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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How does bromine in bromine water become polarized enough for electrophilic substitution with phenol?

There's a question in my obscure school textbook that I couldn't find an answer to online. How does Bromine in Bromine water become polarized enough for electrophilic substitution with Phenol? This ...
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Contrast the unstable electron-deficient cationic intermediate with the stable pyridinium ion [closed]

Why is the pyridinium ion not unstable, such as an unstable electron-deficient intermediate cation in electrophilic aromatic substitution, after the pyridinium ion has a positive charge on nitrogen?
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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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Can't aluminium chloride do electrophilic substitution as an electrophile?

In halogenation reaction 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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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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Effect of the isotopes of hydrogen in electrophilic aromatic substitution

Replacing hydrogens in benzene by deuterium slows down halogenation and sulfonation but not nitration. I am not able to figure this out by their mechanisms. Why does this happen?
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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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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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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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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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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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Kinetic isotope effect in nitration of benzene

What is the effect of changing all the hydrogen atoms in benzene to deuterium? For example, which of the following reactions occurs at a faster rate?
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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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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 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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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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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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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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273 views

Electrophilic substitution on Borazole

As Borazole ($\ce{B3N3H6}$) is aromatic, it shows electrophilic aromatic substitution. Now, my question is when borazole undergoes electrophilic aromatic substitution reaction, on which atom does the ...
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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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162 views

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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Lactone acylation

Can anyone propose/draw a mechanism for Method A, below, from this paper? Almost all other literature use method B and reagents such as SOCl2.
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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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244 views

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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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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Friedel-Crafts synthesis - How is HCl produced?

In the mechanism for the acetylation of bromobenzene, how is $\ce{HCl}$ gas produced? The reactants are acetic anhydride, bromobenzene, $\ce{AlCl3}$ and dichloromethane. Initially, 4-...
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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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267 views

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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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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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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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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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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764 views

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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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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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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187 views

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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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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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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How does a halogen react in an electrophilic substitution reaction

From what I understand, electrophiles are electron deficient and therefore would be attracted to the electron-rich benzene ring. So would the correct answer be A?
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Solvent Effects in Friedel–Crafts Reaction

While reading about the factors affecting the product of Friedel–Crafts acylation with acetyl chloride, I came across a reaction involving napthalene in two different solvents: in nitrobenzene ...
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386 views

Is m-cresol or p-cresol more reactive towards electrophilic substitution?

Which is more reactive towards electrophilic substitution, meta-cresol or para-cresol? Both oxygen and methyl are activating groups. I don't know on what basis do I compare their reactivity. There's ...
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Electrophilic substitution of benzene with conc. HNO₃ and HNO₂

The following question was given in my FIITJEE study material: $$\ce{Benzene + \text{conc.} HNO_3 + HNO_2 ->}$$ Final product of the reaction is: , , , I started with the solution by deciding ...