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ordenblitz
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[*] posted on 31-7-2005 at 19:24
Nitrobenzene


Following the procedure for nitrobenzene outlined in Vogel, 3rd ed:

70ml concentrated HNO3, (used 90% fuming) placed in a flask, and added to that is 80ml concentrated H2SO4 (used 95.6%) added in portions with shaking. While keeping the mixture below 55º, 60ml C6H6 (used material made from sodium benzoate/calcium hydroxide) was added dropwise, with stirring in a cooling bath. After the addition was complete, the flask was setup for reflux in a 60º water bath and held there for 1 hour. The contents were crashed into 800ml cold water. At this point there is supposed to be two liquid layers forming, the upper acid/water layer and the lower nitrobenzene layer.

But I got what you see in the picture below. Upon checking in Davis, I realized that "concentrated" should have meant ~70% HNO3
Tomorrow I will retry with that. Oh well, the conciliation is I now have a lovely batch of m-dinitrobenzene after recrystallization from IPA.

C6H4N2O4.JPG - 21kB
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[*] posted on 31-7-2005 at 19:44


At least it looks neat :)

I followed the procedure from Vogel too (I think, or was it Chemistry of Powder and Explosives..?) Anyway, I don't think I added any sulfuric acid, just 70% HNO3 to the benzene with shaking, it heated up readily as I recall. I heated it at 60C for an hour and when I was done I had a beautiful red/carmel liquid that smelled great and gave me head aches whenever I took the time to indulge the smell. It fractioned nicely as I recall. Now that I have such a toxic yet wonderfull smelling liquid for which I have no use I wonder why I ever made such a thing (preparation of the alkali metals through electrolysis of course ;))




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ordenblitz
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[*] posted on 31-7-2005 at 20:03


Interesting that you got a red liquid.
As my drops of benzene hit the mixed acid, they turned a lovely shade of red until being stirred in, and changing to a light yellow. I expected a yellow colored finished product and I did get a small amount of nitrobenzene as witnessed by the color of the crash water.
Vogel simply says "concentrated HNO3"
Davis says, "sp 1.4"
Too bad I didn't read davis first. What the heck am I going to do with this dinitrobenzene?

I was headed toward aniline and took a wrong turn.

[Edited on 1-8-2005 by ordenblitz]

[Edited on 1-8-2005 by ordenblitz]
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[*] posted on 1-8-2005 at 01:54


"What the heck am I going to do with this dinitrobenzene?"

Well, you could reduce it to m-phenylenediamine, which is used as a component of some hair-colors like Clairol. ;)

Diazotise the m-phenylenediamine and make some fancy dyes or explosive diazonium salts maybe?

Otherwise, I don't know... is it even decently detonable (methinks not)?

"...I had a beautiful red/carmel liquid that smelled great and gave me head aches..."

Yeah, I also like the smell of "oil of mirbane". :) Too bad it's toxic. Maybe smell benzaldehyde instead (smells the same to me). Or real bitter almonds? :D

sparky (~_~)




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ordenblitz
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[*] posted on 1-8-2005 at 17:23


I decided to finish the batch of m-dinitrobenzene since most of the work had been done already. I filtered the wet crystals from the wash water and dissolved them in the minimum quantity of hot isopropanol. While hot I filtered the solution than put in the freezer to cool.
http://img206.imageshack.us/img206/184/dinitrocrop9hm.jpg

After suction filtering out as much IPA as possible I washed again with small portions of clean IPA.
http://img206.imageshack.us/img206/8202/washing2gz.jpg

The crystals are very fine and flexible. They are just about exactly like blown fiberglass. This looks like a lot of product but really is only about 15 grams.
Wet
http://img206.imageshack.us/img206/8227/crystals1tx.jpg
Dry
http://img206.imageshack.us/img206/3706/drying5fn.jpg
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ordenblitz
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[*] posted on 1-8-2005 at 17:42


Had another go at C6H5NO2
This time with 70% HNO3 and 90% H2SO4

The usual setup, in ice this time to hasten the process.
http://img206.imageshack.us/img206/8616/nitration20lp.jpg

