Sciencemadness Discussion Board

Attempt at chlorination of toluene using in situ TCCA... massive runaway!

evil_lurker - 12-7-2006 at 08:28

Crap!

Tried adding 500ml of toluene to 1 mole of TCCA in a flask and then slowly heating it up .

Big mistake.

Everything was ok for a while, then all of a sudden massive amounts of foaming suddenly occurred and TCCA/toluene shot out all over the place.

I killed the power, and began the process of disassembling the whole works.

Well I had my condensor and what not off, and strangely about 3 minutes later, the reaction picked up again from the remnants of what was in the flask.

This time it spontaneously heated up and started to shoot a huge cloud of smokey toluene and TCCA vapors 3 feet up in the air! :o

I thought the shit was going to blow at any second!

When the smoke stopped and everything cooled down there was this rust looking moon rock looking mess in the flask... and heard a slight tinking sound... the flask was cracking... :(

I have to go finish cleaning everythign now, hopefully my hotplate will still work... it has a nice white coating all over the outside and inside that will be hell to get off. :mad:

Anyways, just a warning for those that might be interested, DON'T TRY IT!

Nicodem - 12-7-2006 at 10:34

That was a very stupid thing to do, but I’m glad nothing really bad happened. Mixtures of strong oxidizers with reducing organic compounds tend to do that. You are lucky the whole thing did not just explode considering that you used no excess of toluene.

If you wanted to chlorinate the toluene on the ring you should have used a several fold excess of toluene and an acid catalyst so that it could be done at room temperature. If you wanted to chlorinate it on the side chain you should have also a several fold excess of toluene and a radical initiator or sunlight or else the reaction tends to be heat controlled. And when exothermic reactions are heat controlled they tend to self sustain, speed up and run out of control.

I guess it is not that bad after all. It could be worse and at least you learned something doing it: To keep your reactions under control.

chromium - 12-7-2006 at 11:18

This is why i love microscale chemistry.

[Edited on 12-7-2006 by chromium]

evil_lurker - 12-7-2006 at 12:12

It was a good lesson indeed... I imagine the same thing could happen with the loomis patent method as well.

Interestingly enough I attempted to do the same thing yesterday using the same proportions, except in reverse order... the TCCA was cautiously added to boiling toluene... again some foaming upon addition, but otherwise no reaction.

It was very messy, and because of the lack of reaction of that I assumed that it would be safe to just go ahead and heat up the contents of the flask all at once since there was essentially no reaction the last time... after an hour at full reflux in the sun only a trace of benzyl chloride was to be had.

ordenblitz - 12-7-2006 at 17:29

Moved to the proper thread.

[Edited on 14-7-2006 by ordenblitz]