| Pages:
1
2 |
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
Thunder in a test tube
Today i had decided to make some chloral hydrate, however i admit i hadnt realy read up on it alot, i simply saw a wikipedia article on how it is the
same as a haloform reaction but it uses acidic conditions instead of basic ones.
My apparatus went a bit like this:
I had one 250ml conical flask for producing chlorine via the NaOCl + HCl reaction. From this flask a delivery tube lead to large test tube of
methlated spirit to which i had added some dil. hydrochloric acid. I had used crap grade, purpe meths becase i thought i was going to distill it
anyway to get tid of any chlorinated methanol impurities so whats the point of purifiing it before.
As i started bubbling chlorine through at a steady rate it started to heat up as expected. Almost immedietly after chlorine had bean bubbling through
the dye had been bleached and a yellow solotion of chlorine in ethanol was being fomed.
I kept this going for about 3 mins and continuesly nothing happened till oncei put another small load of sodium hypochlorite in the flask to top up
the chlorine levels and immedietly where the chlorine was comming out there were small flashes, these flashes reminded me of the reaction between
sulphuric acid/potassium permanganate and ethanol: http://uk.youtube.com/watch?v=ZCrPKtAyhFY
I thought that these flashes would ignite the ethanol but it didnt. i let them keep going for a while (becuase it was awsome to watch ) but after a while i stopped.
What was left in the flask was a colourless liquid with small patches of black powder (presumably carbon) floating in it and stuck around the sides of
the tube.
Does anybody know what happened here?
I presumed it was just overheating causing the ethanol to ignite (because it wasnt in an icebath) but then i ruled that out becuase why didnt the
flash spread and ignite the ethanol?
Any information would be appreciated,
Picric-A
|
|
|
kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
Wow! this is very bizarre! I can't even think of a reaction that would cause that! Especially because other people have done this and haven't
mentioned this, at least I haven't seen anyone mentioning it.
Thank you for posting about it! So, what did it sound like? Was sunlight hitting the test tube? Any other possible information that was left out?
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
it sounded exactly like the Mn2O7/C2H5OH reaction, quite loud pops and flashes.
Yes i did have sunlight hitting it, it was quite bright because it had a bublb right next to it becuase i tought that would speed the reaction a
little bit (forming free radicals and all...)
the chlorine was bubbled through at a rate of about 2 or 3 bubbles a second (quite fast).
Do you think the methanol or dye had anything to do with it? i doubt it but it shouldnt be ruled out...
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
HClO and ethanol gives ethyl hypochlorite. This was then initiated by chlorine alone, or sunlight.
[Edited on 31-7-2008 by Schockwave]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
if it formed ethyl hypochlorite, why doesnt it do that with other peoples synthesis of chloral hydrate?
reading that page... do you think i could of formed methyl hypochlorite somehow... and as small amounts of it formed it exploded?
|
|
|
kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
Well, to make chloral hydrate I don't think you are supposed to have any water, There has been talk about this somewhere on the forum I believe. I'd
have to search to be absolutly sure however.
After re-reading your first post, it seems you used methanol.
Methanol cannot turned into chloral hydrate I'm pretty sure! (Methanol = CH3OH vs Ethanol = CH3CH2OH)
Chloral is also known as trichloroacetaldehyde.
There has been talk about doing this on the forum I believe. I'd have to search to be absolutely sure but I believe the synthesis of chloral hydrate
has given many people problems. I haven't read of anyone succeeding - but then again, I haven't read to much about this!
If i were to try it with what i know at this moment, I would try to use absolute ethanol and dry chlorine gas, that is probably the way to go about
making it. - but of course, I wouldn't try to make it now, I would research it more.
If you ever make it, you might also be interested in turning it into Alpha-Chloralose by reacting it with glucose. http://en.wikipedia.org/wiki/Chloralose
I want to point out that this is a great example of why to make sure you know what you are doing. Mixing chlorine, methanol and water doesn't really
sound to bad, seems unlikely that anything to dangerous would form, but it ends up producing a very unstable explosive. Imagine if you say, didn't
have sunlight hitting it, or something like a higher or lower pH, more or less water, etc?This could perhaps have lead to more forming, and caused
some serious injury, or at least a broken test tube!
