Sciencemadness Discussion Board - Toxicity of phosgene

Toxicity of phosgene

woelen - 9-8-2008 at 11:39

Many times, people on sciencemadness are talking about the toxicity of phosgene and experiments (or synths) in which this gas is involved are avoided like the plague. On the other hand, people are comfortably using chlorine (e.g. leading it through all kinds of liquids). For some members, working with e.g. SOCl2 also is an option.

What makes phosgene so special, compared to other toxic/corrosive substances. IIRC it quickly hydrolyses to CO2 and HCl in water, so wouldn't it be of the same level of toxicity as gaseous HCl? SOCl2 for instance is as toxic as HCl and SO2, because that are the gases, formed in contact with water vapor, so I would expect COCl2 to be as toxic as HCl (CO2 is not toxic).

Sauron - 9-8-2008 at 12:00

That's easy. Phosgene is insidious, chlorine is not. If chlorine is present in harmful concentrations you will know it and you will not be able to force yourself to remain in its presence even if you wanted to.

Phosgene is not reliably detectable by the nose (reported limit of detection 4 mg/m3 air) and is non-irritating in lethal concentrations, its action is delayed, so you may be unaware that the hood is not working properly or that you are being exposed. The onset of pulmonary edema is 30-40 minutes away, meanwhile you feel just fine.

It is possible to prepare test paper that will indicate the presence of phosgene and to place strips of such paper around the hood periphery. Commercial phosgene detectors use the same test paper and color change. A method is described in Org.Syn. in one of the preps utilizing phosgene. Several more are described in Sartori. Unfortunately in several instances these test papers are either not very specific (same color change is brought about by HCl or Cl2 or sunlight) or else the test paper is short lived, or must be moistened with 50% alcohol to work. In short, this does not appear to be a detection system one would care to bet his lungs on.

The insidiousness of phosgene is precisely why it was preferred as a war gas.

For these reasons phosgene if used at all, should be used in a good hood and with the worker wearing a SCBA.

BETTER - if prep calls for phosgene, use diphosgene instead, much less volatile liquid. Less reactive though. STILL BETTER - use solid nonvolatile triphosgene, although it is less reactive than diphosgene.

The prep of diphosgene is in Org.Syn. and is the UV catalyzed chlorination of methyl chloroformate. That ester is best prepared by chlorination of methyl formate in the cold and without UV irradiation (or bright light.) It can also be prepared by phosgenation of methanol but we are trying to avoid phosgene, yes, like the plague.

That of triphosgenbe, an article from Angew.Chem. Intl Ed. by Eckert, has been posted by me previously. It is the UV catalyzed chlorination of dimethyl carbonate in CCl4. Very high yield and easy workup.

You cannot judge the toxicity of anything by either its precursors or its degradation products.

Phosgene is formed from CO and Cl2. It is far more toxic than either.

SO2Cl2 is formed from SO2 and Cl2 and is far more aggressive than either.

[Edited on 10-8-2008 by Sauron]

[Edited on 10-8-2008 by Sauron]

ScienceSquirrel - 9-8-2008 at 12:10

During the First World War there were cases in which men inhaled phosgene in small doses over a period of time.
They would go to bed feeling fine, hours later they would get up, start coughing and the blisters in their lungs would burst and they would drown in their own tissue fluid.

Sauron - 9-8-2008 at 12:20

As I said. Insidious.

Very very few of the industrial chemicals tested or used as war gases have this characteristic. Most are immediately irritating and so relatively ineffective because troops will don masks.

Read Sartori.

JohnWW - 9-8-2008 at 14:22

Quote:

Originally posted by woelenWhat makes phosgene so special, compared to other toxic/corrosive substances. IIRC it quickly hydrolyses to CO2 and HCl in water, so wouldn't it be of the same level of toxicity as gaseous HCl? SOCl2 for instance is as toxic as HCl and SO2, because that are the gases, formed in contact with water vapor, so I would expect COCl2 to be as toxic as HCl (CO2 is not toxic).

I think COCl2 is much more likely to hydrolyse (except in the presence of a good supply of oxygen and an adsorbing metallic catalyst) to CO + HCl, not CO2. This would certainly account for toxicity on the same level as CO. By comparison, CO2 and HCl can kill, in much larger concentrations, only by suffocation and acidification.

