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Little_Ghost_again
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Spin off from Phosgene thread
Hi,
I am sure most are aware of the phosgene thread currently in Organics.
It did however give me an idea, in the thread someone mentioned (sorry I forget now who it was) That first the person should try and make say Chlorine
and do a clean up without getting a single wiff of it.
I think this could actually be really useful for noobs like me to try!
Although I am making a Chlorine generator for bleach lets put that aside for a minuet.
What I was thinking was collecting some ideas of synths that all produce a stench or some kind of nasty but non lethal effect if they are smelt.
Now I dont have a clue which would qualify for this but how about starting with some that are pretty harmless but the idea is you try and do it with
ANY exposure, those with the knowledge can explain how best to do the clear up etc.
These could then progress upto say Chlorine, that way some of us would get a really good practice at techniques and there would be a thread for those
with over ambitious ideas to start lower and work up without much risk.
Does any of that makes sense?
Dont ask me, I only know enough to be dangerous
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aga
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Sounds very sensible indeed.
Chlorine would be OK so long as the calculated volume were very low.
You;d be able to smell it, and (if the calculation is correct) there would never be enough to kill you.
Edit:
Having one tiny whiff of it is a Good idea - you know what it smells like after that.
[Edited on 14-10-2015 by aga]
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OneEyedPyro
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A little whiff of chlorine isn't going to kill you and it can be smelled at very low concentrations, just the fact that you considered making phosgene
but are having second thoughts about making Cl is kind of ridiculous sounding 
Realistically making Cl is not that dangerous generally speaking, now if you can synthesize chloroacetone and cleanup without smelling Cl or feeling
the effects of the chloroacetone you're doing pretty well.
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Little_Ghost_again
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Quote: Originally posted by aga  | Sounds very sensible indeed.
Chlorine would be OK so long as the calculated volume were very low.
You;d be able to smell it, and (if the calculation is correct) there would never be enough to kill you.
Edit:
Having one tiny whiff of it is a Good idea - you know what it smells like after that.
[Edited on 14-10-2015 by aga] |
My reasoning for starting with something other than Chlorine is this.
If a real noob like me gets it wrong in a bad way I will get more than a wiff, that is apparently not good.
So I thought there must be other chemicals that humans can detect in tiny amounts by the nose that are fairly harmless if the very worse happens.
I am thinking maybe putricine?? I dont actually know which one to start at hence the thread, but getting a list of procedures together that got up in
risk might be good training.
I know some do little more than stream the eyes and hurt like hell, but that is a good way to learn, I think it might sharpen us noobs up. Slowly
increasing the risk also means you take it seriously (or should), look at the phosgene thread!! No matter what gets said nothing is going to convince
the guy a single wiff is bye bye, but if people start at something harmless but hurts alot, and know each synth increases in risk then hopefully
skills will be truly honed.
I am especially keen to learn how the hell you clean some of this equipment up afterwards! I distilled Nitric acid and cleaning the condenser etc was
a real mare, I am sure people here who have had training and proper education know a few tricks on how to do this in a safe way.
I wouldnt suggest starting at chlorine as getting it badly wrong isnt going to end well. Think of it as a complete beginners guide to handling synths
with risk
Dont ask me, I only know enough to be dangerous
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aga
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What does Cl smell like ?
I've only ever smelt Cl2.
LG2.397 was not the one trying to make phosgene.
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OneEyedPyro
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I believe Cl is immediately oxidized to ClO₂ upon but that's a good question, what does Cl smell like? I know Br smells very similar to ClO₂ so
I'd guess the same goes for Cl.
[Edited on 14-10-2015 by OneEyedPyro]
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aga
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Cl immediately forms Cl2 on hitting Cl.
Cl is never seen, ever.
Closest is Cl<sup>-</sup> as the ion.
Cl2 experiment :-
Test tube with a few grains of TCCA (trichlorocyanuric acid) Pool Shock stuff.
1 drop of HCl.
At 20% HCl concentration that should eventually release a total of 0.004114 mol of Cl2 which equates to around 100ml of the gas.
Edit:
Enough to Whiff, not enough to Stiff.
[Edited on 14-10-2015 by aga]
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Detonationology
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Chlorine gas is said to have slight smell of almonds. My chlorates always always have a nutty smell.
“There are no differences but differences of degree between different degrees of difference and no difference.” ― William James
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OneEyedPyro
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Well, yes of course. Just like oxygen, nitrogen, hydrogen etc they exist diatomically.
When I saw Cl I automatically thought of Cl₂ and failed to make the distinction.
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softbeard
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Why don't you try to synthesize concentrated ammonia water "ammonium hydroxide" with an ammonia gas generator and water.
Don't forget, it is possible to induce pulmonary edema with NH3 but the NH3 concentration necessary is
intolerable.
Ammonia gas is usually considered safe enough vs. lethal poisoning so long as a person isn't forced to breath it by circumstances.
See if your containment system allows you to do the preparation without smelling ammonia.
