Author Topic: cl2 + koh + iso = mdp2p  (Read 11664 times)

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Osmium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #40 on: November 12, 2001, 06:01:00 PM »
> when you make bromine from NaBr+H2O2+HCl there will be no
> HBr at all in your reaction mix.

?? Well, there will be H+ and Br-, which is just as good.

Hansje

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #41 on: November 14, 2001, 10:06:00 PM »

Well, there will be H+ and Br-, which is just as good



...for oxidising the Br- into Br2, yes. For making Hydrobromic acid, no.
Admitted: that was not the topic. It was just all these NaBr+HCl ---> NaCl+HBr-like equations above that triggered my corrective instincts.
O well, I'm off now mixing vinegar with gypsum, cause I'm almost out of sulfuric... ::)


Hansje high in proteine and fibre!

FreeBee

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #42 on: November 21, 2001, 05:14:00 PM »
Would sulfuryl chloride work for this reaction?  (It is a great chlorinating agent.)  Also, is it possible to just form the epoxide after the KOH reflux or would subsequent conversion to ketone be assured?

Finally, Is the ten hour reflux just a far worst case number?  Would a slightly higher conc. of KOH allow shorter times?

Thanks

Vibrating_Lights

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #43 on: November 22, 2001, 06:41:00 PM »
What is the sensitivity to the ammount of Br2 in the Iso/Dcm mix.  Must the Br2 be added as it reacts or could it all be added at once.  can anyone see any adverse affects to having a large exess of Br2 in the solution so long as it is washed out before the solvent is removed.
2.  We all know that acedic conditions destroy the asarone molocule  but what about the affects of basic conditions. would the Koh reflux destroy the molocule.  if one was to suscessfully produce the asarone ketone, is the best way to TMA 2  via condensation with hydroxlamine then Al/Hg considering no NaBH4 is available.
VL_

Rhodium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #44 on: November 22, 2001, 07:18:00 PM »
An excess of bromine in the solution would be bad, as then the benzene ring would probably be partly brominated in the 6-position. I don't believe asarone is as sensitive to bases as it is with acids.

zooligan

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #45 on: November 24, 2001, 07:00:00 AM »
Why do the majority of the posts in this thread deal with Br addition when the subject line s about chlorination?  What happenned to the chlorination routine after the third post from the top?  It seems to be completely forgotten.  what's up?


z


"And if we don't get some cool rules ourselves, pronto, then we'll just be bogus too!"

terbium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #46 on: November 24, 2001, 07:53:00 AM »
Yeah, chlorine gas is easier for the clandestine chemist to produce and handle than bromine. A good chlorination procedure could possibly give a more facile and OTC route to P2Ps than even peracid. The biggest question I see is: what could be used for a solvent other than CS2 and CCl4, both of these are not very OTC. Any chance that DCM would work?

Chromic

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #47 on: November 24, 2001, 09:09:00 AM »
DCM is fine for chlorination as free radical reactions have slower rates of reaction compared to forming the chloronium ion intermediate in halogen addition to alkenes. However, I personally think this route sucks... but to each their own.

Rhodium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #48 on: November 24, 2001, 01:09:00 PM »
Yes, DCM is perfectly fine for the halogenation reaction.

terbium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #49 on: November 24, 2001, 08:08:00 PM »
However, I personally think this route sucks...
So, you are just going to leave me hanging? Why, pray tell, do you think this route sucks?

jacob019

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #50 on: November 26, 2001, 03:59:00 PM »
I tried this once with disasterous results.  At first I used amounts of everything as I had calculated above, but not all the KBr reacted so I ended up using a 50% excess of sulfuric acid and H2O2,  sulfuric acid worked better than HCl for some reason.  So first I mixed the sulfuric acid with the KBr.  That way it wouldn't be too acidic when I added the iso.  Would sulfuric hurt iso?  Then I mixed in the DCM and the iso.  I let this stir for a while and it turned yellow.  Then I started to drip in h2o2(15%) but there was no color change when it hit, so I just threw it all in.  It took a couple minuites to turn orange.  I had the worst time making sure it had all reacted.  I would let it stir for an hour in the future.  I played with it for the longest time, washed the water 3X with DCM, added all the DCM/dibromoiso together and weighed.  It was rediculously underweight, but I had played with the liquids so much that I could have lost a lot.  Anyway I decided to distill out the DCM.  I setup to distill and forgot about it. OOPS!!!  When I came back the room was so thick with bromine gas that I couldn't see, breath, etc.  I put on my gas mask, and proceded to the setup. I turned off the hotplate. And pulled out the stoppers.  A LOT of gas escaped and It was presurized.  ALL the glass had filled up with a tar.  Once it cooled it had the consistancy and color of charcoal.  The volume of the stuff must have increased 10 times at least.  It was rediculous.  The stuff was rock hard.  I tried cleaning it with everything.  HCl did nothing, DCM, toluene, and acetone did nothing.  Sulfuric reacted a little and loosened it enough so that air could go in one end and out the other and finally methanol dissolved it a little.  I setup for reflux with methanol and that cleaned out half the condensor.  I guess I'll distill a whole lot of methanol.  Anyway what happened?  I thought it would come over in the order of DCM/Br2?/dibromoisosafrole.  Insted the dibromostuff must have broken down.  Or was something else wrong.  I want to try this again.

