02-05-02 18:49
No 265705
I need help. I have performed the modified performic several times , always with success, but this time however I have hit a snag. It all goes normally, including colours, temperatures etc, but when I distil I get a yellow oil with the slightest hint of green in it that comes over just before iso-saf, this oil is quite fluid, is shelf stable and does not smell like the ketone or iso or saf.
My own suspicions are the quality of iso (but previously never been a prob), the quality of the peroxide(????) and that’s about it.
Any help at all would be much appreciated, I really have hit a snag, so to speak.
What is the product if the performic is performed on saf?
wacka wacka wacka
(Newbee)
02-07-02 00:44
No 266376
the secondary alcohol of iso-safrole, does anyone have any physical data on it. i have suspiscions this may be my yellow oil because of its broad fluidity range from -20-180.
The primary alcohol, any data on it?
any help would be interesting
wacka wacka wacka
(Daddy)
02-07-02 14:33
No 266634
YES, this seems to have become a problem NOT only for you. Several members have addressed the same fuckin problem to me, and up till now we have not found a solution for this nagging big problem.
It seems btw conceiled only to the american subcontinent, including US and Canada.
It seems that one of the ingredients, formic acid, hydrogen peroxide, is the culprit.
If there is a hidden additive in there, then it will be quite difficult to find it.
What method of Isomerization did you use? KOH or Alliquat?
What is your main problem? The Isosafrole is already no good, or is it the distillation of the raw ketone AFTER the 15% H2SO4?
The 15% H2SO4 can be the problem, if the temp inside the reaction is not watched carefully then the reaction time of 2 hours can be too short and you have lots of unreacted isosafrole hanging in there. Lately Vibrating_Lights came up with the idea of checking your conversion to ketone with a blacklight lamp.
So you could take small reagens tube samples of your reactionfluid every 15 minutes or so, quickly boil off all volatiles and check the colour of your small sample of raw ketone mixed with still unreacted isosafrole!
Only problem could be: you introduce a lot of heat to boil off those volatiles in that test tube, thus interfering with the reaction itself. So better quickly boil off under high vacuum, it's worth the time taken for it in my opinion, because after doing this meticulously ONE time, you know exactly the point in time where your precious isosafrole has been converted maximal to ketone.
Any one know the data for his alcohol questions? LT/
WISDOMwillWIN
(Newbee)
02-07-02 20:19
No 266739
The problem appears after distillation of the final ketone, up until that point everything sems dandy, might give some thought to your 15% sulphuric idea, this may be plausible, normally i take it off a bit early if anything, so i might look into this step in my process.
Thanks for the reply, it is valuable, i will let you know how i go.
caio
wacka wacka wacka
(Newbee)
02-17-02 23:37
No 271168
Could my yellow oil be the diol? If this is the case I would just boil it up again in more sulfuric to obtain the ketone, what is the diol like? My sulfuric may not be as active as i think, i must do a titration on it, if the sulphuric was say 10%, instead of 15% would this perahaos leads to only partial hydrolysis to the diol, which is more sensitive to the acid the glycol or the diol, can you turn the hydrolysis off half way at all or will you always get some ketone.
If one had a known diol what would you guys out there in lal alala land do to convert it to the ketone.
Any help would be appreciated as i have heaps of this shit.
Also is the diol shelf stable, as my yellow (not ketone) oil is.
wacka wacka wacka
(Hive Addict)
02-18-02 07:51
No 271269
Did your mystery oil freeze or is it just like a fluid (non viscous) ketone?
Chaque un à son gout
ah, never mind. So you received this gift as well. I can only think that the safrole didn't convert and the H2SO4 did something to the safrole. I got the same thing from an oxone reaction.
If it was the peroxide or the formic, then it couldn't have happened to me as well, since I used oxone. Only thing left is the safrole -> iso unless it wasn't safrole to start with, which it must have been, since the same source worked the next time.
(Newbee)
02-18-02 12:11
No 271380
Thanks for the reply NOJ, who knows, I think the yellow oil will go towards a pyre (is that how that is spelt), If i ever feel as if I have more info on the problem I will let you all know. Other than that cheers for now
wacka wacka wacka
(Newbee)
03-08-02 16:59
No 279169
it appears the problem was due to too much water in the intial KOH used for the isomerisation. I dehydrated my own KOH, but with heat only not vacuum, perhaps the presence of too much water causes some sort of hydrolysis in the double bond, the odd thing is when the iso was distilled its physical characteristics where correct, so i don't know but hte prob has gone away now that i got some KOH flakes (atmos isomerisation @ 140 for 8hrs, effectively no safrole left in the sass oil)
anyway thought i would report on the results
wacka wacka wacka
(Her Majesty, Stoni's Kitty)
03-08-02 18:18
No 279201
The modified performic and the oxone only work for isoalkene (if alkene is used, it doesn't react and you get it back). But the classic performic works on both alkene and isoalkene.
(Hive Addict)
03-08-02 18:55
No 279218
"32.4g isosafrole dissolved in 120mL of acetone added to a stirring solution of 150g 80% formic acid and 32g of 30% hydrogen peroxide at a slow enough rate such that the temperature does not climb above 40C"
Is this what you mean by the 'classic' performic? Are you saying straight saffy gets to the same place in this method?
z
"No one can build his security upon the nobleness of another person." -- Willa Cather
(Chief Bee)
03-08-02 19:40
No 279232
Psychokitty: What epoxidizing reagents will turn safrole into the terminal epoxide, if you knowe that those two does not?
Zooligan: Safrole will turn into the terminal diol if subjected to the classic performic (yes, the one you cited), but as far as I know, H2SO4 rearrangement will give aldehydes as products,and not the desired MDP2P. However, the epoxides derived from either safrole and isosafrole rearranges to MDP2P by reflux with LiI in ethyl acetate.
(Her Majesty, Stoni's Kitty)
03-08-02 20:13
No 279247
Zooligan and Rhodium: This should answer both your questions.
The classic performic as Zooligan described it will:
1.) Hydroxylate both alkene and isoalkene to form thier respective glycols which can then be dehydrated to the ketone (for isoalkene) or the aldehyde (for alkene).
Zooligan, NO, you cannot go from alkene DIRECTLY to desired 2-ketone using the classic performic. Sorry. You have to form isoalkene first through base-catalyzed migration of the double bond. But you know this already bubba.
The modified performic:
1.) Converts isoalkene to glycol.
2.) Does not react with alkene.
The oxone reaction:
1.) Under buffered conditions yields epoxide from isoalkene.
2.) Under non-buffered conditions yields glycol from isoalkene.
3.) Does not react with alkene.
That's the best explanation I can give.