Questions tagged [electrophilic-substitution]

use for reactions where an electrophile (electron-deficient species) displaces a substituent. Reactions like nitration fall under this category

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Does vinyl chloride have greater electrophilic addition rate than ethene? [closed]

Which of the following will have a greater rate of electrophilic addition? Since the rate of electrophilic addition AdE is proportional to nucleophilicity of the substrate, I assume chloroethene $\ce{...
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Ferrocene and electrophilic abilities

Why will ferrocene not undergo electrophilic substitution with concentrated sulfuric acid, nitric acid, or bromine? I thought its activity was comparable to benzene since it is aromatic but clearly ...
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Why does aromatic sulfonation of 3-aminobiphenyl occur at the para position of the adjacent ring?

I know that the amino group $\ce{-NH2}$ is a strong activator, so the sulfonate group $\ce{-SO3H}$ should be directed at the ortho or para position. However, the sulfonation occurs at para position on ...
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2 votes
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Electrophilic substitution on disubstituted benzene, when deactivating groups are at para

As far as I have been able to understand this, the sites of electrophilic substitution are majorly decided on basis of the fact that "Where the electron density is more, electrophilic ...
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addition of HBr to a conjugated alkene

here we shift double bond and change the carbocation from 3 degree to 2 degree, by doing so we are saying that hindrance matters more than carbocation stability, is this always the case in such ...
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Partial rate factors in EAS

In the electrophilic aromatic substitution of benzene, at the para position in toluene, why do the partial rate factors follow the order $Br^+>Cl^+>NO_2^{+}$? I understand that if the ...
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3 votes
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Electrophilic Substitution of Substituted Benzene

I know that phenol doesn't undergo the Friedel-Crafts Alkylation and Acylation reactions, because the reagent $\ce{AlCl3}$ forms a complex with phenol, as the oxygen atom donates it's lone pair to the ...
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Effect of trifluoromethyl substituent on electrophilic substitution [duplicate]

Problem - Find which carbon is most susceptible to electrophilic attack (among carbons numbered $1$ to $6$): Answer given (may not be the correct one) - My question - $1.$ I know that $\ce{-CCl3}$ ...
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7 votes
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Electrophillic susbtitution of bromine on styrene and cinnamic acid in the presence of FeBr3, a Lewis acid

Bromine gas, in the presence of $\ce{CCl4}$, undergoes on addition reaction at the double bond in both styrene and cinnamic acid, illustrated below. Styrene: Cinnamic acid: Bromination of benzene in ...
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About the Vilsmeier-Haack formylation of this compound

I was reading an article and found the following reaction sequence: The second step involves a formylation of the hydrazone with the Vilsmeier reagent to, first synthesize the pyrazole ring and then, ...
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6 votes
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Can't aluminium chloride do electrophilic substitution as an electrophile?

In halogenation reactions of benzene, $\ce{AlCl3}$ is used as a catalyst in order to form electrophile $\ce{E^+}$. So I was wondering that $\ce{AlCl3}$ is a Lewis acid (that fact being also used in ...
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Competition between aromatic sulphonation and nitration

Say you take a substituted benzene* and react it with oleum and nitric acid. Would it result in a nitrated ring, a sulphonated ring, or some sort of a combination? Thinking about it in terms of the ...
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Meta-directing nature of anilinium cations

The comments on this answer seem to detail a trend in which $\ce{NR3+, NHR2+, NH2R+}$ all show meta-directing nature towards electrophilic substitution, with the slightly stronger para-direction of $\...
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3 votes
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Why do resorcinol and iodine react to give 2-iodobenzen-1,3-diol?

I am supposed to perform the above shown reaction in the lab soon, but I don't really understand the mechanism behind it. I got told by my lab assistant that the mechanism is an electrophilic aromatic ...
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Lack of polysubstitution in Friedel–Crafts t-butylation of phenol

According to our lab manual: In general, Friedel–Crafts alkylation is not employed to make monoalkyl benzene derivatives because of the polysubstitution. But our professor told us that while we are ...
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Why does (2-methoxyethyl)benzene undergo nitration at the ortho position (major product)?

