment reacted with ________ immediately.

Answer 16

The bromide ion

Question 17

What kind of reaction does triphenylmethanol undergo?

Answer 17

SN1

Question 18

Why does triphenylmethanol undergo an SN1 reaction?

Answer 18

It is a tertiary alcohol

Question 19

What does the “S” in SN 1 stand for?

Answer 19

Substituted

Question 20

What does the “N” in SN 1 stand for?

Answer 20

Nucleophile

Question 21

What was the nucleophile in this reaction?

Answer 21

Bromide ion

Question 22

What does the “1” in SN1 stand for?

Answer 22

The fact that this reaction is unimolecular, meaning that a single molecule is present in the transition state. One substituent must leave before another can attack

Question 23

What does the “2” in SN2 stand for?

Answer 23

The fact that this reaction is bimolecular, meaning that two molecules are present in the transition state.

Question 24

Because the nucleophile attacks while the leaving group is leaving, SN2 reactions are known as ______ _______.

Answer 24

Concerted processes

Question 25

SN2 reactions involve ______ _______ of -OH

Answer 25

Direct displacement

Question 26

How many steps are involved in an SN1 reaction? SN2?

Answer 26

2 steps-> SN1 | 1 step->SN2

Question 27

What is the solvent choice for an SN1 reaction? SN2?

Answer 27

SN1: Polar, protic solvent SN2: Polar, aprotic solvent

Question 28

What is an example of a polar protic solvent?

Answer 28

Water, methanol, ethanol, acetic acid, etc.

Question 29

What is an example of a polar aprotic solvent?

Answer 29

DMSO, acetone, dichloromethane, diethyl ether

Question 30

What is the leaving group in an SN1 reaction? SN2?

Answer 30

SN1: Tertiary, secondary SN2: Secondary, primary, methyl

Question 31

How strong should the nucleophile be in an SN 1 reaction? SN2?

Answer 31

SN1: Moderate to weak, H2O, NH3, CH3OH SN2: Moderate to strong, CN-, N3-, CH3S-, HO-, Br-, I-

Question 32

How is the stereocenter rearranged during an SN1 reaction? SN2?

Answer 32

SN1: A racemic mixture is formed (equal parts of both configurations) SN2: Final product is inversion of stereochemistry

Question 33

Does an SN1 reaction form a carbocation? SN2?

Answer 33

SN1: Yes. A carbocation intermediate is formed during the rate limiting step SN2: No. The reaction is concerted

Question 34

What are the two reasons why a tertiary alcohol and a primary alcohol undergo two different types of reactions?

Answer 34

Stability and steric hindrance

Question 35

Tertiary carbocations are very (stable, unstable), and they have a very (high, low) energy of activation for their formation.

Answer 35

Very, low

Question 36

Primary carbocations are very (stable, unstable), and they have a very (high, low) energy of activation for their formation.

Answer 36

Unstable, high

Question 37

The kind of reaction undertaken in this reaction is a _______ reaction.

Answer 37

Substitution.

Question 38

What kind of solvent is acetic acid?

Answer 38

Polar protic.

Question 39

Alkyl groups are electron (donating, accepting)

Answer 39

Donating

Question 40

More substituted = ?

Answer 40

More stable