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Author: Subject: Problem with Chloroform via Haloform reaction
Octavian
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sad.gif posted on 2-7-2015 at 08:35
Problem with Chloroform via Haloform reaction


I decided to try my hand at synthesizing chloroform using the well known Bleach + Acetone reaction. The strongest bleach I could find at a realistic price in any of the 7 stores I visited was 4% NaOCl (The strongest was 5% but something like $4/Lt) so I grabbed 12Lt of this and after chilling the acetone in the freezer and bleach in an ice bath, I made the addition of 33ml Acetone to each 2Lt bottle of bleach in 3 additions with shaking between each. Two of the 2Lt bottles that i forgot to chill did heat up quite a bit but the other 4 never got above room temp thanks to the ice bath - I may have screwed up the stoichiometry there? It was late and I haven't rechecked it since.

The bottles were left to sit for around 12 hours in the bath before they were decanted and the raw chloroform bottled, Yield was around the 130ml mark, I didn't see the point in measuring it exactly at this point since it wouldn't have been a true indicator of overall yield. The CHCl3 was milky white and cloudy. Unfortunately it had to stay bottled like that for 2 days before the clean up could be done.

The raw CHCl3 was added to a sep funnel and an equal volume of dH2O was added and shook for around 30 secs, followed by another 30sec of swirling before being left to separate for 10-15min while I did other things. The CHCl3 was still very opaque and cloudy so it was drained into an E-Flask, the sep funnel rinsed out and another washing was done - CHCl3 still come out of this cloudy. From my limited past experience (not with chloroform) I've found this to usually be cause by disolved water so this time it was drained into a dry E-Flask with ~1tsp of CaCl2 and periodically stirred for around 30min. It was still cloudy after this with no real noticeable change so I poured the CHCl3 into a 250ml RB flask, added in a fresh 2tsp of CaCl2 and set up for simple distillation using a water bath.

The first drops hit the receiving flask at a head temp of 49C with 2 drops per second, and was kept at 1-2 drops per second all through the distillation. The first 50-60ml come over at a constant head temp of 49C to 49.5C, some time after that the flow slowed a little and the head temp dropped as low as 44C but raised back up only to drop again, this continued to rise and fall from 44C to 51C until I had collected exactly 100ml at which point I ended the distillation. The boiling flask still contained approximately 30-40ml and most of the CaCl2 had dissolved.

Here is what I'm pulling my hair out over. 1) The collected distillate was still white and cloudy, only slightly better than when it went in. 2) The B.P of CHCl3 of course is 61C, I have looked through all the azeotropes for chloroform I can find and none of them have a boiling point matching what I recorded - What am I missing?. 3) If what i have isn't chloroform - what is it? If it is, is it possible to salvage it or should I safely dispose of it and try again from scratch?

Possibly an important note: One of the 2Lt bottles of bleach seemed to have a detergant of some kind in it ever though it wasn't listed and post-rxn there was a white foamy 3rd layer in the middle of the CHCl3 and water which didn't seem to wash out at all and took several hours to separate. Some of this DID make it into the distillation flask due to inattention on my part - could this explain the problems?

I have had a quick search but turned up nothing that could apply to what I have experience here, sorry if I have overlooked something on TFSE or google.
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blogfast25
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[*] posted on 2-7-2015 at 09:26


Bleach is quite alkaline and haloalkanes undergo alkaline hydrolysis (by substitution, forming alcohols).

Leaving 12 hours before work-up may have caused partial hydrolysis of the chloroform, with potentially multiple halo alcohol thingymejibs that might be hard to separate out later.

I'm no expert on this synthesis though...


[Edited on 2-7-2015 by blogfast25]




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crazyboy
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[*] posted on 2-7-2015 at 09:41


I think you used way too much acetone for the amount of NaOCl you had and as a result your product has significant quantities of unreacted acetone. I believe when I did this reaction I used amounts from erowid:

"For every 1g of acetone (1.27mL) you want to oxidize, use 71.2g (61.4mL) of 10.8% NaOCl (142.3g of 5% NaOCl)"

But don't take that as gospel run the math yourself. Anyway using bleach with detergents and fragrances is also highly undesirable as is 5% NaOCl. A big hardware store like Home Depot or Lowes will have 10% NaOCl for pool treatment with nothing else added.
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[*] posted on 2-7-2015 at 11:16


Thanks blogfast, From what i read there is a bit of a balancing act between getting the CHCl3 out ASAP (3 hours) before it can break down and leaving it up to 24 hours to make sure the rxn goes to completion - I do still have VERY much to learn so I could be wrong! Might explain why I'm getting a boiling point that doesn't match up to any non-polar, denser than water solvent or azeotrope that i can find tho, especially since I had to let it sit raw in a bottle for 2 days before being able to wash and distil it.

