tsathoggua1
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Correcting a blockage in an ICl synthesis..troublesome
Got a little bit of a problem here.
I've been doing a synthesis of ICl, pretty simple setup, a Cl2 generator (originally KMnO4/HCl, but due to the cost of KMnO4, and running out, I had
to switch oxidant to NaOCl.
The setup is fairly simple, two liebig condensers, one containing an iodine packing, the other with a modest quantity of anhydrous CaCl2 to dry the
chlorine before its contacting the I2.
These are connected via distillation adapters, one with, and one without a vacuum barb, the former is the one connected to the Cl2 generator to enable
addition by syringe of further acid and hypochlorite solution. This was held in place by a little tuft of steel wool (which has now been removed,
although to no avail) just enough to stop the CaCl2 backing up and falling into the chlorine generator.
There is, when its running, a one hole stopper plugged with a length of borosilicate tubing, connected on the external side to a length of hose, which
leads into first a suckback trap with a one-way valve, permitting exit but not entry, and this leads off a hose connected to a diffusion stone
submerged in saturated sodium carbonate solution in order to prevent escape of fumes, which in the case of iodine monochloride, are of the most
noxious character. The main problem is, now the system has become pressurized with Cl2 on the generator side.
The receiving flask still contains some ICl, and the iodine column has slowly been converting the dregs to ICl3. That side can be dealt with by
shock-freezing the ICl and condensing any vapor in the flask (and there is a fair bit of that). I can't currently separate the two columns and need to
clear this blockage. Taking off the clamp keeping the hose attached to the vacuum barb to any degree leads to quite a lot of Cl2 rushing out, so
disconnecting it is going to be an unpleasant task at best, Cl2 generation still hasn't completely ceased.
The entire setup now is significantly pressurized. Taking the two condensers apart is going to be a job for when the system is cleaned out, because of
what ICl does to greases (I've since switched to thick layers of teflon to cover stoppers and connections, I don't know if I'll ever be able to free
the two condensers. Certainly, I don't want to try whilst its still pressurized with Cl2 and ICl vapors. I've seen what the latter does to organic
materials, and a fair few inorganic ones for that matter and it is not something I want spraying back at me.
I think its the dessicant thats perhaps swollen, or if not, then the joint spaces in the middle of the condenser line getting choked with ICl3.
Suggestions as to the best (I.e safest, and preferably leading to the loss of the least iodine, ICl and ICl3 of course) way to find out which spot
exactly is causing the blockage?
Somewhere along the line, there is a blockage
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woelen
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One thing which may help is using a hairdryer (fohn) on a moderately hot setting. With this you can heat the place which is clogged by solid ICl/ICl3.
The heat leads to melting of ICl and decomposition of ICl3. The heat, however, only is very moderate and will not lead to cracking of glass or joints.
You can even touch the glass after heating it with the hairdryer.
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tsathoggua1
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I'd thought of that. But I think the blockage may well be in the drying agent section close to the Cl2 generator. And the issue is, that the system is
pressurized, under a fair positive pressure of Cl2. One only has to unclip a hose leading to the input line for further oxidant/acid a little and the
result is a jet of concentrated chlorine gas. If one were to do that not wearing a suitable mask, well fitting and with adequate space in the
absorbent cartridges attached thereunto, it would without doubt be sufficient to knock the person so doing sideways, if not do some serious harm. I
DON'T want to heat this thing, its one thing, heating it at the opposite end, at the upper level of the flask, whilst running iced down coolant lines
recircilating ice-salt-acetone-diethylene glycol-alcohol mixture through it in order to condense the ICl residue (a few ml left, but there is plenty
of something dark and iodine-like in the condenser closest to it (arranged horizontally for distillatiion in configuration), warming the upper half
of the flask and cooling the bottom right down in order to condense the last of the reagent prior to harvest (I think I'll turn what is left into
ICl3, kill two birds with one stone so to speak, get two reagents for the price of one)
But heating the Cl2 generator, if its there that is backed up, could lead to the joints being forced apart and a significant release of Cl2.
Can anybody see issue with plumbing in a suckback trap and one-way valve, as I used in scrubbing any escapee ICl fumes, before taking off the
hose-clamp, and then slowly loosening it, whilst the outlet from the trap is submerged in hot NaOH solution, so as to recycle any Cl2 in the form of
NaClO3. or better yet, KOH, to give potassium chlorate, before then taking off the Cl2 generator flask and distillation bend, either separately or
retaining the two joined together, then raking out any stuck CaCl2 with fr.ex. a piece of the same solidly built single rod nickel alloy fretwire?
this can, conveniently, be sharpened to a razor sharp pointed tip by means of molten mixed NaOH and potassium hydroxide whilst passing a current down
it and using a second piece as a cathode, or using one of my graphite crucibles as both cathode and pot for holding the KOH/NaOH mixture? the wire
isn't attacked much even by prolonged electrolysis of fused NaOH at a current of either 35A or 14A at 5v or 15v respectively, and for some reason, not
nearly so quick to be assaulted by KOH alone, but a mixture of the two, has the advantage of both being a eutectic melting at a reasonable
temperature, a blowtorch will do just fine with propane or propane/butane mixture, and the mixture will flay the bejeesis out of this fretwire when
used as an anode in pretty short order. Its just the opening of the system thats bothering me really. That and the fact that I have access to pretty
much an entire bucket full of this fretwire as used guitar frets enough to last me a generation of lifetimes worth of sleepless nights spent at the
bench, pumping coulombs merrily through fused caustic melts, not sure if the one who uses the fretwire for the actual guitars would give me a long
enough piece (I'd need about a meter of it, and whilst the person who uses it doesn't mind in the least me helping myself to as many handfuls of
pieces as I could possibly ever want for whatever I want, a big long length of new fret wire might be another matter, and the used stuff is of course
cut to the width of a guitar fingerboard, works plenty well for electrolysis, but I don't know if he'd part with a long rod of it. Might do, if its
just the one piece, to be sharpened for clearing out the blockage whereever it is; raking out first the CaCl2 and then using it to shove any
solidified ICl3/ICl in solid crystals after cooling right down down into the ICl collection flask along with any remaining I2, back-fill it after
cooling on a freezing mixture bath with pentane, and then bubble excess Cl2 through the pentane, forming solely ICl3 which ideally should precipitate
out from the pentane, whilst the solvent can easily be distilled off without damaging the ICl3 causing it to disproportionate.
