Chapter 19 - Benzene & Aromatic Compounds

Question 1

Benezene formula

Answer 1

C6H6

Question 2

Benzene + Br2

Answer 2

No Rxn

Question 3

Benzene + Br2 + catalyst

Answer 3

Substitution Reaction
C6H5Br + HBr

Question 4

2 benzene rings bonded

Answer 4

naphthalene

Question 5

3 benzene rings bonded

Answer 5

phenanthrene

Question 6

phenanthrene

Answer 6

3 benzene rign

Question 7

3 benzene rings bonded

Answer 7

phenanthrene

Question 8

phenanthrene

Answer 8

3 benzene rings bonded together.
Carcinogen foundin cigarettes

Question 9

3 criteria to be aromatic

Answer 9

1- cyclic
2 - planar
3 - compeletely conjugated
4 - odd number of pi electron pairs

Question 10

The pi cloud must have an ___ number of pairs of pi electrons

Answer 10

odd

Question 11

criteria for antiaromatic compounds

Answer 11

1 - cyclic
2 - planar
3 - every ring atom must have a p orbital
4 - even number of pi electron pairs

Question 12

C5H5N

Answer 12

pyridine

Question 13

pyridine

Answer 13

C5H5N

Question 14

Is pyridine aromatic or not?

Answer 14

Aromatic

Question 15

furan
forumula + aromatic?

Answer 15

C4H4O

aromatic b/c it can rehybridize

Question 16

pyrrole
forumula + arromatic?

Answer 16

C4H4NH

aromatic because it can rehybridize

Question 17

what does rehybridization allow for?

Answer 17

it allows an sp3 hybrid to become an sp2 hybrid so that a compound may be aromatic and more stable.

Question 18

annulene

Answer 18

hydrocarbons containing a single ring with alternating single and double bonds.

Question 19

[6]-annulene AKA

Answer 19

benzene

Question 20

How to tell if one ring is more acidic than another?

Answer 20

the conj. base (product after a hydrogen is removed) will be aromatic and therefore stable. This means the starting material is acidic.

Question 21

How to tell if one ring is more basic than another?

Answer 21

the conj. acid (product after a hydrogen is added) will be aromatic and therefore more stable. This means the startic material is basic.

Question 22

How to tell if one ring is more basic than another?

Answer 22

the conj. acid (product after a hydrogen is added) will be aromatic and therefore more stable. This means the startic material is basic.

Question 23

Why does benzne do substitution reactions and not addition reactions?

Answer 23

If benzene participates in an addition reaction, it looses its aromaticity and is therefore more unstable.

Whereas if it participates in a substitution rxn in stead, it maintains it aromaticity and stability.

Question 24

What is the difference between Y- acting as a a nucleophile and Y- acting as a base in aromatic reactions?

Answer 24

If it were to react as a nucleophile it would add to the benezene ring and cause it to lose its aromaticity.

If it acts as a base, it removes an H and reforms the double bond, maintianing aromaticity and stability.

Question 25

Expected vs Actual energy difference b/w benzene and cyclohexane

Answer 25

Expected -360 Actual -208

Question 26

cycloalkene + Br2

Answer 26

vicinal dibromide (anti-addition prouduct) proceeds through electrophilic addition

Question 27

benzene + Br2

Answer 27

no reaction

Question 28

beneze + Br2 + FeBr3

Answer 28

bromobenzene (electrophilic aromatic substitution)

Question 29

What catalyst is typically used to react benzene with bromine?

Answer 29

FeBr3

Question 30

What type of catalyst does FeBr3 act as?

Answer 30

lewis acid catalyst

Question 31

What is the rds in electrophilic aromatic subsitution?

Answer 31

the 1st step where the aromatic ring is openened

Question 32

Nucleophiles attack ________.

Answer 32

electrophiles

Question 33

Bases attack ________.

Answer 33

hydrogens

Question 34

nitric acid

Answer 34

HNO3

Question 35

sulfuric acid

Answer 35

H2OS4

Question 36

What are the 2 main mechanistic steps in electrophilic aromatic substitution?

Answer 36

1 - Generation of the Reactive Electrophile 2 - Rxn b/w the E+ and benzene

Question 37

Electrophile for Halogenation of Benzene

Answer 37

Br+ or Cl+

Question 38

Electrophile for Nitration of Benzene

Answer 38

NO2+

Question 39

Electrophile for Sulfonation of Benzene

Answer 39

HSO3

Question 40

Catalyst for halogenation of benzene

Answer 40

FeBr3 or FeCl3

Question 41

Reagents for Bromination of Benzene

Answer 41

Br2 FeBr3

Question 42

Reagents for Chlorination of Benzene

Answer 42

Cl2 FeCl2

Question 43

Reagents for Nitration of Benzene

Answer 43

HNO3 H2SO4

Question 44

Reagents for Sulfonation of Benzene

Answer 44

SO3 H2SO4

Question 45

Reagents for Acylation of Benzene

Answer 45

Acid Chloride AlCl3

Question 46

Reagents for Alkylation of Benzene

Answer 46

Cl-R AlCl3

Question 47

When forming the electrophile for nitration of benzene, _______ acts as a base because ___________ is a stronger acid.

Answer 47

Nitrous Acid acts as a Base Because Sulfuric Acid is a Stronger Acid

Question 48

What acts as a good leaving group in the formation of the electrophile for nitration of benzene?

Answer 48

H2O

Question 49

Acylation and Alkylation lead to the formation of __ - ___ bonds

Answer 49

Carbon-Carbon