ChemicalSolution (Hive Bee)
01-15-02 20:01
No 256765
      chloromethylation question  Bookmark   

In the chloromethylation procedure in TSII using a benzene, paraformaldehyde, toluene as the solvent, and hydrogen chloride gas, about how much H2SO4, HCl should go in the generator for, say, a 1 mole batch to be able to gas for 2-3 hrs?

From TFSE, Scooby said to drip the H2SO4 at a rate of two drops per second..  But SWIM isn't sure about the amounts of the acids to use.

xoxo
Julia
 
 
 
 
    terbium
(Old P2P Cook)
01-16-02 03:52
No 256945
      Re: chloromethylation question  Bookmark   

If you don't have very good ventilation/fume hood you may want to reconsider performing this reaction. I believe that this will produce the extremely carcinogenic bis(chloromethyl) ether. I believe that someone here recently posted some variations on this procedure that are supposed to reduce the bis(chloromethyl) ether production.

Edit:
Here we are: thread beginning with Post 250931 (Antoncho: "A safe an easy way to chloromethylate.", Novel Discourse)
 
 
 
 
    Osmium
(Stoni's sexual toy)
01-16-02 11:16
No 257149
      Re: chloromethylation question  Bookmark   

Once the reaction seems to be fairly saturated with HCl I'd put a balloon on it and stop the HCl generation. No need to release all that excess HCl gas.
I don't know how much HCl you will need. Probably quite a lot. Like 5 moles or more for the batch size given.
 
 
 
 
    foxy2
(Distinctive Doe)
01-16-02 11:29
No 257158
      Re: chloromethylation question  Bookmark   

Don't forget about salt in your HCl generator.  I don't think you want to dehydrate aqueaous HCl for this much HCl gas.

I hate my government, does this mean I'm a terrorist??
 
 
 
 
    Osmium
(Stoni's sexual toy)
01-16-02 13:55
No 257194
      Re: chloromethylation question  Bookmark   

5 moles of HCl gas means about 500ml muriatic acid. Not too bad if you ask me. And the H2SO4 can either be boiled to concentrate it for reuse or it can be used for neutralisation, A/B etc.

../rhodium/chemistry /hclgas.argox.html
 
 
 
 
    ChemicalSolution
(Hive Bee)
01-16-02 16:22
No 257220
      Re: chloromethylation question  Bookmark   

Post 253440 (ChemicalSolution: "Easy(er?) chloromethylation", Novel Discourse)

SWIM posted this a while ago for review.. Not much was said.  This seems 10x easier than the HCl method... But she wanted to try both of them to compare.

In the HCl method, what would the molar ratio of benzene:ZnCl2 be?

Julia
 
 
 
 
    foxy2
(Distinctive Doe)
01-16-02 17:36
No 257232
      Re: chloromethylation question  Bookmark   

Comparing them is a great idea, however if I was you i would try the easy procedure and if it yeilds well then I might just say screw the comparison.

I hate my government, does this mean I'm a terrorist??