Substituição Eletrofílica Aromática

Prévia do material em texto

Prof. Calçada 1 
Substituição eletrofílica aromática 
 
RESUMO 
 
1. O benzeno é estabilizado por ressonância 
 
O calor de hidrogenação do benzeno nos dá uma medida da sua estabilidade. Observe que o valor experimental é menor que o valor teórico (para 
o “1,3,5-cicloexatrieno”). 
 
2. Substituição eletrofílica aromática 
 
 
E+X- pode ser: 
 
X – X (halogenação) 
HO – NO2 (nitração) 
HO – SO3H (sulfonação) 
R – X (alquilação) 
X – C – R (acilação) 
 || 
 O 
Em cada caso é importante conhecer o catalisador e mecanismo de catálise. 
 
3. Dirigência 
 
A presença de um grupo no anel dá origem aos fenômenos da dirigência. 
 
 
Grupos doadores de elétrons direcionam a substituição para as posições orto e para e aceleram a reação de substituição. 
Grupos que retiram elétrons direcionam a substituição para a posição meta e diminuem a velocidade da reação de substituição. 
 
O gráfico abaixo mostra o efeito de um grupo orto-para dirigente no intermediário da reação: 
 
 
Uma outra forma é pensar que os grupos que doam elétrons (D) ativam as posições orto 
e para e os que retiram elétrons (W) desativam essas posições e, por isso, facilitam a 
substituição em meta. 
 
 
 
