Chapter 9 Notes

Question 1

nucleophilic substitution

Answer 1

any reaction in which an electron rich nucleophile replaces a leaving group

Question 2

leaving group

Answer 2

the group that is displaced in a substitution reaction or the Lewis base that is lost in an elimination reaction

Question 3

acid base reaction

Answer 3

this is often not classified as one of the five types of organic reactions, but it is an incredibly common transformation that occurs within them and can eb classified with nucleophiles and electrophiles

Question 4

addition reaction

Answer 4

two atoms or groups of atoms react with one double bond to form a compound with two new atoms bonded to the carbons of the original double bond

Question 5

substitution reaction

Answer 5

one atom or group of atoms is substituted by another atom or group of atoms

Question 6

elimination reaction

Answer 6

two atoms are removed from a molecule to form one new double bond

Question 7

oxidation-reduction reaction

Answer 7

transfer of electrons between two species

Question 8

radical reaction

Answer 8

any reaction involving radicals

Question 9

SN2 Mechanism

Answer 9

-a bimolecular (two species involved) nucleophilic substitution reaction

Question 10

SN1 mechanism

Answer 10

a unimolecular (one species in rate determining step) nucleophilic substitution reaction
-solvolysis: a nucleophilic substitution in which the solvent is also the nucleophile
step 1: break a bond
step 2: make a bond
step 3: remove a proton

Question 11

kinetics of SN2

Answer 11

reactions are bimolecular and the rate of reaction is affected by concentration of both the electrophile and nucleophile

Question 12

kinetics of Sn1

Answer 12

reaction is unimolecular the rate of reaction is only affected by the concentration of the electrophile

Question 13

stereochemistry of SN2

Answer 13

SN2 leads to complete inversion of the chiral center due to “backside attack” this can be monitored with isotopic labeling

Question 14

stereochemistry of SN1

Answer 14

SN1 goes through an achiral carbocation intermediate that can be attacked from either side, leading to partial or complete racemization of stereochemistry

Question 15

SN2 structure

Answer 15

• governed by mainly steric factors
• steric hindrance: the ability of groups because of their size to hinder access to a reaction site with a molecule
• SN2 can occur with primary and secondary haloalkanes but not tertiary
• steric hindrance also occurs from beta branches slowing the rate of SN2 reactions

Question 16

SN1 structure

Answer 16

• governed mainly be electronic factors

- resonance stabilizes carbocations, thus increases likelihood of SN1 over SN2

Question 17

leaving group

Answer 17

more stable an anion is on a Lv the better the Lv

Question 18

the solvent

Answer 18

• the solution the reaction is run in influences
• nonpolar solvents aree bad at screening charges
• polar solvents are good at screening changes
• aprotic solvents cannot serve as a hydrogen donor

Question 19

effect of solvent on SN1 reactions

Answer 19

-polar protic solvents “solvate” the intermediate Staes increasing the reaction rate

Question 20

effect of solvent on SN2 reaction

Answer 20

-polar protic solvents “solvate” the nucleophiles, decreasing its reactivity/reaction rate

Question 21

B-elimination

Answer 21

all nucleophiles are also bases; competing reactions depend n nucleophilicity vs basicity

Question 22

dehydrohalogenation

Answer 22

type of B elimination where -H and -X are removed from adjacent carbons to form an alkene

Question 23

Zaitsev’s rule

Answer 23

predicts that the more substituted (more stable) C=C double bond product from a B elimination reaction is favored

Question 24

E1 Mechanism

Answer 24

E1 reaction: unimolecular B-elimination reaction
step 1: break a bond
step 2: take a proton away

Question 25

E2 mechanism

Answer 25

E2 reaction: bimolecular B-elimination

Question 26

E1 Kinetics

Answer 26

• unimolecular

- rate of reaction is only affected by the concentration of the electrophile

Question 27

E2 Kinetics

Answer 27

• bimolecular

- rate of reaction is affected by the concentration of both the electrophile and nucleophile

Question 28

E1 Regioselectivity

Answer 28

the major product is the more stable alkene by going through the more stable carbocation intermediate

Question 29

E2 regioselectivity

Answer 29

the major product is the more stable alkene by going through the lower energy transition sate

Question 30

E2 stereoselectivity

Answer 30

-the Lowest energy transition Tate is when -Lv and -H are oriented anti and coplanar to each other