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Author: Subject: Nitrobenzene
Douchermann
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[*] posted on 29-6-2006 at 17:26


I would imagine its possible, unless someone else thinks otherwise. I can't think of a problem that would arise during seperation compared to the normal procedure.



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[*] posted on 4-7-2006 at 02:55


Yesterday I made nitrobenzene. To a few milliliters of H2SO4 in a measuring cillinder I aded a few grams of NH4NO3. I say a few because I didn't measure anything. To the nitrating mixture I added a few drops of C6H6 every 1min. When I added the first drops of benzene the drops turned green and the mixture heated up strongly. Some benzene boiled away. Then I put the measuring cillinder in a baker with cold water until the measuring cillinder cooled down. Now above the NH4NO3/H2SO4 mix a orange layer formed. When it cooled down I continued to add benzene at the rate of a few drops every 1min. When I finished adding benzene (I don't know how much) I left the mixture standing for around 20-30 minutes and then I poured it in a flask and capped it. I didn't remove the acid from the nitrobenzene because I don't need it. I made it just because I was in the mood for nitrating.:)
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Douchermann
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[*] posted on 4-7-2006 at 20:02


Well you have to get rid of it some way. You shouldn't just dump that down the sink. Nitro derivatives of benzene are extremely poisonous. IIRC the inhalation was 2g/m3 and the oral was half a gram. I only know this because I worked with nitrobenzene a lot, working on production methods and improving yeilds and whatnot.



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[*] posted on 5-7-2006 at 02:05


Just dump it in a beaker of Fenton's reagent. It'll tear apart aromatics and chlorides, so nitrobenzene shouldn't pose any kind of problem.



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[*] posted on 5-7-2006 at 13:11


Today my nitrobenzene and wich I didn't seperate from the H2SO4/NH4NO3 mix turned from murky green to clear orange and it was more oily than before. I made it two days ago. Do you know why?

P.S. I forgot to say in my previous post that the mixture of nitrobenzene and H2SO4/NH4NO3 turned green when I poured it from the measuring cillinder in to the flask because some water was in the flask.
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[*] posted on 12-7-2006 at 08:30


Today I added water to it and it turned from oily clear orange to less viscous and clear green. On top of the liquid a layer of nitrobenzene formed. Why did the liquid turned green?



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[*] posted on 12-7-2006 at 10:22


Nitrobenzene can often be slightly green if not purified. Some impurities, I guess.

Quote:
On top of the liquid a layer of nitrobenzene formed.


Seams like you still have a considerable amount of benzene there since nitrobenzene is quite heavier than water (1.199 vs. 1 g/ml).

You can't really complain about the color of a product unless you clean it.;)




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[*] posted on 12-7-2006 at 11:15


Now several hours later I notied a small amount of white powder formed on the bottom.



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[*] posted on 14-7-2006 at 08:29


The white powder is ammonium bi/sulfate. Nitrobenzene will sink to the bottom unless you didn't add enough water to the acid mixture because of the density of sulfuric acid.



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[*] posted on 16-7-2006 at 12:30


It is possible that since you didn't neutralise the nitrobenzene it continued to nitrate itself to dinitrobenzene and then it precipitated. If you want to test it you can dissolve some of it in water and then add some NaOH. If you smell ammonia it is ammonium bi/sulfite.
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[*] posted on 18-7-2006 at 03:35


I made a mistake in my last post here. I wrote ammonium bi/sulfite but it was supposed to be ammonim bi/sulfate. If nothing happends it is probably dinitrobenzene.
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[*] posted on 5-4-2007 at 02:55


Is nitrobenzene explosive? Somewhere I heared that it is (I don't remember where).
To me it doesn't seam explosive (bad oxygen balance).




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[*] posted on 5-4-2007 at 07:20


The nitro group being a deactivating one, you will have difficulty chlorinating nitrobenzene. If you succeed at all you will obtain m-chloronitrobenzene, that is 3-nitrochlorobenzene.

You would be better off nitrating chlorobenzene, and since Cl is also deactivating you will obtain same isomer.

If you overnitrate you may get some 3,5-dinitrochlorobenzene as well.
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[*] posted on 5-4-2007 at 09:49


The chlorine and other halogen substituents on benzene are ortho/para directing for electrophilic substitutions. They are deactivating to all positions by inductive effect and activating for para and ortho positions by mesomeric effect (deactivating by overall effect since in halogens the inductive effect is stronger than mesomeric). Mononitration of chlorobenzene gives a mixture of 2- and 4-nitro-chlorobenzene.

PS: Who asked about nitrobenzene chlorination anyway?




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[*] posted on 3-8-2013 at 07:09
Toxicity


Quote: Originally posted by garage chemist  
Be careful with the m-dinitrobenzene, it's extremely toxic, about as toxic as KCN.


Could you please provide some resources for this ? I was only able to find the nfpa 704, French wiki claims a '2' raiting in health, and the msds from sciencelab for m-dinitrobenzene claims a '3' and an LD50=42mg/kg for birds (higher for other animals)

As for the other isomers, p-dinitrobenzene is claimed to have a '3' health rating , As for the o-isomer .. I've not been able to find much data.

KCN has a health '4' rating and the LD50=5-10mg/kg in animals

I've recently made (accidentally) some dinitrobenze (presumably a mix of the isomers, although the majority should be the m-isomer since -NO2 is meta orienting) and I'd like to know more about it's toxicity.

Thanx




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