 
668 B e n z e n e a n d A r o m a t i c i t yC H A P T E R 1 5
In Summary Charged species may be aromatic, provided they exhibit cyclic delocalization 
and obey the 4n 1 2 rule.
Exercise 15-21 Try It Yourself
The triene A can be readily deprotonated twice to give the stable dianion B. However, the neutral 
analog of B, the tetraene C (pentalene), is extremely unstable. Explain.
!
!
ð ð
Base
A B C 
H
H
H
H
15-8 SYNTHESIS OF BENZENE DERIVATIVES: ELECTROPHILIC 
AROMATIC SUBSTITUTION
In this section we begin to explore the reactivity of benzene, the prototypical aromatic com-
pound. The aromatic stability of benzene makes it relatively unreactive, despite the presence 
of three formal double bonds. As a result, its chemical transformations require forcing 
conditions and proceed through new pathways. Not surprisingly, however, most of the chem-
istry of benzene features attack by electrophiles. We shall see in Section 22-4 that attack by 
nucleophiles is rare but possible, provided that a suitable leaving group is present.
Benzene undergoes substitution reactions with electrophiles
Benzene is attacked by electrophiles, but, in contrast to the corresponding reactions of alkenes, 
this reaction results in substitution of hydrogens — electrophilic aromatic substitution — not 
addition to the ring.
Under the conditions employed for these processes, nonaromatic conjugated polyenes 
would rapidly polymerize. However, the stability of the benzene ring allows it to survive. 
Let us begin with the general mechanism of electrophilic aromatic substitution.
Electrophilic aromatic substitution in benzene proceeds by 
addition of the electrophile followed by proton loss
The mechanism of electrophilic aromatic substitution has two steps. First, the electrophile E1
attacks the benzene nucleus, much as it would attack an ordinary double bond. The reso-
nance stabilized cationic intermediate thus formed then loses a proton to regenerate the 
aromatic ring. Note two important points in the formulation of this general mechanism. 
First, always show the hydrogen at the site of the initial electrophilic attack. Second, the 
positive charge in the resulting cation is indicated by three resonance forms and is located 
ortho and para to the carbon that has been attacked, a result of the rules for drawing reso-
nance forms (Sections 1-5 and 14-1).
Electrophilic Aromatic Substitution
" E"X!
Electrophile
" H"X!
H
H
H
H
H
E
H
H
H
H
H
HReactionRReaction
Mechanism
696 E l e c t r o p h i l i c A t t a c k o n D e r i v a t i v e s o f B e n z e n e C H A P T E R 1 6
Chapter 15 described the use of this transformation in the preparation of monosubstituted 
benzenes. In this chapter we analyze the effect of such a fi rst substituent on the reactivity 
and regioselectivity (orientation) of a subsequent electrophilic substitution reaction. Specifi -
cally, we shall see that substituents on benzene can be grouped into (1) activators (electron 
donors), which generally direct a second electrophilic attack to the ortho and para positions, 
and (2) deactivators (electron acceptors), which generally direct electrophiles to the meta 
positions. We will then devise strategies toward the synthesis of polysubstituted arenes, such 
as the analgesics depicted on the previous page.
para
meta meta
orthoortho
Donor Acceptor
Activated ring Deactivated ring
16-1 ACTIVATION OR DEACTIVATION BY SUBSTITUENTS 
ON A BENZENE RING
In Section 14-8 we discussed the effect that substituents have on the effi ciency of the Diels-
Alder reaction: Electron donors on the diene and acceptors on the dienophile are benefi cial 
to the outcome of the cycloaddition. Chapter 15 revealed another manifestation of these 
effects: Introduction of electron-withdrawing substituents into the benzene ring (e.g., as in 
nitration) caused further electrophilic aromatic substitution (EAS) to slow down, whereas the 
incorporation of donors, as in the Friedel-Crafts alkylation, caused substitution to accelerate. 
What are the factors that contribute to the activating or deactivating nature of substituents 
in these processes? How do they make a monosubstituted benzene more or less susceptible 
to further electrophilic attack?
NO2 CH3
! !
Increasing rate of EAS
The electronic infl uence of any substituent is determined by an interplay of two effects 
that, depending on the structure of the substituent, may operate simultaneously: induction 
and resonance. Induction occurs through the ! framework, tapers off rapidly with distance, 
and is mostly governed by the relative electronegativity of atoms and the resulting polariza-
tion of bonds (Tables 1-2 and 8-2). Resonance takes place through " bonds, is therefore 
longer range, and is particularly strong in charged systems (Section 1-5, Chapter 14).
Let us look at both of these effects of typical groups introduced by electrophilic aromatic 
substitution, starting with inductive donors and acceptors. Thus, simple alkyl groups, such 
as methyl, are donating by virtue of their inductive (Section 11-3) and hyperconjugating 
! frame (Sections 7-5 and 11-5). On the other hand, trifl uoromethyl (by virtue of its elec-
tronegative fl uorines) is electron withdrawing. Similarly, directly bound heteroatoms, such as 
N, O, and the halogens (by virtue of their relative electronegativity), as well as positively 
polarized atoms, such as those in carbonyl, cyano, nitro, and sulfonyl functions, are induc-
tively electron withdrawing.
ITA	-	Química	4 
6471 5 - 3 P i M o l e c u l a r O r b i t a l s o f B e n z e n e C H A P T E R 1 5
Now let us look at the experimental data. Although benzene is hydrogenated only 
with diffi culty (Section 14-7), special catalysts carry out this reaction, so the heat of 
hydrogenation of benzene can be measured: DH 8 5 249.3 kcal mol21, much less than the 
278.9 kcal mol21 predicted.
Figure 15-3 summarizes these results. It is immediately apparent that benzene is much 
more stable than a cyclic triene containing alternating single and double bonds. The differ-
ence is the resonance energy of benzene, about 30 kcal mol21 (126 kJ mol21). Other terms 
used to describe this quantity are delocalization energy, aromatic stabilization, or simply 
the aromaticity of benzene. The original meaning of the word aromatic has changed with 
time, now referring to a thermodynamic property rather than to odor.
In Summary The structure of benzene is a regular hexagon made up of six sp2-hybridized 
carbons. The C – C bond length is between those of a single and a double bond. The electrons 
occupying the p orbitals form a ! cloud above and below the plane of the ring. The struc-
ture of benzene can be represented by two equally contributing cyclohexatrieneresonance 
forms. Hydrogenation to cyclohexane releases about 30 kcal mol21 less energy than is 
expected on the basis of nonaromatic models. This difference is the resonance energy of 
benzene.
Figure 15-3 Heats of hydrogenation provide a measure of benzene’s unusual stability. 
Experimental values for cyclohexene and 1,3-cyclohexadiene allow us to estimate the heat 
of hydrogenation for the hypothetical “1,3,5-cyclohexatriene.” Comparison with the experimental 
DH8 for benzene gives a value of approximately 29.6 kcal mol21 for the aromatic resonance 
energy.
E
Cyclohexene
Cyclohexane
Benzene
Resonance energy
= !29.6 kcal mol–1
 (!124 kJ mol–1)
Measured heat of
hydrogenation
" !28.6 kcal mol–1
 (!120 kJ mol–1)
Measured heat of
hydrogenation
" !54.9 kcal mol–1
 (!230 kJ mol–1)
Estimated heat of
hydrogenation
" !78.9 kcal mol–1
 (!330 kJ mol–1)
Measured heat of
hydrogenation
" !49.3 kcal mol–1
 (!206 kJ mol–1)
1,3-Cyclohexadiene
“1,3,5-Cyclohexatriene”
+ 3 H2
+ H2
+ 2 H2 3 H2 + 
15-3 PI MOLECULAR ORBITALS OF BENZENE
We have just examined the atomic orbital picture of benzene. Now let us look at the 
molecular orbital picture, comparing the six ! molecular orbitals of benzene with those of 
1,3,5-hexatriene, the open-chain analog. Both sets are the result of the contiguous overlap 
of six p orbitals, yet the cyclic system differs considerably from the acyclic one. A com-
parison of the energies of the bonding orbitals in these two compounds shows that cyclic 
conjugation of three double bonds is better than acyclic conjugation.
Observe que na nitração do tolueno a 
Ea para formar os compostos com 
substituição em orto e para é menor que 
a da nitração do benzeno em si. Logo a 
nitração do tolueno é mais rápida que a 
nitração do benzeno. 
 