As I mentioned above, immediately as a portion of benzene is added to the acid mix, the color goes red for a few seconds then changes back to yellow again. I took 4 pictures in a row after the addition… you can see what happens.
http://img206.imageshack.us/img206/3691/colorchange6aw.jpg

This is what is supposed to happen!
http://img206.imageshack.us/img206/6965/2layer4ai.jpg

After heating @60º for 60 min. It lightens up a bit more.
http://img206.imageshack.us/img206/6158/afterheat6ze.jpg

Washing out the acid with portions of water.
http://img206.imageshack.us/img206/9219/washsep7mt.jpg

I still ended up with a small amount of C6H4N2O4 so I think using acids of even a lesser concentration would work well.

Tomorrow I distill.

aftersep.JPG - 28kB
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[*] posted on 1-8-2005 at 18:40


Very nice work, great pictures!

What are the respective M.P.s and B.P.s, of the different nitrobenzenes?
To me most of it looks like solids - I can't figure out the second last picture (washsep7) when there is this mass in the funnel.

Also, I see you are using nice glassware, I remember from nitration the problem of NO2 evolution and runaways - weren't you a little scared it might run out of control? A long time ago I vowed to myself to never do nitrations in a closed container, i.e. a container without a big fat exit hole like a beaker :P




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ordenblitz
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[*] posted on 1-8-2005 at 18:53


>What are the respective M.P.s and B.P.s, of the different nitrobenzenes?

Nitrobenzene C6H5NO2 - mp 6º bp 210º
m-dinitrobenzene C6H4(NO2)2 - mp 90º bp 300º

>To me most of it looks like solids -
>I can't figure out the second last picture (washsep7)
>when there is this mass in the funnel.

It's actually liquid. The upper nitrobenzene oily layer and the lower water layer in which a small amount of the upper layer is mixed making it look milky. It settled better upon standing.

>Also, I see you are using nice glassware

Thanks, I have been collecting a long time.

>I remember from nitration the problem of NO2 evolution and runaways -
>weren't you a little scared it might run out of control?

Not really it's a pretty tame reaction all told. It used to be standard lab practice to do this without cooling. I use the ice so I could push it fast. I'm not sure this reaction will run away, probably the worst is boil off the volatiles.
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[*] posted on 1-8-2005 at 20:18


Yes, nice work! I can see why you made nitrobenzene as it seems like a fundamental aromatic nitration. It is on my "to do" list also.

Isn't nitrobenzene a solvent used for cleaning gun barrels such as made by Hoppe and Outers. I use this to clean my shotgun and it does smell sweet. But I think its carcinogenic so try to do my barrel cleaning outside.




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[*] posted on 2-8-2005 at 18:35


I heard that it is in solvents for cleaning gun barrels and for furniture polishes. However I have checked a number of gun cleaning solvents to find no trace of nitrobenzene and furniture polishes normally do not list ingredients. The 'Household Products Database" gives no hits for products that contain nitrobenzene.



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[*] posted on 3-8-2005 at 01:41


Nitrobenzene in a OTC product seems highly unlikely to me, given it's acute toxicity and carcinogenity, certainly because it'll readily penetrate the skin.

Use caution when handling.




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[*] posted on 3-8-2005 at 06:37


Quote:
Originally posted by BromicAcid
I heard that it is in solvents for cleaning gun barrels and for furniture polishes. However I have checked a number of gun cleaning solvents to find no trace of nitrobenzene and furniture polishes normally do not list ingredients. The 'Household Products Database" gives no hits for products that contain nitrobenzene.


Hmm...nitrobenzene used as solvent to clean gun barrels? Never really heard of it. I thought nitrobenzene is used in the manufacturing of aniline, dyes, pesticides and synthetic rubber?
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[*] posted on 3-8-2005 at 09:30


Thinking my gun barrel cleaning solvent was nitrobenzene was a guess based on its smell and "super nitro powder solvent" on the label. It is Gunslick brand made by Outers Labs. This is a fairly old bottle. A newer bottle does not mention "nitro" but says "contains petroleum distillates."



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[*] posted on 4-8-2005 at 09:23


"Oil of mirbane" (can you tell I love archaic names ;)) was once used as a cleaning solvent, until toxicity concerns promptly limited/cutailed its use in consumer products...

