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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 ...
user4114's user avatar
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49 votes
1 answer
30k views

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 ...
ManishEarth's user avatar
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37 votes
1 answer
39k views

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 $\ce{-NH3+}$ ...
ravi's user avatar
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27 votes
1 answer
29k views

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?
RobChem's user avatar
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25 votes
2 answers
9k views

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.
1110101001's user avatar
  • 3,276
27 votes
2 answers
24k views

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-...
stochastic13's user avatar
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13 votes
4 answers
2k views

Stability of 4-pyridone vs 4-pyridinol

In kryptomerism assignment, there was a question to compare more stable tautomeric form between 4-pyridone (1) and 4-pyridinol (2): Answer: 4-pyridone. My friend gave two plausible reasons: $\ce{C=...
Zenix's user avatar
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13 votes
2 answers
31k views

Why is the lone pair of pyridine's nitrogen atom not part of the aromatic ring?

In pyrrole, the lone pair of electrons belonging to the nitrogen is part of the aromatic ring. However, in pyridine it is part of an sp2-hybridized orbital. Why can't it be in the p-orbital and take ...
CowperKettle's user avatar
  • 3,286
12 votes
2 answers
30k views

Is nitrogen of aniline sp² or sp³ hybridized? [duplicate]

I found a thread which discussed this which totally confused me. (refer to the part of the link which talks about $\ce{sp^2/sp^3}$) The question "How to rationalise the resonance structures and ...
Wong's user avatar
  • 123
12 votes
1 answer
30k views

Why methyl group is 2,4-directing?

Why methyl group is 2,4-directing? I am an A level student and this isn't required at this level. I am looking for a simple explanation which a high school student can understand.
Suchal's user avatar
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9 votes
3 answers
8k views

Is the aromaticity broken in some resonance structures of para-nitro-aminobenzene?

According to my course of organic chemistry, para-nitro-aminobenzene has to break his aromaticity to delocalize the electrons of the amino-group in the nitro-group. I don't really see this, when I ...
Simon Ravelingien's user avatar
16 votes
2 answers
6k views

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, ...
Hritik Narayan's user avatar
16 votes
3 answers
42k views

Friedel–Crafts reaction of phenol

Does phenol undergo Friedel–Crafts reactions or does it react with Lewis acids like aniline does?
user63762453's user avatar
15 votes
2 answers
17k views

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: ...
Shrish Shankar's user avatar
12 votes
1 answer
16k views

Friedel-Crafts reaction of anisole?

We know that phenol and aniline, despite being strongly activating, are unable to to undergo Friedel-Crafts reactions because they form complexes with $\ce{AlCl3}$, thanks to the lone pair on nitrogen ...
Sawarnik's user avatar
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11 votes
1 answer
5k views

Basicities of nitrogen atoms in purine

Arrange the sites in purine in order of basicity. I feel that 9 is the least basic as nitrogen's lone pair is delocalised. However, I am unable to rank 1, 3, and 7 in a particular order. Is there a ...
user488460's user avatar
5 votes
2 answers
9k views

What is the numbering of substituted benzene derivatives according to IUPAC nomenclature?

According to the lowest locant rule shouldn't the numbering of the compound 1 start from the carbon at the 4th position, thus giving the IUPAC name as 1,2-dimethyl-4-hydroxybenzene? For compound 2 ...
Tajammul Saleem's user avatar
29 votes
3 answers
12k views

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{-...
Shubham's user avatar
  • 501
27 votes
2 answers
5k views

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-...
Philipp's user avatar
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26 votes
1 answer
10k views

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,...
Tan Yong Boon's user avatar
18 votes
2 answers
27k views

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'...
Preeteshwar's user avatar
17 votes
2 answers
5k views

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 ...
Aditya Garg's user avatar
16 votes
2 answers
1k views

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 ...
Nilay Ghosh's user avatar
  • 26.3k
14 votes
1 answer
380 views

Does aromaticity require a co-planar pi system?

It's well established that angular twisting can decrease the degree of delocalization across a $\pi$ system (e.g. biphenyl). Moreover, there's considerable debate about aromaticity in spherical ...
Geoff Hutchison's user avatar
13 votes
3 answers
13k views

Competing resonance and inductive effects in a substituted benzene

A molecule of phenol is much more inclined to under go an electrophilic substitution reaction than a molecule of benzene because the $\ce{-OH}$ group is highly reaction favoring. From what I ...
Tyler's user avatar
  • 305
13 votes
0 answers
18k views

Mechanism for an Étard reaction (chromium complex) [duplicate]

In the following reaction, a chromium complex is formed during the Étard reaction: I have the following questions: How is this complex formed? How does its hydrolysis take place? (What's the ...
JM97's user avatar
  • 3,477
9 votes
4 answers
40k views

Why should the temperature be maintained at 0–5 °C in a diazotisation?

I know that in a diazotisation reaction, the temperature should be carefully maintained within the range of 0–5 °C by use of an ice bath. Why is this so? How does the temperature affect the stability ...
Karthi Keyan's user avatar
9 votes
2 answers
4k views

Why is formyl chloride unstable while higher acyl chlorides are stable?