Prof. Calçada 2 
O quadro a seguir resume a os efeitos de dirigência dos diversos grupos: 
 
 
 
No caso de termos dois ou mais grupos no anel podemos usar a seguinte generalização: 
 
NR2, OR > X, R > meta dirigentes 
 
Um bom exemplo é a nitração total do tolueno ou do fenol. Os produtos finais são, respectivamente o TNT e o ácido pícrico (ambos usados como 
explosivos). 
 
Além desses os compostos abaixo também são explosivos, isto é, são compostos de alta 
densidade energética que, ao contrário dos propelentes (como os de foguetes, por 
exemplo), não queimam mas autodetonam. Frequentemente geram muito calor e 
produtos gasosos, produzindo uma onda destrutiva onda de choques. O grupo nitro é 
frequente nessas moléculas pois funciona como um oxidante do esqueleto de carbono 
(produzindo CO e CO2), bem como precursor de N2. 
O TNT é um caso interessante. Ao contrário da nitroglicerina, ele é estável ao choque, 
seguro de manusear, fácil de preparar. Além disso tem baixa volatilidade e toxicidade. 
Atualmente o TNT é raramente usado puro, sendo misturado a outros explosivos 
como o Tetril e o RDX. 
 
Outras moléculas tem sido estudadas. O octanitrocubano, sintetizado em 2000, no qual a tensão 
dos anéis ajuda a quebrar a molécula. Sua fórmula molecular, C8N8O16, indica que pode formar, 
por exemplo, 8 CO2 e 4 N2 com uma grande expansão de volume. Um exemplo recente, de 2012, 
é o TKX-50, no qual dois átomos de carbono são rodeados por 10 nitrogênios e 4 H2O. 
 
 
 
 
 
Outros exemplos são o nitropenta (IME 2015) e a já citada nitroglicerina. 
 
 
 
 
 
 
 
1. Livro de mecanismos: ler páginas 54 a 63. 
2. Livro de mecanismos página 65: Q01 a Q07 
3. Livro 3 – página 26 e 27 – Ler o item substituição em aromáticos ( inclusive dirigência). 
4. Livro 3 – revisando – de 1 a 6. 
5. Livro 3 – propostos 6 e 13 e complementares 3 a 7 e 9. 
6. Resolva o restante da lista. 
 