This is an option in a question in which we needed to mark all the correct reactions: According to the answer key, this is a correct option. As an alkyl group is directly bounded to the benzene ring, ...
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Major product of the nitration of benz[cd]indol-2(1H)-one

Decide major product for given reaction of electrophilic aromatic substitution: Is the major product a because of steric hindrance, or is it b because of hydrogen bonding?
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Why doesn't aromatic substitution add at multiple positions in one reaction?

When you do aromatic substitutions, you usually see the major products with one substituent added. My question is why can't you add multiple substituents in one reaction? For example, the image below ...
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Aromatic Substitution in acidic medium

Find product A. I tried solving but why isn't the answer this The answer is given this
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1 answer
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What is the electrophile in Perkin's condensation reaction?

In Perkin's reaction, an aromatic aldehyde reacts with an acid anhydride to give an alpha-beta unsaturated aromatic acid. Which reactant is the electrophile and which one is the nucleophile?
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Hell-Volhard-Zelinski Reaction [closed]

What is the role of red phosphorus in hvz reaction? Initially I think that red phosphurus is nothing but a catalyst. But it is not a catalyst.
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Electrophilic Aromatic substitution reactions of aromatic compounds [closed]

Benzene and substituted benzene (phenols, aromatic ethers, benzaldehyde, aromatic ketones like acetophenone, benzoic acid, aniline and nitrobenzene) generally can undergo electrophilic Aromatic ...
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What happens when FeF3 is reacted with benzene? [closed]

My text book says that halobenzenes can be prepared by aromatic substitution on benzene ring by using Fe or FeX3 as Lewis acid but this method isn't useful for preparation of fluoro benzene because of ...
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The main difference between using AlCl3 and FeCl3 in Friedel-Crafts alkylation

What is the main difference between using $\ce{AlCl3}$ and $\ce{FeCl3}$ in Friedel-Crafts alkylation? Is that $\ce{FeCl3}$ disfavors carbocation rearrangement in Friedel-Crafts alkylation?
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4 votes
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Electrophilic Substitution with Ceric Ammonium Nitrate and Lithium Bromide as reagents

The 2020 IChO Preparatory Problem List (source here) had the following reaction as part of the solution to the first question: (CAN = Ceric Ammonium Nitrate). What is the mechanism for this '...
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Why don't phenol behave like aniline in electrophilic substitutions?

As far as I know, many electrophilic aromatic substitution reactions fail to undergo the usual way in aniline. This is due to $\ce{-H2N}$ group being basic (pKa of $\ce{NH3}$ = 38), even it is ...
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Acids used in Friedel-Crafts alkylation

I am learning adding alkyl groups to benzene using Fridel-Crafts alkylation: I know that it is very common to use $\ce{AlCl3/AlBr3}$ as Lewis acid catalyst in this reaction. But I am just wondering ...
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activating and deactivating groups and directing effect

In electrophilic aromatic substitution: I have just learnt a 'rule' about benzene with more than 1 substituents attached (excluding the effect on steric hindrance): if a strong activating group (EDG) ...
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Electrophilic substitution on Borazole

As Borazole ($\ce{B3N3H6}$) is aromatic, it can show electrophilic aromatic substitution. Now, my question is when borazole undergoes electrophilic aromatic substitution reaction, on which atom does ...
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Regioselectivity in Electrophilic Aromatic Substitution of Pyrrole and Indole

If we look into the structures of Pyrrole and Indole, they are very similar. Only Indole has one extra Benzene ring attached to it, i.e. if we attach one Benzene ring to Pyrrole, what we'll have is ...
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Nitro-substitution [closed]

Here I expected (b) to happen via nucleophilic substitution, but contrary to that (a) is the one occuring. What exactly is happening here?
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Steric Effects in Friedel-Crafts Reactions

I recently came across a Friedel-Crafts reaction happening between benzoyl chloride and mesitylene with $\ce{AlCl3}$ as a catalyst. Apparently this reaction doesn't occur due to steric effects even ...
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Which is the major product of bromination of 3-(dimethylamino)benzamide, ortho or para?

I know that A will most probably not happen because of high steric hindrance. However between B and C, will B become the major product? Because $\ce{-N(CH3)2}$ is less bulky compared to $\ce{C=O-NH2}$,...
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When we cannot use Friedel-Crafts acylation to insert alkyl group?