ScienceSquirrel - 9-8-2008 at 14:42

The rate of hydrolysis of phosgene is a lot slower than thionyl chloride or acetyl chloride.
They both fume in warm moist air, phosgene does not.
Most acid chlorides and chlorine have a rapid choking effect, phosgene does not.
Hence it is readily inhaled deep in to the lungs without immediate ill effect.
Phosgene casualties do not die of carbon monoxide poisoning. They die of pulmonary edema.

There was a case many years ago of a woman who was employed as a cleaner. She was given a bottle of carbon tetrachloride and set the task of removing some stains. The woman was a very heavy smoker and as she worked she inhaled the carbon tetrachoride vapour through her cigarette where it pyrolysed to phosgene. She went home feeling fine, on getting out of bed the following day the blisters burst and she died in minutes.

woelen - 9-8-2008 at 14:43

Sauron, I understand the issue about the insidiousness. Good to know that. Not that I had plans to do something with phosgene, but I just wondered.

JohnWW, I do not think that you are right. Hydrolysis is not a redox reaction and in your case, the carbon is reduced to the +2 oxidation state. Conversion to CO and HCl only could be possible if something else is oxidized, but there is nothing to be oxidized, so no CO is formed.

len1 - 9-8-2008 at 16:32

Ive yet to hear of anyone harmed by talking about phosgene. Its a perfectly safe compound for 95% or so of posts that never get beyond that here

[Edited on 10-8-2008 by len1]

JohnWW - 9-8-2008 at 19:46

Woelen: The C-Cl bond in COCl2 is more easily broken than a C-O bond. Also, in CO, the C resonates between being tetravalent as a carbanion (by far the more favored canonical form, with the O as a tetravalent oxonium, there being three covalent bonds and an ionic bond) and being divalent as a diradical (which is the far more chemically active canonical form, enabling CO to bond via the C atom to the Fe(III) in hemoglobin).

Besides, volatile chlorocarbon and bromocarbon compounds, including the likes of CCl4, CHCl3, CH2Cl2, CH3Cl, (CCl3)2O, CH3CCl3, etc., as well as COCl2, are well-known as liver toxins, which would add to the toxicity of any COCl2 that is not hydrolysed.

ScienceSquirrel - 9-8-2008 at 20:14

Quote:

Originally posted by len1
Ive yet to hear of anyone harmed by talking about phosgene. Its a perfectly safe compound for 95% or so of posts that never get beyond that here

[Edited on 10-8-2008 by len1]

That about sums it up.
Out of the thousands of members on here there are only hundreds of regular posters and only a few dozen of them carry out practical chemistry on a regular basis.

Sauron - 9-8-2008 at 21:09

I believe the thread author started off mentioning how we shun phosgene like the plague. Not everyone who actually gets some wet lab work done is inclined to photograph the procedure and post it here.

Besides, about 98% of the time, setups are mundane, flask contents are water white, and there really isn't anything pictorially very interesting going on.

As regards phosgene, the important thing to remember is: at home, just say no way. Even if you have a hood and a SCBA and a scrubber and a phosgene detection system, have a care for your wife, your kids, your pets, and your neighbors.

Besides, you don't need phosgene to carry out phosgenation. Take the time to make some triphosgene (stable, solid, essentially nonvolatile phosgene replacement.)

There's an Illustrated Guide suggestion for you, len1. Hexachlorodimethyl carbonate.

[Edited on 10-8-2008 by Sauron]

len1 - 9-8-2008 at 21:26

Yes thanks, Ive already got that on.

What you get out of doing experiments is actually intimate knowledge of what youre talking about. Its a bit like watching softball on TV and imagining oneself an expert. Theres a lot more to it than pictures.

As opposed to all these boasters with thousands of posts of 'Im going to do this and that' but than not one of 'Ive done it here are the results' - b.....it

Sauron - 9-8-2008 at 21:45

Not everyone here is a lens-louse, len1. Your disdain for your fellow members is unbecoming. You are not a performer, and they are not your captive audience. Feed them a diet of that sort of bile and they will turn on you.

Which is the real len1, they will ask? The dedicated pedagogue who selflessly leads by example? Or the sneering, arrogant prig who is so clearly contemptuous of all who do not emulate his shining self?

In case you did not notice, the thread topic is TOXICITY OF PHOSGENE. Would you propose an Illustrated Guide to Pulmonary Edema? A mini-WWI re-enactment? Come on, show us all why and how we should NOT make phosgene at home and drown in our own body fluids!

