24 votes
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What is Y-aromaticity? Is the trinitromethanide anion aromatic?

Introduction It is fairly obvious that the statement given by Wikipedia cannot be entirely correct. There is some evidence that the anion (which obeys the 4​n+2 Hückel rule) is aromatic. The ...
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20 votes
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Selective nitro reduction of poly nitro compounds

Is there any way to predict which nitro group will be reduced After having gone through three pages of Google Scholar and reading several research papers looking for an answer, there is definitely no ...
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17 votes
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Reaction mechanism for reduction of nitrobenzene to aniline in catalytic and acidic media

The first reaction is called a catalytic reduction. Here is a picture of how it works with an olefin like ethylene. You can see that the first step involves adsorption of hydrogen onto the catalyst ...
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16 votes

Acidity order of nitrophenols

You have correctly identified that m-nitrophenol should be the weakest acid among the isomers as the resulting anion cannot be stabilised by the $\text{-M}$ effect of nitro group owing to its meta ...
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  • 5,206
15 votes
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Why is picric acid more explosive than TNT?

You're trying to define the stronger explosive by comparing the reagents, but in this case comparing the products is far more important. Trinitrotoluene is a rather oxygen-poor explosive, to the ...
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15 votes
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What is the significance of the 2 and 4 positions in 2,4-DNP?

Probably any DNP could work if you could get it. But, because of the directing character of substitutents in electrophilic substitution you inherently favor the 2,4 isomer: the hydrazine group (or ...
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13 votes
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Why are triamino compounds so rare?

You may be familiar with the equilibrium that exists between a gem-diol and the corresponding carbonyl compound, as shown in the figure below. The carbonyl double bond is very strong, so in most ...
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12 votes
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What will be the major product on chlorination of m-nitrophenol?

But why is the activating nature of hydroxyl group dominating over the deactivating nature of Nitro group? This is the precise reason why Picric acid is formed. ( Check here ) The activating ...
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  • 2,115
12 votes

How can an aromatic ketone be reduced in the presence of a nitro group?

You will most likely be successful if you convert the ketone to the corresponding tosylhydrazone and reduce that with $\ce{NaCNBH3}$ (DOI). A previous study (Bull. Chem. Soc. Jpn., 1974, 47, 2323-...
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12 votes

Are groups other than carbonyl reduced by Clemmensen reduction?

I would look at it in the following way: The oxidation state of the carbonyl carbon is +II, while the oxidation state of the nitrogen in the nitro group is +III. So nitrogen is in a higher oxidation ...
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11 votes

Nitrobenzene reduction with (tin) Sn catalyst: Why is C-H bond cleavage preferred over O-H bond cleavage?

I don't buy that mechanism. Like you noted, breaking a C-H bond in methanol seems unlikely, especially since the reaction is run in the presence of acid, so a ready source of protons is available. ...
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11 votes

Most favorable position of attack of an electrophile on 4-trifluoromethyl-1,2-diphenylbenzene

This is an another way to answer the question: On the way, I also want to show OP that why central ring bearing $\ce{CF3}$ group has the highest electron deficiency at ortho- and para-positions (...
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10 votes

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

Your teacher is correct, some of the resonance structures in your figure are not aromatic. Still though, as resonance structures they contribute to the overall description of the molecule, just less ...
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10 votes
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Reduction of α,β-unsaturated nitro compounds

I'm not aware of a $\ce{NaBH4}$-based reduction of nitroalkenes to saturated amines, such as in: It is however possible to reduce nitroalkenes to saturated hydroxylamines using $\ce{BH3*THF}$ in the ...
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10 votes
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Nitration of pyrrole with sulfuric and nitric acids

Would 2,5-dinitropyrrole be a product of nitration of pyrrole with $\ce{H2SO4/HNO3}$? I doubt it and would rather expect a lot of tar to be formed here. Pyrrole tends to undergo acid-catalyzed ...
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10 votes
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Mechanism of initiation in contact explosives?

