Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
benzene odour
I have just made nitrobenzene. I'm ususally not an organic hobbyist, but for one time I wanted an exeption.
This was performed in my home made fume hood, wich has never given me smells until now.
I slowly added benzene, and after addition I heated on a water bath. I had no problems.
But then I started cleaning. I cleaned all benzene touched parts with a little acetone, and poured in a waste bottle. Next I started cleaning from the
sink. What do I smell? A sweet aromatic smell, I wondered where it came from. I continued cleaning all parts, and that smell was appearant all the
time. It was nice by itself, but when you know it's a carcinogen, you like it less!
I soon discovered a strong smell of benzene on my hands, wich was probably the source.
Anyway, I got a 30 minute exposure I think, with the first 20 minutes some occassional smells, and in the last 10 minutes a continuous smell.
I was looking for odour threshholds after the experiment. I was shocked. I saw 60-100ppm!!! This would have been a very large exposure. Then as a
relief another source stated 1,6-4,7ppm. That is acceptable.
Does anyone know the real value? All sources state different things. What is your experience with benzene? I seems that it smell goes everywhere, when
I smell my hands, even after washing with xylene/isobutanol and warm water, there is still that faint sweet odour 
The good thing is that benzene is really not a very potent carcinogen, being one of the lowest on a list I posted some months ago. Increased cancer
was detected in persons with 5+ years exposure. I have only 30 nminutes 
But I do not want to go through this again. I am seriously thinking of pouring my 150ml benzene in a paint thinner bottle, together with 800ml
xylenen/isobutanol and brining it to a waste facility where they burn it.
|
|
|
vulture
Forum Gatekeeper
Posts: 3330
Registered: 25-5-2002
Location: France
Member Is Offline
Mood: No Mood
|
|
Don't get upset. Ever spilled gasoline? Wonder how many people spill gasoline over their hands everyday? A former professor used to wash his hands
with benzene in the past. Still alive.
[Edited on 10-3-2009 by vulture]
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
|
|
|
chemoleo
Biochemicus Energeticus
Posts: 3005
Registered: 23-7-2003
Location: England Germany
Member Is Offline
Mood: crystalline
|
|
I agree.
Cancer is rarely a problem for a single exposure of carcinogen. The habitual or continuous exposure is what presents a problem. This is because
mutations are cumulative, and cumulative mutations only lead to cancer - there is no KNOWN single mutation (single amino acid change) that is
sufficient to induce cancer. Because there are always two alleles (so a functional gene copy remains), and the likelihood for the second mutation to
acquire the same mutation during that same carcinogen exposure in the same cell is pretty much zero.
I'd rather be worried about cycling in exhaust fumes every day (which is what I do) 
I hate these car drivers poisoning our world! (ok I'm being simplistic.. but it's fun!  )
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
As for the sweet aromatic smell, nitrobenzene has a wonderful sweet smell. But it's incredibly toxic and gives horrid nitro headaches. Could have
been that, that you were smelling.
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
That could indeed also be it. I had a slight headache after. However nitrobenzene is much less volatile. It is indeed very toxic, even worse that
benzene.
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
I once made nitrobenzene in an university chemistry laboratory class. It has a smell like that of benzaldehyde - bitter almond oil.
|
|
|
panziandi
Hazard to Others
Posts: 490
Registered: 3-10-2006
Location: UK
Member Is Offline
Mood: Bored
|
|
I hate nitrobenzene, it has a horrid smell, I find it is a bit like benzaldehyde but with a slight twist. Gives me headaches, leeches into plastic and
is very noticable at low concentrations, I can smell it in my solvent cupboard even though the bottle hasn't been opened in about 2years!
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Wow yes nitrobenzene smell is really strong. It appears to be the same smell as yesterday, wich I though was benzene. But now I really liked the
stuff, probably because I knew it was not benzene but nitrobenzene --> I really don't like chronic poisons. Yes nitrobenzene appears to be very
toxic (lethal dose 1 to 5 grams! absorbed through skin!) but chronically much less toxic, it is a carcinogen, but a very weak one, and it has some
reproductive toxcity.
Also does nitrobenzene react with acetone? When I filtered my nitrobenzene after drying , I think still traces of acetone were present in the
filtering flask, and now my nitrobenzene is not completely clear. Not a real concern, I want to use it for aniline synthesis.
When I was cleaning the measuring cylinder I used to transfer nitrobenzene with acetone, there was instant smoke above the liquid (a little bit like
HCl + NH3).
I see no way how nitrobenzene casn react with acetone. Maybe some other chemicals rom the synthesis still present?
I did like this:
-Pour reaction mixture in 250mL water.
-Stir well.
-separate
-Wash with 15ml water
-separate
-dry on anhydrous CaCl2
-Filter
I made it out of benzene, and HNO3/H2SO4
Any ideas?
|
|
|
Globey
Hazard to Others
Posts: 183
Registered: 9-2-2009
Member Is Offline
Mood: No Mood
|
|
Nitrobenzene odor will make you sick in the same way as when you have a snack you are addicted too, and you overdo it (to the point you get naceous
just thinking of eating any more). But like everyone else said....do NOT worry about what has hapened...que sara, and just think of being careful in
the future.=) Who knows, it may turn out small sporatic exposures could, indirectly, prove beneficial in the long run (I'm sure I'll get shot for
saying something so un PC).
Last time I saw benzene for sale OTC was in early 80's, here:
h__P://ww_.ramseyoutdoor.com/
Is there any place in US one could pick it up OTC?
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