Question-Solid ICl3 needs to be kept under an atmosphere of gaseous, dried Cl2 doesn't it, after first purging the bottle it is to be stored in under
argon in ordeto remain stable?
Of the interhalogens, the only ones which attack glass would be some of the fluorinated ones, no? and any vessel suitable for confining either ICl,
I2, or Cl2, should be able to handle ICl3 should it not? (I don't plan on making any of the fluorine based interhalogens, for safety reasons, ICl and
other iodine, bromine and chlorine-based interhalides are fairly hazardous reagents as they are, without introducing the potential for decomposition
into HF or worse still, F2 into the equation. Whilst I don't have any issue with the other interhalogens being stored in the lab, so long as I store
them carefully, and WELL separated from anything such as metal powders, ethers, chlorate/perchlorates, azide/cyanides etc. and away from organics, I
have no wish to have even the theoretical possibility of an accident with halogien fluorides. I'm not sure what these chemical resistant bottles I
have are made out of, either the vitreous portion thereof, or the cap. I have a fair few, after one episode of the ongoing donut muncher-orchestrated
campaign of abuse, hate and prejudice, when the filth broke into the lab on the flimsiest, most ghostly excuse for a false pretence.
Morons broke into the lab, trashed it, did quite a lot of damage and almost burned the house down by taking out some alkali metal from a container and
left it out on the counter, placed up against opened bottles of EtOEt and THF and just left them there! allegedly they were there demanding to 'take
samples for analysis'. They just brought some highly resistant chemical bottles, presumably teflon capped since its the only plastic that I have known
to be inert towards iodine monochloride, even in storage for many months there has been no leakage of a small sample nor decomposition, and zero
attack upon the polymer itself. So the filth broke in, 'took samples' with said bottles, destroying several items of glassware in the process, and
then quite simply, leaving the so called samples, in these resistant bottles on the benchtop and departing without them, arresting me with zero
probable cause, after refusing to show ID and being witnessed admitting they were just there to try and 'see if we can find anything that proves your
doing anything we think you shouldn't' in other words, fishing hoping to justify their used bog roll excuse for a warrant ex post facto.
So, as it happens, I still have the reagent bottles, and they stand up to some pretty damned virulent reagents, especially in the case of powerful
oxidizers and reducing agents and halogenating agents, strong acids and bases as well as any solvent that I've ever spot tested. I presume the filth
must use such vessels in sampling because they don't know what is going to be in any given lab, and it could be anything from table salt to HF
(although I've never tested the vitreous portion with HF, it wouldn't surprise me if they were fused quartz and teflon caps or some other
perfluorinated polymer plastic caps with an inner liner seal that again resists attack by even the most brutal reagents that I've ever thrown at the
bottles. Wouldn't altogether shock me if these things would stand up to piranha acid (not that I'd even try to store that!) or aqua regia (likewise).
Good idea about the hairdrier though if its ICl3 blocking the bore. If its CaCl2 though I won't have a choice but to carefully connect a suckback trap
inline with a container full of hot KOH (aq.) to recycle the Cl2 as chlorate. I've got a hairdrier, that AFAIK, I have never, and now will never, use
to dry hair, its been dedicated to lab use since I first got given it.
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woelen
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Why not open all doors/windows to the room with the setup, then simply release the pressure of chlorine and then quickly leave the room without
breathing while you are in the room? The chlorine quickly disappears and then you can handle the mess more easily.
I have done experiments where hundreds of ml of chlorine were accidently released. I simply left the room with ventilation on, windows open and
returned 10 minutes later. Chlorine can be managed in this way, albeit things can become smelly, like a swimming pool. Vapor of ICl is of similar
toxicity as that of Cl2 so you can handle that as well.
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Praxichys
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My usual Cl2 knockdown solution is to fill a big spray bottle with 5-8% aqueous ammonia. (Surfactant-free "janitorial ammonia" from the hardware
store).
As soon as you open the apparatus, start misting. You'll get a lot of ammonium chloride smoke but It's so hygroscopic that it settles out in a humid
environment rather quickly. You can use a pan of steaming water (I use an electric saucepan) to knock it down and keep humidity in the room up. The
ammonium chloride is much easier on the lungs than straight Cl2. I use this every time I disassemble a chlorine generator.
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tsathoggua1
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Oh, this setup isn't indoors. Wouldn't make ICl indoors for safety reasons just on principle, AFAIK its significantly more toxic than Cl2, at least as
toxic as Br2 IIRC.
Even the garden nearby the area has been partially bleached by fumes from either/both.
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Texium
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Thread Moved
18-5-2017 at 08:46 |
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