7051 6 - 3 D i r e c t i n g E f f e c t s o f S u b s t i t u e n t s i n C o n j u g a t i o n C H A P T E R 1 6
Complete ortho, para nitration of methylbenzene (toluene) or 
phenol furnishes the corresponding trinitro derivatives, both 
of which are powerful explosives: TNT (discovered in 1863) 
and picric acid (1771). Both compounds have long histories 
as military and industrial explosives.
NO2
CH3
NO2
O2N NO2
OH
NO2
O2N
2-Methyl-1,3,5-trinitrobenzene
(2,4,6-Trinitrotoluene, TNT)
2,4,6-Trinitrophenol
(Picric acid)
Explosives are generally high-energy-density compounds 
capable of extremely rapid decomposition. In contrast to 
propellants (such as rocket fuel), they do not burn, but 
detonate under their own power. They frequently generate 
high heat and a large quantity of gaseous products, producing 
a (usually destructive) shock wave: TNT has a detonation 
velocity of 7459 m s21 (!4.6 mi s21). An explosion can be 
initiated by impact (including blasting caps), friction, heat 
and fl ame, electrical discharge (including static), and ultraviolet 
irradiation, depending on the compound. The nitro group 
features prominently in these materials, because it functions 
as an oxidizer to the surrounding carbon framework (producing 
the gases CO and CO2) and as a precursor to N2.
TNT is the most widely used military explosive in history. 
The reasons for its popularity are its low cost and simplicity 
of preparation, safe handling (low sensitivity to impact and 
friction), relatively high explosive power (yet good chemical 
and thermal stability), low volatility and toxicity, compatibility 
with other explosives, and a low melting point, allowing for 
melt-casted formulations.
TNT has become such a standard, particularly in military 
uses, that the destructive power of other explosives, especially 
in bombs, is often compared to that of an equivalent of 
TNT. For example, the fi rst atomic bomb—detonated on 
July 16, 1945, in New Mexico—had the equivalent power of 
19,000 tons of TNT. The device exploded over Hiroshima, 
Japan, which killed more than 140,000 people, had the 
power of 13,000 tons of TNT. Although these numbers 
appear huge, comparison with the hydrogen bomb—with the 
destructive equivalent of 10 million tons of TNT—dwarfs 
REAL LIFE: MATERIALS 16-1 Explosive Nitroarenes: TNT and Picric Acid
them. For further calibration, all of the explosions of World 
War II combined amounted to the equivalent of “only” 
2 million tons of TNT.
Picric acid has some commercial applications other than 
as an explosive—in matches, in the leather industry, in electric 
batteries, and in colored glass. It is called an acid because of 
the unusually high acidity of its hydroxy group (pKa 0.38; 
Section 22-3), which is increased beyond that of acetic acid 
(pKa 4.7) and even hydrogen fl uoride (pKa 3.2; Table 2-2) by 
the electron-withdrawing effect of the three nitro groups. This 
property was in part responsible for its replacement by TNT 
in military uses. For example, in artillery shells, it would 
corrode the casing and cause leakage, thus creating a hazard.
TNT and picric acid have been replaced gradually by 
tetryl, RDX, and nitroglycerine (Section 9-11). On the 
research front, chemists are continuing to explore novel 
structures. A case in point is octanitrocubane, synthesized 
in 2000, in which ring strain adds to the brisance of the 
compound. Its molecular formula, C8N8O16, indicates the 
potential to generate 8 CO2 1 4 N2 molecules, with an 
associated 1150-fold volume expansion. A recent example 
from 2012 is the exotic salt TKX-50, in which two lone 
carbon atoms are surrounded by 10 nitrogens and the 
equivalent of 4 H2O moieties.
Spherical shock waves generated by the fi ring of the huge guns of 
the USS Iowa are clearly visible on the ocean surface.
2,4,6-Trinitrophenyl-
N-methylnitramine
(Tetryl)
1,3,5-Trinitro-1,3,5-
triazacyclohexane
(RDX)
Octanitrocubane TKX-50
NO2
NO2
NO2
NO2
O2N
O2N
O2N
O2NNO2
NO2
O2N
N
O2N CH3H E
N
N
N
N
N
N
N
N
O! H3NOH
"
H3NOH O!"
A
N
NO2
NN
NO2
O2N
HE
Guia de estudo 
Cuidado!! 
 