From Bruice's Organic Chemistry, section 18.6 Friedel–Crafts acylation of benzene [1, pp. 876–877]: Friedel–Crafts acylation places an acyl group on a benzene ring, and Friedel–Crafts alkylation ...
Seshank K's user avatar
  • 165
6 votes
1 answer
1k views

Are 2-pyridone and cycloheptatrienide antiaromatic?

Determine which one of the following compounds is not aromatic: I think 2-pyridone (preferred name: pyridin-2(1H)-one) (1) is non-aromatic. It already contains three double bonds. If I take the lone ...
MKJ's user avatar
  • 71
6 votes
1 answer
9k views

How to explain (non-/anti-) aromaticity in fulvene with the help of resonance structures?

Can someone please explain why the resonance structures of fulvene 1 is non-aromatic and 2 is anti-aromatic? Why is fulvene non-aromatic, even though it has four $\pi$-electrons and no $\mathrm{sp^3}$...
Amruta Koshe's user avatar
3 votes
2 answers
7k views

Resonance structure of cyclobutadiene?

I studied cyclobutadiene as an anti-aromatic compound. But I am unable to draw the resonance structures for cyclobutadiene. Can anyone help me? What is the driving force for the resonance to start? ...
vamsi's user avatar
  • 331
48 votes
2 answers
17k views

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?
Andrew's user avatar
  • 2,322
35 votes
1 answer
4k views

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 $\ce{AlCl3}$, ...
Charles's user avatar
  • 2,725
22 votes
4 answers
67k views

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 ...
Eliza's user avatar
  • 2,413
19 votes
3 answers
24k views

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 ...
Dhruba Banerjee's user avatar
16 votes
1 answer
6k views

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 ...
DSVA's user avatar
  • 5,792
15 votes
3 answers
1k views

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 ...
Dissenter's user avatar
  • 19k
14 votes
1 answer
1k views

Why can't antiaromatic compounds just escape planarity and become non-aromatic to avoid destabilization?

Why can't just all anti-aromatic systems lose planarity (and hence conjugation) and be non-aromatic like cyclooctatetraene ? ...
Abhirikshma's user avatar
  • 1,916
13 votes
2 answers
3k views

Is the resonance depiction of benzene typically portrayed incorrectly?

I can understand that the carbon atoms in benzene have delocalized p electrons that are shared amongst all 6 of the carbons in a cloud on either side of the ring. I also understand why this could be ...
ringo's user avatar
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12 votes
2 answers
14k views

Why is the nitroso group a deactivating group for electrophilic aromatic substitution?

Does the lone pair of nitrogen in nitrosobenzene take part in resonance? If not, then why? If it takes part in resonance then the hybridisation of nitrogen is sp. Can a sp hybridised atom be attached ...
Adarsh chaturvedi's user avatar
11 votes
1 answer
12k views

Nitration of pyrrole with sulfuric and nitric acids

Would 2,5-dinitropyrrole be a product of nitration of pyrrole with $\ce{H2SO4/HNO3}$? It seems that 2,5-dinitropyrrole is not formed when using $\ce{Ac2O/HNO3}$ (ref 1). Is this just because of the ...
J. LS's user avatar
  • 2,590
9 votes
1 answer
4k views

How does toluene react at higher temperatures and why?

Reaction of toluene at high temperatures gives us (o-m)toluene; whereas at normal conditions of electrophilic attack, it gives us (o-p) directing. Why does this happen at high temp although as methyl ...
Preeteshwar's user avatar
8 votes
2 answers
2k views

Alkylation of benzene

I was solving a question where I had to determine a way to convert benzene into n-propyl benzene. I figured out a way by first performing Friedel-Craft acylation with propanoyl chloride and then ...
Vamsi Krishna's user avatar
7 votes
3 answers
5k views

Relative acidity of p-chlorobenzoic acid and p-flurobenzoic acid

I want to compare the relative acidity of p-chlorobenzoic acid and p-flurobenzoic acid. Both of the facts below point to p-chlorobenzoic acid being more acidic: The carboxylic acid group is too far ...
xasthor's user avatar
  • 1,632
7 votes
2 answers
1k views

Steam distillation- how it actually works?

To obtain phenylamine after it is formed from the reduction of nitrobenzene with tin, we carried out steam distillation. This is what I learned in class: "During the process,steam is injected into ...
Eliza's user avatar
  • 2,413
2 votes
1 answer
5k views

Converting cyclic compounds to linear compounds (possible ?)

Can one convert from cyclic convert to linear compound? Like $Cyclohexane$ $+$ $?=Hexane$ Even in High Temp and Pressure? I know it is very tough since we are going from a stable compound to a ...
NeilRoy's user avatar
  • 1,683
38 votes
2 answers
2k views

IUPAC nomenclature for an interesting looking organic compound

How can I name this organic compound while adhering to the IUPAC standards?
Panglossian Oporopolist's user avatar
27 votes
3 answers
17k views

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 ...
bon's user avatar
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20 votes
3 answers
3k views

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 ...
Ben's user avatar
  • 343
19 votes
3 answers
2k views

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 ...
Rory's user avatar
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