Sciencemadness Discussion Board - Some Haloform questions

Some Haloform questions

NEMO-Chemistry - 14-7-2016 at 12:43

After reading a thread on here and having run out of Acetone, i decided to give IPA and bleach a go.

It does seems to work, despite the thread being pretty vague it did make Chloroform.

If you add an excess of IPA you get a somewhat strange solvent appear as a distinct upper layer, i was unable to get this to make more chloroform by adding extra bleach after the main reaction.

But the process has got me thinking, one of the things i liked about using IPA was lack of much heat increase from the reaction.

Even in summer no cooling of bleach was required, the bleach and IPA were approx 17C when added and rose to ~27C.

What interest me is the following.

If i used a container with a bottom tap, that allowed removal of chloroform as it was made. Could i add chlorine from a chlorine generator to the container and then more IPA?

It would drastically cut down on the volume of liquid you end up with when trying to make 1-2 Ltr of chloroform.

When i use Chloroform for extractions my main soxhlet is around 250ml, i dont like using too little solvent and subjecting the extracted material to alot of heat, i prefer to start with ~500ml of Chloroform in a flask, that way i know i have plenty of solvent in the main flask while extracting.

Any thoughts on if adding more chlorine as the solution of bleach gets depleted would work?

I would probably have to add some cooling doing it this way. I dont want to just try it as i would probably do a test run around 2ltr of bleach to start with.

Just wondered if anyone had any thoughts on it.

NEMO-Chemistry - 15-7-2016 at 04:24

I tried some of this out on a small scale. Normal chemistry is a struggle for me let alone organic chemistry! So forgive me if i have gone rushing up the wrong tree.

According to the original post extra sodium Hydroxide and sodium Chloride (no amounts given) were added to bleach, then IPA added.

I dont have much 99% IPA so couldnt do that many experiments, but this is what i got so far.

Apparently once the chloroform was formed more bleach was added and more IPA, some of the chloroform dissapered and a distinct upper layer of sweet smelling solvent formed.

I think the extra Sodium Hydroxide is probably a red herring, unless it reacts with something?? I know it makes the solution more alkali but i got similar results without adding the Hydroxide.

So on a smaller scale (500ml flask), if you add 10-12% strengh bleach and an excess of IPA (around 3-5% extra), you do get chloroform.

Adding sodium chloride to saturation (salt seen on the flask bottom) gives a upper layer, at this point it looks and smells like IPA. According to wiki IPA can be salted out from water and this makes sense to see an upper layer, what i didnt get was why you would get a different solvent smelling layer and loss of chloroform if you add more bleach.

So leaving the chloroform in the flask after the completion of the reaction you get, chloroform on the bottom and a layer of hydrodixe and salt water (i presume), then the upper layer of IPA (at this point).

Adding more bleach stirs things up and you get a small amount of chloroform made, if you also add more IPA then again the mixture is mixed up and the upper layer starts to smell differently and the chloroform decreases.

Looking at wiki Chloroform and IPA are miscible, so i think what you see is a mixing of the chloroform and IPA and this sits on top of the salt layer at the top.

I dont think the upper changes to anything just a mix of IPA and Chloroform. Had the OP of the other post distilled the upper layer I think they would have recovered both IPA and Chloroform, i am not sure if they form an Azeotrope as i am still waiting for a torrent download of some tables

(crc hand book).

So what has this got to do with my original question?

Well i think if you take the chloroform out of the flask as its formed and add more chlorine, then as long as i dont have too much excess IPA it should keep making chloroform, at least for a while. But the whole point is to try and reduce the amount of waste liquid and large volumes of liquid produced when you want a couple of litres of chloroform.

Sorry i dont have any equations but i am just learning by experimentation at the moment. I have around 3/4 ltr IPA left so i will try this out some more later and post amounts used etc. But i can confirm the rise in temperature during the reaction is only around 10-12c starting from a room temp of around 14C (cold shaded Garage).

The reaction seems to take around 25 minuets to an hour 1/2 to complete using IPA. I havnt tried adding extra Hydroxide, i think this would just add problems..

