Exam 3

Question 1

What happens to axial substituents when you do a chair flip?

Answer 1

They become equatorial substituents

Question 1

What happens to equitorial substituents when you do a chair flip?

Answer 1

They become axial substiuents

Question 2

What happens to up substituents when you do a chair flip?

Answer 2

They become down

Question 3

What happens to down substituents when you do a chair flip?

Answer 3

They become up

Question 4

What kind of substituents are these?

Answer 4

Axial Hydrogens

Question 5

What kind of substituents are these?

Answer 5

Equatorial Hydrogens

Question 6

Which confirmation group is preferred by groups and why?

Answer 6

Equatorial because there are no 1,3 diaxial van der waal repulsions

Question 7

What is a syn addition?

Answer 7

Substituents get added to the same side

Question 8

What is an anti addition?

Answer 8

Substituents get added to different sides

Question 9

What is a substitution with retention of configuration?

Answer 9

The leaving group is on the same side as the nucleophile. The asymmetric carbons have the same configuration.

Question 10

What is substitution with inversion of configuration?

Answer 10

Leaving group is on different side than nucleophile. Asymmetric carbons have different configurations

Question 11

What stereochemistry is the addition of a halogen to an alkene? Why?

Answer 11

Anti-addition; When you make a halogen ion, you occupy 1 side of the face so the opposite side is only space available for another addition.

Question 12

What are stereospecific reactions?

Answer 12

Reactions in which different stereoisomers of a starting material give differ stereoisomers of a product

Question 13

What is the stereochemistry of a hydroboration-oxidation?

Answer 13

Syn Addition

Question 14

What is the stereochemistry of oxymercuration-reduction?

Answer 14

Anti addition

Question 15

What is the stereochemistry of a hydrogenation reaction?

Answer 15

Syn addition

Question 16

To be an alcohol, the OH group has to be attached to what?

Answer 16

An sp3 carbon

Question 17

What are the intermolecular forces?

Answer 17

1. Van der Waal’s attraction
2. Polarizability
3. Permanent Dipoles
4. Hydrogen bonds

Question 18

What happens to the Van der Waal’s attraction with the surface area of the interacting electron cloud?

Answer 18

Van der Waals’s attraction increases with increasing surface area/molar mass

Question 19

What is the relationship between Van Der Waals’s attraction and boiling point?

Answer 19

As VDW attraction increases, boiling point increases because the bond is stronger and therefore harder to break

Question 20

What is polarizability?

Answer 20

The polarizability of a molecule is a direct measure of how easy it is to create a dipole moment in a molecule

Question 21

What is the relationship between EN and polarizability?

Answer 21

The more EN the halogen, the less polarizability and therefore the weaker the VDW attraction

Question 22

What is a hydrogen bond IMF?

Answer 22

An attraction between the H on one atom with an unshared electron pair on another

Question 23

What is a protic solvent?

Answer 23

An H-bond donor

Question 24

What does it mean if a solvent is a donor?

Answer 24

Lewis Base / electron donator

Question 25

What high dielectric constant classifies a molecule as polar?

Answer 25

>15 = polar

Question 26

What is a polar solvent?

Answer 26

A polar solvent effectively separates, or shields ions from one another

Question 27

What does the rule like dissolves like mean?

Answer 27

Molecules with similar IMFs can break & form new IMFs between the solute and solvent, therefore dissolving in one another

Question 28

When do nucleophilic substitution reactions happen?

Answer 28

Occur with primary alkyl halides

Question 29

If you make an alkene as a product, is the reaction substitution or b-elimination?

Answer 29

B-elimination

Question 30

What is the a-carbon in a B-elimination reaction?

Answer 30

The carbon bonded to the halogen

Question 31

When do B-elimination reactions occur?

Answer 31

Occur with tertiary alkyl halides

Question 32

What kind of reactions do secondary alkyl halides undergo?

Answer 32

Both substitution & B-elimination

Question 33

Which side does equilibrium favor?

Answer 33

Equilibrium favors side with the weaker base

Question 34

What is a Sn2 reacton?

Answer 34

Substitution-Nucleophilic-Bimolecular. A mechanism in which electron-pair donation by a nucleophile to an atom displaces a leaving group from the same atom in a concerted manner (occurs simultaneously)

Question 35

What does bimolecular mean?

Answer 35

The rate-limiting step of the reaction involves 2 species

Question 36

Which reaction is faster: Sn2 or Acid-Base?

Answer 36

Acid-base reactions occur instantaneously while most nucleophilic substitution reactions are much slower

Question 37

What is a factor that influences the rate of Sn2 reactions?

Answer 37

The less branching there is on the alpha carbon and beta carbons, the faster the reaction will go.