My guess would be cavitation, presumably 'non-inertial cavitation': Non-inertial cavitation is the process in which a bubble in a fluid is forced to oscillate in size or shape due to some form of ...
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10 votes

Synthesis of 2-methyl-4-nitrophenol from benzene?

There is a lot of good thinking in your proposed synthetic strategy. The one major shortcoming is, as @Mithoron points out, $\ce{OH^{-}}$ is not an electrophile. We need to introduce a methyl, ...
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10 votes
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Why is the ortho product major in the nitration of anisole with nitric acid and acetic anhydride?

It is complicated, as this paper from Olah et al. here shows, but this passage offers a possible explanation: With the reactive nitronium salts, the isomer distribution of the nitration of anisole ...
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9 votes
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Why is picric acid more acidic than carbonic acid?

So you want to compare the acidity of different Brønsted–Lowry acids. This means ultimately you want to compare the equilibrium constants for reactions of the type $\ce{HX <=> H+ + X-}$. To do ...
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9 votes
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Aromatic ring substitution: how are MNT and DNT further nitrated if nitro groups deactivate benzene rings?

On a industrial scale by using highly concentrated nitric acid known as fuming nitric acid (usually > 90%, but in the last step from DNT to TNT may also be anhydrous) along with oleum, which is a ...
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  • 6,053
8 votes

Selective nitro reduction of poly nitro compounds

Source: Maity, Sunil K.; Pradhan, Narayan C.; Patwardhan, Anand V. "Reduction of p-nitrotoluene by aqueous ammonium sulfide: Anion exchange resin as a triphasic catalyst". Chemical Engineering Journal....
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8 votes
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Why does a mixture of nitrous acid with concentrated nitric acid cause nitration of benzene instead of nitrosation?

You were absolutely correct when you said that nitrosation takes place. What actually happens is that after nitrosation occurs, concentrated $\ce{HNO3}$ oxidises the nitroso group to form ...
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8 votes

Selective reduction of nitro group to amine, in benzene ring containing nitrile?

My answer is intended to support Waylander's suggestion elsewhere. I thought it'd be better to give OP some insight of this reduction mentioned (Ref.1). To my knowledge, after doing thorough ...
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8 votes
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What products do 4-nitrobenzaldehyde and 3-nitrobenzaldehyde give in a crossed Cannizzaro reaction and why?

The first thing to point out is that the products of the Cannizzaro reaction do not necessarily correspond to the most stable products, i.e. the reaction is not necessarily thermodynamically ...
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8 votes

Most favorable position of attack of an electrophile on 4-trifluoromethyl-1,2-diphenylbenzene

TL;DR - The ring with positions 1, 2, and 6 on it is more deactivated than the ring with positions 3, 4, and 5, so the correct answer cannot be position 2 (as marked) or positions 1 and 6 (as you ...
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8 votes

Can primary amine be produced using Grignard reagent?

Grignard reagents, in addition to being nucleophiles, are strong bases. Attempting to react a Grignard $\ce{RMgX}$ with nitrous acid is simply going to result in protonation of the Grignard to give $\...
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7 votes
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Amine addition to nitro group

A reasonable mechanism for the transformation is shown below. Since this is under basic conditions, I've written a mechanism that avoids cationic intermediates. Deprotonating the hydrazine gives a ...
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  • 10.5k
7 votes

Reliable data describing acidity of 2,4,6-trinitrobenzenesulfonic acid

The reference for the PubChem entry for picryl sulfonic acid is: Serjeant, E.P., Dempsey B.; Ionisation Constants of Organic Acids in Aqueous Solution. International Union of Pure and Applied ...
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7 votes
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Is 4-nitrobenzaldehyde or 4-aminobenzaldehyde more likely to be hydrated?

I think you're asking about the following equilibrium This equilibrium will shift to the left as the aldehyde becomes more stabilized. So the question becomes, which R group, $\ce{NO2}$ or $\ce{NH2}$...
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7 votes
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How to selectively convert benzene to p-nitrotoluene?

I'd doubt that exclusive nitration of toluene in para position is possible in homogenous solution. But imagine to stuff a toluene molecule into a very narrow "tube". This tube will block any attack ...
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