isohuman (Newbee)
08-18-02 00:18
No 346291
      "...for my next trick, the buffered peracetic."  Bookmark   

Well, for starters, I would like to say it's great to be back, as I have not had internet access in over 6 months, but I am taking advantage of this opportunity to swing by a cyber cafe I happened to run by.  Anyhow, here is some scant details of a dream I've had about 6 times in 6 weeks.
ISO will provide more details sooner, but is unprepared at the moment.

40% peracetic acid was prepared(i.e. 4moles h2o2 to 10moles acetic acid)and 6ml sulfuric acid was added per 300g acetic acid.  And allowed to MAGNETICALLY STIR(necessary) for no less than 72 hours.  At this point, it was dripped into an amount of iso-alkene that would amount to a ~1.4 to 1 molar ratio of h2o2 to iso-alkene. no icebath, no chilling of reagents.  The iso-alkene was dissolved in twice it's volume of dichloroethane(because it was readily available, dcm would work fine) and a 1:1 molar ratio of NaHCO3(less can probably be used, but this amount works)and a little water to facilitate better stirring.  A lot of effervesence occured, but the reaction was not very exothermic.  Reaction was performed in a 2 litre erlenmeyer flask.  No condenser was used.  Drip in the peracetic as slow or fast as one wants, just be careful not to bubble over.  After 24 hours of stirring, layers were allowed to seperate, and the bottom layer tapped off, top layer extracted once with a small amount of dce.  DCE was vac distilled to give a QUANTITATIVE yield of the epoxide.  The usual amount of 15% H2SO4 was used for 2 hours with 75-80C temp, to yield ~80% MDP2P after vac distillation.  Amination positive, product confirmed active.  ISO will attempt to make his way back to a computer soon, with the details of a trial reaction handy this time.  BTW, disreguard this post if someone else has come up with the same synthesis in ISO's 6 month absense from the hive.
 
 
 
 
    Chromic
(Synaptic Self-Mutilator)
08-18-02 00:42
No 346297
      Excellent work!  Bookmark   

You must have missed my posts & write up on Rhodium. smile

Excellent work! cool

Btw, there's no way you prepared 40% peracetic acid from that mix. 35% H2O2 and GAA will make 15% peracetic. Read my writeup. The only way to prepare 40% is from 50% H2O2 and acetic anhydride.

Also, if you use DCM sit the flask in cold water or use a condenser. The reaction is exothermic and will boil the DCM otherwise, DCE obviously didn't have that problem.... also, stirring the peracetic for 72hrs is not necessary, but I'd recommend you let it sit 5-7 days (3 is an absolute minimum!). I can find a ref if you don't believe me. smile Stirring the reaction, is of course, essential...

The yield of glycol / epoxide / acetyl glycol (depends on rxn conditions) is nearly quantitative as you said, but the 15% H2SO4 hydrolysis does really lower the yields. I've been doing more work with the OTC tosic acid, but screwed things up due to a high temp distillation with a short (75mm) column. A 250ml flask filled with black carbon (looks like what H2SO4 / sugar makes... heh)

I've also found that the reaction is pretty much over at 2hrs, but going atleast 5hrs is recommended...

Keep up the good work. smile
 
 
 
 
    isohuman
(Newbee)
08-22-02 22:15
No 347780
      Congratulations Chromic!  Bookmark   

Congratulations Chromic!  I guess it pays to stay logged on to the hive.  I just checked out your post, excellent work.
You are correct about the peracetic acid %, that was a typo.  Also, I have found that the peracetic acid forms more quickly when stirred, and that is why I said it was necessary.  If not stirred, 3 days is insufficient.
 
 
 
 
    GC_MS
(Hive Bee)
08-23-02 22:28
No 348209
      Pertrifluoroacetic acid  Bookmark   

You happen to know if pertrifluoroacetic acid can be synthed in the same way?

Doped(TM) since 19.... euhm... a long time smile
 
 
 
 
    Rhodium
(Chief Bee)
09-02-02 11:28
No 351740
      Yes, and you probably don't need any catalyst, as ...  Bookmark   

Yes, and you probably don't need any catalyst, as CF3COOH is pretty strong as is. See the last reference in ../rhodium/chemistry /peracid.html for an online review of peracid synthesis.