.. speaking of of the ethanol, H2SO4, KMnO4 reaction, that sounds scary! What if it were mixed better? :S
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
Picric-A wasnt using methanol, he (assuming you're a guy picric  ) was using
methylated spirits. This is a form of denatured ethanol, where the denaturant is methanol (usually <10%) and pyridine (in a small amount, 1% ish
IIRC). Water may or may not be present, it is at the manufacturers discretion. The purple dye is methylene violet (again IIRC, I did post the
composition of UK "meths" somewhere on SMDB previously). So some chloral should have formed, as ethanol was present as a fair proportion (about 85-95%
of the "meths" I should think). Like you say kclo4, any water present may prevent chloral synthesis, and schockwave is probably correct in assuming
the production of ethyl hypochlorite as the water present would react with the chlorine gas, disproportionating to HCl and HClO, the latter forming
the hypochlorite ester.
[Edited on 1-8-2008 by DJF90]
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
| Quote: | Originally posted by Picric-A
if it formed ethyl hypochlorite, why doesnt it do that with other peoples synthesis of chloral hydrate?
reading that page... do you think i could of formed methyl hypochlorite somehow... and as small amounts of it formed it exploded?
|
Methyl hypochlorite too of course since it was methylated spirits. Like mentioned above, choral hydrate uses anhydrous ethanol, so there is a
difference in water content of the reagents.
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
The methlated spirits i was using is lab grade so it states the ingredients:
Ethanol 96%
Methanol 3%
methyl violet 1%
i doubt a extremly dangerous amount of methyl hypochlorite formed in that reaction?
DJF90 -yep im a guy
If your supposed to do this in anhydrous conditions how are you supposed to acidify it?
do you have to bubble anydrous HCl through the ethanol to dissolve it?
thanks,
Picric-A
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
1% methyl violet??? I thought the standard was 1g in 1000 liters?
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
thats what my bottle says... maybe wrong it is the 'Baker' brand
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
| Quote: | Originally posted by Picric-A
The methlated spirits i was using is lab grade so it states the ingredients:
Ethanol 96%
Methanol 3%
methyl violet 1%
i doubt a extremly dangerous amount of methyl hypochlorite formed in that reaction? |
If it's only 3%, then duh! 
| Quote: | If your supposed to do this in anhydrous conditions how are you supposed to acidify it?
do you have to bubble anydrous HCl through the ethanol to dissolve it? |
There is a procedure for chloral hydrate at LamdbdaSyn. After hours long chlorination, the reacted mixture is acidified with conc. H2SO4, then treated further.
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
Something also possible is that some NaOClO2 formed in aged NaOCl and by addition of HCl made some ClO2 free (from HOClO2)...this can cause explosive
troubles...especially with organics...
I once had a big flash explosion with toluene after a reacting delay of a few 30 minutes in contact with ClO2/Cl2; but toluene is immiscible with
HClO3 while methanol and ethanol are...
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
Ketone
Harmless
Posts: 17
Registered: 24-8-2008
Member Is Offline
Mood: Dipolar
|
|
My guess is Chlorine dioxide too but "produced" in a bit of a different way than suggested before..
I'd say that since you don't seem to have any ice bath or any other kind of cooling for your solution and mentioned a temperature rise..
Shouldn't the product be NaClO3 instead of NaOCl?
As 6NaOH + 3Cl2 -> NaClO3 + 5NaCl + 3H2O should be the reaction if the temperature is above 60 (If I remember the temp right..)
And with that Hydrochloric acid..
NaClO3 + HCl -> NaCl + HClO3
You should get Chloric acid which is quite unstable, specially if you heat it. And it's decomposition, in turn, can form Chlorine dioxide..
First post. Yay.
[Edited on 25-8-2008 by Ketone]
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
Where are you getting NaOH from? Picric-A never mentioned using it.
Cl2 will react with NaOH, Na2CO3, etc. solutions even at room temperature to form NaClO3, NaCl.
