Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OCHEM 335 > Quiz 3 > Flashcards

Quiz 3 Flashcards

1
Q

describe a benzene ring

A

six-membered ring with alternating double bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe toluene

A

benzene ring with one methyl (CH3) attached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe xylene

A

benzene ring with a two methyls either in the ortho or meta position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe indene

A

one benzene ring with a 5 membered ring attached (the two rings share a double bond)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe napthalene

A

two benzene rings attached to one another (the two rings share a double bond)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe biphenyl

A

two benzene rings attached by a single bond in the center (looks like a dumbell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe anthracene

A

three benzene rings all attached to each other (one end ring and the center ring share a double bond, while the other end ring and the center ring just share a single bond) - ARE ALL IN A ROW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe phenanthrene

A

three benzene rings all attached to each other (one end ring and the center ring share a double bond and the other end ring and the center ring share a double bond) - IN ALMOST A TRIANGLE SHAPE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what would be the name of a benzene ring with a bromine attached

A

bromobenzene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is -CH2CH2CH3

A

propyl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what would be the name of a benzene ring with a -CH2CH2CH3 attached

A

propylbenzene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a benzene ring with an OH group attached called

A

phenol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a benzene ring with an NH2 group attached called

A

aniline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is a benzene ring with an SO3H group attached called

A

benzenesulfonic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is a benzene ring with an OCH3 group attached called

A

anisole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is a benzene ring with a CH=CH2 group attached called

A

styrene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is a benzene ring with an aldehyde group attached called

A

benzaldehyde

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is a benzene ring with a carbon double bonded to an oxygen and single bonded to an OH group attached called

A

benzoic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is a benzene ring with a carbon double bonded to an oxygen and single bonded to a CH3 group attached called

A

acetophenone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

phenyl vs. benzyl

A

phenyl: benzene ring

benzyl: benzene ring with a CH2 bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what would be one benzene ring on the left bonded to an O bonded to another benzene ring on the right called

A

diphenyl ether

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is an ether

A

R-O-R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

ortho

A

(1,2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

meta

A

(1,3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

para

A

(1,4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

naming disubstituted benzenes rules

A
  • the substituents are listed in alphabetical order
  • the first-mentioned substituent is assigned as position 1
  • the ring is numbered to give the second substituent the lowest possible number
  • some substituents can be incorporated into the common names
  • an incorporated substituent is assigned as position 1 (but not necessarily numbered as one)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is a benzene group with two methyls in the meta position called

A

meta-xylene

1,3-dimethylbenzene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

can ortho / meta / para only be used for disubstituted benzenes

A

yes. once a benzene derivative has three or more substitutents attached to it, you can only number the substituents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the molecular formula of benzene

A

C6H6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

how many degrees of unsaturation does benzene have

A

4 (a ring and 3 double bonds)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what does it mean when it says “benzene has delocalized bonding”

A

benzene is also a cyclic molecule in which all of the ring atoms are sp2-hybridized that allows the π electrons to be delocalized in molecular orbitals that extend all the way around the ring, above and below the plane of the ring. all the benzene bonds have the same length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is the hybridization of the carbon atoms for a benzene ring? what is the structure of benzene? what is the bond angle of the bonds? what is the orbital for the hydrogen?

A
  • carbon atoms = sp^2 hybridized
  • planar structure
  • 120 degrees
  • hydrogen = s orbital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

explain the electropotential landscape of benzene

A
  • each orbital has one electron (6 pi electrons)
  • all pi electrons are fully and equally shared across all siz carbons in the ring (fully delocalized pi system)
  • the delocalizd pi orbitals make the center of a benzene ring electron rich.
  • the outer edge of the ring is less electron dense
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

explain delocalization energy

A

the delocalization energy (resonance energy) is the extra stability that a compound has as a result of having delocalized electrons.

the resonance hybrid is more stable than any of its resonance contributors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what is the value of the delocalization energy of benzene

