hypnos - 22-9-2009 at 20:12
hey can anyone see any errors or exclusions in this synth?
propionic anhydride is (easily) made in this case calcium proionate 1 mol is mixed with na2s207 sodium pyrosulfate intimately mixed and reacted at 140
C for two hours and distilled at 172C.
results:
propionic anhydride is distilling.
just mix nas207 (sodium pyrosulate) with calcium proionate (any salt will do) even the ammonium salt or the sodium salt it does'nt matter.
heat it to 100-140 C in a grolsh beer bottle for 2 hours.
distill the propionic anhydride swij gets about 50%
the nas2o7 is made by taking a cast iron skillet covering it with a thin layer of sodium hydrogen sulfate (pool ph -) then, heat this directly on a
charcol fire, you'll know when finished becasue it gives of wate rand it will no longer appear molten.
so son't fuss with the acid just do it right the first time!!!
pm me if you need help.
the two have to be intimately mixed in a blender for this to work.
propionic acid give 63 yeilds at best.
and that's with a 20+ hour rxn time.
calcium ppropionate is not wated it's a food preservative and it's found at our favorite auction site for around 1$/lb.
JohnWW - 22-9-2009 at 21:14
If that synthesis is feasible and cost-effective, propionic anhydride would be a possible alternative to the use of acetic anhydride in various
organic syntheses, in places where the purchase of the latter is "restricted" or "watched".
zed - 23-9-2009 at 00:38
In my neck of the woods, the outright purchase of propionic anhydride, would arouse much more interest than the purchase of acetic anhydride.
jon - 9-11-2009 at 15:36
it works for sure done it myself even penned that quote
beebo - 12-6-2010 at 06:50
RE dehydrating sodium hydrogen sulfate
how much is a thin layer in a iron skillit ?
and can this be done in glass on a hot plate ?
bbartlog - 12-6-2010 at 15:22
Although the original instructions are somewhat lacking, they do indicate heating directly on a charcoal fire. Even without further information I
think you're talking at least 500 C which would mean hot plates and glass (other than specialty) are not going to do the job.
mr.crow - 14-6-2010 at 15:17
I guess it doesn't work well for acetic anhydride but is fine for propionic. Go figure
Someone tried the pyrosulfate method out in the AA thread without success
https://www.sciencemadness.org/whisper/viewthread.php?tid=9&...
beebo - 16-6-2010 at 10:21
beebo did this end to end last weekend: no problems !
pryosulfate by dehydrating on an electric stove elemant, placing a stainless grill between the element and the pyrex..
first it melted, then the water bubbled out ( stirred to assist )
and then when the bubbling stopped and it just started to smoke,, we discontinued heating..
Allowed it to cool slowly and then released the chunk around it's edges and it fell out of the pyrex in one piece..
This was used to make propionic anhydride successfully..
At least the anhydride worked for an esterfication that done next.
Waffles SS - 5-5-2011 at 10:06
I tried this method several times(US1430304) but i am sure that this method dont work for acetic anhydrid
I really dont know who accept this patent on 1922 and published it ? may be he was drunk!
[Edited on 5-5-2011 by Waffles SS]