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BromicAcid
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Carbon Tetrachloride CCl4
This has always been one of the reagents that I've wanted but been unable to get due to environmental regulations and it seems many other people
want it to, so... time to start a thread! The ways that I knew of to get make it included:
CH4 + 4Cl2 ---> CCl4 + 4HCl
But this one requires somewhat high temperatures, although I am tempted to try it, using sodium acetate plus hydroxide to form the methane and
reacting it with chlorine in a glass tube filled with broken pottery. But it seems like it will be such a hassle for such a tiny bit of CCl4.
So what about the reaction of carbon disulfide with chlorine in the presence of iron I asked myself.
CS2 + 3Cl2 --Fe--> CCl4 + S2Cl2
Then heat that with more carbon disulfide and...
CS2 + 2S2Cl2 ----> CCl4 + 6S
But the hurdle for this reaction is obtaining carbon disulfide. Sure, I can make it but it's a messy process and of course dangerous, so why
would I want to use what little bit of that perfectly good solvent I have to make a tiny amount of a different. Plus this is run at elevated
temperatures, not terribly high but with carbon disulfide and potentially volitle sulfur compounds I get a little worried (well actually I pretend to
get worried to appease my reasonable self).
So I did some research in the library and came up with:
CaCN2 + HCl(g) ---> CaCl2 + CCl4(g) + 2NH3
At elevated temperatures, doesn't look like a bad reaction but where to get the calcium cyanamide?
Also found:
5C + 2CaCl2 ----> CCl4(g) + 2CaC2
Of course seeing something that produces calcium carbide you might be automatically thinking that this reaction takes place in an electric arc
furnace. You would be right, and that is the hurdle that this specific reaction poses.
Finally I come to what might be the most feasible reaction:
CHCl3 + 2ICl ----> CCl4 + HCl + I2
That seems somewhat reasonable if you are willing to trade chloroform for carbon tetrachloride, which I'm willing to do. Also there is the fact
that the haloform reaction also produces amounts of carbon tetrachloride especially if the halogen is used in excess as pointed out by someone on this
board.
So everyone, what reactions sound like they could be most easily turned into a procedure to make carbon tetrachloride that us mad scientists could
use?
I've made my choice on which one I want to try when it gets warmer but I think I'll keep it a secret till some more people comment on
theirs. Also, does anyone have any other reasonable synthesis for CCl4, that might prove to be even more helpful!
[Edited on 1/27/2004 by BromicAcid]
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vulture
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At elevated temperatures, doesn't look like a bad reaction but where to get the calcium cyanamide
Certain fertilizers contain calciumcyanimide. Look for nitrogen rich chalk or something.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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chemoleo
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Good News :)
| Quote: | Originally posted by BromicAcid
So I did some research in the library and came up with:
CaCN2 + HCl(g) ---> CaCl2 + CCl4(g) + 2NH3
At elevated temperatures, doesn't look like a bad reaction but where to get the calcium cyanamide?
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Very interesting. In fact it is not hard to get hold of calcium cyanamide! It is a common component of certain fertilisers, and is, as far as I know,
as high as 70%. It is a black substance - although this maybe related to the remaining 30 %. My book doesn't state colour.
In fact, calcium cyanamide seems an interesting compound for other purposes- hydrolyiss with H2O (dont know what temp) yields free cyanamide
(crystalline, mp 45 deg C) according to CaNCN+H2O +CO2--> CaCO3 + H2NCN. This dimerises at 80dg C to (H2N)2C=NCN, which can be converted to
melamine (triamino cyanuric acid) by heating in NH3. (Maybe this warrants another thread, the uses of cyanamide)
Anyway, BromicAcid, it would be good if you found out what conditions are required for this reaction to occur. As I said, calcium cyanamide is easy to
obtain 
Edit - oops, overlap with vulture.
[Edited on 27-1-2004 by chemoleo]
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Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Alchemist
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Calcium Cyanimide
If ya find exactly where to get calcium cyanimide please let us all know, I have been trying for about a year now. I have tried 3 really good
ag's in my area and have called several others with no luck. I asked for lime-nitrogen and also calcium cyanimide by name. One place over the
phone said it was not used for fertiliser anymore and has been replaced with better nitrogen fertilisers (names not given to me). Another Ag-store
said they could order it so I said OK. A few days latter they called back and said it was no longer avaible. I live in Calif.. Good luck! I really do
hope you find a good source.
[Edited on 27-1-2004 by Alchemist]
[Edited on 27-1-2004 by Alchemist]
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chemoleo
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as far as I remember they are lawn fertilisers. they go as high as 70%. black grains. I once tried to play with it myself - I would be very surprised to hear that they don't exist anywhere in the US if
they exist here in Europe!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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chloric1
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UV rays!
Bromic acid- Dude!, Forget elevated temperatures. Just take your haloform reaction chloroform and bubble chlorine through it. Then you can set it in
ordinary sunlight at 25C! Heck if its the cold temperatues that bother you, put
a tight fitting stopper in the flask and put it in a cozy sunny window sil for about 5 or 6 hours. Maybe it may take a few days of this but I need
to try it myself. But UV rays are all you need to chlorinate at room temp according to my organic chemistry text.
[Edited on 1/28/2004 by chloric1]
Fellow molecular manipulator
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Mumbles
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Winter UV rays are not as strong. It would take much longer than in summer, even if the liquid was warmed to the same temp. It is a nice idea to try
in the warmer months. Just another thing added to my to do list.
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BromicAcid
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Chloric1, yeah, I thought about UV rays. I once used chloroform to extract bromine form a solution, the red color disappeared in short order after it
sat in the sun and the lid bobbed on the top from releasing fumes of CHCl3/CCl3Br/ Br2/HBr from the heat and sunlight. Maybe I'll give that a
try but chloroform has such crummy yields. Also, you wouldn't even need light as I got the feeling that the reaction of chloroform with
iodinemonochloride was somewhat catalytic. The reaction yields iodine which would react with the chlorine and make iodinemonochloride and the
reaction would continue. Both are still better then making carbon disulfide in any quantity.
Hows about this. I wouldn't consider it as being useful but....
CH4 + Cl2 ----> CCl4 + 4HCl
Run the exit gasses through a condesner to get out the chlorinated hydrocarbons and react the remaining HCl with calcium cyanamide:
4CaCN2 + 4HCl(g) ---> 4CaCl2 + 4CCl4(g) + 8NH3
Finally take the calcium chloride byproduct and react with carbon:
10C + 4CaCl2 ----> 2CCl4(g) + 4CaC2
I just thought that it was weird that it worked out that way, the 'waste' products of two of the reactions could be put back into two of the
other reactions.
Tommorow at school I will find the reference for the cyanimide reaction and maybe try and find a source for it too. Wish me luck!
[Edited on 1/28/2004 by BromicAcid]
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Polverone
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Calcium cyanamide is formed by the thermal decomposition of calcium cyanate. Calcium cyanate can be prepared like the alkali metal cyanates (heating
its carbonate or hydroxide with urea). So calcium cyanamide can be formed by strongly heating urea with calcium carbonate or hydroxide.
PGP Key and corresponding e-mail address
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BromicAcid
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| Quote: |
Tommorow at school I will find the reference for the cyanimide reaction and maybe try and find a source for it too. Wish me luck!
~Bromic Acid
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Finally got around to doing that today. Looked up the reaction in the "Encyclopedia of Chemical Reactions" again and this is everything it
says:
| Quote: |
CaCN2 HCl
Hydrogen Chloride is passed over heated calcium cyanamide, yielding the products shown in the equation.
CaCN2 + HCl(g) ---> CaCl2 + CCl4(g) + 2NH3
Montemartini and Losana, Giorn. Chim. ind. applicata, 6, 325
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And that's it, couldn't get the material to look up more, maybe someone else out there? Plus I looked up more on the Cyanimide, looks like
it is still avalible in fertilizers, guess I've got some hunting to do come summer.
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BromicAcid
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"Another reply, that could only mean Bromic's been back at the library again!"
Yes, that's true.... Anyway, turns out that there's a method to make carbon tetrachloride by reacting methanol with a sulfur chloride or
just with chlorine in the presence of sulfur. All I got in the reaction description was that the reaction occurs under pressure... yeah, it was
pretty vague. Well, turns out that some companies that produce CCl4 have switched over to this method so I would expect to be able to find something
on it. I googled and looked around at school but came up empty handed. Anyone have something else to add on this?
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chloric1
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| Quote: | Originally posted by Mumbles
Winter UV rays are not as strong. It would take much longer than in summer, even if the liquid was warmed to the same temp.
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Yeh I see your point. Now it is late March and by April 30th we have the same intensisty sunlight as August 1st here at 39 degrees North!!! So I dont
have long to wait for UV experiements. Plus, I dont ahve the motivation to do shit during the colder months anyhow.
Incidently, I see plenty of 4 watt shortwave(235 nm) UV lamps on ebay. I have one that runs off NiMH and it will make tiny amounts of ozone in a few
minutes! Dont know if this would be enough power but if the flask of chlorinated chloroform was close enough... I dunno maybe. Also a a strong acid mix of HCl and FeCl3 with citirc acid added, should give off CO2
and FeCl2 in sunlight! I wanna do this too!
Fellow molecular manipulator
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Quantum
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| Quote: |
My book doesn't state colour.
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I googled for a MSDS and found one that said the color is white to off white. The fertalizer must have impurities.
MSDS
You need to click on the MSDS link to get the PDF file.
Tetrachloromethane seems like a very interesting chemical but its toxic effects have shattered my rose colored glasses. Anyway I don't even have
CHCl3 so an even more dangerous solvent is out of the question for the time being.
What if, what is isn\'t true?
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BromicAcid
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I've been keeping an eye out for methods of making CCl4 for a while now and I found some interesting methods of manufacture.
One thing that I didn't mention further up was the further chlorination and subsequent splitting of C-C bonds in already chlorinated
hydrocarbons.
I found examples of reacting the highly available Cl2CCCl2 with chlorine at moderate temperature and yielding carbon tet almost quantitatively.
Cl2CCClH which is also quite avilible can do the same. Although it was probably common knowledge to many of you, at the time of working in this
thread I didn't know these two chemicals were so readily avalible (at least in the states) so I didn't consider the possibilities. But
now...
Organikum, any input on working with a chlorinating apparatus that you could put in this thread for completeness?
Other interesting things that I found, hydrolyzing tetrachloroethene in the presence of copper yeilds trichloroacetic acid, phosgene, and carbon
tetrachloride among other products. Similar case with 1,1,2-trichloroethene.
One other thing, reacting tetrachloroethene with nitric oxide produces various nitrated chlorinated carbons, chloropicrin and carbon tetrachloride
among them.
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Mumbles
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Just thought I'd comment on the black color. It is from graphite. The reason it is sold in up to 70% purity is because that is the purity of
industrial production. It is produced by electrolysis of Ca(OH)2/CaO, (maybe Carbon, or they use the carbonate) and Urea(don't hold me to those
chems) with graphite electrodes. There is impurity of Ca(OH)2, CaO, and graphite of course.
Back to the topic at hand. I had read something about the decomposition of Hexachloroethane in some compositions to give carbon tetrachloride.
Perhaps this could be optomised. I believe the reaction with Chlorine will give the tetrachloride at semi-reasonable temps(less that 500C).
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garage chemist
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The calcium cyanamide fertilizer is made by reacting powdered calcium carbide with nitrogen (from the air) at about 1000°C.The process is exothermic.
It is one of the very few processes that uses gaseous nitrogen as a precursor.
The reaction goes as follows:
CaC2 + N2 ---> CaCN2 + C(this causes the black color!)
If you heat a lump of CaC2 in air, you will notice that it goes black. This is because of this reaction!
During war, there was an attempt to use CaCN2 as a source for urgently needed nitrogen compounds (HNO3 for production of explosives). The CaCN2 was
hydrolyzed with water under pressure to give ammonia, which could then be combusted into NO2.
The process was too expensive to be of any use, because of the very energy- consuming production of CaC2.
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Theoretic
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You could use ammonium cyanamide instead of CaCN2, the CaCl2 residue can prevent the reaction happening to the full.
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BromicAcid
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Is ammonium cyanimide significantly easier to acquire. I must confess that I specifically searched for calcium cyanimide so I really don't know
of the occurrence of ammonium cyanimide, but if it is a reasonably easy to acquire chemical I might give it a shot.
Right now I am planning on just chlorinating my hexachloroethane further with chlorine gas and cleaving the C-C bond, so I am going to need some
reaction tube and such. I better get to work.....
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chemoleo
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Right, so why do you think CaCl2 would inhibit the reaction? I don't follow this.
Also - I'd bet that 'ammonium cyanamide' isn't exactly OTC, nor easily prepared - that is if it exists at all (i.e. I could
imagine it'd polymerise or decompose to something else).
Never Stop to Begin, and Never Begin to Stop...
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Theoretic
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Calcium chloride would eventually predominate in the solid residue from hydrochlorination, the remaining reactant will be spread throughout the volume
of waste CaCl2 and will react slowly.
Ammonium cyanamide doesn't produce any relevant Google hits, however when calcium cyanamide is made into a slurry and carbonated with CO2,
cyanamide (hydrogen cyanamide) NH2CN is made along with CaCO3. If you make a slurry of finely powdered calcium cyanamide and add ammonium carbonate,
this will hopefully give you CaCO3 and (NH4)2CN2 solution. Another advantage of ACN is that you'll need less HCl gas, because at high t NH4Cl
decomposes and HCl is freed, this doesn't happen with CaCl2.
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chemoleo
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Theoretic - sorry but I don't quite see the point.
It's natural for any reaction to slow down once reactants are depleted. You are lessening the concentration of CaCN2, and hence lessening the
rate of reaction. Although I agree that mixing of the reactants may be a problem that could be avoided if things were in solution. But this is not the
case here anyway as this is a solid state reaction.
Anyway, more importantly, you say yourself that CO2 liberates cyanamide. Meaning that H2CO3 is a stronger acid. Meaning that H2NCN is an extremely
weak acid, as it is even displaced by CO2.