Anyway more details later now i have a rough idea of what to do. I might try and titrate the bleach first, but when i switch to Chlorine i am not sure how to quantify the amount added.

myristicinaldehyde - 15-7-2016 at 05:40

I believe the purpose of the hydroxide is to prevent the formation of chloroacetone, an extremely nasty tear gas. However, hydroxide does hydrolyze chloroform.

I tried the IPA oxidation, and all I got was acetone- my bleach is too weak to oxidize and chlorinate.

It should be possible to make very concentrated bleach by bubbling cl2 through hydroxide (never tried this) or by trichlorocyanuric acid or dichlorocyanurate (I tried this, but I couldn't get it to work well)

I would NOT recommend direct chlorination! This will produce chloroacetone, as an intermediate in the halo form from IPA is acetone! I have no idea about chlorinating chloroform.

Try butanone. It undergoes the halo form reaction well (I tried this- dribble in the ketone into 150mL 5% bleach yielded 5-8mL chloroform. It was a very crude setup.) and as a bonus, you get propionic acid!

NEMO-Chemistry - 15-7-2016 at 06:31

Quote: Originally posted by myristicinaldehyde

I believe the purpose of the hydroxide is to prevent the formation of chloroacetone, an extremely nasty tear gas. However, hydroxide does hydrolyze chloroform.

I tried the IPA oxidation, and all I got was acetone- my bleach is too weak to oxidize and chlorinate.

It should be possible to make very concentrated bleach by bubbling cl2 through hydroxide (never tried this) or by trichlorocyanuric acid or dichlorocyanurate (I tried this, but I couldn't get it to work well)

I would NOT recommend direct chlorination! This will produce chloroacetone, as an intermediate in the halo form from IPA is acetone! I have no idea about chlorinating chloroform.

Try butanone. It undergoes the halo form reaction well (I tried this- dribble in the ketone into 150mL 5% bleach yielded 5-8mL chloroform. It was a very crude setup.) and as a bonus, you get propionic acid!

Thats really interesting.

I was following the post from little ghost Again posted ages ago, what intrigued me was the description of a upper layer of sweet smelling solvent.

I can get the same results using bleach i believe is somewhere between 10 and 12% chlorine content (says 12% on bottle but is slightly old).

Its not acetone smell which i know well, and its not like chlotoform. But i think its a mix of IPA with chloroform together. If it dosnt form an azeotrope (or maybe even if it does) i can distill and take a temperature reading.

I cant get access easily to the strong pool chemicals, and bleach around 18% and higher dosnt seem to work with IPA.

I will do some more tests but take better measurements this time.
I might try making the bleach and weighing it for concentration or maybe a sg reading as well.

I dont want to titrate each batch at the moment. I am just looking for a way to make chloroform and reduce the amount of liquid involved.

IPA certainly involves alot less heat in the reaction, i was wondering if a slow addition of chlorine into the solution as chloroform is taken out, would result in more bleach being made? then add more IPA?

I am going to take it slow as i dont have a fume cupboard so will have to use precautions and wash bottle etc.

No idea about organic chemistry but the haloform reaction is really interesting, i have made loads of chloroform in the past. I use it alot for extractions as i cant get hexane.

But normally i use acetone, now my supply of acetone has dried up. I might try making acetone from IPA

One the main problems we have is the local courier company, even DHL use them as subcontractors as we are not on a main route, the local delivery guys wont carry chemicals.

Royal mail will deliver but using them cost a fortune, you end up paying more for postage than the chemical!

NEMO-Chemistry - 15-7-2016 at 06:35

I will also add some Hydroxide (not sure how much yet), i will start with a 1-2 M solution and take it from there, maybe 1-2% by volume.
I am taking detailed notes, but mostly posting the main points rather than the full details. I will post full details once i get something working.

Garage out of action for a couple of hours, the chlorine ate through the plastic tubing and leaked a little chlorine into the garage.

Not alot and the garage venting at the moment. Sure seems to eat through plastic tubing quickly