Crazyboy, I did have a feeling that 33ml of acetone was probably too much, in my late night under caffeinated state some how I managed to add up that 33ml would be just under the required amount freeing me of one azeotrope drama. Giving it a quick look again now...

33ml = 26.1g / 0.45mol Acetone
2Lt 4% = 84g / 1.13mol NaOCl
If what I read was correct, I need 3mol for NaOCl to 1mol Acetone, meaning.... I need coffee.... 21.84g or 27.6ml of Acetone is required for 2Lt of 4% (42g/Lt) bleach.

Here in Australia I've been having no luck finding anything above 5% - and the 5% ones all seem to carry a detergent or other adulterant with them. The 4% doesn't seem to have a detergent (aside from that one bottle - different brand) but costs me around $1/Lt so it's not too cost effective, even if it did work, since 0.8g CHCl3 dissolves in every 100ml water. Considering trying this again without letting it sit for so long to see if I'm successful, then trying to make a more useable amount from Calcium hypochlorite which I can buy as a pool treatment.
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[*] posted on 2-7-2015 at 12:00


I tried this with a 5L bottle of 5% bleach and followed a procedure from yootoob which used ~58ml of acetone.

The process was to remove around 100ml bleach from the 5L bottle, then stick it in the freezer overnight.

Then add in the acetone, cap n shake well, remove cap (enough to release pressure) then i stuck it in my swimming pool overnight.

Apparently it is an exothermic reaction, and higher temperatures lead to loss of product, so it needs to be kept as cool as possible. The words 'extremely exothermic' are used, but it isn't.

In the morning i decanted off most of the bottle contents and put the last 200ml in a 250ml sep funnel and the chloroform separated out nicely.

When distilled it came over at 60 ~ 63 C.

It seems that the reaction products react with each other, albeit slowly, so if you do not separate the product soon enough, then there is no desired product.

Perhaps it was this video : https://www.youtube.com/watch?v=j-PrAczOGb0 although it doesn't look entirely familiar.

Perhaps it's been updated, or maybe i got the wrong video.

If you succeed, do not forget to add 1w% anhydrous ethanol to your product - that appears to prevent Death if you store your chloroform for any length of time.




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[*] posted on 2-7-2015 at 12:56


Quote: Originally posted by Octavian  
The first drops hit the receiving flask at a head temp of 49C with 2 drops per second, and was kept at 1-2 drops per second all through the distillation. The first 50-60ml come over at a constant head temp of 49C to 49.5C, some time after that the flow slowed a little and the head temp dropped as low as 44C but raised back up only to drop again, this continued to rise and fall from 44C to 51C until I had collected exactly 100ml at which point I ended the distillation. The boiling flask still contained approximately 30-40ml and most of the CaCl2 had dissolved.


Were you using a heating mantle or another source? Sounds like you either were not bringing enough material up the column to 'bathe' your head thermometer in vapor, were you distilling using a heat source that was cycling, or perhaps you just had your head thermometer misplaced. Or, maybe what you had left was high-boiling and you were just having trouble milking the last bit out of that material due to reduction of the overall vapor pressure. Did you get pot temperatures? Did you have stirring in your pot? Lots of things can lead to inconsistent head temperatures. Remember also that carbon tet is an impurity though if you can get a revised procedure to favor carbon tet vs chloroform in this reaction I think you would have a lot of devotees.

But really this could just be splitting hairs, your temperature was hanging out at ca. 50C at the start of your distillation, according to the CRC the boiling point of a chloroform/water azeotrope is 53.3C which would be spot on given the calibration standards of most home chemistry equipment. Even though you had drying salts in there they may have been exhausted since you only need a few % water to make the azeotrope. That being the case it does not bode well that your calcium chloride 'dissolved'. You should have likely filtered it out of your pot, and the fact that it was still hazy would make me think you still had water in there anyway. Besides, the higher hydrates are not stable under heating, they give off water, even at these low temps.

