A conjugated ring of unsaturated bonds, lone pairs, or empty orbitals which exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. This tag should also be applied to antiaromatic compounds. This tag should not be applied to general questions about ...

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59 views

In Hückel's rule, can n be any integer?

Hückel's rule says that any planar compound with a ring of conjugated p orbitals with $4n+2$ electrons is aromatic. Here, can $n$ be any integer, or does $n$ have to be related to the number of p ...
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1answer
25 views

Suggestion for a Synthesis of Paracetamol — plausible?

I have seen a number of different plausible syntheses for paracetamol but they suffer from problems such poor regioselectivity of aromatic substitution (usually when nitrating phenol getting a mixture ...
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19 views

Order of melting points of Compounds [duplicate]

I don't get the order of melting points of the ortho, para and meta isomers of dichlorobenzene. My book says that the order of melting points is para-isomer > ortho-isomer > meta-isomer. Now, I get ...
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19 views

Acidity order of Halobenzene [on hold]

We know that the halide groups show $+R$ and $-I$ effect. Among this $+R$ effect tends to decrease the acidity and $-I$ effect increase the acidity of the group to which it is attached to. Now, in ...
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65 views

Paracetamol: does oxygen participate in the delocalization of p-orbitals

I'm analyzing the molecular structure of paracetamol and one of the things I have to do is to make a commentary about the delocalization of p-orbitals in this compound. Well I know that in the cyclic ...
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26 views

How phenyl shift is possible in Benzil-benzilic rearrangement?

We know C-C bond is much stronger than C-OH bond (because similar sized atoms have maximum overlap)as in case of phenyl-cabonyl carbon bond. Also due to resonance there is double bond character in ...
3
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1answer
123 views

What is the mechanism for the reaction of an organic hydroperoxide with sulfuric acid?

The question asked to react the organic hydroperoxide substrate, $\ce{R-OOH}$, with dilute sulfuric acid, $\ce{H2SO4}$. In the last step, I removed a proton, making it act like a catalyst, along with ...
3
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1answer
48 views

Does 6-methyl-2-(methylamino)pyrimidin-4-ol show aromaticity?

Does this structure show aromaticity? Or does this not work with nitrogen?
3
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2answers
113 views

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

According to the lowest locant rule should'nt the numbering of the compound start from the Carbon at the 4th position thus giving the iupac name as 1,2-dimethyl-4-hydroxybenzene? EDIT Here they ...
2
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1answer
82 views

Why are spherical compounds with a half filled HOMO concidered aromatic?

In planar annulenes, huckel's rule effectively states that compounds with a full HOMO for their conjugated $\pi$ systems are considered aromatic while those with a half filled outer shell are ...
3
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30 views

Oxidation of Poly Aromatic Compounds using KMnO4

How is tetracene oxidised by $\ce{KMnO4}$ It appears that the product is a white solid with a benzene ring inside. What is the reaction mechanism? Is it radical based? Or does the $\ce{MnO4^-}$ ion ...
4
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2answers
30 views

Why is nylon formed using carboxylic acids, while aramids are formed with acyl halides?

I was reading about carbon polymers and noticed something interesting about the difference between the reaction used to form nylon and the reaction used to form aramids: in the former, the monomers ...
1
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1answer
21 views

Regioselectivity of pyridine for SnAr

Say there's a pyridine ring with leaving groups on the $\ce{C_2}$ and $\ce{C_4}$ atoms. Why would a nucleophile prefer to attack at the $\ce{C_4}$ position? They form very similar intermediates with ...
-3
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1answer
56 views

Stability between cyclopentdiene compound

What will be the order of stability? According the me it should be : Cyclopentadienyl anion > Cyclopentadiene > Cyclopentadienyl cation because the order of stability is aromatic > non-aromatic > ...
0
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1answer
45 views

Why does nitration of aromatic amines give meta directed nitro compounds?

