SN1/SN2/E1/E2

Question 1

How many products are there in an SN2 reaction

Answer 1

1

Question 2

Does SN2 display retention, inversion, or both (in regards to stereochemistry)?

Answer 2

Inversion ONLY

Question 3

What kind of alkyl halide is best for an SN2 reaction

Answer 3

Primary

Question 4

What kind of nucleophile is best for an SN2 reaction

Answer 4

Strong nucleophile (negative charged)

Question 5

What kinds of solvents are ideal of an SN2 reaction

Answer 5

Polar aprotic

Question 6

What are common examples of polar aprotic solvents

Answer 6

DMSO, acetone, DMF, THF,

Question 7

Describe the single, concerted step of SN2 reactions

Answer 7

Loss of a leaving group (alkyl halide leaves), as nucleophile attacks the electrophile (usually alpha carbon)

Question 8

What are the ideal conditions of an SN2 reaction (describe alkyl halide, strength of nucleophile, stability of leaving group, and type of solvent

Answer 8

1.) Methyl/Primary alkyl halide
2.) less electronegative / more neg charged nucleophile
3) Weak bases (I > Br > Cl > F)
4) Polar aprotic solvent

Question 9

What makes a good leaving group for an SN2 reaction?

Answer 9

Weak bases (I > Br > Cl > F)

Question 10

What is zaitsev’s rule?

Answer 10

It predicts the major product in an elimination reaction: the more stable alkene (aka the more substituted alkene) will be the primary product of the elimination reaction. This means the hydrogen will be removed from the carbon with fewer hydrogens, leading to the formation of the more substituted alkene.

Question 11

Which rule does E2 follow

Answer 11

Zaitsev’s rule

Question 12

Is E2 multi-step or concerted?

Answer 12

Concerted

Question 13

What kind of alkyl halide is best for an E2 reaction

Answer 13

Tertiary alkyl halide

Question 14

What kind of nucleophile is best for an E2 reaction

Answer 14

Bad nucleophiles. Strong, bulky, bases

Question 15

What kinds of solvents are ideal for an E2 reaction

Answer 15

Polar aprotic solvents.

Question 16

Describe the single, concerted step of E2 reactions

Answer 16

Base attacks beta hydrogen (from carbon with fewer hydrogens), hydrogen forms a pi (double bond), and loss of leaving group (alkyl halide)

Question 17

What are the ideal conditions of an E2 reaction (describe alkyl halide, strength of nucleophile, stability of leaving group, and type of solvent

Answer 17

Tertiary alkyl halide
Bad nucleophile (strong bulky base)
Weak base as LG
Polar aprotic solvent

Question 18

Describe acid strength trend on the periodic table

Answer 18

Acid strength increases across a row (from left to right) and down a column.

Question 19

What is a good leaving group for E2 reaction

Answer 19

Weak base

Question 20

What does it mean to be anti peri planar, and which reaction does this idea pertain to?

Answer 20

Antiperiplanar configuration means two groups are 180 degrees from one another (across a single bond, one wedge and one dash). In order for E2 reactions to proceed, the leaving group and the beta hydrogen atom must be anti periplanar to one another.

Question 21

What are the product(s) in an SN1 reaction

Answer 21

Usually a racemic mixture of both enantiomers

Question 22

Is SN1 multi-step or concerted?

Answer 22

Multi step

Question 23

What kind of alkyl halide (substrate) is best for an SN1 reaction

Answer 23

Tertiary

Question 24

What kinds of solvents are ideal for an SN1 reaction

Answer 24

Polar protic solvent

Question 25

Describe each step of SN1 reactions

Answer 25

1.) Loss of leaving group, which leads to formation of a carbocation intermediate 2.) (optional) Carbocation rearrangement 3.) Nucleophilic attack of carbocation

Question 26

What are the ideal conditions of an SN1 reaction (describe alkyl halide, stability of leaving group, and type of solvent)

Answer 26

Tertiary substrate, weak base as LG, polar protic solvent

Question 27

What is a good leaving group for SN1 reaction

Answer 27

Weak bases

Question 28

What are examples of polar protic solvents

Answer 28

Water, alcohol, carboxylic acids

Question 29

When do you get a single product vs. racemate for SN1 reactions?

Answer 29

A racemate is produced when there is a chiral center (stereocenter) in the molecule. Otherwise, only one product should be generated

Question 30

Which reactions follow Zaitsev's rule?

Answer 30

E1 and E2 reactions

Question 31

What is the difference between E1 and E2 reactions

Answer 31

E1 reactions are two-step processes involving a carbocation intermediate, while E2 reactions are one-step processes that do not form a carbocation.

Question 32

Are E1 reactions concerted or multistep

Answer 32

Multi step

Question 33

Which reactions form carbocation intermediates?

Answer 33

E1 and SN1

Question 34

What kind of alkyl halide (substrate) is best for an E1 reaction

Answer 34

Tertiary

Question 35

What kinds of solvents are ideal for an E1 reaction

Answer 35

Polar aprotic solvents

Question 36

Describe each step of E1 reactions

Answer 36

1. Loss of leaving group 2. (Optional) Carbocation rearrangement 3. Deprotonation of more substituted beta hydrogen (nucleophile attacks H, H attacks single bond to create pi bond)

Question 37

What are the ideal conditions of an E1 reaction (describe alkyl halide, stability of leaving group, and type of solvent)

Answer 37

Tertiary alkyl halide Weak bases Polar aprotic solvent