Derivatives of Aromatic Hydrocarbons Flashcards
(92 cards)
1
Q
hydrocarbons containing sigma bonds and delocalized pi electrons between carbon atoms in a ring
A
aromatic hydrocarbon
2
Q
aromatic hydrocarbons are known as aromatic due to their __ __
A
pleasant smell
3
Q
benzene-CH3
A
toluene
4
Q
benzene-OH
A
phenol
5
Q
benzene-NH2
A
aniline
6
Q
benzene-C(=O)CH3
A
acetophenone
7
Q
benzene-CHO
A
benzaldehyde
8
Q
benzene-COOH
A
benzoic acid
9
Q
benzene-CN
A
benzonitrile
10
Q
1,2-dimethylbenzene
A
ortho-xylene
11
Q
benzene-CH=CH2
A
styrene
12
Q
aromatic compounds are also called as __ or __
A
- aromatics
- arenes
13
Q
aromatic compounds are characterized by the presence of __ or __ __ and are __ __ __
A
- one or more rings
- uniquely stable structures
14
Q
result of strong bonding arrangements between certain pi electrons of molecules
A
uniquely stable structures
15
Q
Two categories of aromatic compounds
A
- Benzenoids
- Non-benzenoids
16
Q
contains benzene rings
A
benzenoids
17
Q
exhibits an aromatic behavior but does not contain a benzene ring
A
non-benzenoids
18
Q
polarity of aromatic compounds
A
non-polar
19
Q
solubility of aromatic compounds in water
A
non-miscible
20
Q
reactivity of aromatic compounds
A
usually unreactive
21
Q
carbon to hydrogen ratio of aromatic compounds is __
A
high
22
Q
aromatic compounds flame
A
sooty yellow flame
23
Q
classification of aromatic compounds
A
- nuclear-substituted compounds
- side chain substituted compounds
24
Q
any aromatic compound whenever any substituent or functional group is directly linked to the benzene ring
A
nuclear-substituted compounds
25
any aromatic compounds if the functional group is available in the side chain of the ring
side chain substituted compounds
26
one of the most commonly known aromatic compounds with chemical formula C6H6
benzene
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benzene is a naturally occurring substance produced by __ and __ __
- volcanoes
- forest fires
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benzene is said to be highly toxic in nature and is also known as a __
carcinogen
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average mass of benzene
78.112 g/mol
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property of cyclic and planar molecules having resonance bonds exhibiting more stability than the connective or geometric arrangements within the same kind of atoms
aromaticity
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Huckel's Rule of Aromaticity
1. planar
2. conjugated
3. presence of (4n+2)=π (n=2, 6, 10, 14)
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entire molecule must be fully planar
planarity
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entire molecule must have complete delocalization of the pi electrons
conjugated
34
proposed huckel's rule of aromaticity
Erich Huckel
35
when one of the positions on the ring has been substituted with another atom or group of atoms
monosubstituted benzene
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how are monosubstituted benzenes named
using the substituent followed by benzene without number to indicate position
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when two of the positions on the ring has been substituted with another atom or group of atoms
disubstituted benzene
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disubstituted benzenes can be named __, __, and __ or numbers
- ortho
- meta
- para
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benzene with more than two substituents
polysubstituted derivative
40
benzene can be found in household products like:
- glue
- adhesives
- cleaning supplies
- paint strippers
- gasoline
- tobacco smoke
41
used to make latex, synthetic rubber, and polystyrene
styrene
42
styrene is produced using
ethyl benzene
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sources of aromatic hydrocarbons
- high temperature distillation of coal tar
- heating petroleum at high temperature and pressure over a catalyst
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organic reactions wherein an electrophile replaces an atom that is attached to an aromatic ring
electrophilic aromatic substitution
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is preserved in an electrophilic aromatic substitution reaction
aromaticity of aromatic system
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most common electrophilic substitution reactions
1. halogenation
2. nitration
3. sulfonation
4. friedel-craft alkylation
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halogen group replaces hydrogen
halogenation
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NO2 group replaces hydrogen
nitration
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SO3H group replaces hydrogen
sulfonation
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an alkyl group replace hydrogen
friedel-craft alkylation
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resonance-stablized carbocation intermediate
sigma complex
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the process (chlorination or bromination) makes use of a __ __
Lewis acid
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Lewis acid in chlorination or bromination takes a pair of electrons to form a permanent bond dipole in the __ bond or the __ bond
- Cl-Cl
- Br-Br
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as a result of the dipole, the bromine or chlorine has a __ __ __
formal positive charge