Halogênios, embora 
desativadores são 
orto-para dirigentes. 
7051 6 - 3 D i r e c t i n g E f f e c t s o f S u b s t i t u e n t s i n C o n j u g a t i o n C H A P TE R 1 6
Complete ortho, para nitration of methylbenzene (toluene) or 
phenol furnishes the corresponding trinitro derivatives, both 
of which are powerful explosives: TNT (discovered in 1863) 
and picric acid (1771). Both compounds have long histories 
as military and industrial explosives.
NO2
CH3
NO2
O2N NO2
OH
NO2
O2N
2-Methyl-1,3,5-trinitrobenzene
(2,4,6-Trinitrotoluene, TNT)
2,4,6-Trinitrophenol
(Picric acid)
Explosives are generally high-energy-density compounds 
capable of extremely rapid decomposition. In contrast to 
propellants (such as rocket fuel), they do not burn, but 
detonate under their own power. They frequently generate 
high heat and a large quantity of gaseous products, producing 
a (usually destructive) shock wave: TNT has a detonation 
velocity of 7459 m s21 (!4.6 mi s21). An explosion can be 
initiated by impact (including blasting caps), friction, heat 
and fl ame, electrical discharge (including static), and ultraviolet 
irradiation, depending on the compound. The nitro group 
features prominently in these materials, because it functions 
as an oxidizer to the surrounding carbon framework (producing 
the gases CO and CO2) and as a precursor to N2.
TNT is the most widely used military explosive in history. 
The reasons for its popularity are its low cost and simplicity 
of preparation, safe handling (low sensitivity to impact and 
friction), relatively high explosive power (yet good chemical 
and thermal stability), low volatility and toxicity, compatibility 
with other explosives, and a low melting point, allowing for 
melt-casted formulations.
TNT has become such a standard, particularly in military 
uses, that the destructive power of other explosives, especially 
in bombs, is often compared to that of an equivalent of 
TNT. For example, the fi rst atomic bomb—detonated on 
July 16, 1945, in New Mexico—had the equivalent power of 
19,000 tons of TNT. The device exploded over Hiroshima, 
Japan, which killed more than 140,000 people, had the 
power of 13,000 tons of TNT. Although these numbers 
appear huge, comparison with the hydrogen bomb—with the 
destructive equivalent of 10 million tons of TNT—dwarfs 
REAL LIFE: MATERIALS 16-1 Explosive Nitroarenes: TNT and Picric Acid
them. For further calibration, all of the explosions of World 
War II combined amounted to the equivalent of “only” 
2 million tons of TNT.
Picric acid has some commercial applications other than 
as an explosive—in matches, in the leather industry, in electric 
batteries, and in colored glass. It is called an acid because of 
the unusually high acidity of its hydroxy group (pKa 0.38; 
Section 22-3), which is increased beyond that of acetic acid 
(pKa 4.7) and even hydrogen fl uoride (pKa 3.2; Table 2-2) by 
the electron-withdrawing effect of the three nitro groups. This 
property was in part responsible for its replacement by TNT 
in military uses. For example, in artillery shells, it would 
corrode the casing and cause leakage, thus creating a hazard.
TNT and picric acid have been replaced gradually by 
tetryl, RDX, and nitroglycerine (Section 9-11). On the 
research front, chemists are continuing to explore novel 
structures. A case in point is octanitrocubane, synthesized 
in 2000, in which ring strain adds to the brisance of the 
compound. Its molecular formula, C8N8O16, indicates the 
potential to generate 8 CO2 1 4 N2 molecules, with an 
associated 1150-fold volume expansion. A recent example 
from 2012 is the exotic salt TKX-50, in which two lone 
carbon atoms are surrounded by 10 nitrogens and the 
equivalent of 4 H2O moieties.
Spherical shock waves generated by the fi ring of the huge guns of 
the USS Iowa are clearly visible on the ocean surface.
2,4,6-Trinitrophenyl-
N-methylnitramine
(Tetryl)
1,3,5-Trinitro-1,3,5-
triazacyclohexane
(RDX)
Octanitrocubane TKX-50
NO2
NO2
NO2
NO2
O2N
O2N
O2N
O2NNO2
NO2
O2N
N
O2N CH3H E
N
N
N
N
N
N
N
N
O! H3NOH
"
H3NOH O!"
A
N
NO2