NaClO3 would occur if the hypochlorite had been decomposed like by heat, or sitting for a long time, with NaClO2 occurring as an intermediate by
decomposition of aqueous NaClO.
|
|
|
Ketone
Harmless
Posts: 17
Registered: 24-8-2008
Member Is Offline
Mood: Dipolar
|
|
| Quote: | Originally posted by Schockwave
Where are you getting NaOH from? Picric-A never mentioned using it. |
Shit.. you're right. I got the reaction in this thread mixed up with the one in the ethyl hypochlorite thread.. somehow combined (parts of them
atleast) in my head.
The link there probably didn't help.
Great way to introduce myself on the forum though, with a stupid mistake.. :/
[Edited on 25-8-2008 by Ketone]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
yea i never used Soidum hdyroxide.
Simply chlorine, made by 15% Sodium hypochlorite (no additives, pool grade and i bought it the day before) and soidum bisulphate (also pool rade but
this was about 9 months old ).
Maybe chlorine dioxide... I dont see how it could be made though...
I will probably try this some time:
1. Put 10ml of the methylated spirit in a boiling tube along with 1 ml 30% HCl.
2. in a second boiling tube add 5grams of sodium chlorate and 1 gram of soidum carbonate.
3. Slightly heat the MeOH/EtOH/HCl mix to get it to around 30-35 degrees.
4. Add conc sulphuric acid to the NaCO3/NaClO3 mix
5. Bubble the resulting gasses through the Boiling tube containing the MeOH/EtOH/HCl mix
Finally observe the results.
Before i start i have a few questions:
Are the quantities i have used sufficiantly small?
Will carbon dioxide present make the test and 'unfair' test?
Thanks,
Picric-A
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
Ease up on chlorine dioxide. It's highly explosive on its own in high concentrations, e.g. liquid ClO2 explodes from the most insignificant mechanical
influences, like just by dripping one drop from a height of 20 cm into a glass. ClO2 explodes on contact with rubber and cork, liquid ClO2 explodes
violently on contact with those.
In order to avoid an explosion when working with ClO2 it can only come into contact with glass, so if you were using rubber and cork stoppers I also
doubt any significant amount of ClO2 was generated. Any preparation of ClO2 also has to be carried out in the dark, because even diffused daylight can
cause an explosion. Some preparation procedures (Gmelin Cl [Syst. No. 6] p. 236) also include very pure oxalic acid with the chlorate, in order to
form a mixture with CO2. This dilution is used in the bleaching industry to lessen the explosiveness of ClO2.
I can't speak for Louis, but I'm thinking his suggestion was that if the hypochlorite was several years old. So if it's fairly new and still has a
good amount of odor to it, then it's not likley this happened, and that organic hypochlorites are responsible for the reactions.
Note also that since ClO2 itself is explosive, there is a possibility of a reaction with an organic travelling back to ClO2 and exploding that.
[Edited on 26-8-2008 by Schockwave]
|
|
|
woelen
Super Administrator
Posts: 7978
Registered: 20-8-2005
Location: Netherlands
Member Is Online
Mood: interested
|
|
I have done quite a few experiments with ClO2 and it is not as sensitive as Shockwave describes. I had one accidental explosion, unintended, but it is
not true that the slightest contact with rubber makes it explode. It CAN make it explode and that is the dangerous thing. You feel comfortable if
thing go well for 10 times or so, but every next time the little devil may pop out of the tube/flask/bottle.
The ClO2 is an interesting gas on its own though:
http://woelen.homescience.net/science/chem/exps/ClO2_propert...
EDIT by woelen: Changed link, so that it works again.
[Edited on 12-6-12 by woelen]
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
| Quote: | Originally posted by woelen
I have done quite a few experiments with ClO2 and it is not as sensitive as Shockwave describes. I had one accidental explosion, unintended, but it is
not true that the slightest contact with rubber makes it explode. It CAN make it explode and that is the dangerous thing. You feel comfortable if
thing go well for 10 times or so, but every next time the little devil may pop out of the tube/flask/bottle.