Some things are best left unreduced to experiment, and this is one of them.

[Edited on 10-8-2008 by Sauron]

Pyrovus - 10-8-2008 at 02:03

The other danger of phosgene, in addition to its hydrolysis, is the fact that it is also a very strong acylating agent. The carbon centre is strongly electrophilic, and chloride is a very good leaving group, meaning that phosgene will readily add to any nucleophilic organic molecules (such as the bases in DNA). Not only will this lead to cell death in the short term, but in the long run you also have to worry about cancer. Thus, the toxicity of phosgene is much more akin to that of mustard gas or dimethyl sulphate, than of chlorine or HCl.

BromicAcid - 10-8-2008 at 07:05

Quote:

Originally posted by Sauron
Phosgene is not reliably detectable by the nose (reported limit of detection 4 mg/m3 air) and is non-irritating in lethal concentrations, its action is delayed, so you may be unaware that the hood is not working properly or that you are being exposed.

Commercial phosgene detectors alarm at 0.1 ppm and 0.2 ppm. 0.1 ppm is the OSHA 8 hour exposure limit and at even this low of a level phosgene does have an odor so long as you know what it smells like (and it smells very faintly sweet at this level). At 0.2 ppm the odor is just as faint, this is the upper limit to what a person can work at for a short period of time (15 minutes). At 2.0 ppm phosgene has a strong odor, and is in the IDLH (Check out the information at the CDC website for detailed info)). Point being that although you can smell it, to be able to quantify it using your olfactory senses is folly, and you will likely end up getting yourself seriously injured.

Quote:

It is possible to prepare test paper that will indicate the presence of phosgene and to place strips of such paper around the hood periphery. Commercial phosgene detectors use the same test paper and color change.

I've seen the paper phosgene detectors in operation. They use a roll of ticker tape that travels through the machine and measures the phosgene at intervals, they work very good for high concentrations. The FID style personal detectors are much better though, they have a fast response time but a long relaxation time (once they go off, even after moving away from the source they will continue to alarm for some time). They are small and somewhat affordable. But their detection limits max out at 2.0 ppm because they are for saving lives and not just measuring phosgene concentrations. Also of note are the phosgene badges which are available. They are stored in a refrigerator and are one time use. You put them on at the beginning of your shift and they change color slowly during the shift if you get phosgene exposure. Then at the end of your shift you compare them to the standard to see if you stayed under 0.1 ppm for the day as a weighted average. Problem is they have a very slow response time and even when held in a stream of phosgene they are slow to change so they are no help of you are trying to save yourself, only if you are trying to meet OSHA requirements.

As Sauron said, and everyone else, phosgene is insidious because its lethal effects are not known and can be delayed for more than 24 hours. Diphosgene and triphosgene are somewhat better but under most effective reaction conditions they do break down to form phosgene and can also pose a hazard for workup for this reason.

SCBA works well for handling phosgene but don't overlook supplied air, providing you can set your intake in a safe place.

Note that scrubbing effluent with caustic has to be done in an efficient column at high pH ~14. Phosgene is somewhat hydrophobic, the neutralization is not as instantaneous as some of us would like to believe. Ammonia solutions make much better scrubbers because the nucleophilic attack on the phosgene is much faster to form urea and ammonium chloride.

Sauron - 10-8-2008 at 10:52

All good sound advice.

My advocacy os triphosgene and diphosgene as replacements for phosgene, take second place to my preference to avoid phosgenation entrely whenever possible.

For an example see the current thread on ethyl centralite. Nothat one is a five finger exercise, I have no particular use for centralite.

More important to me are various peptide reagents for protecting groups, such as benzyl chloroformate (Z reagent), Boc2O and Boc-ON. The Z reagent is now virtually unobtainable. Boc2O (Boc-anhydride) has a short shelf life and turns into expensive tert-butanol. Boc-ON is stable but expensive. Everyone of these requires a phosgenation step. (See Org.Syn.) So, I'd go with diphosgene or triphosgene and take appropriate measures in workup.

But if at all possible, I'd go a long way round to avoid phosgenation.

Klute - 10-8-2008 at 11:06

Can't benzyl chloroformate be prepared in-situ from benzyl chloride and carbon monoxide? Granted, hardly a safe substitution, but I recall seeing this at several occasions.

