Sciencemadness Discussion Board - Preparation of propionic acid

Preparation of propionic acid

Ramium - 29-3-2015 at 22:55

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]

morganbw - 30-3-2015 at 00:01

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-).

@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.

CuReUS - 30-3-2015 at 06:35

isn't sodium propionate sold as a preservative for bread? you could ask your baker.

Magpie - 30-3-2015 at 08:03

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?

blogfast25 - 30-3-2015 at 08:16

Quote: Originally posted by Magpie

I suspect it may be disguised under some brand name?

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]

Magpie - 30-3-2015 at 10:24

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]

Ramium - 30-3-2015 at 10:48

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]

Ramium - 31-3-2015 at 21:17

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

Metacelsus - 1-4-2015 at 07:20

I would evaporate the water first, so purification will be easier.

blogfast25 - 1-4-2015 at 07:42

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.

Ramium - 1-4-2015 at 10:58

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]

DraconicAcid - 1-4-2015 at 12:01

Quote: Originally posted by Ramium

Also wouldn't the NaCl react with the propionic acid to form sodium propionate?

No, because chloride ion is a feeble base, and propanoic acid is not a strong acid.

Ramium - 2-4-2015 at 21:18

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]

Etaoin Shrdlu - 3-4-2015 at 09:28

Yes, HCL should work.

Magpie - 4-4-2015 at 09:07

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.

Ramium - 4-4-2015 at 10:37

Quote: Originally posted by Magpie

Then one could also make the anhydride via the same method as making acetic anhydride.

maybe I will make propionic anhydride next

Ramium - 6-4-2015 at 13:04

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

blogfast25 - 6-4-2015 at 16:55

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/cm3. Divide your 18.4 g by 1.165 g/cm3, that gives you 15.8 cm3 (mL).

Ramium - 6-4-2015 at 18:05

Thanks blogfast!

Ramium - 8-4-2015 at 15:27

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]

Ramium - 8-4-2015 at 19:33

I have waited 5 hours and there is no chloroform layer and the mixtures still yellow
No chloroform smell either. :mad:

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]

gdflp - 9-4-2015 at 03:17

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.

blogfast25 - 9-4-2015 at 06:06

Quote: Originally posted by Ramium

Did i do something wrong?

Please describe better what you did.

Loptr - 9-4-2015 at 06:19

https://www.sciencemadness.org/whisper/viewthread.php?tid=10...

Check out the description of the process by woelen.

Ramium - 9-4-2015 at 11:33

Quote: Originally posted by blogfast25

Quote: Originally posted by Ramium

Did i do something wrong?

Please describe better what you did.

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]

Ramium - 9-4-2015 at 12:15

Quote: Originally posted by gdflp

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.

the reaction dident seam to heat up. This is my MEK Source http://www.tmkpackers.co.nz/index.php/site/gallery/category/...

Ramium - 9-4-2015 at 18:07

Had a closer look at the mixture and i saw a separite layer on the bottom!!!

It was hiden by the curve of the glass

Is there anyway to test the layer to see if its chloroform?

The layer looks cloudy

Texium - 10-4-2015 at 12:42

Remove the aqueous layer with either by decanting or using a separatory funnel. Then take the chloroform layer and set up a simple distillation. The boiling point is 61.2 C, so the vapor should come over at close to that temperature. You can salt out any remaining water with anhydrous magnesium sulfate if you wish. Otherwise, take the distilled product (which should be clear) and store it in an amber glass or otherwise dark bottle. Add a few drops of ethanol to stabilize it (prevents decomposition to phosgene).

blogfast25 - 10-4-2015 at 13:36

Quote: Originally posted by Ramium

Is there anyway to test the layer to see if its chloroform?

The layer looks cloudy

Dry it with CaCl2, then determine density. The 1.49 density is quite a lot higher than most organics.

Weighing accurately how much you've got can give a good idea of conversion of the reaction. Be careful with chloroform, though! Read up, if you haven't already.

Ramium - 10-4-2015 at 13:50

thanks guys.

will distil it today

[Edited on 10-4-2015 by Ramium]

Ramium - 15-4-2015 at 22:19

I added HCl to the rest of the mixture. then tried to salt out the propionic acid from the mixture but it didn't work. I then started thinking about how to dispose of the mixture.
then i tested to with PH paper and it was alkaline. So I took it to a chemical disposal plant.