Questions: Show a probable synthethic pathway to obtain the first molecule, I. Will the same strategy be used to insert the alkyl group for J. Explain. My answers (please tell me if there is any ...
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Friedel-Crafts's alkylation of Toluene [duplicate]

In the Friedel-Craft's alkylation of Toluene with $\ce{CH3Cl}$ in the presence of $\ce{AlCl3}$, the major product was meta - substituted. My teacher gave it to me as an exception. Is there any ...
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Will ipso substitution work in both cases of vanillic and isovanillic acids here or not?

What will be the product of the 2 reactions when bromine is taken in excess? I think ipso substitution will work here and there will be two $\ce{Br}$ substituting in both products, but in the book it ...
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1 vote
1 answer
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Order of activating ability in electrophilic aromatic substitutions

From A Guidebook to mechanism in organic chemistry by P. Sykes [1, p. 155]: The activating effect of $\ce{Y}$ on the nucleus is found to increase, i.e. the overall rate of substitution increases, in ...
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2 votes
1 answer
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Does the first step in electrophilic aromatic substitution follow equilibrium? If so, can equilibrium constant be calculated?

Using chlorine (a Lewis base) and ferric chloride (a Lewis base) as an example, the first step I saw in the textbook looks like this: The picture above depicts the Step 1 in the EAS mechanism using ...
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1 vote
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Electrophilic attack of X+ on double bond

Is it the double bond attacking the $\ce{X+}$ ion or the other way around? Also, does it form a cyclic transition state if it isn't bromine or chlorine? Eg. cyclohexene $+ \,\ce{Cl+ ->}$ cyclic ...
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2 votes
1 answer
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What happens to the NMR of an alcohol when D2O is added?

What difference you expect in the 1H NMR spectrum of phenol in $\ce{CDCl3}$ after a drop of $\ce{D2O}$ is added to the test tube? 1) Since the $\ce{-OH}$ of the phenol is quite acidic, it undergoes ...
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2 votes
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Bromination on the aromatic ring vs aliphatic chain

I thought that the answer would be a simple electrophillic aromatic substitution and as the carbonyl is a meta director, the bromine would be present meta to the group. But the given answer was the α-...
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9 votes
1 answer
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Kolbe Schmitt followed by methylation

The first step in this synthesis is a Kolbe Schmitt process, but why is two equivalents of base needed? Also, what is the purpose of the two equivalents of methyl iodide? I assumed that there will be ...
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3 votes
2 answers
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Why are Friedel Crafts reaction not possible for molecules less activated than benzene?

I know that Friedel Crafts alkylation reaction are not possible for aniline and phenol since they form complexes with Lewis Acids. But our teacher told us that Friedel Crafts reactions aren't possible ...
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Major product of mononitration of 3-methylphenol

From NCERT Class Chemistry Part 2: Example 11.5 Write the structures of the major products expected from the following reactions: (a) Mononitration of 3-methylphenol (b) Dinitration of 3-methylphenol ...
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Reactivity in electrophillic substitution [closed]

When comparing maximum reactivity of a compound in electrophillic addition, what factors are kept in mind while comparing propene and trans-2-butene? Why is trans-2-butene more reactive in this case ...
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How far does the delocalisation (resonance) effects for substituents extend for a conjugated system?

Let's say we have a conjugated system like this one: Now, the delocalisation of the benzene electrons with the nitrate system means that the ortho, and para positions on the immediate benzene ring ...
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5 votes
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Reimer-Tiemann reaction on indole

According to me net reaction should be at $\ce{C3}$ when Reimer-Tiemann reaction is done on indole (see image), since in the resonance structure, negative charge is on this carbon. But, the answer ...
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1 answer
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Validity of the leveling effect of water in nitration reactions

Wikipedia gives this as the levelling effect of water Any acid that is stronger than $\ce{H3O+}$ reacts with $\ce{H2O}$ to form $\ce{H3O+}$. Therefore, no acid stronger than $\ce{H3O+}$ exists in $\...
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1 vote
1 answer
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Directing effect in Intramolecular Friedel Crafts Alkylation

This reaction should cause ring closure at either the $o-$ or $p-$ position relative to the methyl substituent on the ring (as methyl is an $o,p-$directing group), giving the following products: The ...
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2 votes
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Explanation of the third ortho effect

The third ortho effect is, according to Wikipedia, the phenomenon where in a ring with a meta and an ortho-para director both meta to each other has the incoming nucleophile go ortho to the meta ...
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