Why is benzyl chloroformate unobtainable? Does it release phsogene? I'm not much of a peptide chemist myself..

woelen - 10-8-2008 at 11:14

Is there a possibility that experiments with oxalyl chloride produce phosgene? All the things, described above, look very scary and not something I would like to handle (I do not have the suitable equipment, my protection is working outside when it is not raining). I, however, only use quantities of 0.1 or 0.2 ml of oxalyl chloride, so not much phosgene can be formed in my experiments (if any), but if there are reactions with oxalyl chloride, which can release phosgene, then I certainly would like to know. I do not heat my oxalyl chloride, I just use it in dilute solutions in DCM or ethylacetate or methylacetate.

In one of my experiments, I obtained a lot of colorless gas, and I tried igniting this. This gas did not burn, but when the flame of my cigarette lighter is kept in the stream of gas, then a lot of soot is produced. Could this be due to presence of phosgene? I once made pure CO with formic acid and sulphuric acid, and that burns with a nice blue flame.

All this stuff about phosgene has made me somewhat scared of working with oxalyl chloride as well.

[Edited on 10-8-08 by woelen]

Sauron - 10-8-2008 at 11:24

Sartori describes decomposition of oxalyl chloride to CO and phosgene under three conditions:

-- vapor phase 600 C in a tube over a bed of something or other (pumice I think)

-- contact with AlCl3

-- UV irradiation

So store it in brown bottles out of sunlight. Avoid the other conditions, that ought to be easy.

woelen - 10-8-2008 at 12:48

Sauron, thanks for this clear answer. The oxalyl chloride is stored in a brown bottle, in a dark place, so that is not a problem. The others are not an issue at all, I don't do that in my experiments and heating things to 600 C I never do at all.

Ozone - 10-8-2008 at 17:55

My oxalyl chloride label states that it contains: Phosgene <1%. The better grade (mine is 98 %, Aldrich) is much more expensive, but does not declare phosgene content.

It came in an amber bottle in a bag in a can in a box which was in a silver mylar bag.

Honestly, I just transfer with care in the hood (as long as it's in solution, it's far less intimidating). I made some DNPO last week, no problem. Working only with small amounts can greatly minimize the risks (particularly on work-up, here I was much more worried about the 2,4-DNP, which, in toluene, goes right nitrile gloves.).

BUT--I do this kind of work in a university lab. It is not at all safe to do at home (although there are some really nice hoods on display here) even with a hood because the thing has to vent somewhere. Somehow I have not yet seen a burner or scrubber applied to the vent of an amateur hood. These safety features are required--the ass you save might not be your own. That said,

When I need phosgene (and triphosgene will not work for one reason or another), I get it as a 5% (IIRC) solution in either hexanes or ether. I dispense the solution via cannula whilst cold from the freezer (you ought to see how fast the scroungers close your freezer when they see that in there

.

Cheers,

O3

7-cartridge - 16-11-2011 at 23:28

Even if phosgene is intraperitoneal injection, pulmonary edema happens.
Many people know only the inhalational toxicity.

http://www.journalarchive.jst.go.jp/japanese/jnlabstract_ja....
(Japanese)

The contents of the paper.
Phosgene was injected in the abdominal cavity of a rabbit (weight of about 2 kg).
In the case of 0.5 ml, a rabbit died one hour later and four hours later.
In the case of 0.3 ml, one rabbit died six hours later, and one rabbit still lived 72 hours later.
In the case of 0.1 ml, all rabbits lived 72 hours later.

DDTea - 8-12-2011 at 20:24

I remember reading the introduction to a book about phosgenation reactions. Pretty much, it stated that a lot of the reluctance of chemists to handle phosgene is unnecessary. When we grill meats, a fair amount of acrolein is emitted in the smoke. Acrolein has similar inhalation toxicity as phosgene, yet we don't think about personal protective equipment as we grill. When handled reasonably, phosgene is perfectly safe to handle and opens doors to a lot of exciting, useful synthetic chemistry.

However, "reasonably" is a very vague word. I didn't finish reading the book, so I can't say much more on the matter.

BromicAcid - 9-12-2011 at 15:04

Author Andrew Dequasie has a wonderful quote on working with boron hydrides and derivatives in his book "The Green Flame":

Quote:

Each job has hazards of its own. In general, we know that we can handle our own dog, no matter how apprehensive our neighbors may feel about the creature. On the other hand, we do hope that our neighbors will keep that vicious brute of theirs on a chain.