Amines are activating groups and donate electrons to the resonance structure using the lone pair of electrons on Nitrogen. But when aromatic amines are nitrated, for example when benzyl amine is ...
3
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1answer
55 views

Semi-sandwich complex IUPAC name

I've tried looking here, but I can't figure it out. As a start, what is just the cobalt and cyclopentadienyl anion compound called. How does that name get added to the trimethylphosphine and carbonyl ...
4
votes
1answer
73 views

What molecule is mostly responsible for the smell of petrol/gasoline when I refill my car?

Is it benzene or is there another aromatic molecule in gasoline with "heavier scents"? Does anybody know of a scientific investigation to provide evidence for an answer?
0
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2answers
57 views

Substitution of nitro benzene

In the following reaction why OEt does not get attached to meta of NO2 . As there would be -M of NO2 and -I of Cl. But why it get attached at para of NO2 1: I am thinking of compound as ...
10
votes
1answer
149 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 ...
8
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1answer
623 views

Why is the cyclopropenyl anion “Not Aromatic”?

Is the following compound "Anti Aromatic" or "Not Aromatic" ? The above compound contains a single ring, has conjugation and also has $4 \ (=4n)$ electrons. So, according to Hückel's Rule, ...
1
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1answer
118 views

What is the IUPAC name of this Di-Benzene like compound? Is it Aromatic?

What is the IUPAC name of this compound? Is it Aromatic? The above compound has $12 \ \pi$ electrons and according to Hückel's Rule, it should not be aromatic because $12 \neq 4n+2$, but it ...
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0answers
19 views

what is the bond order if chloro benzene?

my teacher taught me to first find the confirming/canonical structures then selecting a pair of atoms connected by a bond and then use the formula Total no of bonds present between the pair in all ...
3
votes
1answer
85 views

How are the electrons of benzene actually configurated?

I found this diagram here: According to it, it is not true that the six electrons of carbons in the pi-orbitals above the ring are all identical. But, how can it be the case, seeing that this ...
0
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28 views

Will non planar electrophiles attack benzene ring faster than corresponding planar electrophiles of comparable electrophilicity

Will non planar electrophiles attack benzene ring faster than corresponding planar electrophiles of comparable electrophilicity . As we all know know that benzene is a planar molecule with the pi ...
10
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1answer
191 views

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 ...
3
votes
1answer
87 views

Why are antiaromatic compounds unstable?

Antiaromaticity is so destabilizing that it can cause compounds such as cyclobutadiene to elongate or manipulate their orbitals so that the pi system is no longer aromatic. I understand that aromatic ...
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0answers
12 views

Friedel craft alkylation of toluene [duplicate]

When toluene is reacted with CH3Cl , AlCl3 with heat . Then the product is m-xylene. But methyl group is o,p-director , so according to me o-xylene and p-xylene must be formed .
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1answer
54 views

Hybridization of nitrogen in a ring [closed]

Is there a well defined way to discern the hybridization of a nitrogen atom in ring, like pyrrole? How can you know whether the nitrogen's lone pair are in the conjugated system or not?
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22 views

Ortho para or meta directing [duplicate]

As we know CH3 is ortho para directing . Then why the following rection gives meta directing .
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2answers
125 views

Is ciprofloxacin acidic or basic?

I would expect an aqueous solution of ciprofloxacin to be basic for the following reasons: The carboxyl group has pKa = 6.09 and the secondary amino group has pKa = 8.74. Because 8.74 is further ...
19
votes
1answer
858 views

Why is pyrimidine less basic than pyridine?

From Wikipedia's article on pyrimidine: Because of the decreased basicity compared to pyridine, electrophilic substitution of pyrimidine is less facile. But why is pyrimidine less basic than ...
3
votes
1answer
124 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 ...
0
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2answers
119 views

Why can't oxygen in furan be sp-hybridized?

From ChemWiki's article on Huckel's Rule: So far, you have encountered many carbon homocyclic rings, but compounds with elements other than carbon in the ring can also be aromatic, as long as ...
8
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1answer
93 views

How much steric hindrance does a phenyl group offer?

