The Hive => Methods Discourse => Topic started by: abuse on October 09, 2003, 03:51:00 PM
Title: Question on MDP2P from Oxone
Post by: abuse on October 09, 2003, 03:51:00 PM
I read Chromic's write-up at Rhodiums site twice and although I have a fairly well understanding of the procedure, I just wanted to get confirmation. Feel free to correct me where I might be wrong...
(I'm specifying the overall synth, so some details might be left out intentionally)
Part 1: Epoxidation 1) React isosafrole with oxone/baking soda in dH2O/MeOH in a 2L flask for 5 hours. 2) After reaction, decant solution while avoiding solids. Extract solution with DCM and pool the extracts. 3) Strip DCM from the extract via distillation.
At this point, you have a glycol.
Part 2: Hydrolization 4) To the glycol add MeOH and H2SO4. 5) Reflux for 3 hours. 6) After reflux, load contents into sep funnel and separate bottom (ketone) layer. 7) Extract ketone with DCM and pool extracts. 8) Wash extracts with NaOH and separate in funnel (bottom layer has the goods). 9) Strip off DCM via distillation. 10) Recover ketone via vacuum distillation.
I'm assuming this method is considered the "unbuffered" approach, whereas using formic acid is the "buffered" route that creates an epoxide instead of a glycol.
Title: oxone experience
Post by: runne on October 09, 2003, 06:13:00 PM
Part 1: Epoxidation
BEFORE doing #1 below, do: Add dH2O and Oxone - let 100% dissolve Add MeOH - stir, let settle. You should be able to see the white percipitate on the bottom. Decant off water and LEAVE the percipitate behind. If a little gets in, not a real concern.
1) React isosafrole with oxone/baking soda in dH2O/MeOH in a 2L flask for 5 hours. Runne - Depending on scale of reaction you may need to increase the duration. On the 250ml scale or so SWIM does 8 hours.
2) After reaction, decant solution while avoiding solids. Extract solution with DCM and pool the extracts. Runne - Before decanting, SWIM adds a bunch of dH2O to the mix. This help make the oil less soluble in the solution and drop to the bottom. SWIM usually adds a bit of DCM for the first decant. SWIM usually lets it sit for 15 minutes to let oil fall to bottom. SWIM usually uses two buckets. Take reaction contents, add DCM to 2nd bucket and decant 1st(reaction) bucket into 2nd one. Use seperatory funnels each decant/extract DCM each time. Usually after two or three extracts the DCM layer will be nearly clear.
3) Strip DCM from the extract via distillation. Runne - YOu may find buts of white percipitate in the flask as you evap or extract. SWIM finds that if he does a dH2O wash before the evap he ends up with a much cleaner ketone in the next steps.
At this point, you have a glycol.
Runne - You should try and go for the epoxide. SWIM's yields almost doubled when even 1/2 the recommending amount of bicarb is added. He usually adds enough bicarb to make the solution a steady PH 5 to 6 or in the beginning of the reaction. He also finds that as the hours go by the reaction goes more acidic - he has not attempted to continue to add buffer. Any bees tried to maintain a PH of 5 to 6 to avoid excess acidity?
Runne (sorry for spelling. Tired.)
Title: Part 2: Hydrolization
Post by: runne on October 09, 2003, 06:22:00 PM
Part 2: Hydrolization 4) To the glycol add MeOH and H2SO4. Runne - SWIM would true for epoxide. Yields seem higher. Also easier to distill. As long as you don't add too much buffer, the worst that will happen is that you will have some epoxide and some glycol (?).
5) Reflux for 3 hours.
Runne - You will see a color change about an hour into the reation. Usually yellow/orange juice color to a more brown/red tone.
6) After reflux, load contents into sep funnel and separate bottom (ketone) layer.
Runne - Once again, adding water seems to help extraction.