A

36 kcal/mol

(36 kcal/mol of aromatic stability)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

why doesn’t cyclooctatetraene have delocalized electrons

A

for maximal p orbital overlap, the atoms that share the delocalized electrons must lie in the same plane (cyclooctatetraene is shaped like a boat due to the four double bonds). Hence, the molecule doesn’t have delocalized electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

whats the criteria for a compound to be aromatic

A
  • parallel p-orbitals
  • uninterrupted cloud of pi electrons that are cyclic, planar, and every ring atom must have a p orbital.
  • the pi cloud must have an odd number of pairs of pi electrons (Huckel’s Rule - 4n + 2)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Explain Huckel’s Rule

A

4n + 2 Rule for Aromaticity
- aromatic compounds have 2 (n=0), 6 (n=1), 10 (n=2), etc. pi electrons in their uninterrupted cyclic pi cloud

39
Q

explain antiaromatic compounds and give an example

A

Example: cyclobutane (two double bonds, four pi electrons)

antiaromatic –> molecules have an uninterrupted cyclic cloud of 4n (n = 1, 2, 3, etc.) pi electrons. these molecules are very unstable

40
Q

explain non-aromatic compounds and give an example

A

Example: cyclooctatetraene (four double bonds, eight pi electrons)

non-aromatic: it would be antiaromatic if it had a planar structure, but it’s not planar so it doesn’t have an uninterrupted cyclic cloud of pi electrons

41
Q

can a compound be an aromatic ion if it is a five membered ring but contains one lone pair in one of the orbitals? (6 e- total)

A

yes

42
Q

can a compound be an aromatic ion if it is a seven membered ring but contains one empty orbital? (6 e- total)

A

yes, empty p-orbital but still has the correct number of electrons so it can delocalize and be aromatic

43
Q

non-aromatic

A
  • no uninterrupted cyclic cloud of pi electrons because of the sp^3 carbon atom (CH2) at the top of the ring –> none of the benzene carbons can be sp^3
  • 4n + 1
  • UNSTABLE
44
Q

antiaromatic

A
  • 4n uninterrupted cyclic cloud of pi electrons
  • UNSTABLE
45
Q

aromatic

A
  • 4n + 2
  • uninterrupted cyclic cloyd of pi electrons
  • STABLE
46
Q

pyridine

A

benzene but instead of one of the carbons, a nitrogen is there with a lone pair (three double bonds total)

  • lone pair is orthoganol to the pi system and do not participate in the aromatic pi system.
  • a doubly bonded N only contributes ONE electron to the aromatic pi system (electron density around the sp^2 nitrogen)
  • electron dense aroun the nitrogen, electron poor everywhere else
47
Q

pyrrole

A

five membered ring but instead of one of the carbons, a nitrogen is there with a lone pair and a hydrogen attached (two double bonds total)

  • lone pair is part of the aromatic pi system
  • singly bonded nitrogen = contributes one electron, doubly bonded nitrogen = contributes two electrons.
  • more electron rich than pyridine because the electron rich nitrogen can dump / donate lone pair into the backbone
48
Q

furan

A

five membered ring but instead of one of the carbons, an oxygen is there with two lone pairs (two double bonds total)

  • the first lone pair is part of the aromatic pi system
  • the second lone pair is orthoganol to the pi system and does not participate in the aromatic pi system
  • because furan is a five membered ring, on of the pi orbitals (the one above the oxygen) has a lone pair (2 e-s)
49
Q

thiophene

A

five membered ring but instead of one of the carbons, a sulfur is there with two lone pairs (two double bonds total)

  • lone pair is part of the aromatic pi system
50
Q

what are polycyclic aromatic hydrocarbons

A

molecules with multiple aromatic rings fused together

51
Q

naphthalene structure

A

two benzene rings

52
Q

how many resonance forms of naphthalene are there

A

three (one resonance with no double bond in the middle)

