Chapter 6

Question 1

The chemistry of vinyl and aryl halides is different from that of alkyl halides because of their _______ and _______

Answer 1

bonding and hybridization

Question 2

halogens are more _______ than carbon, making the C-X bond _______

Answer 2

electronegative
polar

Question 3

For common (“trivial”) name as alkyl halide
1) name the _______ group
2) name the _______

Answer 3

alkyl
halide

Question 4

_______ dihalide: two halogen atoms are bonded to the same carbon

Answer 4

geminal

Question 5

______________ dihalide: two halogen atoms are bonded to adjacent carbons

Answer 5

vicinal

Question 6

the larger the surface area of an alkyl halide, the _______ the boiling point
- Larger _______ take priority

Answer 6

higher
halogen

Question 7

alkyl flourides and chlorides are _______ dense than water, so in bilayer it will occupy the _______ layer

Answer 7

less
top

Question 8

alkyl chlorides with 2 or more Cl atoms are _______ dense than water, so in bilayer it will occupy the _______ layer

Answer 8

more
bottom

Question 9

all alkyl bromides and iodides are _______ dense than water

Answer 9

more

Question 10

What are the 2 types of substitution reactions?

Answer 10

1) bonds broken and formed at the same time (Sn2)
2) old bond breaks, then new bond forms (Sn1)

Question 11

bimolecular nucleophilic substitution (_______) have __ molecules in r.d.s

Answer 11

Sn2
2

Question 12

Sn2 reactions are ___-step reactions, where the bond is broken and formed _______

Answer 12

1
simultaneously (concerted)

Question 13

What type of intermediate is present in the SN2 reaction of cyanide with bromoethane?

Answer 13

there is no intermediate

Question 14

What are the 3 options that could result from attack at the chiral electrophilic carbon

Answer 14

1) retention
2) inversion
3) racemization

Question 15

Sn2 reactions occur with 100% _______ of configuration at the electrophilic carbon. This is a _______ reaction

Answer 15

inversion
stereospecific

Question 16

to form a new bond, the _______ must approach the electrophilic C from the side that is _______ of the leaving group. This is called a _______

Answer 16

nucleophile
opposite
backside attack

Question 17

The best leaving groups are
1) _______: strong EN creates a partial positive on carbon
2) stable:
3) polarizable:

Answer 17

1) electron-withdrawing
2) should be weak bases (conjugate bases of strong acids)
3) maintain partial bonding with the carbon atom in the TS

Question 18

What is the most common leaving group that we will see in Sn2 reactions?

Answer 18

sulfonate

Question 19

different alkyl halides undergo Sn2 reactions at different rates:
1) place your focus on the carbon attached to the leaving group, this is the _______ C
2) _______ hindrance plays a large role in the rate of Sn2 reactions

Answer 19

electrophilic
steric

Question 20

________ stabilizes the transition state which results in the _______ of the rate

Answer 20

resonance
increase

Question 21

Sn1 reactions have ___ molecule in r.d.s

Answer 21

1

Question 22

The rate of Sn1 reactions are completely dependant on the concentration of the _______

Answer 22

electrophile

Question 23

SN1 reactions are ___-step reaction where the old bond is broken first and then the new bond is formed

Answer 23

2

Question 24

What are the steps to an Sn1 reaction?

Answer 24

1) LG leaves
2) nucleophile attacks carbocation
3) solvent attacks new positive charge

Question 25

The rate-limiting step of the Sn1 reaction is ionization to form a carbocation which is an extremely _______ process

Answer 25

endothermic

Question 26

Hammonds postulate: the structure of the transition state most resembles the species to which it is closest in _______

Answer 26

energy

Question 27

rates of Sn1 reactions depend strongly on _______ stability - then depends on _______

Answer 27

carbocation leaving group

Question 28

rank 1°, 2°, and 3° and their allylic and benzylics for Sn1 rates

Answer 28

3°allylic and benzylic > 3°, 2° allylic and benzylic > 2°, 1° allylic and benzylic > 1°

Question 29

In the Sn1 mechanism, the carbocation formed is _______ and _______

Answer 29

planar achiral

Question 30

Sn1: attack from both faces gives _______ enantiomers of the product

Answer 30

50% retention 50% inversion racemic mixture - little more inversion

Question 31

Trends in nucleophiles (Sn2): 1) when comparing charged vs neutral, _______ is stronger 2) nucleophilicity _______ from left to right in the periodic table 3) in the same group (column), nucleophilicity _______ as you move down 4) bulky groups _______ nucleophilicity due to their steric hindrance

Answer 31

1) charged 2) decreases 3) increases 4) decrease

Question 32

more EN atoms have more tight held nonbonding electrons that are _______ reactive toward forming new bonds

Answer 32

less

Question 33

Solvent: a liquid that can dissolve the _______. It interacts with reactants, products, and intermediates during the reaction process

Answer 33

reactants

Question 34

What are the 2 main types of solvents?

Answer 34

1) polar protic (p/p) - SN1 2) polar aprotic - SN2

Question 35

_______ solvents have acidic hydrogens (O-H and N-H) that can solvate the nucleophile, reducing their nucleophilicity

Answer 35

polar protic (p/p)

Question 36

_______ solvents do not have acidic protons and cannot hydrogen bond

Answer 36

polar aprotic

Question 37

What is one example of a polar protic solvent?

Answer 37

EtOH or H2O

Question 38

What is one example of a polar aprotic solvent?

Answer 38

THF or diethyl ether

Question 39

Carbocations (C+) frequently undergo structural changes called rearrangements to form more stable ions when possible. What are the 2 different rearrangements?

Answer 39

1) hydride shift 2) alkyl shift

Question 40

In Hydride shift, you can _______ make the C+ worse or same, you have to make it _______

Answer 40

never better

Question 41

In Alkyl shift, an ________ group can rearrange to make the carbocation more stable

Answer 41

alkyl

Question 42

What are the steps to ring expansion?

Answer 42

1) check carbocation to see if you can relieve ring strain 2) then look at C+ stability - Ring strain trumps C+ stability

Question 43

_______: both nucleophile and electrophile within the same molecule

Answer 43

intramolecular

Question 44

When you have an intramolecular molecule, what are you allowed to do to the molecule?

Answer 44

cyclizations or ring formation