I've come across a question in my revision in which I am asked to compare the steric hindrance provided by a number of substituents. Those relating to phenyl are ranked relatively low, despite it ...
1
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1answer
143 views

Why are anti aromatic compounds unstable?

Just like aromatic compounds, anti aromatic compounds have several resonance structures and some of them are also conjugated ( 1,3-cyclobutene). Why is it that just having 4n electrons makes them ...
0
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0answers
27 views

Resonance in phenoxide anion [duplicate]

Why is resonance possible in phenoxide anion as when the electron pair of oxygen is involved in conjugation we have 4 pairs of electrons in resonance which should imply that the ring has become anti ...
3
votes
1answer
127 views

Friedel-Crafts alkylation of five-membered heterocycles

The five-membered heterocycles pyrrole, furan, and thiophene undergo Friedel-Crafts acylation, but I have not seen them undergoing a simple Friedel-Crafts alkylation reaction with a Lewis acid such as ...
0
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1answer
60 views

Basicity of heterocyclic compounds

Pyrrol, furan or thiophene don't have any bond pair electrons free to release which is why they shouldn't be basic, but the lecturer of organic chemistry is saying that they are basic as they react ...
4
votes
1answer
76 views

Synthesis of indigo from anthranilic acid - reaction not taking place

I was trying to synthesise indigo via the Heumann indigo synthesis (II.), which involves heating antrhanilic acid and chloroacetic acid, both dissolved in isopropanol. After heating up, a hydroxide or ...
3
votes
1answer
58 views

Formation of Tropylium carbocation

I've read that Tropylium carbocation is formed by the ring expansion of benzyl carbocation. But in benzyl carbocation, the $\ce{C}$ atoms in the benzene ring are $sp^2$ hybridized i.e. $120^\circ$ is ...
2
votes
2answers
93 views

Most acidic compound amongs the following unsaturated ketones?

In the given picture, I know that the most acidic will be (a), because of potential of ring expansion. I tried a few times but wasn't able to get a satisfactory six membered ring. I think (a) is the ...
3
votes
1answer
91 views

Why does selenophene not undergo aromatic substitution?

Other derivatives like thiophene, pyrrole give electrophilic substitution but why not selenophene? Is it because selenophene does not have enough electron donating effect and not having its electrons ...
12
votes
1answer
209 views

Are graphite and boron nitride aromatic

Are graphite and boron nitride aromatic? Graphite has a planar network of $6$-membered rings with each carbon connected to three other carbons. Since the valency of carbon is not satisfied, there ...
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29 views

Determining where a group will direct an addition

I'm looking at a phenol with a ketone in one of the meta positions being treated with $$ \frac{Cl_2}{AlCl_3} $$ I know the Alcohol is the stronger activator because ketone is a deactivator. I'm ...
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0answers
21 views

Which catalyst should I use? [closed]

What is the catalyst should I use in the reaction of halogenation " electrophilic substitution reaction" of Benzene? Fecl3 or FeBr3 ? And why?
8
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2answers
382 views

Comparing the reactivity towards aromatic electrophilic substitution reaction

In the following pairs of molecules, which is more reactive towards electrophilic substitution reaction? 1) 1,4-dinitrobenzene or 1,3-dinitrobenzene (don't consider the ortho isomer) 2) benzene-...
6
votes
1answer
172 views

Why is imidazole considered an electron deficient heterocycle?

The paper I'm looking at mentions electron deficient heterocycles such as (di)azines, benzothiazole and imidazole. Can you tell me the criteria to determine whether a heterocycle is electron ...
4
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2answers
79 views

How is it possible that meta xylene exists?

Methyl group is ortho para directing so it should direct the second methyl group to ortho or para position giving rise to ortho or para xylene but how can meta xylene be formed?
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1answer
80 views

Numbering in chlordiazepoxide

The IUPAC name of chlordiazepoxide is given as : 7-chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepine-4-oxide, but when I started numbering the structure, I am unable to find chlorine on 7th carbon, ...