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Magpie
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I have made Cl2 many times. Never without smelling it. My powerful fume hood allows me to have small mishaps without consequence. After much
practice I now have an equipment train for creating dry chlorine without equipment failure.
There is an experiment in Brewster for making malachite dye. The author says that if you can make this dye without getting green all over your person
and clothes you are a good chemist. I was doing fine until I did one
manipulation poorly. I ended up with green all over the place!
Why does this test chemical have to be dangerous or toxic. Why not try making benzaldehyde or amyl acetate without smelling them?
edit: tip for LGA and others wanting to rid their vessels of poisonous gases at the end of a synthesis: top those vessels off with water
before removing them from the hood.
[Edited on 14-10-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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battoussai114
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Ammonia, Thioacetone or Thiols in general are what I can think of...
[Edited on 14-10-2015 by battoussai114]
Batoussai.
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j_sum1
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| Quote: Originally posted by Magpie | | edit: tip for LGA and others wanting to rid their vessels of poisonous gases at the end of a synthesis: top those vessels off with water
before removing them from the hood. |
First get a hood!
Actually I really like this as a challenge. Make something smelly without smelling it. What excellent practice and opportunity to develop skills and
test equipment and technique.
I am pretty sure I could do ammonia even without a fume hood. But I'd be relying on the fact that it is absorbed by water so well. Chlorine? Not so
much. But it doesn't scare me like it used to. I am not sure if that is a good thing or not.
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Little_Ghost_again
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I had a fume hood, I will get another at some point. And just for the record NO it wasnt me trying to make phosgene!!
Malachite green I like the sound of, and the water tip is noted.
They dont have to be dangerous, especially at the start. But once you kind of master the less toxic stuff it would be good to add a little fear and
see if you can still perform. I am just thinking that mentally there might be a difference to how you approach something you know wont hurt and
something you know would hurt.
The smells one is great! So what smells at very very low concentrations and isnt toxic? This would make a great aga challenge if we had a scratch and
sniff forum!
Dont ask me, I only know enough to be dangerous
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deltaH
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Organic isocyanides (from wiki):
| Quote: |
Their disagreeable odour is legendary. To quote from Lieke, "Es besitzt einen penetranten, höchst unangenehmen Geruch; das Oeffnen eines Gefässes
mit Cyanallyl reicht hin, die Luft eines Zimmers mehrere Tage lang zu verpesten, ..." (It has a penetrating, extremely unpleasant odour; the opening
of a flask of allyl [iso]cyanide is enough to foul up the air in a room for several days). Note that in Lieke's day, the difference between isocyanide
and nitrile was not fully appreciated.
Ivar Karl Ugi states that "The development of the chemistry of isocyanides has probably suffered ... through the characteristic odor of volatile
isonitriles, which has been described by Hofmann and Gautier as 'highly specific, almost overpowering', 'horrible', and 'extremely distressing'. It is
true that many potential workers in this field have been turned away by the odour."[5] Isocyanides have been investigated as potential non-lethal
weapons.[6]
Some isocyanides convey less offensive odours such as malt, natural rubber, creosote, mild cherry or old wood.[7] Non-volatile derivatives such as
tosylmethyl isocyanide do not have objectionable odors.[8] |
They can be prepared from primary amines easily with reagents you have:
| Quote: | | In the carbylamine reaction (also known as the Hofmann isocyanide synthesis) potassium hydroxide reacts with chloroform to produce dichlorocarbene.
This then converts primary amines to isocyanides. As it is only effective for primary amines it is used as a chemical test for their presence.
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aga
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First place Cl was mentioned was in your own post.
[Edited on 14-10-2015 by aga]
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gdflp
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| Quote: Originally posted by aga | Cl immediately forms Cl2 on hitting Cl.
Cl is never seen, ever.
Closest is Cl<sup>-</sup> as the ion.
|
Not true. Look up chlorine radicals, they're important intermediates in many organic reactions, and they do exist. Has blogfast not covered that yet
in your class?
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phlogiston
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Nice idea. Two candidates:
<b>Tetrahydrothiophene</b> has an odour threshold of just 1 ppb. In many countries, this compound is added to natural gas to allow a leak
to be detected by smell. If you fuck up with this compound, expect a massive response from whoever is responsible for handling a gas leak.
The odour threshold of <b>trimethylamine</b> is about 0.21 ppb. Its smell resembles spoiled fish. However, about 7% of people are anosmic
to its odour.
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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aga
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| Quote: Originally posted by gdflp | | Look up chlorine radicals, they're important intermediates in many organic reactions, and they do exist. Has blogfast not covered that yet in your
class? |
I wish at this this point to Thank Everyone in this forum from whom i have managed to gain the small amount of knowledge of Chemistry that i currently
possess.
The New (to me) knowledge that has been freely given is very much appreciated, so a huge THANK YOU to all contributors.
blogfast25 stands out (for me) as an excellent educator.
You have tought me as well gdflp, like it or not.
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careysub
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The standard of not having *any* exposure is impossible to reach without (or maybe even with) a completely sealed perfectly engineered system.
