# Tag Info

23

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 trinitromethane anion cannot obey the Hückel (4​n+2) rule because it is neither monocyclic nor planar. And assigning a number of π electrons is fuzzy at best, so ...

14

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 surface followed by dissociation of the hydrogen molecule into its catalytically active form. The same things happen with nitrobenzene. As the following ...

13

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 cases the equilibrium lies far to the carbonyl side. The same type of equilibrium exists in the case of bis- and tris-amino compounds where all of the amino groups ...

13

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 more accurately the chlorine atom which is converted to a hydrazine group) is ortho/para directing. the nitro groups are deactivating and meta directing. So ...

12

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, 2323-2324) has shown that the tosylhydrazone of cyclohexanone can be reduced to cyclohexane with $\ce{NaBH4}$ in polar aprotic solvents. $\ce{NaCNBH3}$ is an even ...

12

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 nature of the $\ce{-OH}$ group is strong enough to counter the deactivating nature of the nitro groups. Look at Ron's comment on the question over here. Even methyl ...

12

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 point that when detonated as a pure substance, it produces carbon soot and hydrogen gas: $$\ce{2C7H5N3O6 -> 3N2 + 5H2 + 12CO + 2C}$$ The production of $\ce{CO}$...

11

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. Most of these reactions that involve a metal surface proceed through what is known as a single electron transfer (SET) mechanism. Reductions of nitro compounds, ...

11

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 location. The acidity order of the remaining two nitrophenols can be explained in this way: Hydrogen bonding is possible in both of them. But note that: \text{...

10

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 way to predict the product here for every general case. The most detailed paper on the topic of Zinin reduction by far is Porter, H. K. Organic Reactions 2011, ...

9

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 mixture of $\ce{SO_3}$ and sulfuric acid. Preparation in the lab may be achieved by more or less ordinary nitration at elevated temperatures. In a micro scale ...

9

I'm going to assume by 'good explosive' you mean 'high energy to mass ratio', which by no means implies anything about whether the explosive is 'good' in the 'won't suddenly explode when thought about' sense. This is not intended to be a full answer as it doesn't touch on the terrifying explosivity of organic peroxides, however it's a start. The presence of ...

9

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 presence of catalytic amounts of $\ce{NaBH4}$. (DOI) If there's a chance to perform the desired transformation in one step via catalytic hydrogenation at ...

9

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 energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers, etc. The ...

9

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, hydroxy and nitro group onto a benzene ring. If we look into our synthetic "toolbox" here are some thoughts that might come to mind: A methyl group can be readily ...

8

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 than the structures that are aromatic. The resonance structures at the right and left end of your figure are aromatic. The fourth resonance structure (the one ...

8

There are, actually, several types of explosives by use: initiating (primary) explosives, secondary explosives and blasting agents. Initiating explosive must be sensitive to shock/friction, but not too sensitive. The most famous primary explosive is mercury fulminate, but others are known. To act as primary explosive, substance must have hi-energetic ...

8

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 so, you'll have to analyse what stabilisation/destabilisation effects are present in each acid $\ce{HX}$ and each conjugate base $\ce{X-}$. This is easier said ...

8

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 polymerization! For decades, acetyl nitrate, formed by addition of fuming nitric acid to acetic anhydride, is the reagent of choice. Mononitration of pyrrole ...

8

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 controlled. Instead, one should consider the transition state—a six-membered ring as taught generally in organic chemistry—and note that after the reaction the compound ...

7

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 very nucleophilic nitrogen that can attack the nitro group. Proton transfer gives a nitrogen anion, which can kick out hydroxide. Two additional proton transfer ...

7

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 at C-2 (and C-3), while a nitrating agent may approach C-4. Exactly this has been done in the vapour phase nitration of toluene with nitric acid over a zeolite (...

7

Explosives chemistry is a rather complex topic. I've heard that this book is a good source of information about it (I haven't read it). In a nutshell, your intuition about the nitro group is accurate. Formation of $\ce{N2}$ is highly energetically favourable. To get an explosive, what we need is a rapid reaction that produces a lot of heat and gas to both ...

7

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 $\ce{NH2}$, will tend to stabilize the aldehyde the most? A substituent that further delocalizes the positive charge shown in the dipolar resonance form would tend to ...

7

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. 141 (1-3): 187–193. doi:10.1016/j.cej.2007.12.013. The name of the reaction of reducing di/trinitrobenzenes to di/triaminobenzene is called Zinin reduction. ...

7

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 nitrobenzene. Source A Guidebook To Mechanism In Organic Chemistry; Chapter 6, section 6.2;Peter Sykes

7

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 literature search, the aromatic nitro group reduction by $\ce{SnCl2.2H2O}$ is the best method so far in the presence of other sensitive groups such as nitrile group on ...

6

LHM...Look at this mechanism that I posted as an answer to an earlier SE Chem question/answer relating to the reduction of nitrobenzene by metals. In most reactions that occur on metal surfaces, many of the mechanistic details are not fully understood (see @Martin's comments in the earlier post). Nonetheless, this mechanistic scheme shows several steps ...

6

Zinin reduction was discovered by a Russian organic chemist Nikolay Zinin in 1842 (Wikipedia) and revieved by Porter (1973; Ref.1). As pointed out by @Gaurang Tandon and @Nilay Ghosh in their answers, this reaction gives the best chance to convert polynitro aromates like 1,3-dinitrobenzene to 3-nitroaniline by selectively reducing one nitro group with sodium ...

6

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 state and it is also more electronegative. Thus, isn't it sensible that it gets reduced first before the carbonyl group? In fact, reduction of a nitro group is ...

Only top voted, non community-wiki answers of a minimum length are eligible