Author Topic: 1st performic, need help!  (Read 874 times)

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methlab

  • Guest
1st performic, need help!
« on: March 23, 2004, 11:19:00 PM »
Hi! I did my first performic a la LabTop, with 125g Isosafrole. After stiring for 24 hours, orange coloured DCM seperated to bottom, yellowish rest on top. After stripping off the DCM i was left with about 130ml very dark liquid, looking similary like safrole/KOH mix after isomerizing with KOH, but not so dark, i would say dark brown, but it is not an orange liquid, like LabTop writes. What is wrong? Did it fail or is this normal? Hope someone can help me, thanx.

Rhodium

  • Guest
Continue as if nothing happened
« Reply #1 on: March 24, 2004, 12:36:00 AM »
Just go on as usual, you cannot tell anything by looking at the color at this stage.

Did you wash the DCM layer with water and brine as in the

Buffered Performic Oxidation

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/peracid.html#performic3)
If you didn't, heating the product without washing away residual formic acid first is likely the culprit.

Also, don't start a new thread each and every time you reach another step in this procedure, continue in any of the other ones you have already started.


methlab

  • Guest
ok
« Reply #2 on: March 24, 2004, 12:49:00 AM »
will keep this in mind. but will others read them ?

Thanx

Rhodium

  • Guest
What would YOU do?
« Reply #3 on: March 24, 2004, 01:09:00 AM »
Do you only read posts made in new threads, and never older threads with new posts in them?


ApprenticeCook

  • Guest
So long as the thread isnt locked any thread...
« Reply #4 on: March 24, 2004, 01:21:00 PM »
So long as the thread isnt locked any thread with a new post is brought to the top of the list when you look at the forum. So anyone who comes in can see there has been a new post on that thread since they last looked at it...

methlab

  • Guest
i know
« Reply #5 on: March 26, 2004, 09:05:00 PM »
i know the newest are on top, but i thought that other bees will not read all of them, i thought they might choose posts depending on the topic. I will use more general topics for my questions in the future, so that i can post my questions in just one thread, instead of opening an new one for every similar question. Thanx for your advice.

baalchemist

  • Guest
"orange coloured DCM seperated to bottom
« Reply #6 on: March 28, 2004, 12:29:00 PM »
"orange coloured DCM seperated to bottom", "but it is not an orange liquid, like LabTop writes"

And you say you dont see any resemblence to Labtops description, huh?  Stop huffing the DCM!!!


methlab

  • Guest
i was talking about the colour AFTER stripping
« Reply #7 on: March 28, 2004, 08:23:00 PM »
i was talking about the colour AFTER stripping off the DCM, look at his writeup:

[LabTop, 08-31-01, 'The ONE and ONLY buffered Performic']
... "Turn off the stirrer after these 24 hours, allow the two layers to settle. Separate off the bottom layer (DCM), and extract the remaining top residue-layer 2 times with a small amount of DCM, and add these to the already separated main DCM body. Take this combined portion to a 22 liter Rotavap or conventional distillation machine, distill off the DCM in 15 liter portions, and collect all the resulting ORANGE SYRUP portions ... "

This confused me because my syrup was dark brownish almost black, it looked like safrole after izomerizing with koh. After doing all the washes like Rhodium told me, it was orange coloured, but LabTop is doing the washes after the glycolisation step.

The result was suprisingly good, i got 85g MDP2P from 125g Isosafrole after doing my first buff. performic. I'm sure the second try will give a higher result, but i can live with that. After trying Brightstar's and MM wacker recipes i got nearly the same result, except that they use much more safrole (160g/178g). So i think the buff. performic is the choice for my future experiments...

greetings

biffman

  • Guest
yields between different ketone preparations
« Reply #8 on: April 05, 2004, 01:02:00 AM »
I too also found the buffered performic with DCM method much easier, quicker and cleaner than the older performic method.  However the yields of my final end product always seem to be significantly lower if I use the buffered performic/DCM ketone.
Has anybody else noticed this or is there some variability in the preparation that I am missing and haven't figured it out yet.  It has gotten better each time I've tried it so I'm thinking it's probably something I'm doing. 
 The first time I got only about a 6g (!) yield rather than the 40g which Shulgin reports for those batch sizes.  The next batch of ketone I prepared I got up to about 26g but with the older performic method I usually got greater than 35g each time.
Any thoughts anyone?

abacus

  • Guest
its the peroxide
« Reply #9 on: April 06, 2004, 05:09:00 AM »
Labtop makes it quite clear that in the buffered performic you need FRESH peroxide.  There a many posts on this where newbees have discovered this as well.

The yields using good peroxide and the procedure as written never gives less than 70%, mostly 75% weight to weight.  That is 100g good iso gives 75g MDP2P.

Yields aside, the best thing about the buffered performic is you need less formic acid and an easier workup IMO.