I have been a phosgene chemist now going on five years, day in and day out I am refluxing phosgene but I see nothing life threatening about it, I've been well trained and safety systems are in place. There are a number of toxic compounds we work with in our profession and hobby that have the capacity to kill, but phosgene lends itself to a special class of compounds that can deliver a lethal dose easily in the event of an accident.

A concentration of 50 PPM is considered lethal after a short exposure, to put this in perspective if you were in a box 6'x6'x7' and 1.48 grams of liquid phosgene were placed into that box you would be in this range. In gaseous form that would be ca. 350 mL. If you have a setup generating phosgene or a flask full of phosgene you have your lethal dose there. And if something were to go with you close by, forget that room scenario, the room is now only the space in your lungs. The above value is from "Phosgene and Related Carbonyl Halides" and it is described as 'Rapidly Fatal'.

One or two lung fulls might be enough to do you in. But it wouldn't feel that way, a little stingy, very sweet, and your eyes would burn, but you'd feel better in a few minutes.

If you barely smell it, it's likely not enough to kill you, if you smell it pretty good the same might hold true. But the fact remains that if something goes wrong and you have a release your time might expire.

@ DDTea, you may have been reading the above mentioned Phosgene and Related Carbonyl Halides, the first hundred pages or so are on the phobias associated with phosgene throughout history including snippets of comic books and poems written during phosgene attacks from WWI. In comparing acrolein toxicity one study using rats exposed them to acrolein at 4 PPM, 6 hours a day, 5 days a week for 62 days, mortality rate was ca. 50%. Compare that at 5 PPM the mortality rate after just 1 hour is 50% with phosgene. Still I guess the main difference is that at least in this topic we are not talking about harvesting and concentrating acrolein, afterall it is only the dose that determines the poison.

eyeofjake - 2-1-2012 at 23:45

As a weapons specialist, I have to say that it can be deadly....and it can't. Chemical weapons vary in effectiveness heavily by weather, environment, temp, and delivery. Phosgene is lethal, but it isn't a fast killer. It can take several days before pulmonary edema finally kills you. Good chem agents kill or injury a soldier on the field immediately as they are no longer fighting. Phosgene was weaponized as grenades. Since phosgene wouldn't destroy electronics like cyanide, a grenade of it would end a tank crew fast. Yet, out in the open you would have to lay down a ton as it mixes with air and drops it's lethality.

Despite all this, a simple wind gust would make the weapon you use your death. Spray some of it and then a gust of wind blows it your way......bad day. I don't like dealing with chem weapons really. I hate getting into a SCALP suit and wear a gas mask for hours. It's not fun. So I wouldn't be mixing it up in the house or in an enclosed area.

peach - 3-1-2012 at 10:17

Quote:

The other danger of phosgene, in addition to its hydrolysis, is the fact that it is also a very strong acylating agent. The carbon centre is strongly electrophilic, and chloride is a very good leaving group, meaning that phosgene will readily add to any nucleophilic organic molecules (such as the bases in DNA). Not only will this lead to cell death in the short term, but in the long run you also have to worry about cancer.

Carbon monoxide can also enter the body entirely undetected and the only warning sign is of imminent death is feeling a bit sleepy, but the point in bold above is important:

"There are 2 mechanisms of injury, hydrolysis and acylation. In hydrolysis, damage caused by phosgene is due to the presence of a highly reactive carbonyl group attached to 2 chloride atoms. The gas dissolves slowly in water, but when this occurs, it hydrolyses to form carbon dioxide and hydrochloric acid. This slow dissolution allows phosgene to enter the pulmonary system without significant damage to the upper airways. However, in the lower airways and alveoli, the tissue undergoes necrosis and inflammation. After the first few hours of exposure, the carbonyl group attacks the surface of the alveolar capillaries, causing leakage of serum into the alveolar septa. The tissue fills with fluid, causing hypoxia and apnea. Massive amounts of fluid (up to 1 L/h) leak out of the circulation, leading to a noncardiogenic pulmonary edema, with associated hypoxemia and volume depletion.

Acylation involves the reaction of phosgene with nucleophilic moieties causing denaturation of proteins, changes in cell membranes, and disruption of enzymes. The permeability of the blood-air barrier is altered, leading to interstitial edema, and the inflammatory cascade is activated. This primarily occurs in the bronchioli and alveoli since they are not protected by a mucous layer."