53
Q

delocalized naphthalene

A

the ten electrons are fully delocalized throughout both rings

54
Q

quinoline

A

two benzene rings with one carbon replaced by a nitrogen with a lone pair

55
Q

indole

A

benzene ring attached to a five membered ring with one carbon replaced by a nitrogen with a lone pair and a hydrogen

56
Q

imidazole

A

five membered ring that has a nitrogen with one lone pair in place of one carbon, and another nitrogen with a lone pair and a hydrogen in place of another carbon. The two nitrogens are across from each other (meta)

57
Q

purine

A

benzene attached to a 5 membered ring.

on the benzene: theres a nitrogen with a lone pair in place of one carbon and a nitrogen with a lone pair in place of another carbon (meta).

on the five membered ring: one nitrogen with a lone pair in place of a carbon and another nitrogen with a lone pair and a hydrogen in place of another carbon (meta)

58
Q

pyrimidine

A

benzene with a nitrogen with a lone pair in place of one carbon and a nitrogen with a lone pair in place of another carbon

59
Q

orbital structure of imidazole and pyrimidine

A

electron pair on NH is part of the aromatic pi system, whereas the lone pair on the doubly-bonded nitrogen atom participates in the aromatic pi system (it only contributes one pi electron)

60
Q

is benzene aromatic? why or why not?

A

yes, because benzene is cyclic, planar, and has an uninterrupted cloud of pi electrons, which provides benzene with stability.

61
Q

how does benzene react with electrophiles

A

aromatic compounds undergo electrophilic aromatic substitution reactions.

62
Q

why do aromatic rings undergo substitution rxns? what would happen if it was an addition rxn?

A

substitution leaves an aromatic ring in the product. addition across one of the double bonds in the ring would destroy the aromatic ring, losing its 36 kcal/mol of resonance stabilization

63
Q

what are the last two steps that many mechanisms have in common for benzene reactions with electrophiles

A
  1. a base (with lone pair) attacks and captures the electrophile (the H+)
  2. regain the aromaticity (H+ removed)
64
Q

compare the reaction of an electrophile with an alkene and with benzene

A

benzene rxn is slower than the alkene rxn because of the stability of the aromatic ring. benzene does not want to lose its 36 kcal/mol of resonance. the delta G double dagger for benzene is much higher than that of alkene

65
Q

is the benzene substitution exothermic or endothermic

A

exergonic because the product retains the stability of the aromatic ring

66
Q

what is the complete reaction mechanism for the electrophilic aromatic substitution

A
  1. electrophile adds to the aromatic ring which breaks or disrupts aromaticity. This makes a higher energy intermediate
  2. higher energy cationic intermediate is resonance stabilized. the proton is removed from the carbon that has formed the bond with the electrophile.
  3. loss of proton regenerates the aromatic ring (product: ring with electrophile attached + HB+)
67
Q

halogenation

A

benzene with a halogen (F, Br, Cl, I) attached

68
Q

nitration

A

benzene with an NO2

69
Q

sulfonation

A

benzene with an SO3H

70
Q

alkylation

A

benzene with an R group

71
Q

acylation

A

benzene with a ketone (c with O double bond then R group)

72
Q

explain the bromination and chlorination of benzene

A

requires a lewis acid and catalyst (FeBr3 or FeCl3) because the aromaticity of the benzene causes the molecule to be less reactive than a normal alkene

73
Q

how to generate the electrophile for bromination and chlorination

A

(Cl can be replaced with all Brs here)
TYPICALLY you have a ring + Br2 –FeBr3–>
1. lone pair on the Br from the Br2 is the leaving group that bonds to the FeBr3 to create Br-Br-FeBr3
2. double bond on ring attacks one of the Br2 Brs which creates a ring with one Br and one H on a carbon

then you have the rest of the process

74
Q

how to generate the electrophile for iodination of benzene

A

you have a benzene ring + I2 —-H2O2—->
1. I2 + H2O2 –> 2 H-O-I
2. double bond from benzene ring attacks I+ to create ring with H and I bonded to a carbon
3. OH (remaining from I) helps the proton come off to regenerate the ring

