Sciencemadness Discussion Board

Bromination of benzodioxole

Fischer - 16-5-2010 at 01:42

Hello everyone!

I have been reading a book called "Total Synthesis II" and in it is described how a carbon string is attached to Benzodioxole by first substituting a bromine atom to it. The final result of this is suppose to be 5-(2-propenyl)-1,3-benzodioxole.

However my problems is that the Bromo-Benzodioxole's bp is so high that, according to the book, a 10mmHg vacuum is needed to distill it, or otherwise it will "fry". The vacuum I have is only 75mmHg. Can anyone recommend a way around this? Preferably one that will work!

Thanks!



[Edited on 16-5-2010 by Fischer]

[Edited on 16-5-2010 by Fischer]

not_important - 16-5-2010 at 06:34

A) get a better vacuum pump, one that can pull down to 1 mmHg or better, and a cold trap and vac regulator.

B) steam distill, which will not allow much fractionation between benzodioxole and the methylenedioxybromobenzene, but will separate them from tars.

The pump you have will do fine with removing solvent and traces of Br2, both of which are better done with an aspirator anyway as with the water pump there's no worry of contaminating the pump oil.

As Strike says, you need serious vacuum.


BTW - you mistitled the thread, since it is nit benzene you're brominating and which would both require a different method of bromination and different work-up. On top of that you failed to provide a decent reference to the procedure, some searching should turn up journal references to the procedure


[Edited on 16-5-2010 by not_important]

Sedit - 16-5-2010 at 11:02

Quote:
Can anyone recommend a way around this? Preferably one that will work!


Just a suggestion and not really a good one but possibly hydrolysis of the Bromobenzodioxole with excess NaOH which I would assume would form the Sodium Phenolic salt, more then likely a solid, and remove the other materials like benzodioxole with a solvent like Dichloromethane. Once purified rebrominate it back to Bromobenzodioxole.

Hell of a work around to avoid getting a stronger vaccume pump though.
My worry is that if your looking for "workarounds" this early in an Ecstacy synthesis someones going to get hurt.

Fischer - 16-5-2010 at 14:01

Alright, I edited the tittle.

Im not so much looking for "workarounds" as planning ahead for back up plans. I havent been able to find a pump that could pull below 10mmHg and would cost less than 1000e. (I live in the EU)

Also I tried to be a bit secretive since I didn't know how people here react to this topic. I have already found some articles about going around the distillation of a halogenic substance. Witch afaik is the only reason one would need a strong vacuum. Strike says at the beginning of his book that "any commercially availible pump is ok" and when it comes to distilling the bromo-benzodioxole, I dont think he mentiones anything about it being decomposed at low temperature, thus needing a good vacuum. The guy who says this is his co-writer.

Here's what I have found:

1. Here whit allylbromide added to cathecol. See picture below.
However, this page is the only one that mentiones this method. So, I dont know if it is away of getting around of buying the expensive pump.

And 2nd in the book "Total Synthesis II" there is a short description at page 244. In it allyl chloride is added whit small amount of powdered Cu to benzodioxole.
What I dont understand is why Strike would write so little about it, it only takes one page and looks very easy compared to the Grignard reaction method (the one whit brominated benzodioxole getting distilled). He has a habit to hype things in the book. And he doesnt do to whit this method. Witch makes me wonder if it will work.
Quote: Originally posted by not_important  

B) steam distill

Im unfamiliar whit steam distillation, but Ill keep this possibility in mind.

[Edited on 16-5-2010 by Fischer]

entropy51 - 16-5-2010 at 15:52

Quote: Originally posted by Fischer  

Also I tried to be a bit secretive since I didn't know how people here react to this topic. ....Im unfamiliar whit steam distillation, but Ill keep this possibility in mind.


Hmmm. Are you interested in chemistry or making a consumer product? Why the need for secretiveness? Sounds as if your chemistry is as poor as your spelling.

I can't find this journal "Strike" that is your primary reference.

[Edited on 16-5-2010 by entropy51]

Nicodem - 16-5-2010 at 23:44

Quote: Originally posted by Fischer  
However my problems is that the Bromo-Benzodioxole's bp is so high that, according to the book, a 10mmHg vacuum is needed to distill it, or otherwise it will "fry". The vacuum I have is only 75mmHg. Can anyone recommend a way around this? Preferably one that will work!

I'm sorry, but someone who is so poorly educated in practical chemistry that he never even heard about aspirators and furthermore uses Strike's book and Wikipedia as his final references instead of checking the primary literature, is certainly not going to be able of doing any such multistep synthesis (at least not without injuries and mishaps). I suggests to you to either start learning chemistry (properly) or give up now. If your only motivation is greed you will get nowhere anyway, because with money obfuscating your mind you will never be able to learn or understand anything. Chemistry does not work when using recipes. Yet, if your motivation is based on the passion for science, then rather start a proper learning process and then maybe someday you will be able to synthesize not only MDMA, but also much better and legal drugs.

PS: Meanwhile, for beginners questions like stuff about vacuum distillation, use the Beginners section of the forum (where I'm moving this thread). There we also have several good threads about vacuum distillation and fractionation that you should have checked first.

Ephoton - 16-5-2010 at 23:47

this thread is probably better suited for thevespiary :D

difference in objectives thats all.

Sedit - 17-5-2010 at 05:28

Possibly your right Ephoton but it would also suck for Thevespiary to become a catching net for all those just looking into making drugs and know nothing about chemisty itself.

Nicodem said it best himself a while back (<- hows that for ass kissing:D), that if you learn mechanisms many questions won't need to be asked. I still wounder where the chem world would be today if people asked about the mechanics of a secondary alcohol reduction using HI/rP instead of asking " How doz I mak Mef".

not_important - 17-5-2010 at 07:18

Sort of following along - not knowing what steam distillation is puts you in a similar situation as someone using a cookbook that has a section on preparing a 9 course dinner but is stopped by the phrase "grate the cheese" because they don't know how to grate cheese or even what that means.

Note that the yields from the copper based route are maybe 30%, and it creates a yucky mess that has to be worked up.

An understanding of the basic is really helpful, both the "why" and "how-to" learned may mean you don't get stumped at some point where things didn't turn out just as expected to, or you are lacking some reagent or apparatus.

Fischer - 17-5-2010 at 10:43

I'm not motivated only by greed. Iv been studying chemistry for awhile now, and I'm going to uni next semester. But I haven't taken any lab. Unfortunately, there does not seem to be any schools near by that would offer a lab course during summer. Note that I only asked advise whit safrole synthesis and not the whole MDMA. Also rest assured that I am taking safety seriously and Iv invested a lot money to it.