yalikeit
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Chlorine???
Where does one get chlorine gas for use in the lab? This is obviously a noob question and something I thought would be self-explanatory but I'm having
trouble working this one out.
I'm intending to chlorinate propionic acid to make propionyl chloride. One of the routes I am considering requires chlorine to be bubbled through the
acid in the presence of sulphur monochloride.
The other requires the preparation of PCl3 which I don't know how to do because of the chlorine problem.
[Edited on 2-6-2016 by yalikeit]
[Edited on 2-6-2016 by yalikeit]
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IceDahl
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You should check this thread out: http://www.sciencemadness.org/talk/viewthread.php?tid=66219
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urenthesage
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Quote: Originally posted by yalikeit  | Where does one get chlorine gas for use in the lab? This is obviously a noob question and something I thought would be self-explanatory but I'm having
trouble working this one out.
I'm intending to chlorinate propionic acid to make propionyl chloride. One of the routes I am considering requires chlorine to be bubbled through the
acid in the presence of sulphur monochloride.
The other requires the preparation of PCl3 which I don't know how to do because of the chlorine problem.
Go to a pool/spa supply shop and buy chlorine pucks, you'll also need hardware store muriatic acid (usually 30 -31%HCl). drip the acid slowly onto a
crushed up puck (use a 2 neck flask) from an addition funnel. The chlorine gas produced will travel up the main neck and into whatever system you have
set up for the reaction.
[Edited on 2-6-2016 by yalikeit]
[Edited on 2-6-2016 by yalikeit] |
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Sulaiman
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http://www.sciencemadness.org/talk/viewthread.php?tid=9713
is a good place to start
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yalikeit
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thankyou very much people 
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Marvin
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Firstly, let's all remember chlorine was the first chemical weapon of WW1. Molar amounts of the gas would not be a good noob experiment.
Secondly it might be worth double checking the method. Acid chlorides are not normally made with chlorine gas, this is more typical of radical
chlorinations replacing hydrogen on the carbon backbone.
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woelen
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If you bubble Cl2 through propionic acid, then I expect that you will mostly get chlorinated variations of propionic acid and no propionyl chloride. I
expect replacement of H-atoms in the CH3-CH2-group and not replacement of -OH in the -C(=O)OH groep.
There are two forms of chlorination, the one is a radical reaction with replacement of H-atoms, directly attached to carbon atoms. This can be
regarded as a form of oxidation. The other form is replacement of hydroxyl groups by chlorine atoms. The latter requires so-called acyl chlorides or
covalent (frequently high-oxidation-state) chlorides like PCl5, NbCl5 or PCl3.
Making chlorine is easy for the home chemist. Making acyl-chlorides or the covalent chlorides, useful for replacing hydroxyl groups, is a lot harder
and requires meticulous exclusion of water (either as vapor in air, or as liquid). Alkaline drying agents like carbonates, hydroxides or metals like
Na, K are not useful for this purpose, they react with the acyl chlorides and high-oxidation-state chlorides.
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Sulaiman
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I am presently experimenting with chlorine gas,
IF you are VERY careful, working outdoors without a gas mask is ok,
I have been paranoically careful yet I smelled chlorine,
I am on my third re-arrangement of my chlorine generator.
I think that a pressure-equalised addition funnel or equivalent is required for safe working,
I've not found a simple safe way around that.
An extremely small pressure is required to fill flasks with gas etc.
but to bubble gas you need pressure greater than the depth of water,
this is where it gets 'tricky' .... volumes of chorine gas under pressure,
and you can't just directly vent any over-pressure
IF you have GOOD fume extraction you also have to be careful
... where are the fumes extracted to ?
I'ts not just a nasty smell ...
If my calculations are correct,
ONE of the small 20g TCCA tablets with HCl can produce 6 litres of chlorine gas ... lethal in a confined area.
A significant cause of accidental domestic deaths in UK is chlorine gas generated by mixing cleaning products.
I would suggest test-tube level experiments first,
1/4 or less of a 20g TCCA tablet + HCl.
(even 1/4 tablet worst-case could be very bad)
Even the dust generated when grinding up a TCCA tablet can be quite irritating.
Even cleaning out my 1l flask used as the generator releases 1l of Cl2
I think that with reasonable care, chlorine gas is safe for hobbyist use,
I guess that many chemistry hobbyists can identify lots of hazardous chemicals by smell .... 
Go ahead but treat with respect (or in my case, fear 
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byko3y
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I have a bad experience generating chlorine indoors, but it's more because I was staying for a long time inside a room with leaking chlorine generator
trying to figure out what to do. That day I generated approx 100 g of chlorine. Had some cough for a next day.
I won't tell you about my bromine experience, when I was trying a patented dehydration method of phase separation near bromine boiling point. 
Halogens are extremely dangerous, although knife is equally dangerous when you deliberately cut your hand and continue despite the fact it hurts.
Well, in fact once I was wondering what it feels like to breath in a concentrated chlorine, and took a slight breath of concentrated chlorine has...
not recommending, that's one of too things you should avoid when working with chlorine gas (after not staying for a long time in a room filled with
perceptible amount of chlorine gas). Oh, those were funny days.
Speaking about propionyl chloride: you can actually make it with sulfur chloride, as well as propionic anhydride. But you need to know the
procedure.... and we would be glad to take a look at the procedure you are going to use.
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