NN
NO2
O2N
HE
7051 6 - 3 D i r e c t i n g E f f e c t s o f S u b s t i t u e n t s i n C o n j u g a t i o n C H A P T E R 1 6
Complete ortho, para nitration of methylbenzene (toluene) or 
phenol furnishes the corresponding trinitro derivatives, both 
of which are powerful explosives: TNT (discovered in 1863) 
and picric acid (1771). Both compounds have long histories 
as military and industrial explosives.
NO2
CH3
NO2
O2N NO2
OH
NO2
O2N
2-Methyl-1,3,5-trinitrobenzene
(2,4,6-Trinitrotoluene, TNT)
2,4,6-Trinitrophenol
(Picric acid)
Explosives are generally high-energy-density compounds 
capable of extremely rapid decomposition. In contrast to 
propellants (such as rocket fuel), they do not burn, but 
detonate under their own power. They frequently generate 
high heat and a large quantity of gaseous products, producing 
a (usually destructive) shock wave: TNT has a detonation 
velocity of 7459 m s21 (!4.6 mi s21). An explosion can be 
initiated by impact (including blasting caps), friction, heat 
and fl ame, electrical discharge (including static), and ultraviolet 
irradiation, depending on the compound. The nitro group 
features prominently in these materials, because it functions 
as an oxidizer to the surrounding carbon framework (producing 
the gases CO and CO2) and as a precursor to N2.
TNT is the most widely used military explosive in history. 
The reasons for its popularity are its low cost and simplicity 
of preparation, safe handling (low sensitivity to impact and 
friction), relatively high explosive power (yet good chemical 
and thermal stability), low volatility and toxicity, compatibility 
with other explosives, and a low melting point, allowing for 
melt-casted formulations.
TNT has become such a standard, particularly in military 
uses, that the destructive power of other explosives, especially 
in bombs, is often compared to that of an equivalent of 
TNT. For example, the fi rst atomic bomb—detonated on 
July 16, 1945, in New Mexico—had the equivalent power of 
19,000 tons of TNT. The device exploded over Hiroshima, 
Japan, which killed more than 140,000 people, had the 
power of 13,000 tons of TNT. Although these numbers 
appear huge, comparison with the hydrogen bomb—with the 
destructive equivalent of 10 million tons of TNT—dwarfs 
REAL LIFE: MATERIALS 16-1 Explosive Nitroarenes: TNT and Picric Acid
them. For further calibration, all of the explosions of World 
War II combined amounted to the equivalent of “only” 
2 million tons of TNT.
Picric acid has some commercial applications other than 
as an explosive—in matches, in the leather industry, in electric 
batteries, and in colored glass. It is called an acid because of 
the unusually high acidity of its hydroxy group (pKa 0.38; 
Section 22-3), which is increased beyond that of acetic acid 
(pKa 4.7) and even hydrogen fl uoride (pKa 3.2; Table 2-2) by 
the electron-withdrawing effect of the three nitro groups. This 
property was in part responsible for its replacement by TNT 
in military uses. For example, in artillery shells, it would 
corrode the casing and cause leakage, thus creating a hazard.
TNT and picric acid have been replaced gradually by 
tetryl, RDX, and nitroglycerine (Section 9-11). On the 
research front, chemists are continuing to explore novel 
structures. A case in point is octanitrocubane, synthesized 
in 2000, in which ring strain adds to the brisance of the 
compound. Its molecular formula, C8N8O16, indicates the 
potential to generate 8 CO2 1 4 N2 molecules, with an 
associated 1150-fold volume expansion. A recent example 
from 2012 is the exotic salt TKX-50, in which two lone 
carbon atoms are surrounded by 10 nitrogens and the 
equivalent of 4 H2O moieties.
Spherical shock waves generated by the fi ring of the huge guns of 
the USS Iowa are clearly visible on the ocean surface.
2,4,6-Trinitrophenyl-
N-methylnitramine
(Tetryl)
1,3,5-Trinitro-1,3,5-
triazacyclohexane
(RDX)
Octanitrocubane TKX-50
NO2
NO2
NO2
NO2
O2N
O2N
O2N
O2NNO2
NO2
O2N
N
O2N CH3H E
N
NN
N
N
N
N
N
O! H3NOH
"
H3NOH O!"
A
N
NO2
NN
NO2
O2N
HE
NITROPENTA 
Prof. Calçada 3 
 
