Comparative study of OTC Acetone in AP Synthesis

[Rbick]

My goal in this was to determine what type of OTC acetone would work best in AP synthesis. The idea came about when Mega suggested someone test the yields on acetone from various sources. To do this, I purchased five samples of acetone from several well-known sources. Before I go over those, a little on AP…

AP is formed in an acid-catalyzed nucleophilic addition when 3 acetone molecules (when referring to AP, I will be referring to the trimer form) bond with 3 atoms of oxygen (the oxygen being the nucleophile) in an aromatic ring structure with the carbon atoms in the ring bonded with 2 methyl groups. There are also dimer and open monomer forms, but those are not what we are going for here, as they are more unstable than the trimer. The reason AP is so sensitive can be seen in its molecular structure, with the single O-O bonds being very weak, making it sensitive to shock, friction, and heat. In acidic and relativley cool conditions, the trimer form is created more readily than the dimer and monomer forms. Drawing of AP structure (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/AP.jpg)


You can see how this comes about by looking at the structure of acetone here (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/acetone.jpg)

Note the double C=O bond (which classifies acetone as a ketone)

The oxidizer used is Hydrogen Peroxide, or H2O2. When the catalyst (HCl or H2SO4) is added, the peroxide molecules donate one oxygen atom, resulting in a water byproduct. Oxygen, being extremley electronegative, is attracted to the more partially positive charge (research polarity) of the carbon atom of the acetone molecule that is double bonded with an oxygen. The double bond is broken, and the carbon atom now possesses two single covalent bonds with oxygen atoms. This can be seen in the equation:


3H2O2 + 3C3H6O ---> C9H18O6 + 3H2O

A common misconception is that AP decomposes into CO2 and H2O. This is however apparently wrong. A paper posted HERE (http://www.technion.ac.il/~keinanj/pub/122.pdf) states that most byproducts are acetone and ozone. My assumption is that when AP is mixed with an oxidizer like AN, these byproducts then decompose into CO2 and H2O, although I am not certain. Read the article for more details.

Now for my test results:

I collected acetone from the following sources, listed in no particular order. The manufacturer of the acetone is placed next to the supplier along with the price per 1 liter.

Ace Hardware : ACE, $5.99
K-Mart : EZ, $5.99
Fleet Farm, Lowes, and Home Depot: Klean Strip, $4.49
Menards : Sunnyside, $4.98
Walgreens : Nail Polish Remover, N/A
Online Chem Supplier: Reagent grade, $3.75 per 30mL

The following quantities were used:

25mL Acetone
12.8mL 35% Hydrogen Peroxide acs/reagent grade(calculated to have same amount as in mega’s synthesis)
4mL 31.45% HCl
Temps:

All reactants were measured carefully and put into separate vessels prior to mixing. Care was taken to ensure the samples never mixed or came in contact with each other. All peroxide was cooled to 7* C. All acetone was cooled to –10* C. HCl was kept at room temp.

Reactants were mixed first without catalyst and temperature change was recorded. I assume the intensity of the temperature change will reflect somewhat the level of reactivity. HCl was added and progress was checked at 1 hour, 2 hours, 3 hours, and 12 hours. Reaction was complete by 12 hours and crystals were filtered. Other measurements taken can be seen down below.

EZ:
Temperature increased to 14*C
Density: .80g/mL
pH: 6
Final yield: 7.2g
Crystals were large in size compared to other samples, as large as 1cm long

Sunnyside:
Temperature increased to 28*C, did second test and it rose to 20*C
Density: .80g/mL
Final yield: 7.2g
pH: 6
Crystals finest of all OTC acetone products

ACE:
Temperature increase to 15*C
Density: .81g/mL
Final Yield: 7g
pH: 7

Klean Strip:
Temperature increased to 13*C
Density: .81g/mL
Final yield: 7.2g
pH: 6

Nail Polish Remover:
Temperature increased to 8*C
Density: .9g/mL
Final yield: 5.6g
pH: 7
Had largest crystals out of all samples, as large as 1.5cm in length

Reagent:
Temperature increased to 21*C
Density: .79g/mL
Final yield: 7.4g
pH: 6
Crystals were very fine and smooth

Over the first 3 hours after adding the HCl, I monitored the speed of the reactions. I’m assuming that the speed of the reactions reflects the amount of impurities in the sample. The slower the reaction, I assume that would mean more impurities. The density measurements should also reflect the level of impurities. Pictures can be seen through the below links:
1 hour: 1 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/fridgeleft1h.jpg) and 2 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/fridgeright1h.jpg)
2 hours 1 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/fridgelefth2.jpg) and 2 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/fridgerighth2.jpg)
3 hours 1 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/left3h.jpg) and 2 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/right3h.jpg)
12 hours 1 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/12hleft.jpg) and 2 (http://i164.photobucket.com/albums/u6/pudgedog69/Experiment/12hright.jpg)

The speeds of reactions went as follows fastest to slowest: Reagent, Sunnyside, Klean Strip, ACE, EZ, Polish Remover.