It is standard procedure for example for spies looking for uranium enrichment or chemical weapon production sites to detect them by environmental
sampling outside the plant. No plant is so good that traces are not detectable.
You need to discuss what levels are acceptable/unacceptable.
Chlorine is detectable at 0.5 ppm, can cause slight temporary respiratory impairment at 1 ppm if inhaled for a few hours, is intolerably irritating at
10 ppm, but at that level is not a lethal hazard even after hours of exposure. Immediately hazardous concentrations are in the hundreds of ppm.
Thus this is a reasonable experiment to test how good you are at keeping the gas contained at the 1 ppm level. If you exceed this by much you will
know it right away, and be motivated to clear the area immediately.
Really potent odiferous compounds (ethanethiol and other thiols) can be detected at 0.0002 ppm. With these compounds making them in any but micro
quantities becomes a problem not because they are dangerous, but because of the nuisance odor problem.
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j_sum1
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Interesting careysub.
My problem with these kinds of descriptions is having some sort of reasonable guestimate as to how potent the thing is that I am smelling. I find
that I need some kind of frame of reference. A couple of examples:
I open the door to the shed containing the pool filter and also where the pool chemicals are stored. There is an obvious smell of chlorine in the
air. Not exactly unpleasant, but not somewhere i want to sit down and have a picnic. On the scale above, what kinds of concentrations am I
experiencing here.
I lived in an area with quite a bit of geothermal activity. H2S would literally come out of the ground. Mostly it would disperse in the wind but
there were still days with low lying cloud where the smell would be a lot more noticeable. To the point that you could fart and no one would notice.
I regularly read here how toxic H2S is, how vile it smells and what ought to be done to avoid exposure. Low levels don't bother me a bit and I
associate the smell with hot mineral springs -- quite pleasant memories. My question: what level of H2S exposure am I likely to have been
experiencing and how does this compare with levels at which one should take precautions?
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gdflp
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| Quote: Originally posted by aga | | Quote: Originally posted by gdflp | | Look up chlorine radicals, they're important intermediates in many organic reactions, and they do exist. Has blogfast not covered that yet in your
class? |
I wish at this this point to Thank Everyone in this forum from whom i have managed to gain the small amount of knowledge of Chemistry that i currently
possess.
The New (to me) knowledge that has been freely given is very much appreciated, so a huge THANK YOU to all contributors.
blogfast25 stands out (for me) as an excellent educator.
You have tought me as well gdflp, like it or not. |
Indeed, that is the reason all of us are here, both to learn new information and teach others what we know. That's why this forum is so successful,
because the members are willing to share their knowledge with others, while still keeping open ears and recognizing that some have more knowledge and
experience in different areas, be they chemistry, physics, or any other topic.
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careysub
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| Quote: Originally posted by j_sum1 | Interesting careysub.
My problem with these kinds of descriptions is having some sort of reasonable guestimate as to how potent the thing is that I am smelling. I find
that I need some kind of frame of reference. A couple of examples:
I open the door to the shed containing the pool filter and also where the pool chemicals are stored. There is an obvious smell of chlorine in the
air. Not exactly unpleasant, but not somewhere i want to sit down and have a picnic. On the scale above, what kinds of concentrations am I
experiencing here. |
A few ppm.
| Quote: | I lived in an area with quite a bit of geothermal activity. H2S would literally come out of the ground. Mostly it would disperse in the wind but
there were still days with low lying cloud where the smell would be a lot more noticeable. To the point that you could fart and no one would notice.
I regularly read here how toxic H2S is, how vile it smells and what ought to be done to avoid exposure. Low levels don't bother me a bit and I
associate the smell with hot mineral springs -- quite pleasant memories. My question: what level of H2S exposure am I likely to have been
experiencing and how does this compare with levels at which one should take precautions? |
H2S is faintly detectable at 1 ppm, easily detectable at 5 ppm, strongly unpleasant at 25 ppm, causes eye irritation and coughing from 50-100 ppm, the
LC01 concentration for 30 minute exposure is 200 ppm.
A special problem with H2S is that 10 minute exposure at 50-100 ppm destroys the sense of smell and thus results in the loss of ability to sense its
presence through smell.
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j_sum1
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Ok. By that reckoning, the day I caught a strong whiff of Cl2, held my breath and evacuated the shed, it was probably tens of ppm and climbing.
Strongly irritating was the word I would use, but I also knew the concentration was climbing and it wasn't going to get any better in the short term.
I am aware of that particular issue with H2S. I guess the rule of thumb is that if you smell it, it is not going to necessarily cause harm. If it
smells really unpleasant, you should be out of the situation and breathing some fresh air. And if you know it is around but can't smell anything,
then you are in deep serious yoghurt.
I understand that the same olfactory numbing occurs with thioacetone. Is this a general thing with sulfur compounds?
edit: spelling
[Edited on 15-10-2015 by j_sum1]
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careysub
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Right.
If you ever encounter a strongly unpleasant smell of hydrogen sulfide, your nose is telling you to get the *bleep* out of there!
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