- medscape.com

A member of our own forum died not too long ago as the result of an experiment involving phosgene.

Witness how even DuPont can get it wrong:

<iframe sandbox width="640" height="360" src="http://www.youtube.com/embed/ISNGimMXL7M" frameborder="0" allowfullscreen></iframe>

Rather than building an entirely enclosed and computer controlled storage room, another option they could have looked at would have been enclosing the cylinders in liners. Such that, if the cylinder began to leak, it would do so through the scrubber. That may have cost significantly less than $2.2M to implement. It would have also been easier to control the atmosphere around the cylinder it's self (keeping it dry), to prevent hydrolysis and subsequent corrosion caused by cylinder leaks. Temperature control would have been easier, allowing for better process control.

Any leak occurring would produce a more rapid build up of concentration within the liner due to the small volume for dilution, allowing a detector to pick up the early signs of failure.

Many of the cylinder companies supply cabinets for storing dangerous cylinders. A lot of these are vented at the top. If the cylinder begins to leak, it is exhausted through the vent.

A simple vented cabinet (a liner):

Note the vents attached at the top:

Here's the high tech GasGuard from Air Products (designed to not only store the cylinder and provide a safe venting, but also control the delivery via an in built computer). I would guess this one is from some form of semiconductor place given it has silane written on the front. An environment where precise control is required:

These liners are designed for one to three cylinders sat in a lab. For bulk work, as DuPont were doing, they could have built the liners themselves from large diameter HDPE pipe (or something similar), to save capital on the fancy paint job and pretty aesthetics.

The description of the burst hose doesn't make total sense. Unless they were cooling the cylinders, the phosgene in the hose would be at approximately the same temperature it was at under normal transfer conditions, and so a similar pressure. There is also an issue with the idea that the guy was looking at swapping them over knowing that the hose hadn't been correctly purged.

The only way that could be achieved without detaching the still full hose would have possibly been to stand it up (or otherwise get the dip tube out of the phosgene) and purge it.

Given the weight of them and length of the hoses, a more likely approach would have been to simply disconnect it.

Assuming they don't have flow stops on the ends of the hoses, that would entail exposure to the contents. He would have been partially exposed even if they did feature stops.

In other words, he should have had a suit on given the problem at hand. Lack of communication perhaps meant he didn't realise precisely what was going on.

I can offer two other possible causes for the accident (which could involve charges against DuPont if they were true):

- The video mentions the hoses being over exposed. PTFE may be slightly permeable with regards to phosgene, but how readily does phosgene actually alter PTFE? If hose age is the issue, it seems more likely the phosgene would permeate the liner and then attack the braid. But an alternative explanation is the hose being damaged by kinking and abuse, due to it dangling in mid air as heavy cylinders are being moved around. Note in the video at 9.25 that it appears someone has stuck something directly over the point where the hose ruptured, which is either pure coincidence or a previously damaged spot being covered.

- He was actually sprayed when he was told to unscrew the hose, not realising it was still full and under pressure, without a suit on.

[Edited on 3-1-2012 by peach]

mr.crow - 5-1-2012 at 08:12

Interesting post. Poor guy

Those tanks look scary as hell, no way I would be working on them without a suit

Would acyl chlorides have the same danger? They are supposed to be potent lachrymators so it wouldn't have the delayed effect. Alkylating agents would also have similar acute toxicity. How about acetic anhydride?

MrHomeScientist - 5-1-2012 at 10:26

Thanks for posting that, peach. I'm a fan of documentaries, and that was a very good one. Man, I'd be terrified working next to that much pressurized phosgene.

BromicAcid - 5-1-2012 at 15:06

Here I am learning to be a phosgene chemist, note the big smile on my face since it was one of my first days along with the phosgene cylinder to my left. Despite the danger of phosgene it still finds heavy use in industry since it is such a clean way to make isocyanates, carbamoyl chlorides, isonitriles, chloroformates, acyl chlorides, etc. The facility where this picture was taken is no longer in operation however from what I have seen of other places that use phosgene, enclosures around cylinders and additional safety measures aside from nearby escape masks are not used save in bulk use.

Magpie - 5-1-2012 at 19:31

BromicAcid, weren't you concerned about working with phosgene with no gas mask or hood?

I remember way back when some customers were complaining about a "smell of fresh mown grass" when using a copier with my employer's paper. We thought it might be phosgene released by the heat of the copier.