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the formal positive charge of bromine or chlorine makes the group electrophilic enough to simply overcome the
activation energy produced by benzene ring's loss of aromaticity
56
in halogenation of benzene, it requires __ to initiate the reaction
catalyst
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due to high stability of benzene, there is low reactivity. Thus, bromine or chlorine is reacted with __ or __ to give an electrophile
- FeBr3
- FeCl3
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reaction that replaces the hydrogen with an electrophile
electrophilic aromatic substitution reaction
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friedel-crafts alkylation is an electrophilic aromatic substitution reaction in which a __ is attacked by a __ __
- carbocation
- pi bond
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sulfonation is a reversible reaction that produces __ __
benzenesulfonic acid
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sulfonation is a reversible reaction that produces benzenesulfonic acid by adding __ __ and __ __ __
- sulfuric trioxide
- fuming sulfuric acid
62
changes to a system equilibrium will result in predictable and opposing changes to achive new equilibrium state
Le Châtelier’s Principle
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Le Châtelier’s Principle:
reactant concentration increases
reactant concentration increases
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Le Châtelier’s Principle:
pressure increases
side with fewer gas molecules is favored
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Le Châtelier’s Principle:
temperature increases
endothermic reaction is favored
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Le Châtelier’s Principle:
product concentration increases
reactant formation is favored
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Le Châtelier’s Principle:
pressure decreases
side with more gas molecules is favored
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Le Châtelier’s Principle:
temperature decreases
exothermic reaction is favored
69
EAS
electrophilic aromatic substitution
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effects of substituents on EAS
1. rate of reaction of the ring
2. position of attack
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position of attack called __ __
directing effects
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rate of reaction (2)
1. activated rings
2. deactivation
73
substituents on the ring donate electrons and increase EAS reaction rates
activated rings
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substituents on the ring withdraw electrons and decrease EAS reaction rates
deactivation
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position of attack (2)
1. ortho-, para-
2. meta-
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electron donating groups (D) direct the reaction ot the ortho- or para- position
ortho-, para-
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the withdrawing group directs the reaction to the meta position, which means the electrophile substitutes for the hydrogen on carbon 3 relative to the withdrawing group
meta-
78
useful tool in predictin the behavior of aromatics
theory of reactivity and orientation
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when a monosubstituted benzene undergo electrophilic substitution reaction, the group already present in the rings controls the __ _ __ and the __ __ __ __
- rate of reaction (reactivity)
- site of electrophilic attack (orientation)
80
the attacking electrophile is directed towards the position that provides the __ __ __
most stable intermediate
81
aromatics exhibit high stability due to the __ _ __ _ __ __
delocalization of electrons in pi system
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the reactivity of aromatic ring depends on the __ __ or __ __ attached to it
- electron-donating
- withdrawing groups
83
electron--donating groups
activators
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electron-withdrawing groups
deactivators
85
increase the electron density on the ring, making it more susceptible to electrophilic attack
electron-donating groups
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decrease the electron density on the ring, making it less reactive towards electrophiles
electron-withdrawing groups
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in presence of substituent that donates electrons, the attacking electrophile is directed towards the position that has the least destabilizing effect on the intermediate. what are these positions
ortho (1,2), para (1,4) position
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all electron-donating are in what position
ortho- and para- position
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all deactivators are __ directors, except halogens which are deactivators but are __ directors
- meta-
- ortho- and para- directors
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common chemical reaction that involves the introduction of oxygen atom into the side chain of an organic compounds
oxidation of alkyl side chains
91
most common reagents in the oxidation of alkyl side chains
- potassium permanganate (KMnO4)
- chromium trioxide (CrO3)
- potassium dichromate (K2Cr2O7)
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application of aromatics
1. perfume and fragrances
2. food and beverages
3. pharmaceuticals
4. cosmetics
5. cleaning products