That stuff which i thought was chloroform isn't chloroform after all. Its turned white and viscous and i realised the strog smell was actully MEK.

I guess i failed.

.

Anyone know any other feasible methods for making propionic acid?

[Edited on 16-4-2015 by Ramium]

DraconicAcid - 15-4-2015 at 22:36

If it was alkaline, then you hadn't added enough HCl. The stuff that you thought was chloroform might have been impure chloroform...who's to say?

Ramium - 15-4-2015 at 23:06

I guess. But sadly i have already disposed of the mixture.

I'll try the experiment again

I'm just worried because the first time it didn't seem to heat up at the start, which it was supposed to, so i am not sure if it is going to work the second time

I'll try a differnt brand of bleach.

Loptr - 16-4-2015 at 07:31

Quote: Originally posted by Ramium

I added HCl to the rest of the mixture. then tried to salt out the propionic acid from the mixture but it didn't work. I then started thinking about how to dispose of the mixture.
then i tested to with PH paper and it was alkaline. So I took it to a chemical disposal plant.

That stuff which i thought was chloroform isn't chloroform after all. Its turned white and viscous and i realised the strog smell was actully MEK.

I guess i failed.

.

Anyone know any other feasible methods for making propionic acid?

[Edited on 16-4-2015 by Ramium]

You could oxidize the alcohol to the carboxylic acid.

Amos - 16-4-2015 at 07:38

1-propanol can be reacted with an aqueous solution of potassium permanganate and sodium hydroxide, oxidizing the alcohol to propionic acid which is neutralized immediately by the sodium hydroxide. The permanganate itself is reduced to manganese dioxide, which can be filtered out. The remaining solution can be boiled down until it crystallizes, and the crystals of sodium propionate can be treated with sulfuric acid(or another acid if you don't mind water) and a distillation of the propionic acid can then be carried out.

The 1-propanol can also be oxidized with potassium or sodium dichromate and sulfuric acid, but that's a little bit more messy. I would imagine that the dead reaction mixture after the reaction(which is very, very exothermic) could be heavily salted with sodium chloride and the propionic acid could be extracted with ether or chloroform.

[Edited on 4-16-2015 by Amos]

DraconicAcid - 16-4-2015 at 07:51

I would expect that acidic bleach would also oxidize 1-propanol to propionic acid, but one has to be careful to avoid chlorine formation. I've done bleach oxidations of larger secondary alcohols to ketones, but not to acids.

Amos - 16-4-2015 at 07:55

Quote: Originally posted by DraconicAcid

I would expect that acidic bleach would also oxidize 1-propanol to propionic acid, but one has to be careful to avoid chlorine formation. I've done bleach oxidations of larger secondary alcohols to ketones, but not to acids.

Do you have a link to such a process? I didn't know you could use hypochlorite/hypochlorous acid for those kinds of oxidations.

DraconicAcid - 16-4-2015 at 08:03

Quote: Originally posted by Amos

Quote: Originally posted by DraconicAcid

Do you have a link to such a process? I didn't know you could use hypochlorite/hypochlorous acid for those kinds of oxidations.

Not offhand, but I could probably scan that part from a lab manual and email it to you over the weekend.

Amos - 16-4-2015 at 08:11

Quote: Originally posted by DraconicAcid

Quote: Originally posted by Amos

Quote: Originally posted by DraconicAcid

Do you have a link to such a process? I didn't know you could use hypochlorite/hypochlorous acid for those kinds of oxidations.

Not offhand, but I could probably scan that part from a lab manual and email it to you over the weekend.

I would be interested in that, but I thought typically you would obtain a chloroalkane rather than a ketone or carboxylic acid.

Loptr - 16-4-2015 at 08:19

Quote: Originally posted by Amos

1-propanol can be reacted with an aqueous solution of potassium permanganate and sodium hydroxide, oxidizing the alcohol to propionic acid which is neutralized immediately by the sodium hydroxide. The permanganate itself is reduced to manganese dioxide, which can be filtered out. The remaining solution can be boiled down until it crystallizes, and the crystals of sodium propionate can be treated with sulfuric acid(or another acid if you don't mind water) and a distillation of the propionic acid can then be carried out.

The 1-propanol can also be oxidized with potassium or sodium dichromate and sulfuric acid, but that's a little bit more messy. I would imagine that the dead reaction mixture after the reaction(which is very, very exothermic) could be heavily salted with sodium chloride and the propionic acid could be extracted with ether or chloroform.

[Edited on 4-16-2015 by Amos]

The first procedure is actually the one I had in mind. It would be so much easier, as you end up with insoluble that you filter off, and a soluble, which is the salt of your desired product.

You could also extract the propionic acid in the first procedure using an organic solvent, as is done in the second, if you don't want to have to run a distillation.

Personally, I would start with calcium propionate that can be purchased here: http://www.ebay.com/itm/2-2-lbs-1kg-Calcium-Propionate-Food-...

[Edited on 16-4-2015 by Loptr]

Ramium - 16-4-2015 at 11:49

The 1- propanol method sounds much easyer. i think i'll try that

Ramium - 16-4-2015 at 14:57

I have worked this out so far

C3H8O + KMNO4 = C3H6O2 + ?

Could you please help complete and balance the equation?

Amos - 16-4-2015 at 18:35

Quote: Originally posted by Ramium

I have worked this out so far

C3H8O + KMNO4 = C3H6O2 + ?

Could you please help complete and balance the equation?

I believe the net reaction that takes place is this one:
4 KMnO4 + 3 CH3(CH2)2OH = 4 MnO2 + 3 CH3CH2COOK + 4 H2O + KOH

The solution is made alkaline because it increases the reaction speed and promotes selectivity, according to wikipedia. The base is not needed necessarily, but otherwise it will take quite a long while. The reaction's yield is limited, as the decomposition of potassium permanganate in water is catalyzed by acids, bases, or manganese dioxide, so an excess of permanganate is a must for complete oxidation of the alcohol.

DraconicAcid - 17-4-2015 at 09:27

Quote:

Not offhand, but I could probably scan that part from a lab manual and email it to you over the weekend.

Scanner's down, but here: http://www.chemistry.mcmaster.ca/~chem2o6/labmanual/expt7/ex...

http://ochemonline.pbworks.com/f/03_bleach_oxidation_handout...

http://goose.ycp.edu/~khalliga/Courses/CHM%20236/Spring%2020...

http://www.brynmawr.edu/chemistry/Chem/mnerzsto/Labs/Experim...

When we did this in the lab (OT story ahead), it was as a lab exam. The students were supposed to come in, do the experiment without speaking, and hand in their product. The alcohol was measured out for them in flasks at the front of the lab (this was explained to them at the beginning). One student ("J") came in late.

About half an hour into the experiment, I noticed that there was still a flask of alcohol left on the cart, so I recounted the students, and wondered why there was still a flask left- I was sure there was the right number of flasks at the beginning. Then J came up to me, complaining that their reaction was smelling odd (it was full of green-yellow gas, too, but J hadn't noticed). Upon cross-examination, J explained that they had weighed out the alcohol (pointing at the jar of sodium sulphate, there to be used as a drying agent), and followed the directions to the letter.

Aright, J, *here* is the real alcohol, now start over. J managed to oxidize the alcohol, and then needed to extract the ketone with dichloromethane, and wash the extract with water, then with saturated sodium chloride.

So J pours in some solvent, sees it separate into two layers, keeps the lower layer, and then throws out the top layer. Right down the sink (you can see what's going to happen, don't you?). Then J adds water, and....only one layer forms.

What happened? J is perplexed again. "I added the dichloromethane," J says, pointing at the bottle of saturated sodium chloride. This salted out the ketone, which floated to the top, and was washed down the sink. Naturally.

So J now has about an hour left to write up the lab quiz and hand it in, while the other students are doing their distillation. "Can I have some more alcohol to start over?"

NO!

Amos - 17-4-2015 at 17:56

Sounds like J was a handful. Those reactions are certainly interesting, and I'll probably end up utilizing them later on if I can't find a cheaper oxidizer. I didn't see anything in the resources that described oxidizing primary alcohols, but there's no reason it can't at least be tried!

DraconicAcid - 20-4-2015 at 13:24

According to this: https://www.researchgate.net/publication/222458939_The_oxida...

Primary alcohols will be oxidized by bleach not to the acids, but to the esters....

blogfast25 - 20-4-2015 at 14:36

Quote: Originally posted by DraconicAcid

According to this: https://www.researchgate.net/publication/222458939_The_oxida...

Primary alcohols will be oxidized by bleach not to the acids, but to the esters....

The solvent was acetonitrile:acetic acid (3:2), not for everyone, that. Reported yields were generally good. Wonder if this works also with the straight alcohols. Or perhaps using acetone as a solvent?

Interesting find.

Mesa - 22-4-2015 at 04:38

Quote: Originally posted by blogfast25

The same paper is available in the rhodium archives, it was discussed for it's potential use in preparing benzaldehyde briefly.

I've always wanted to find more information about it, especially the properties needed in the co-solvent(acetonitrile) and what alternative solvent systems were tried besides the one included.

I kinda thought the choice of solvents were to ensure it stopped at the aldehyde/ketone but I couldn't find any related info to confirm/deny.

Acetone would not work as a solvent as it will react readily with hypochlorites, it's one of the more popular methods of preparing chloroform.

[Edited on 22-4-2015 by Mesa]

gdflp - 22-4-2015 at 05:31

Yep, that was discussed very briefly here. Benzyl alcohol is more expensive than toluene in the States, so I'm looking for ways from toluene, if anyone has a good source of benzyl alcohol though, let me know. I've got about 40ml left so I can do some more experimenting with this method.

I did some experimenting with this a few months back and I managed to get around a 70% yield of crude benzaldehyde I think, I'm not entirely sure because I never measured it precisely. From memory, I didn't use any acetonitrile and I used significantly less acetic acid than a 5x scale up would require based on the paper and it still seemed to work. Because of the relatively small scale, I couldn't distill the product due to the lack of glassware small enough. I can dig up my notes on the exact molar ratios and procedure I used if anyone is interested.

EDIT : Nevermind, I actually used the amount of acetic acid called for.

[Edited on 4-22-2015 by gdflp]

Mesa - 22-4-2015 at 06:24

Sure. I assume you used a liquid bleach as the hypochlorite, the majority of solvent in the reaction consequently being mainly water. Do you know what pH was prior to adding the benzyl alcohol?

Acetic acid is so polar that I'd think solvent extraction should be possible in some respect. If this is not the case, is there any reason NaI or metabisulphate couldn't be used to isolate/purify as their adducts?

DraconicAcid - 22-4-2015 at 09:34

Quote: Originally posted by blogfast25

Quote: Originally posted by DraconicAcid

According to this: https://www.researchgate.net/publication/222458939_The_oxida...

Primary alcohols will be oxidized by bleach not to the acids, but to the esters....

You need the acetic acid there to make the solution acidic. If you wanted to make it easier to isolate the organic product, you could probably use an inorganic acid such as phosphoric, I guess. Just not as much.

gdflp - 22-4-2015 at 14:27

Here is the procedure from my notebook :

38.66g of Ca(OCl)₂(81.22g were used because the package listed it as 47.6%) was dissolved in 400ml of distilled water and the solution was filtered to remove any insoluble salts which were present in the pool-grade chemical used. This was chilled to 0°C in an ice bath and strong stirring was started. Next, a mixture of 50ml of glacial acetic and 19.4ml of benzyl alcohol was added dropwise via a separatory funnel. Finally, the solution was allowed to warm to room temperature over a period of ten minutes while still stirring. The bottom layer of crude benzaldehyde was removed using the separatory funnel to yield approximately 17ml of crude benzaldehyde as a slightly yellow oily liquid. No attempt was made to purify the benzaldehyde as I do not have an apparatus small enough for distilling it and I didn't have any metabisulfite at the time.

I plan to revisit this synthesis soon and do various small scale tests utilizing different amounts of acetic acid as there was likely a large excess of acetic acid, I just used a direct scaleup from the rhodium archive. Unfortunately, I don't have the funds at the moment to purchase any more benzyl alcohol, so I will just ration the amount I have left.