The ClO2 is an interesting gas on its own though:
http://woelen.homescience.net/science/chem/exps/ClO2_propert... |
These weren't really my warnings but those of the literature from Gmelin. They are talking about its pure or highly concentrated form, the more
diluted it becomes like with air, the less explosive. For disinfecting or bleaching purposes, it is in a diluted form. The lower explosive limit of
ClO2 is 10% according to this MSDS information, so below that point it isn't explosive. I've also made some ClO2 in a glass retort, done behind a shield in a moderatley dark
area. At the time I didn't know anything really of its hazards or nature.
EDIT(woelen): Modified link, such that it works again.
[Edited on 8-7-13 by woelen]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
Ok this morning i carried out the following experiments to see the nature of chlorine dioxide on its own before i start bubbling it into meths/Acid,
Explsoive properties:
1. filled a test tube with ClO2 and lit:
Observation- nothing more than a pop and all the dark yellow ClO2 dissapeared (actually quite a nice demo, i would enjoy doing this on a larger scale
to see all the dark yellow gas dissappear  )
2. filled a test tube with ClO2 and lightly bunged it with a rubber bung:
Observations- The tube got considerably darker until a slighly louder pop sent the bung flying about 2 cm above the test tube (hardly powerfull.. :O)
I did all this in semi-dark conditions (not near sunlight but with a light bulb on) and for each different time i used exactly the same wheights of
ingredients to prepare the ClO2, 5g NaClO3, 23 ml conc sulphuric acid.
My verdict is it is much less powerfull and sensitive as people think however i am not in a hurry to try and force the gas through a delivery tube
Picric-A
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
Note that acids and alkali chlorates in solution or not, do not yield pure ClO2, it is mixed with Cl2. With conc. H2SO4 and chlorates if the conc of
HClO3 goes past a certain point, one gets O2, Cl2, ClO2 and HClO4.
Pure ways involve alkali chlorites, or also can be obtained pure by condensing it from reactions to the liquid in a clean vessel, but that's the real
dangerous stuff and there are such preparation details in Gmelin. Quite a few other usually organic materials besides rubber or cork are known to bang
with ClO2 are fats, and occasionally paraffin.
Toxicity of ClO2 in animals: pulmonary oedema occurs in rats at 16-46 ppm also being dose-dependent, no mortality was at 16 ppm for 4 hr. Mean LC50:
32 ppm. In other results, 260 ppm for 2hr caused pulmonary oedema, death, etc. Not stuff to be inhaling either. Toxcitiy data source from INCHEM.
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
hhmmm perchloric acid... interesting lol
otherwise yes i know i wont get pure ClO2 however the only impurity that may muck up the experiment is the perchloric but i doubt this reacts
immedietly with the meths
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
| Quote: | Originally posted by Picric-A
hhmmm perchloric acid... interesting lol
otherwise yes i know i wont get pure ClO2 however the only impurity that may muck up the experiment is the perchloric but i doubt this reacts
immedietly with the meths |
The acid will be in the mixture as a liquid, not in the gases. But a suckback into this mixture could easily cause a very violent interaction,
azeotropic acid will not show a reaction with those in small amounts, but highly concd. or anhydrous acid definetly will. I've also done some
experiments with the chlorate and sulfuric acid in one of my threads, and the interaction is very violent.
| Quote: | | Originally posted by Picric-A .... Observations- The tube got considerably darker until a slighly louder pop sent the bung flying about 2 cm
above the test tube (hardly powerfull.. :O) .... |
Liquid ClO2 has about 33% power of TNT (Chem. Eng. News 80(49):4-5), still with an unintended explosion potentially devastating, it is not very
brisant. With ClO2 in the form of a gas, diluted with Cl2 and air, it is much less of a risk in those small amounts.
[Edited on 29-8-2008 by Schockwave]
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
ok i did the experiment where i bubbled dil. ClO2 thorugh methylated spirit and i didnt get the same flashes as when i bubbled 'chlorine' through
acidified methylated spirit.... im very confused now...
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
