Quiz 6-9 + Worksheets

Question 1

The larger the number of Pkb, the ______ the _____ (base/acid).

Answer 1

Weaker; base

Question 2

Is CH3 a deactivator/activator?

Answer 2

Activator

Question 3

Electron withdrawing groups are mostly ___________ (deactivators/activators).

Answer 3

deactivators

Question 4

List some deactivators.

Answer 4

CN (triple bond)
NO2
SO3H
C=OH … carbonyls
N+R3
Halogens

Question 5

How to find Pkb from Pka?

Answer 5

Subtract Pka value from 14.

Question 6

Is 1,3,5-trihexene aromatic, non aromatic or anti aromatic? Why?

Answer 6

Non aromatic because it is not cyclic.

Question 7

A deactivator as a substituent on a benzene reacting with Br2, FeBr3 produces what major product?

Answer 7

An addition of Br on the meta position of the substituent.

Question 8

What kind of director is NH2?

Answer 8

Ortho/para-director.

Question 9

Why is sulfuric acid used in aromatic nitration?

Answer 9

Because of the tert-butyl cation.

Question 10

What kind of director is OCH3?

Answer 10

Para/ortho-director…activator

Question 11

What kind of director is OH?

Answer 11

Para/ortho director…activator.

Question 12

What kind of director are amines?

Answer 12

Para/ortho-director…activator.

Question 13

Is -NHC=OCH3 a meta directing group?

Answer 13

No, because it is part of the amine group.

Question 14

Which has a UV absorption band at the longest wavelength between a conjugated cyclic and conjugated non-cyclic compound?

Answer 14

Cyclic compound.

Question 15

Can isolated alkenes undergo Diels-Alder reactions?

Answer 15

No.

Question 16

A diene with a OCH3 substituent on the 2nd position and a dienophile with a CHO substituent produces what kind of product?

Answer 16

A 1,4-product.

Question 17

The carbon-carbon bonds in benzene are…

Answer 17

of equal length and intermediate between a double bond and a single bond.

Question 18

How many pi-bonding MOs are in benzene?

Answer 18

3

Question 19

What is the difference between the modern Kekule structures and the original Kekule structures?

Answer 19

The C-C bond lengths in the modern structures are all the same and the modern structures are two resonance structures.

Question 20

Which reaction do benzene tends to undergo?

Answer 20

Substitution rather than addition reactions.

Question 21

What are non-bonding orbitals?

Answer 21

The HOMO and the LUMO MOs.

Question 22

What are the non-bonding MOs of cyclobutadiene?

Answer 22

p2 and p3.

Question 23

Which of the following concepts are used to describe the structure of benzene?
Unsaturation
Harmonic aromatization
Saturation
Resonance

Answer 23

Resonance

Question 24

Another name for cyclobutadiene is…

Answer 24

[4]annulene

Question 25

Is a not basic N (in a cyclic compound) strong or weak base?

Answer 25

Weak base.

Question 26

NH is _____ while N is ______.

Answer 26

not basic; basic

Question 27

Does conjugation increases acidity?

Answer 27

Yes.

Question 28

An ethene substituent added to a benzene is called...

Answer 28

Styrene

Question 29

Describe napthalene's structure.

Answer 29

2 benzenes together.

Question 30

A cyclopentane substituent attached to a benzene is called...

Answer 30

Cyclopentylbenzene or phenylcyclopentane

Question 31

What is the electrophile in the bromination of benzene?

Answer 31

Br+

Question 32

A carbocation at a tertiary carbon is _______ (stable/not stable).

Answer 32

Not stable.

Question 33

When toulene reacts with Br2, why does it not go through addition to form a vicinal dihalide?

Answer 33

It is highly unfavorable because it would result in a nonaromatic product.

Question 34

Name one major difference between the aromatic and antiaromatic compounds.

Answer 34

Only aromatic compounds follow Huckle's Rule.

Question 35

Based on Hammond's Postulate, if the carbocation intermediate is antiaromatic, what can you expect from the reaction?

Answer 35

The activation energy needed to produce the intermediate would be very high.

Question 36

Why is pyrrole a much weaker base than pyridine?

Answer 36

When pyrrole is protonated, the system's aromaticity is destroyed.

Question 37

Name C3N2H4.

Answer 37

Imidazole.

Question 38

Describe or draw imidazole compound.

Answer 38

C3N2H4 (two double bonds)

Question 39

As conjugation ___________, the HOMO-LUMO energy gap becomes _________, and the wavelength of light absorbed becomes __________.

Answer 39

increases; smaller/narrow; longer

Question 40

What does degenerate mean?

Answer 40

"Have the same energy".

Question 41

How many degenerate bonding MOs does benzene have?

Answer 41

2 (pi 2 and pi 3)

Question 42

Antiaromatic compounds are ________, fully _____________, making them highly _________, similar to a ________ (cation/anion/radical).

Answer 42

unstable; conjugated; reactive; radical

Question 43

Deactivator __________ (decreases/increases) the rate of reactivity toward electrophilic aromatic substitution.

Answer 43

decreases

Question 44

Rank in order of stability. Least to greatest. Cumulative Conjugated Isolated

Answer 44

Cummulated < Isolated < Conjugated