Conclusion: There was almost no difference in the final yields of the OTC acetone products. Aside from of course the polish remover, which was expected to have a low yield. I am suprised that I was able to get 5.6g out of it though. However, one has to consider the amount of impurities, the temp change, speed of reaction and quality of the product. Apologies for not having access to a microscope, but the sunnyside product looked by far the best, with finer, smoother looking crystals. So in conclusion, I would go with the sunnyside brand acetone found at Menards. It reacted faster, more intensely, had a good density, and had a better end product than the other OTC samples. It is interesting that the better performing samples were the less expensive ones. Although the yields were close across the board, you can make an educated guess about the impurities from the density. For example, the ACE product had .02 g/mL more mass than the reagent. Multiply .02 by 25, since we used 25mL of acetone. .02 (25) = .5g. So there is a potential .5g of impurities in the yield.

I hope this little study was helpful to people. Any critiques, corrections, or any comments would be great. Again I apologize for having a lack of proper lab equpiment such as a microscope. I’m working on that as we speak. But at least I have a reliable scale and thermometer. Enjoy!

Oh, and also: I now have 40+ g of AP lying around. I need something fun to do with it...

[Hinckleyforpresident]

Excellent work Rbick.

Was your HCl source muriatic acid? If so, what brand was it? Perhaps this study could be completed by trying out different HCl sources, and later maybe trying out different sulfuric acid sources to get a comparison. Perhaps then the Hydrochloric vs. Sulfuric debate could be ended.

[Rbick]

The HCl was muriatic acid, sold in 1 gallon amounts for something like 3 dollars. I'll have to get back with you on the name of the manufacturer, but I also saw muriatic acid sold from the same company as the acetone at menards: Sunnyside. They sold HCl of the same concentration (31%) in 1 gallon and 1/4 gallon amounts. The 1/4 gallon was something like $1.50. I would have gotten the smaller amount had I not bought the gallon from fleet farm first. That will last me a good year or two :D I actually had a gallon of old 27% HCl from at least 5 years ago. There was about 200 mL left and I had to get rid of it, as it finally got too dilute to actually carry out its function.

Considering the quality of the sunnyside acetone, I would feel confident in buying their HCl as well.

Perhaps this study could be completed by trying out different HCl sources, and later maybe trying out different sulfuric acid sources to get a comparison

I thought about that. Maybe with different sources of hydrogen peroxide too? As for now, my funds are stretched, so I'll have to wait a bit before I carry out another experiment. And I have about 2 gallons of acetone lying around I don't know what to do with. I'll use it as a fuel in a FAE or something.

[Charles Owlen Picket]

I think this may get back to the issue of really dry acetone. I was in a store and noticed that they sold two types of acetone; one of which was labeled "extra" or some such shit. There is little doubt in my mind that some are not anhydrous and therefore a poor choice for most synthesis. The trick would be finding methods of determining purity from the source. There MAY be one or two very large concerns which sell off heavy quantities for re-bottling.

.....pulling water out without distillation, finding contaminants, etc. - of this and other solvents had been something that was always in the back of my mind.

[Rbick]

Is this possible to do? I assume because of the volatility of acetone, it would be nearly impossible to separate it without a distillation apparatus. Perhaps a sealed container with a desiccant. The sealed container would prevent acetone or the solvent from escaping to the air and the desiccant would absorb the water. Just throwing that out there. Any other ideas?

[megalomania]

You might be able to pour the acetone over a molecular sieve and physically filter out undesired products, but I don't think anything would be as easy and convenient as distillation. Considering glass distillation equipment is readily available to amateur scientists for the same price as a decent cordless drill I can unabashedly suggest you get the right tool for the job. Saving money is all well and good, but you have to buy "something" to do chemistry.