[Edited on 7/2/2015 by BromicAcid]

[Edited on 7/2/2015 by BromicAcid]




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[*] posted on 2-7-2015 at 13:33


Confused.

"added in a fresh 2tsp of CaCl2 and set up for simple distillation"

"the boiling point of a chloroform/water azeotrope is 53.3C"

So even treating with CaCl2 then distilling with CaCl2 we're still looking at an azeotrope with water ?

Anhydrous CaCl2 absorbs no water !

Why oh why do i use the stuff? Useless !

[Edited on 2-7-2015 by aga]




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BromicAcid
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[*] posted on 2-7-2015 at 14:49


My thought would be that there are multiple hydrates of CaCl<sub>2</sub>, someone correct me if I am wrong but usually a distillation is not done over CaCl<sub>2</sub>. I have seen distillations over Na, LiH, CaH<sub>2</sub>, etc, but not CaCl<sub>2</sub>. The most hydrated forms of CaCl<sub>2</sub> give up their water of hydration easily on heating. My thought would be since there was only liquid left in the pot when the distillation was complete that the CaCl<sub>2</sub> had dissolved in its own water of hydration. In which case it was likely saturated with water in the first place, again with the mention of initial haziness the first thing I thought was that it was not dried completely.

Did you use powder or prilled CaCl<sub>2</sub>? It's hard to tell a complete drying with prilled anything, with powder you watch to see if it clumps up. You keep adding till it is free-flowing (never tried this with CaCl<sub>2</sub>;) which sometimes takes much more than expected. What type of CaCl<sub>2</sub> did you use, OTC? Do you have any idea how dry it was?

Aga, I did not mean to insinuate that CaCl<sub>2</sub> doesn't absorb any water. Just that it is not the best desiccant in the chemist's tool box since it can give up the water easily and does not bind it that strongly. Especially if it is left in the flask during the distillation. But all of this is just conjecture based on Octavian's opening post. Chucking powdered CaCl<sub>2</sub> into a flask with chloroform with water contamination until it is free-flowing and then filtering to remove your drying agent does seem like a reasonable way to dry the chloroform, but as usual the devil is in the details and there are a number of ways it could go wrong based on your technique or reagents no matter how simple it sounds on paper.

Edit: As much as I dislike using Wiki as a source, this is relevant
Quote:
MP 30 °C (86 °F; 303 K)
hexahydrate, decompose


So as low as 30C your hexahydrate is going to start losing water of hydration. At that point is is already dissolved in its own water of hydration as well which might explain the amount of distillate left in the pot as well as the fact that the drying agent that was supposed to be there had 'dissolved;

[Edited on 7/2/2015 by BromicAcid]




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[*] posted on 3-7-2015 at 20:41


Thank you for all the help. To answer some of the questions:

I was using a water bath on a hot plate for heating with no stirring and nothing to measure pot temperature. I didn't consider that my thermometer would be that far (4C) out but now I'm actually keen to try testing it. I skimmed thought Vogels last night and found that he recommends drying chloroform over CaCl2 for at least 24 hours prior to distillation. I was surprised at how milky white my chloroform was right from when it was decanted from the original bottles, from examples I have seen on youtube it seems it's usually quite clear from the start, I am still strongly suspecting that the one bottle that also contained some kind of detergent is the source of at least some of my problems.

I can't remember where I read to distill the CHCl3 over CaCl2, so sorry that I can't reference that. The CaCl2 I used was just standard OTC "DampRid" and not powdered. Also I had no idea that CaCl2 would give up it's water so easily when heated! I'm thinking of taking the 100ml that I recovered and trying to dry it for at least 24 hours over CaCl2 and seeing what effect it has on it's appearance, unless I'm mistaken the CaCl2 will also take out the 1-2% EtOH I added also, yes?

Again, thanks for all the help. Even if I end up failing this synth I've definitely not failed to learn something! :D
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[*] posted on 4-7-2015 at 23:10


Hi, Octavian!