I've often thought that those hoses covered with braided steel give a false sense of security. They look so tough yet the only purpose of the steel braid is to protect the real hose inside from abrasion, and maybe kinking.

mr.crow - 5-1-2012 at 19:37

Quote: Originally posted by BromicAcid

Here I am learning to be a phosgene chemist, note the big smile on my face since it was one of my first days along with the phosgene cylinder to my left. Despite the danger of phosgene it still finds heavy use in industry since it is such a clean way to make isocyanates, carbamoyl chlorides, isonitriles, chloroformates, acyl chlorides, etc. The facility where this picture was taken is no longer in operation however from what I have seen of other places that use phosgene, enclosures around cylinders and additional safety measures aside from nearby escape masks are not used save in bulk use.

Holy Crap! I would have a huge smile on my face too!

BromicAcid - 5-1-2012 at 19:51

Quote:

BromicAcid, weren't you concerned about working with phosgene with no gas mask or hood?

Safety measures were in place, electronic phosgene monitor, dosimeter badge, and air hood present. Prior to running the apparatus is snoop checked to ensure its integrity. Also the add is atmospheric, the setup completely open to a scrubber so there is no potential for pressure buildup. The gas is only pressurized at the regulator. It is safer than it appears although when entering the hood (as I am about to do in the picture) standard practice is to don breathing air. Being new to the job I did not follow this.

With regards to the steel braided line we do not use them due to the DuPont accident. In the picture you see standard PE tubing coming from the regulator. This is so it can be inspected as needed, also since it is atmospheric the worry of it being under pressure is nill.

Edit: That whole apparatus is in a walk-in fume hood. You cannot see the doors though since they are open, it was about 20 feet long.

[Edited on 1/6/2012 by BromicAcid]

mr.crow - 6-1-2012 at 07:53

Can you give us a hint to whats going on? Why do they have a reflux condenser and a distillation column? And its all Aldrich brand, expensive! I love the water jacketed distillation adapter

Magpie - 6-1-2012 at 11:20

What I like is what appears to be an air-driven mixer.

Bromic has the look of: "I can't believe they are paying me to do this."

peach - 7-1-2012 at 02:41

Quote: Originally posted by MrHomeScientist

Thanks for posting that, peach. I'm a fan of documentaries, and that was a very good one. Man, I'd be terrified working next to that much pressurized phosgene.

The greatest risk is the one which we do not consider.

And yay, the dust did explode, mightily... Combustible Dust: An Insidious Hazard

Nice to see you there bromic, stay safe brah!

entropy51 - 7-1-2012 at 06:45

Quote: Originally posted by BromicAcid

The facility where this picture was taken is no longer in operation however from what I have seen of other places that use phosgene, enclosures around cylinders and additional safety measures aside from nearby escape masks are not used save in bulk use.

BromicAcid, was that picture taken at Carbolabs?

BromicAcid - 7-1-2012 at 07:49

Yup, nice to see you recognize the place still

franklyn - 7-1-2012 at 20:39

Why this needs it own thread I can't imagine given that the study of it ranks
second only to that of anesthesia , and online documentation is more than
you could possibly ever read.

See PHOSGENE AND DIPHOSGENE lower paragraph here page 257 ( seen at upper left corner of page ) & 258
http://history.amedd.army.mil/booksdocs/wwi/VolXIV/VolXIVhtm...

See page 311 ( seen at upper left corner of page ) here _
http://history.amedd.army.mil/booksdocs/wwi/VolXIV/VolXIVhtm...

Observe Exposure limits Section 3 here to become a fatal casualty
www.airgas.com/documents/pdf/006297.pdf

Should be noted that Phosgene is perceptibly and physiologically indistinguishable in action from
nitrogen dioxide - http://www.vlib.us/medical/HMSO/chapter7.htm#70 ,71 ,72 ,73

.

Dr.Bob - 19-7-2012 at 13:23

We used to buy a lot of compounds from Carbolabs... They were bought by Aldrich, correct? I bet that was an interesting job. Almost as good as Columbia Organics or some other small organic companies.

When I was in graduate school the lab next door had a huge cylinder of Phosgene strapped to a bench NEAR the hood (not in it), with a tube running in to the hood. We also had bottles of 50% phosgene in toluene in the refrig. as well. It's a miracle that we did not have more accidents back then, as safety in universities was much less then today, and it is still much less then industry.