 
 
1) Escreva, sem mostrar o mecanismo, as reações abaixo (considere 
que as reações ocorrem com os catalisadores adequados): 
 
a) Monocloração do benzeno. 
b) Mononitração do benzeno. 
c) Monosulfonação do benzeno. 
d) Benzeno + cloreto de metila 
e) Benzeno + cloreto de etanoila 
2) Escreva o mecanismo completo das reações abaixo: 
a) benzeno + Cℓ2 
AℓCℓ3
 
b) benzeno + HNO3 
!!!!!
 
3) Complete as reações abaixo completando os espaços. 
 
 
a) Benzeno + Br2 bromobenzeno + HBr 
 
 
 
b) Benzeno + isopropilbenzeno + HCℓ 
 
 
c) Benzeno + H3CCH2COCl + 
 
 
1. (Ita 2015) Escreva a fórmula estrutural do produto majoritário 
formado na reação entre 0,1mol de tolueno (metilbenzeno) e 0,1mol de 
Cl2 nas seguintes condições: 
 
a) Ausência de luz e presença de pequena quantidade de Fe(s) 
b) Presença de luz e ausência de Fe(s) 
 
2. (Ita 2014) Apresente as equações que representam as reações 
químicas de nitração do tolueno, na presença de ácido sulfúrico, 
levando a seus isômeros. Indique o percentual de ocorrência de cada 
isômero e seus respectivos estados físicos, nas condições-padrão. 
 
3. (Ita 2012) A nitrocelulose é considerada uma substância química 
explosiva, sendo obtida a partir da nitração da celulose. Cite outras 
cinco substâncias explosivas sintetizadas por processos de nitração. 
 
4. (Ita 2012) Apresente os respectivos produtos (A, B, C, D e E) das 
reações químicas representadas pelas seguintes equações: 
 
 
 
4. (Unifesp) O naftaleno é um composto utilizado como matéria-prima 
na produção de diversos produtos químicos, como solventes, corantes 
e plásticos. É uma substância praticamente insolúvel em água, 3 
mg/100 mL, e pouco solúvel em etanol, 7,7 g/100 mL. A reação de 
sulfonação do naftaleno pode ocorrer por dois diferentes mecanismos, 
a 160 ºC representado na curva I (mecanismo I) e a 80 ºC, 
representado na curva II (mecanismo II). 
 
 
 
a) Represente as estruturas de ressonância do naftaleno. Explique as 
diferenças de solubilidade do naftaleno nos solventes relacionados. 
b) Explique por que o mecanismo I ocorre em temperatura maior que o 
mecanismo II. Classifique as reações que ocorrem nas curvas I e II, 
quanto ao calor de reação. 
 
 
5. (Ita 2012) A reação de sulfonação do naftaleno ocorre por 
substituição eletrofílica nas posições α e β do composto orgânico, de 
acordo com o diagrama de coordenada de reação a 50 °C. 
 
Com base neste diagrama, são feitas as seguintes afirmações: 
I. A reação de sulfonação do naftaleno é endotérmica. 
II. A posição α do naftaleno é mais reativa do que a de β. 
III. O isômero β é mais estável que o isômero α. 
Das afirmações acima, está(ão) correta(s) apenas 
a) I. b) I e II. c) II. d) II e III. e) III. 
 
 
6) Descreva todas as reações, a partir de benzeno, indicando reagentes inorgânicos e 
catalisadores, na síntese dos seguintes compostos, admita que o isômero orto possa ser 
separado do para ( 5 pontos): 
 
a)
b)
c)
NO2
Br
COCH3
Br
Cl
SO3H
d)
Questões de classe 
AlCl3 
Prof. Calçada 4 
 
EXTRAS GERAIS 
 
1) Desenhe as estruturas de: 
 
 
 
 
 
 
 
2) Esboce todos os passos de um síntese de laboratório dos seguintes compostos a partir de benzeno e/ou tolueno e qualquer outro reagente necessário. Assuma 
que o isômero orto possa ser separado do para. 
 
 
 
3. Resolva as cinco questões da lista a seguir: