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Ramium
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Preparation of propionic acid
I want to make some propionic acid.
I found this archive on its preparation
https://erowid.org/archive/rhodium/chemistry/propionic.acid....
It says propionic acid can be made from MEK and bleach via the haloform reaction,
producing chloroform as a byproduct.
Some questions i have:
Is it the same procedure as this if the acetone is substituted with MEK http://youtu.be/lgcl8ZjMAng
How should i separate the chloroform and propionic acid at the end?
What are the molar ratios of MEK/bleach?
Thanks
[Edited on 30-3-2015 by Ramium]
[Edited on 30-3-2015 by Ramium]
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morganbw
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The molar ratios are given in the reaction formula.
Your will need to figure out the molar masses of the items to the left,
substitute the ethyl radical in place of R
ie.. 2 C2H5-COCH3 + 6 Ca(OCl)2 ->
| Quote: |
2 RCOCH3 + 6 Ca(OCl)2 -> (RCOO)2Ca + 3 CaCl2 + 2 Ca(OH)2 + 2 CHCl3 (in this case, R represents the ethyl radical, or C2H5-).
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@How should i separate the chloroform and propionic acid at the end?
Their experimental section covered this.
It is basically the same procedure you linked on u-Tube.
Observe that the u-tube video showed fairly strong cooling. Take care when
your reaction is exothermic.
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CuReUS
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isn't sodium propionate sold as a preservative for bread? you could ask your baker.
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Magpie
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I asked one of the baking staff at my local Safeway if she used calcium propionate or azodicarbonamide as a preservative in their baking. She said
"no." I suspect it may be disguised under some brand name?
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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It's E282 (calcium propionate). Probably available under various trade names, e.g.:
http://www.niacet.com/food/bakery-preservation-quality/proba...
Propionic acid is itself a food additive, E280.
[Edited on 30-3-2015 by blogfast25]
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Magpie
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I just checked Safeway bakery again - no propionates or azodicarboamide - also unbrominated - and bragging that they use no high fructose syrup.
Walmart baked goods use the azo and HFCS, but no propionates.
--------------------------------------------------------------------------
My favorite bread, Franz' "Cracked Wheat," contains calcium propionate, HFCS, molasses, and honey. Maybe that's why I like it so much. 
I have not found a bakery chemicals supplier that sells propionate OTC, however. They sell it, you just have to contact them by personal message
first.
[Edited on 30-3-2015 by Magpie]
[Edited on 31-3-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ramium
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I might try the haloform reaction method first. If it doesn't work then i will buy calcium propionate.
Thanks
[Edited on 30-3-2015 by Ramium]
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Ramium
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Sorry if this is a stupid question.
So after i do the reaction and have gotten rid of the chloroform i will be left with a solution of calcium propionate in water. How do i convert the
propionate to propionic acid
Will HCL convert it?
C6H1OCaO4 + HCL = CaCl + C3H6O2 ?
Can the acid then by purefied by distillation?
Thanks
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Metacelsus
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I would evaporate the water first, so purification will be easier.
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blogfast25
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Quote: Originally posted by Ramium  | Sorry if this is a stupid question.
So after i do the reaction and have gotten rid of the chloroform i will be left with a solution of calcium propionate in water. How do i convert the
propionate to propionic acid
Will HCL convert it?
C6H1OCaO4 + HCL = CaCl + C3H6O2 ?
Can the acid then by purefied by distillation?
Thanks |
I would add sulphuric acid, as calcium sulphate is quasi-insoluble:
Ca(OOCC2H5)2 + H2SO4 ===> CaSO4(s) + 2 HOOCC2H5
Filter off the CaSO4.
According to wiki, the acid can then be salted out of the solution by saturating it with NaCl. The oily acid floats on top. Separate, then finally
distil.
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Ramium
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When you add the NaCl, does it make the acid rise to the surface because the water becomes heavier with NaCl in it. The acid which is lighter rises to
the surface?
Also wouldn't the NaCl react with the propionic acid to form sodium propionate?
[Edited on 1-4-2015 by Ramium]
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DraconicAcid
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No, because chloride ion is a feeble base, and propanoic acid is not a strong acid.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Ramium
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Cant find any sulphuric acid!!!
I have looked in plumbing stores, hardware stores and cleaning stores!! You can't even buy battery acid here!
If i used HCl to convert the calcium propionate to propionic acid instead, i would get calcium chloride, which would stay in solution, and when i add
the NaCl to salt out the acid it will stay with the NaCl in the water.
This is why I think HCl will work. Will it work?
[Edited on 3-4-2015 by Ramium]
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Etaoin Shrdlu
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Yes, HCL should work.
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Magpie
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I see where Ca propionate is available on eBay for about $11/500g w/free shipping. But I don't have a use for it right now. It seems easy enough to
make the acid. Then one could also make the anhydride via the same method as making acetic anhydride.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ramium
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maybe I will make propionic anhydride next
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Ramium
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I am going to do the experiment with Na(OCl)2 instead of Ca(OCl)2 .
After i removed the chloroform I will add the HCl.
I need 1/6 of a mole which is 6.08g. My HCl is 33% but I can't work out the density in order to work out how many ml to use.
This page below gives density numbers but I don't understand it. Could someone please tell me how many ml I need?
http://wissen.science-and-fun.de/chemistry/chemistry/density...
I have worked out the quantities for everything else
MEK = 59.71ml
42g/L bleach = 2L
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blogfast25
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A 100 g of your 33 % HCl obviously contains 33 g pure HCl, to get 6.08 of pure HCl, you'll need 100 x (6.08/33) = 18.4 g of 33 % HCl.
Your density table tells you that the density of 33 % HCl is 1.165 g/cm<sup>3</sup>. Divide your 18.4 g by 1.165
g/cm<sup>3</sup>, that gives you 15.8 cm<sup>3</sup> (mL).
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Ramium
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Thanks blogfast!
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Ramium
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I just added the methyl ethyl ketone to the bleach! Reactions going well.i will do the rest tomorrow
[Edited on 8-4-2015 by Ramium]
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Ramium
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I have waited 5 hours and there is no chloroform layer and the mixtures still yellow
No chloroform smell either.
Did i do something wrong?
These were my amounts
I scaled down the original molar ratios by 6. This meant I used the following quanitites.
42g/l bleach = 2L Bleach had 4g sodium hydroxide impurity
Methyl ethyl ketone = 59ml
[Edited on 9-4-2015 by Ramium]
[Edited on 9-4-2015 by Ramium]
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gdflp
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Did it ever heat up? What is your MEK source, I'm guessing that it may not be as pure as you originally thought, but it could be the bleach too. At
least there aren't too many possible culprits.
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blogfast25
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Please describe better what you did.
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Loptr
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https://www.sciencemadness.org/whisper/viewthread.php?tid=10...
Check out the description of the process by woelen.
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Ramium
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I poured 2 litres of 42 g/l bleach into a wide glass jar. I placed this in a large plastic dish of iced and salted water. Then i measured 59 ml of MEK
and slowly poured it into the bleach, stirrng all the time. At first nothing seemed to be happening at all, then it suddenly went cloudy then the
cloudiness disappeared and it was a yellowish colour. It never seemed as if any heat was given off (although maybe my ice bath was too cold?). Even
this morning it is still the yellowish co,our with no obvious layer of chloroform.
Any suggestions?
Ps i noticed the woelen in the thread loptr linked added NaOH to the bleach as well as MEK
[Edited on 9-4-2015 by Ramium]
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