Magpie, if you're keen on finding out whether that *has* nitrobenzene, may I suggest the ferrous hydroxide test of yore detailed here.

sparky (~_~)




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[*] posted on 22-8-2005 at 08:11


Ordenblitz: Although late my congratulations by your pictures; but I take advantage of the occasion to raise in the nitration of benzene, seemed more logical to make drip the nitro/sulfuric mixture on benzene in vigorous agitation, so that, always there would be an excess of benzene and for that reason smaller possibility of dinitrobenzene.
Peculiarly in all the texts that I have reviewed the used order he is the one that you used; despite in other aromatic hydrocarbons the order he is inverse.
probably the reason is the smaller reactivity of benzene and the yields do not change significantly, in any case I raise the question to the forum.
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[*] posted on 22-8-2005 at 11:52


The nitro- group significantly reduces the reactivity of a the benzene ring, thus preventing most of the nitrobenzene formed by the initial nitration from reacting again.
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[*] posted on 26-8-2005 at 18:35


Without spirit to follow the discussion it is clear that nitrobenzene is enough the inactive thing as to use it as reliable inert in some reactions of Friedel-Crafts and I have left clear that to use the inverse sense will not modify the results significantly, although in the case of using HNO3 of high concentration as it happened at the beginning of this topic seemed useful... by the way is better to dilute the HNO3.
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[*] posted on 26-8-2005 at 19:14


The old gun cleaning solvents used to contain Nitrobenzene, easily recognizable by it's 'shoe polish' odor. I'm fairly old and remember when "Oil of Mirbane" was available at the drugstore right beside the Sulfur and Potassium Nitrate. I've been told by a racing enthusiast it was sometimes used in fuel mixes to add power.



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[*] posted on 27-8-2005 at 16:21


20 years ago I was still buying sulfur, potassium nitrate, and oxalic acid from the drugstore. Never did I see "oil of mirbane". I guess being 33 is not old enough.:P



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[*] posted on 27-8-2005 at 16:40


The Oil Of Mirbane was in a drugstore in 1968. There was only one 4 oz bottle , and I didn't even know what it would be used for then.



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[*] posted on 28-8-2005 at 02:32


Be careful with the m-dinitrobenzene, it's extremely toxic, about as toxic as KCN.
It also damages the organs in very small doses. Look up the dangers.

In Germany, "concentrated HNO3" always means the azeotropic acid of ca. 65% concentration. The 99% HNO3 is called "fuming nitric acid" or simply nitric acid of sp. gravity 1,5.

On what to do with the nitrobenzene: you could of course reduce it to aniline, which can make interesting colors and interesting compounds when diazotised.

Or you could reduce the NB to hydrazobenzene and then make benzidin (p-diaminodiphenyl), benzidin is used for a very sensitive test for presence of traces of blood on surfaces (benzidin test).
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[*] posted on 27-2-2006 at 05:30


Quote:
Originally posted by garage chemist
Be careful with the m-dinitrobenzene, it's extremely toxic, about as toxic as KCN.
It also damages the organs in very small doses. Look up the dangers.

In Germany, "concentrated HNO3" always means the azeotropic acid of ca. 65% concentration. The 99% HNO3 is called "fuming nitric acid" or simply nitric acid of sp. gravity 1,5.

On what to do with the nitrobenzene: you could of course reduce it to aniline, which can make interesting colors and interesting compounds when diazotised.

Or you could reduce the NB to hydrazobenzene and then make benzidin (p-diaminodiphenyl), benzidin is used for a very sensitive test for presence of traces of blood on surfaces (benzidin test).


Can you give more details on this ? Maybe some syntheses ? Have you ever did benzidin ?
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[*] posted on 28-2-2006 at 11:58


Benzidine is essentially banned in the UK because of its carcinogenicity.
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[*] posted on 5-6-2006 at 03:04
Chlorination


What would be th eisomer composition if I do Chlorination of Nitrobenzene? Any lab results from u experts.

Actually I'm trying to figure out commercial Nos for m_DCB.

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[*] posted on 29-6-2006 at 09:41


Can I make nitrobenzene with the H2SO4/NH4NO3 method?
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