Thor
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Registered: 13-6-2011
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Chlorination recycle
Have had a quick search of the forum and the web, and cannot find an answer to something that has been puzzling me.
In the next few days I am going to attempt chlorination of Toluene to Benzotrichloride, I am basing my experiment on Len1's previous work and also on
a patent uploaded to the forum. The patent looks to be the superior method because it uses a large excess of chlorine in the final stages to push the
reaction to completion.
What's troubling me is that the patent says the chlorine may be recycled to the chlorination vessel after passing through a series of scrubbers to
eliminate HCl and water. I had originally planned to absorb the excess chlorine onto Ca(OH)2 for use later, but recycling it would be much better.
Would a closed system like this work without an additional pump? Chlorine and HCl would be constantly removed from the gas phase, and the heat in the
flask would act as a heat siphon. But im not sure if the chlorine would 'circulate'?
Anyone have any experience with something like this? Id rather have at least an idea that it would work before I start messing with Chlorine gas.
Attachment: Chlorinating Toluene patent.pdf (185kB)
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mr.crow
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Their suggestion is probably for industrial scale applications using pumps and pressure regulators. Just safely neutralize any excess. Cl should be
introduced at such a rate to minimize any escape.
Double, double toil and trouble; Fire burn, and caldron bubble
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Thor
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I guess your right, the amounts used in the patent just led me to believe that it was a benchtop experiment. Hopefully a Ca(OH)2 solution does a good
job of absorbing the gas.
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