75
Q

bromination and chlorination solvent

A

FeBr3 / FeCl3

76
Q

iodination solvent

A

H2O2

77
Q

how to generate the electrophile for nitration

A

benzene ring + HNO3 –H2SO4–>

  1. oxygen with two lone pairs attached to the hydrogen of HNO3 attacks hydrogen on H2SO4 to produce H2O+-NO2
  2. now water is a good leaving group and it leaves to produce +NO2
  3. double bond on benzene ring attacks nitrogen on NO2
  4. base attacks hydrogen one the same carbon as NO2
78
Q

nitration solvent

A

HNO3 and H2SO4

79
Q

sulfonation solvent

A

fuming H2SO4

80
Q

how to generate the electrophile for sulfonation

A

benzene + H2SO4 –SO3 and heat–>

  1. lone pair on oxygen on SO3 (all oxygens are double bonded) attacks the hydrogen of H2SO4 to produce SO3 with a hydrogen attached (that specific oxygen is only a single bond) + HSO4-
  2. sulfuric acid becomes sulfonium ion + water
  3. benzene ring attacks +SO3H (sulfonium ion)
  4. base attacks hydrogen which leaves just SO3H on the ring + HB+
81
Q

which reaction is reversible

A

the sulfonation of benzene

82
Q

what are the friedel-crafts rxns

A

two electrophilic substitution rxns:
- friedel crafts acylation installs and acyl group on a benzne
- friedel crafts alkylation installs an alkyl group on a benzene ring

83
Q

what is a limitation of the friedel-crafts rxns

A
  • cannot undergo rxns with the electrophile in the meta position (meta deactivates benzene)
  • cannot undergo reactions that would leave -NH2, -NHR, or -NR2 in the electrophile position because these compounds are so basic that they react with the solvent instead
84
Q

explain friedel-crafts acylation

A

benzene + acyl chloride (acyl bonded to Cl) –AlCl3–>

  • the strong lewis acid AlCl3 is required to rip off the acyl group
85
Q

what is an acyl group

A

C bonded to R and double bonded to O
(essentially it is half of a ketone or half of an aldehyde)

(R has to be an alkyl (methyl, ethyl, etc.) or aryl (ring) substituent)

86
Q

friedel-crafts acylation solvents

A

AlCl3

87
Q

for friedel-crafts acylation what is the lewis acid and what is the lewis base

A

acyl chloride = lewis base
AlCl3 = lewis acid

88
Q

what is the mechanism for the friedel-crafts acylation

A

benzene + R-C=O (acylium ion)

  1. benzene attacks carbon
  2. H attached to C double bond O and bond to R is attacked by base
89
Q

explain friedel-crafts alkylation

A
  • any alkyl halide works
  • aryl halides and vinyl halides do not react because their carbocations are too unstable
  • carbocation is the electrophile so watch out for rearrangements
  • requires a strong lewis acid (AlCl3)
90
Q

friedel-crafts alkylation mechanism

A

benzene + RCl –AlCl3–>

  1. double bond on benzene attacks R+ which produces ring with R and H
  2. base attacks H bonded to the carbon with the R which produces benzene with R + HB+
91
Q

friedel-crafts alkylation solvent

A

AlCl3

92
Q

friedel-crafts alkylation what is the lewis acid and what is the lewis base

A

lewis base: alkyl halide (R-Cl)
lewis acid: AlCl3

93
Q

what is the caveat for the alkylated benzene

A
  • alkyl groups donate electrons so the product is more reactive than benzene, therefore a large excess of benzene is needed to avaoid multiple alkylations of the ring
94
Q

class encore rule ab ortho / para / meta directors

A

a substituent is an electron donating group if the first atom is MORE electronegative than the second.

a substituent is an electron withdrawing group if the first atom is LESS electronegative than the second.

OCHEM 335 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions