madscientist
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Organic chlorinations
Has anyone successfully carried out an organic chlorination? I recently attempted to chlorinate acetic acid with chlorine gas in the presence of
ultraviolet light and a tiny amount of sulfur - after 15 minutes of exposure to chlorine gas, there was no noticeble change in mass.
Chlorinations with SCl2 or S2Cl2 probably will work much better, but will be more dangerous for me to carry out (my gas mask doesn't scrub sulfur
chlorides or hydrogen sulfide).
I weep at the sight of flaming acetic anhydride.
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vulture
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Have you tried chlorine in statu nascendi, that is forming it in the reaction vessel, for example by adding KMnO4 and HCl to it. Maybe add some NaCl
to the solution and electrolyse, also produces reactive chlorine.
You should collect the chlorine gas and pass it throug a warm NaOH/NaHCO3 solution, this will convert it to sodiumchlorate.
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Polverone
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I've been interested in chlorinating acetic acid recently. One in situ method I thought of was to mix solid lithium or calcium hypochlorite with the
acid and then distill. I tried with calcium hypochlorite. Unfortunately, the acid was unchanged. Some sort of catalyst is definitely needed.
I've seen a few different catalysts mentioned (in ACS articles I was searching, sorry I don't have the references handy). Sulfuryl chloride plus heat
and chlorine will chlorinate acetic acid.
Unfortunately, sulfuryl chloride is really nasty stuff, I don't know how to make it, and the yields (in any case) weren't spectacular, something like
30%-50%.
Another method - apparently the "standard" - is to use PCl3 as the catalyst. Gosh, if only I could pick *that* up at Sears.
Yet another method is to add red phosphorus to the acid, heat, and bubble chlorine (I'm guessing this forms the chloride in situ). This one is just at
the edge of possibility for me. But - ugh - I'd have to collect the phosphorus from match books. Won't that be tedious. Plus the phosphorus thus
obtained is of dubious purity. It's becoming apparent that what I really need is my own furnace for producing phosphorus, or some clever
low-temperature method that I haven't yet seen.
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vulture
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I wonder why you use, hypochlorite, that doesn't yield chlorine at all, only oxygen.
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Polverone
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| Quote: | | I wonder why you use, hypochlorite, that doesn't yield chlorine at all, only oxygen. |
Really? The dry granules stink of chlorine and when I added them to the acetic acid there was a considerable chlorine scent also. It was sold as a
chlorine-adding agent for swimming pools. The JT Baker MSDS says "Reacts with water and acids giving off chlorine gas."
[Edited on 21-6-2002 by Polverone]
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reodor felgen
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| Quote: | Originally posted by vulture
You should collect the chlorine gas and pass it throug a warm NaOH/NaHCO3 solution, this will convert it to sodiumchlorate. |
vulture? have you had any success with this? i am thinking about trying this myself (with NaOH)
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vulture
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Haven't tried it myself, but the procedure is used in the industry to produce chlorate.
The idea is that the Cl2 reacts directly with the NaOH to form NaClO3 while the NaHCO3 will neutralize any chlorine acids present in the solution.
Depending on the temperature you get hypochlorite or chlorate.
The intention was to provide a way of safely disposing the chlorine gas.
Polverone, I always found that hypochlorite very odd stuff.
Think about it, what should happen when it yields chlorine gas?:
2NaOCl -> Cl2 + ?
As when it yields singular oxygen:
NaOCl -> [O] + NaCl
[Edited on 24-6-2002 by vulture]
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plasma
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This is what happens when NaOCl reacts with HCl :
4NaOCl + 4HCl --> 4Na(+) + 4Cl(-) + 4OCl(-) + 4H(+) -->
4NaCl + 4HClO-> 4NaCl + 2H20 + O2 + 2Cl2
The same happens with other acids also.
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Polverone
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I agree that hypochlorites are odd. They can yield chlorine, oxygen, and chlorine monoxide. Don't ask me exactly how they do it.
Thinking of hypochlorites made me start thinking of other over the counter chlorinating agents. What about trichlorisocyanuric acid, commonly used in
tablets for chlorinating pools? I started doing some research and came up with some interesting stuff. I found an article in Organic Process Research
and Development "Trichlorisocyanuric Acid: A Safe and Efficient Oxidant." The authors report on a number of different chlorinations and oxidations. I
cannot post the full article, obviously, but I could summarize it or the more interesting parts of it if there were interest.
The authors' review of the literature found that this chemical hasn't much been used in the lab even though it has been produced for industrial
purposes for decades. This suggests to me that there is possibly room for novel and interesting amateur experimentation. And it is certainly a readily
available and inexpensive substance.
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vulture
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I've seen that stuff, those bottles always carry warnings about poisonous gas release with acids. I wonder if they mean Cl2 or (CN)2?
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madscientist
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Here's an idea that just occurred to me.
Why not add a stoichemitric quantity of a dry ammonium salt (preferrably ammonium chloride) to the organic substance to be chlorinated, and pass dry
chlorine gas through the mix? Ammonium salts easily form nitrogen trichloride when chlorine gas comes in contact with them, and nitrogen trichloride
should be a great chlorinating agent. Basically, the ammonium chloride would be a "catalyst" that got used up in the reaction.
I weep at the sight of flaming acetic anhydride.
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madscientist
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Seems that calcium hypochlorite can be used for organic chlorinations after all: http://www.rhodium.ws/chemistry/benzylchloride.html
I suppose this is how the reaction proceeds:
2PhCH3 + Ca(OCl)2 ----> 2PhCH2Cl + Ca(OH)2
I weep at the sight of flaming acetic anhydride.
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Polverone
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Yes... that's one of the things that inspired me to try using it on acetic acid. Not all chlorinations are equally easy, of course. On the Hive itself
I have seen it suggested that pure lithium hypochlorite is superior to calcium hypochlorite for that particular reaction (toluene chlorination).
Hypochlorites have the somewhat undesirable ability to give up oxygen as well as chlorine, and reactions using them can easily get out of hand. The
brief writeup on Rhodium's site doesn't mention it, but if the temperature rises too high then the reaction can easily lead to fire/explosion instead
of chlorination.
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blip
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I hope this is recognized as a delta: <strike>^</strike>
2NaOCl -<strike>^</strike>-> 2NaCl + O<sub>2</sub>
2NaOCl -<strike>^</strike>-> Na<sub>2</sub>O + Cl<sub>2</sub>
Who knows, this may actually happen:
12NaOCl -<strike>^</strike>-> 4ClO + 8NaCl + 2Na<sub>2</sub>O + 3O<sub>2</sub>
[Edited on 11-6-2003 by blip]
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tryptamine
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vulture: Chlorates are not made by reacting chlorine gas with caustic soda. They do use caustic scrubbing to remove chlorine from the hydrogen stream
coming off the electrolysis cells.
Hypochlorite is made in these scrubbing towers and is recycled back into the cell liquor.
I've never heard of hypochlorites giving off oxygen, only chlorine.
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blip
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NaOH + Cl<sub>2</sub> <sup><u>__</u></sup>> NaOCl + HCl
HCl + NaHCO<sub>3</sub> <sup><u>__</u></sup>> NaCl + CO<sub>2</sub> + H<sub>2</sub>O
3NaOCl <sup><u>_warm_solution_</u></sup>> 2NaCl + NaClO<sub>3</sub>
KCl(aq) + NaClO<sub>3</sub>(aq) <sup><u>_cold_solution_</u></sup>> KClO<sub>3</sub>(s) + NaCl(aq)
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Darkfire
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Yes hypochlorates give off singlet oxygen, a redish glow.
CTR
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
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FloridaAlchemist
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Try using FE as a promotor
When performing chlorination in the presence of UV use FE as a promoter...Iron powder or even iron tacks will work...Also be sure the chlorine is
dry.
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FloridaAlchemist
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Polverone use thionyl chloride
You can use either thionyl chloride or better yet PCl5...Thionyl chloride can be made without to much trouble.
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vulture
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You're guys are mixing things up!
Hypochlorites will yield chlorine with HCl because it oxidizes the Cl- of the HCl to Cl2!
2HCl + NaOCl --> Cl2 + NaCl + H2O
When simply heating hypochlorites they will only lose oxygen.
Very strong acids will yield chlorinemonoxide I suspect.
[Edited on 13-6-2003 by vulture]
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Organikum
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Thanks vulture for this explanaition. I want to add that there is at least with aromatic molecules a big difference to make in reaction conditions and
catalyst/no catalyst if you want to halogenate the ring or the chain.
And yes madscientist I tried several chlorinations (w/w success), mostly aromatics on the chain.
Florida_Alchemist: might you disclose how you make thionylchloride? Ways to this versatile compound are always welcome!
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