Questions tagged [aromatic-compounds]
For questions about the properties and reactions of aromatic compounds. This tag should also be applied to antiaromatic compounds. This tag should not be applied to general questions about resonance, use the [resonance] tag instead.
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Ortho-effect in substituted aromatic acids and bases
When comparing o,m,p-toluidine basicities, the ortho effect is believed to explain why o-toluidine is weaker. But when comparing o,m,p-toluic acid basicities, the ortho effect is stated as a reason ...
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Mechanism of arene side chain oxidation by permanganate
When treated with hot, concentrated acidic $\ce{KMnO4}$, arenes are oxidised to the corresponding carboxylic acids. For example, toluene is oxidised to benzoic acid.
I've tried to examine how this ...
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Why does nitration of N,N-dimethylaniline occur at the meta position?
The nitration of N,N-dimethylaniline with $\ce{H2SO4}$ and $\ce{HNO3}$ gives mainly the meta product, even though $\ce{-NMe2}$ is an ortho,para-directing group. Why is this so?
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IUPAC nomenclature for an interesting looking organic compound
How can I name this organic compound while adhering to the IUPAC standards?
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Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?
If we make a resonance structure for the anilinium ion, with positive charge at either the ortho or the para position, we get a pentavalent nitrogen, which is not possible. So, how is the $\ce{-NH3+}$ ...
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Unusual Friedel–Crafts alkylation with pivaloyl chloride
In class we were told of an anomalous Friedel–Crafts reaction with a tertiary acid chloride — $\ce{(CH3)3CCOCl}$, or pivaloyl chloride. When this reacts with benzene in the presence of $\ce{AlCl3}$, ...
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Why is cyclooctateraene shaped like a "tub" rather than a "chair"?
I understand that for cyclooctatetraene (COT) to "escape" the horrible prospect of becoming an anti-aromatic molecule, it must adopt a non-planar conformation.
The widely touted conformation of COT ...
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Which compound reacts faster in the Cannizzaro Reaction?
Which reacts faster in the Cannizzaro Reaction?
a) $\ce{OHC-C6H4-NO2}$
b) $\ce{OHC-C6H4-OCH3}$
Obviously, a better hydride releasing group will react faster. Therefore my answer was b, as $\ce{-...
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Why are the C-C bonds in benzene closer in length to double bonds than single bonds?
The $\ce{C-C}$ bonds in benzene are $\mathrm{140~pm}$ long which puts them in between single bonds and double bonds (given at $\mathrm{147-154~pm}$ and $\ce{134-135~pm}$ respectively, sourced from ...
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Thermodynamic vs Kinetic Sulphonation of Naphthalene
The left hand isomer is clearly the kinetically favoured product and the right hand isomer is the thermodynamically favoured product. However, I have no idea why. Can you explain?
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Products of Reimer–Tiemann reaction of 4-methylphenol
p-cresol (4-methylphenol), undergoes the Reimer–Tiemann reaction upon treatment with chloroform ($\ce{CHCl3}$) in alkaline medium. Which of the following is the major and minor product?
A. 2-...
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The order of aromaticity of benzene, thiophene, pyrrole, furan, and pyridine
I have been taught that the order of aromaticity is: benzene > thiophene > pyrrole > furan. However, I have been unable to deduce any logical explanation for that order. Also, I wish to compare ...
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Electrophilic Aromatic Substitution: Are protonated OH-groups ortho-/para- or meta-directing?
In Electrophilic Aromatic Substitution ($\text{S}_{\text{E}}\text{Ar}$) reactions groups that can donate an electron pair into the aromatic ring, e.g. $\ce{-OH}$ or $\ce{-NH2}$, are ortho-/para-...
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Chirality of symmetrically substituted biphenyl
I am facing trouble with the following problem: is 2,6-dimethyl-2',6'-dinitro-1,1'-biphenyl chiral?
My idea is that there is a axis of symmetry along the line joining the two benzene molecules. Hence ...
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Why isn't the silicon analogue of benzene flat?
Why isn't the silicon analogue of benzene flat? As far as I understand, silicon and carbon make similar structures and it doesn't make sense that its benzene analogue should be substantially different....
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Why are smoke odors persistent in fabrics?
Obviously smoke is very complex, but apparently phenol compounds are the main components of wood smoke that produce the characteristic odor. (One of more significant of these compounds seems to be ...
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Thermodynamic stability of meta-xylene over ortho- and para-isomers
When talking about the example of the alkylation of toluene by chloromethane in the presence of $\ce{AlCl3}$, Hepworth, Waring and Waring (2002) mentioned that:
At room temperature, a mixture of 1,...
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Is the ring or the chain chosen as the parent structure in octan-2-ylbenzene?
How would you name the above compound according to IUPAC rules? I see some sources say it is 2-phenyloctane, but ChemDraw and a few other sources say it is 2-octanylbenzene.
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Reason for the stronger acidic property of phenol than alcohol
In phenol, pulling the $\mathrm{p}_z$ electrons from the oxygen atom into the ring causes the hydrogen atom to be more partially positive than it is in aliphatic alcohols. This means it is much more ...
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Are there any examples of activating meta directors?
I have heard about activating ortho-para directors. For example: methoxy group, hydroxy group, alkyl group, et cetera.
I have heard about deactivating ortho-para directors. For example: halogen ...
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Does benzene's resonance structure allow it to enter DNA?
According to this link, benzene is able to insert itself into the human DNA. It isn't an authoritative source and appears to be quite biased, so I'm wondering if there's any truth to this.
The ...
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Why are arenes with conjoined benzene rings drawn as they are?
Whilst we are taught to represent benzene as below (A) due to its delocalised electrons, however when two benzene rings share carbons (e.g. naphtalene) it seems to be more commonly represented in ...
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Mechanism of a dephenylation reaction
I recently came across this reaction in my undergraduate labs. The experiment is taken from this article: J. Chem. Educ., 2008, 85, 413.
The condensation of 2-methoxynaphthalene with cinnamoyl ...
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What is the mechanism of chlorosulfonation of benzene?
The above reaction looks very similar to a conventional sulfonation reaction but if the reaction pathway is analogous to sulfonation I do not see how the $\ce{SO_2Cl^+}$ would form. Surely $\ce{Cl^-}$ ...
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Why does benzene bend in this reaction?
From here
I can see why hapticity changes here, but not why it is necessary for the benzene ring to bend. The resonance energy of benzene is pretty large, and there's no balancing increase in ...
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Reaction of furan with chloroform in base
This reaction looks like the Riemer-Tiemann reaction. The only difference is the reactant. First step is the formation of carbene. Second step involves the attack of π-electrons of furan on the vacant ...
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Why is a hydroxyl group more activating than a methoxy group in electrophilic aromatic substitution?
Why is phenol more reactive towards electrophilic substitution than methoxybenzene? Isn't the lone pair on the methoxy group oxygen more available for participating in resonance into the ring than the ...
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Reaction of perchloric acid with cyclopropenol
Question:
Identify A and B.
My attempt
The first step will be the attack of $\ce{PhMgX}$ on carbonyl carbon, that is, 1,2 position followed by hydrolysis, yielding an alcohol.
But how does the ...
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Why are fluorides more reactive in nucleophilic aromatic substitutions than bromides?
In nucleophilic aromatic substitution reactions, why do fluorides react faster than bromides?
Ordinarily bromide is a better leaving group than fluoride, e.g. in $\mathrm{S_N2}$ reactions, so why isn'...
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Is there any special rules for checking the aromaticity of polycyclic compounds?
This question arose in my mind because it's given in a book that pyrene is aromatic. How can it be with 16 π electrons? So, it should be actually anti-aromatic or is there any special rule for these ...
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Ozonolysis conditions for benzene
What are the precise conditions under which benzene undergoes ozonolysis? All anyone can tell me is that it undergoes ozonolysis under "vigorous" conditions. But, what vigorous conditions?
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Does aniline react with diazonium ions at C or N?
In the azo coupling of aniline with benzenediazonium cation, I thought of two possible products 1 and 2 that could be formed. However, I can't work out which will be preferred. What would be the major ...
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Reaction mechanism for reduction of nitrobenzene to aniline in catalytic and acidic media
Can anyone explain the reaction mechanism of the two reactions given below?
They are the conversion of nitrobenzene to aniline in catalytic ($\ce{H2/Pd}$ in ethanol) and acidic ($\ce{Sn/HCl}$ or $\ce{...
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Why use potassium iodide instead of copper iodide in Sandmeyer reaction?
The Sandmeyer reaction is an extremely useful reaction for the functionalization of aromatic rings through a diazonium intermediate. For conversion of a diazonium intermediate to the corresponding ...
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Friedel–Crafts reaction of phenol
Does phenol undergo Friedel–Crafts reactions or does it react with Lewis acids like aniline does?
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Structural representation of substituted benzene
Recently, I was watching a video about separating o-chlorotoluene and p-chlorotoluene from its solution. Following was a reaction demonstrated in the video:
I was curious about the structure of ...
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Basicity Alteration Due To Ortho Effect In Methoxy Aniline System
I wanted to ask something more in reference to this question.
Suppose instead of toluidine, 2-methoxyaniline and 3-methoxyaniline are present. Now, why is 2-methoxyaniline more basic than 3-...
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What is quasi-aromaticity?
During my study of aromaticity, I came through this topic of quasi-aromaticity. Can you please elaborate what Quasi aromatic compounds are and how are they designated?
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Why are aromatic compounds so stable?
I've never actually been told deeper reasons for this. In organic chemistry classes (1 and 2) we're usually told that aromatic compounds are very stable whereas anti-aromatic ones are not, and also, ...
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How is spiro[4.4]nonatetraene antiaromatic
How is spiro[4.4]nonatetraene antiaromatic? I know that spiro compounds exhibit homoaromaticity, but how do they exhibit antiaromaticity?
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Why is the 2-position of pyridine electron richer than the 4 position
I am wondering about the electronic structure of pyridine.
If we look at nucleophilic substitution, which favored on electron poor centers, for 2-chloro and 4-chloro pyridine we see that the ...
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Why can the lone pair not align with the phenyl moiety in 2,6-xylidine?
I am told that for 2,6-xylidine (2,6-dimethylaniline), the amino group cannot line up in such a way that its p-orbital is parallel with respect to the p-orbitals of the carbons in the ring.
I've ...
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Why is this compound named resorcinol?
Substituted phenols or polyhydroxy phenols have their general name apart form IUPAC names. The general names comes from the source it is found like:-
Catechol (1,2-dihydroxybenzene)- obtained from ...
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Why are halogens ortho para directing even though deactivating?
Halogens bonded to benzene ring has three lone pairs. These three electron pairs can cause resonance in benzene ring. But, halogens are also highly electronegative and thus they have strong -I effect. ...
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Mechanism for chloromethylation of benzene with formaldehyde and HCl
What is the mechanism of the above reaction? I have thought of one possibility:
Would this work? How exactly is the chlorine installed on the alkyl chain?
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Is steric inhibition of resonance or steric inhibition of protonation dominant in o-toluidine?
I wish to know which effect out of steric inhibition of resonance (SIR) or steric inhibition of protonation (SIP) is dominant over the other when comparing basicities of o-toluidine and aniline:
...
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Why is it the middle ring of anthracene which reacts in a Diels–Alder?
I'm wondering why maleic anhydride adds to the middle cycle of anthracene, and not the outer two.
I would have expected that a Diels–Alder with the outer ring would be better, because I expected a ...
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Inductive effect of phenyl ring
I completely understand how phenyl group 'releases' or 'donates' electron through resonance, but how is that a phenyl group shows a weak -I effect, despite having electrons literally smeared on itself?...
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Kinetic Isotopic Effect in EAS
It is observed that rate of reaction of two isotopologues of benzene, $\ce{C6D6}$ and $\ce{C6H6}$, is the same for electrophilic aromatic reactions, as the deprotonation is not the rate limiting step. ...
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