Sciencemadness Discussion Board

Nitrobenzene

ordenblitz - 31-7-2005 at 19:24

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

BromicAcid - 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 ;))

ordenblitz - 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]

sparkgap - 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 (~_~)

ordenblitz - 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

ordenblitz - 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

chemoleo - 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

ordenblitz - 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.

Magpie - 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.

BromicAcid - 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.

vulture - 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.

praseodym - 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?

Magpie - 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."

sparkgap - 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 (~_~)

hydrargirum - 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.

neutrino - 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.

hydrargirum - 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.

Mr. Wizard - 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.

chloric1 - 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

Mr. Wizard - 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.

garage chemist - 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).

Maja - 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 ?

unionised - 28-2-2006 at 11:58

Benzidine is essentially banned in the UK because of its carcinogenicity.

Chlorination

technologist - 5-6-2006 at 03:04

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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Zinc - 29-6-2006 at 09:41

Can I make nitrobenzene with the H2SO4/NH4NO3 method?

Douchermann - 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.

Zinc - 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.:)

Douchermann - 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.

neutrino - 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.

Zinc - 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.

Zinc - 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?

Nicodem - 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.;)

Zinc - 12-7-2006 at 11:15

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

Douchermann - 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.

S-Bursic - 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.

S-Bursic - 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.

Zinc - 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).

Sauron - 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.

Nicodem - 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?

Toxicity

PeetPb - 3-8-2013 at 07:09

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