7) Extract ketone with DCM and pool extracts
Runne - ENSURE that the temperature of the reaction has lowered to well below 35C or so (DCM BP 39). BAD things happen when you add DCM to hot solution BAD BAD things.
8) Wash extracts with NaOH and separate in funnel (bottom layer has the goods).
Runne - SWIM usually thinks Bicarb is fine but SWIM is not an expert in this arena. ALSO - it seems to really clean up the solution if you mix/swirl the solution for a while (more than 5 minutes) then let settle.
9) Strip off DCM via distillation. 10) Recover ketone via vacuum distillation.
Runne- If you go unbuffered, you should note that ketone and epoxide have boiling points that are close together. You will see a change from a more yellow color to a slightly more green tinted more "see through" type of liquid which is ketone. OR, you may not. Bees seem to have different experiences with the actual color of the final ketone.
I do not consider myself an expert on the subject. Other comments/changes/corrections would be more than welcome.
Runne
Title: Runne - You should try and go for the epoxide.
Post by: abuse on October 09, 2003, 06:42:00 PM
Runne - You should try and go for the epoxide. SWIM's yields almost doubled when even 1/2 the recommending amount of bicarb is added. He usually adds enough bicarb to make the solution a steady PH 5 to 6 or in the beginning of the reaction. He also finds that as the hours go by the reaction goes more acidic - he has not attempted to continue to add buffer
You're saying to add NaHCO3 (sodium bicarbonate) until the ph is 5 or 6 before or after the reaction? Your wording and placement of comments got me a bit confused :-)
thanks
Title: Ok, I took a closer look at Chromic's write-up
Post by: abuse on October 09, 2003, 07:31:00 PM
Ok, I took a closer look at Chromic's write-up and there is a comment made by "Vibrating Lights" about half way into the document. The following is mentioned which is inline with your comments...
Using the 85% Oxone mix and adding the amount of bicarbonate that Chromic suggest brings the pH too high and renders the epoxidation capabilities of the oxone useless. Swim knows because he had the same problems, then he saw at the Oxone technical information site that pool treatments are usually premixed with 10% Na2CO3/K2CO3. There was no color to the aqueous layers in his dreams until this was realized.
So it seems that less sodium bicarbonate is preferred, otherwise, the ph gets too high. So, the question is How much bicarbonate is enough? According to what you mentioned, you only used half the specified amount to what Chromic recommended. It worked for you, right?
Title: %
Post by: abolt on October 09, 2003, 07:37:00 PM
What is the strength of your oxone?
Title: I don't have any Oxone, but SWIM visited a...
Post by: abuse on October 09, 2003, 08:01:00 PM
I don't have any Oxone, but SWIM visited a pool supply store several weeks ago and read the label on a bag of Spa-Shock and it read only "Contains potassium monopersulfate"
Title: P.H.
Post by: abolt on October 09, 2003, 08:15:00 PM
Dissolve a little in some water and test the P.H. If it measures neutral then don't add the bicarb, if it appears acidic to P.H. then add the bicarb.
Title: oxone strength / bicarb
Post by: runne on October 10, 2003, 05:57:00 AM
SWIM has never seem buffered oxone stuff around where he is. He adjusts PH to 5 to 6 at beginning of the reaction (while stirring). Your oxone may be quite different. I don't think the messages I wrote contain NEW information - just collected from bees such as VibratingLights and Chromic etc.
NOTE: I would note attempt the buffered route without PH Paper on hand. it's cheap, and will take the uncertainty out of the reaction.
Title: Ok, so the ph is definitely adjusted before...
Post by: abuse on October 10, 2003, 08:41:00 PM
Ok, so the ph is definitely adjusted before the reaction. As the reaction runs, does it get more acidic or basic?
Title: Acidic
Post by: Sifty on October 13, 2003, 12:40:00 AM
He also finds that as the hours go by the reaction goes more acidic - he has not attempted to continue to add buffer. Any bees tried to maintain a PH of 5 to 6 to avoid excess acidity?