Rhodium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #51 on: November 26, 2001, 04:01:00 PM »
Yes, sulfuric acid in the reaction mixture would definitely mess up isosafrole. You need to generate the halogen externally, not in situ.

jacob019

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #52 on: November 26, 2001, 04:03:00 PM »
Time is a BIG problem for SWIM.  He hardly ever gets to his imaginary house with a lab.  He was wondering if it was possible to reflux undistiled sassafrass oil with KOH/NaOH for 4 hours at atmospheric.  Then distill out the iso.  That would save a lot of time.

Rhodium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #53 on: November 26, 2001, 04:07:00 PM »
Yes, that would be possible, but you would get lower yields, and as so many other things are present in the reaction mixture, you must distill carefully, preferably a slow fractional distillation to get pure isosafrole. Some unreacted safrole might also be present, so watch out for that fraction and save that for another isomerization.

jacob019

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #54 on: November 26, 2001, 04:08:00 PM »
In response to Rhodium about my disaster:
If I only add enough sulfuric to react with the KBr then add the iso AFTER the reaction has taken place... could I test PH before adding the iso.  If so could it just be adjusted with NaOH?

Rhodium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #55 on: November 26, 2001, 04:22:00 PM »
You cannot measure pH correctly in such a mixture. You are welcome to try your suggestion out, but I don't think it will work well if you don't generate the halogen first, and then add it to the isosafrole solution. Perhaps you could mix your H2SO4/H2O2/KBr in a separate flask and then heat it slightly to lead the formed bromine that will boil off into the isosafrole solution (in dichloromethane, chloroform or carbon tetrachloride). Personally I'd think MnO2 would be safer to use than H2O2 in this reaction.

jacob019

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #56 on: November 26, 2001, 04:33:00 PM »
Osmium said this earlier in this thread:
prepare a solution of NaBr in water, acidify with HCl or H2SO4, add the isosafrole dissolved in some DCM or chloroform or CCl4 or whatever, place in ice bath and switch on the stirrer. Then add H2O2 slowly, dropwise. This will generate Br2 which is extracted into the organic solvent where it immediately reacts with the alkene.
Once the required amount of H2O2 has been added let phases separate, wash organic layer with some water or diluted NaOH, remove solvent, and continue with the KOH reflux.

So what your saying Rhodium is that this wouldn't work because the sulfuric would screw up the isosafrole.  The sulfuric would be in a different layer.  Could more water be added to make it more dilute.  Will the sulfuric not stay in the water layer?  Why couldn't the ph be tested?

Also,
could my problem with the tar be thermal breakdown of the dibromoisosafrole?  Should it be possible to distill the dibromo, or should it just be stripped of solvent and taken directly to the KOH reflux.  The only reason this reaction would be desirable is because it is so OTC. Is MnO2 OTC?
I hate extraction work, but could the KBr/H2O2/H2SO4 be extracted (Would 3X be necissary) into the DCM alone which would be mixed with the iso seperately.  And about the KOH refulux since there is water in the mix, is the original article suggesting that it be refluxed at 100°?

terbium

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #57 on: November 27, 2001, 07:14:00 AM »
jacob019,

You should take your questions over to the Newbee Forum where they belong!

jacob019

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #58 on: November 28, 2001, 03:30:00 AM »
thats not very nice terbium, nor does it help me.  I started this thread because I'm trying a not so well documented procedure, and I ran into some trouble.  I'm trying to figure out if the procedure failed because of thermal breakdown, or if it is as Rhodium suggests the sulfuric acid.  I was merely stating some ideas in the form of questions.  And If I'm reading the original articele correctly the reaction never goes above 100° until after the KOH reflux, and the bromine should be released during the reflux, decreasing the chance of thermal breakdown.  I would apreciate some advice but comments like yours don't contribute.

Aurelius

  • Guest
Re: cl2 + koh + iso = mdp2p
« Reply #59 on: November 29, 2001, 12:02:00 AM »
didn't uemura post a procedure for this just a couple weeks/months back?