Therefore I should doubt ammonium cyanamide is stable unless it is thoroughly excluded from air (containing CO2). In addition - H2NCN is quite prone
to polymerisation ( I think I posted that elsewhere) - and H2NCN would certainly exist in a displacement reaction you describe (CaCN2 + (NH4)2CO3
-> CaCO3 + (NH4)2NCN), simply becuase of equilibrium --> therefore, rather than getting ammonium cyanamide, you'd get various
polymerisation products.
Anyway - this is much speculation for both of us - to be honest I think it's much easier just to go with the fertiliser
'Kalkstickstoff' CaCN2 and accept some minor losses, if that.
Converting it to some unstable air-sensitive ammonia form? No thanks!
Regardless - someone has to try before we speculate too much!
Never Stop to Begin, and Never Begin to Stop...
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Theoretic
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"Theoretic - sorry but I don't quite see the point.
It's natural for any reaction to slow down once reactants are depleted. You are lessening the concentration of CaCN2, and hence lessening the
rate of reaction."
That's my point, using ammonium cyanamide would keep the concentration of the solid reactant 100%, as ammonia formed in the reaction would
evaporate off, as would all of the reaction products. The gaseous reactant concentration wouldn't decrease, I think if anyone tries it that would
be the design solution, a current of HCl gas flowing over ACN or CCN solid, ammonia gas being carried away. But anyway, I think you're right
abouit polymerisation and everything, I also now realised that ACN will probably decompose at the temperatures needed for the reaction to happen.
"to be honest I think it's much easier just to go with the fertiliser 'Kalkstickstoff' CaCN2"
Fertilizer? Hmmm... One application where ACN would be suitable is high-N-content nitrogen fertilizer, being universal application as well, since the
ammonia portion would be available to plants instantly, and the cyanamide would release its N content gradually. ACN would have the N content higher
that NH4NO3 or urea, being second only to ammonia itself, this would slash transportation costs. Hydrolysis by air moisture + CO2 could be avoided if
the fertilizer was contained in plastic bags, which is easy. For CCl4, I agree with you, CCN is better.
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HNO3
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BromicAcid:
I wondered if Tetrachloromethane could be produced from the following reaction: CCl3H + NaOCl -> CCl4 + NaOH.
\"In the beginning, God...\" Wait a minute, God doesn\'t exist!!!!!!!!!! \"OK, in the beginning, ummm, hydrogen...\" Wait a minute, what about the
laws of thermodynamics? \"OK, in the beginning, ummm.....UMMMMM, what\'s left to choose from?
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BromicAcid
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| Quote: | The haloforms, when prepared by the haloform reaction, are contaminated to a greater or less degree by the corresponding tetrahalomethanes. This is
due to the action of the hypohalites on the haloforms by which the latter are converted into the corresponding tetrahalogen compounds:
CHX3 + NaOX = CX4 + NaOH.
This is a general reaction (83, 73, 8, 38); it often becomes the principal reaction when dilute solutions are used. Thus, Wallach (198) found that in
the formation of bromoform from hypobromite and acetone in very dilute solutions, the reaction was slow and that carbon tetrabromide was the chief
product. This influence of the pH on the course of reactions involving hypohalites is frequently noticed (105, 119, 79).
(198) WALLACH: Ann. 276, 149 (1893).
(105) KOLTHOFF: Pharm. Weekbald 62, 652 (1925).
(119) VAN DER LEE: Chem. Weekblad 23, 444 (1926).
(79) HATCHER AND MEELLER: Trans. Roy. SOC. Can. [3] 23, Sect. 3, 35 (1929). |
But it's hard to tell how far this reaction goes, the boiling points of CCl4 (Bp 76C) and CHCl3 (Bp 61C) are so similar that it's difficult
to tell them apart by boiling point, and their physical properties are also very similar. Separation would be a pain, in the physical sense, although
you might be able to do something like take your impure CCl4 and add in solid NaOH, probably the reaction would only proceed with the chloroform,
leaving one with the CCl4 to be distilled.
BTW, I think I got that quote from somewhere on this site.
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alchemie
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Maybe CH2Cl2 could also be used.
You can get it OTC, from paint strippers, in much bigger amounts than you could synthesize CHCl3 using the haloform reaction.
On the other hand it would be harder to separate a mixture of the three halometanes by distillation. so maybe it´s better to stick to the chloroform
only.
As to other methods of separation, here´s what the Merck 13th edition says about the water solubility of the three compounds:
CH2Cl2 - "Soluble in ~50 parts water" (wich means roughly 1.3 ml dissolve in 50ml of water))
CHCl3 - "One ml dissolves in about 200 ml water at 25°"
CCl4 - "One ml dissolves in 2000 ml water"
The number speak for themselves.
I Think that you could get away by washing the mixture with water, as long as you have a significant percentage of CCl4 in the mixture, as the any of
the other two are much more soluble in water.
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