I've been using 27.5ml of acetone for 2l of 5% bleach (I believe this is around 1.424 moles of NaClO, so you use three times less acetone). I've always got only around 50% or little higher yield, which in this case (theoretically) should be 38ml of CHCl3 (someone please, correct me if I'm wrong) so, usually I get about 20ml or little more, though I don't know what is practical yield percentage limit for this reaction (it'd be helpful if someone knows). I know that some of it is lost due to exothermic reaction, but not much if it's well cooled. My chloroform is sometimes cloudy too, but not always (I think it has something to do with too much of acetone being used, although I'm not sure). And also as others have said, don't leave it in reaction mixture so long (I usually let it sit for only one or two hours or so, but last time I did it I think it was only 1/2h - maybe it might be even better to leave it in there for even shorter amount of time). I'd definitely recommend you to stir it really well while adding acetone (so that reaction is more efficient), also add acetone really slowly (don't let the mixture heat up above 30°C/86F/303.15K). If you do all of that, the chloroform should sink to the bottom really quickly, so you can remove it before the reaction proceeds and destroys your chloroform.

Hope this helps :)

BR, xfusion




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[*] posted on 1-8-2015 at 07:45


There are two posts here on the forum where I tried to do the Haloform with IPA and a real mix of odds and ends, I think the soap you got wasnt in the bleach. If you read my posts (they are boring) on the reaction I got I also got a detergent like substance, I have made a fair bit of this stuff for cleaning and have never seen anything that cleans half as well! Using IPA I have never had the reaction go more than 7c over ambient.
LG
Actually your post has made me want to retry this reaction minus the sodium hydroxide I added




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[*] posted on 1-8-2015 at 12:00


Quote: Originally posted by xfusion44  
My chloroform is sometimes cloudy too, but not always (I think it has something to do with too much of acetone being used, although I'm not sure)

Do some Science !

Keep notes, and work out what makes it cloudy.

This is what Science is for ...




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[*] posted on 14-9-2015 at 01:23


I thought I would update this thread with my latest progress :) .

I checked on the 100ml bottle of CHCl3 that I had previously collected a couple of days ago and to my horror it was only half full, even with PTFE thread tape over the mouth of the bottle and the threads the shitty cap must have still allowed it to slowly evaporate, thankfully I tend to plan for the worst and this is exactly why it was stored outside of the house where the only drama was losing half of it. So I dumped what was left into another batch which was made the same way (but with correct stoichiometry this time allowing for a slight excess of NaOCl), however three of the four bottles (IIRC) contained a detergent and left it a hideous milky white colour that would eventually form a layer on top of the CHCl3 if left for a good week or more but would instantly cloud up at the slightest movement. This second batch had been sitting under water w/ some EtOH for a good 3-4 weeks waiting for me to get around to cleaning it, anyway...

Most of the water from the second batch was decanted off along with some of the detergent, it was then poured into a sep funnel and the remaining 50ml or so from the original run was poured in with it, a roughly equal volume of water was added and the funnel shook well for about 45 seconds and then was left an hour to settle (I was doing other things and it took an hour to come back to it), The slightly clearer but still milky bottom layer was drained into a 250ml RB flask containing about 1tsp of CaCl2 and was stoppered. This was swirled around every 10-15 minutes over the next 2-3 hours and then left for another 3 hours, worth noting is that it cleared a little in the first half hour but then returned to it's original colour shortly after.

The chloroform was decanted off of the CaCl2 and filtered using a coffee filter and gravity filtration, in no time the detergent gummed up the filter paper and it took forever to get it filtered. The filtrate was still quite cloudy but not as much as before. The next day the CHCl3 was poured into a 150ml RB flask setup for standard distillation using a water bath and a few boiling chips, this time I used a different thermometer - a mercury one which seems much more accurate, the first drops come over around 50C and around 5ml or so was collected before the head temp settled on 60C and the receiver was swapped, almost everything else come over at 60C - 61C until there was around 10ml of foamy crap left in the boiling flask and the head temperature began to drop back into the 50's. This left me with exactly 70ml of crystal clear highly refractive chloroform, I then added 1ml of 95% denatured EtOH to stabilize it and to my horror it turned cloudy - I'm assuming that would be due to the few percent H2O in the EtOH :( . Aside from aesthetics I'm thinking I can chalk this up as somewhat of a success.

tl:dr: Beware of bleach containing detergents, they're not listed on the label but you can easily tell by shaking the bottle and opening the cap, if it has foamy bubbles, find another brand because it's a pain in the butt to clean.
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[*] posted on 14-9-2015 at 06:21


Cloudyness is because of water suspended in the CHCl3.I dry it with simply adding NaCl.I decanted and then filtered.
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