Sciencemadness Discussion Board

Amino ketone formation ( looking for differing opinions on ketonizations

vannylaholic - 14-5-2018 at 13:40

So I plan to take beta alanine and form the calcium salet and react it with the molar equivalent of calcium acetate , I suspect an amino ketone will form. But I have a feeling that amino group isn't going to fare well under extreme heat needed to distill the calcium salts . any helpful ideas or flaws in my theory before I go for it

brubei - 14-5-2018 at 17:20

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Assured Fish - 14-5-2018 at 21:41

What i think the OP is attempting to do (judging by his post history), is the following reaction, based off the pyrolosis of calcium acetate to form acetone.


Pyrolosis of calcium carboxylates.png - 5kB

Unfortunately the reaction is unlikely to proceed the way you want and would likely lead to some acetone being your only distillate, which you may be able to discern by looking at that sketch but i will clarify.
The calcium salt is able to undergo decarboxylation like that with the acetate because the calcium cation is bound up between the two acetate anions due to calciuims +2 oxidation state.

This of coarse would not occur with sodium or potassium salts with a +1 oxidation state because this decarboxylation is an intramolecular reaction, not an intermolecular reaction.

Thus its not possible for a mole of calcium acetate and a mole of calcium alanine to condense together.

However, If you were to instead try to pyrolize the following salt then your reaction would theoretically work.


a working scheme.png - 2kB

However this still may not work, as the reaction is dependent on the volatility of the final product, as well as how stable it is towards high temperatures.
I did find the following in regards to 4-amino-2-butanone.
http://www.chemspider.com/Chemical-Structure.14185695.html
which indicates a BP of 155*C, which is well below the operating temperature of the reaction. This may work, but would be dependent on how well that ketone would be able to handle those extreme temperatures.
An inert atmosphere may also help to prevent any oxidation which would be disastrous.

vannylaholic - 15-5-2018 at 09:07

Thanks all I will run the experiment and post my results .

brubei - 16-5-2018 at 01:32

mea coulpa, the "Beginnings" section made me misunderstood the question :D

vannylaholic - 17-5-2018 at 06:48

So in a small scale of 1 gram ,I formed calcium alanine and preformed the pyrollsys to my surprise there was no distillate , but only a faint aroma of an amine like (very rotten fisn) aroma. I decided that its was more interesting and sensible to just react the calcium alanine instead of the calcium acetate and alanine. Could have I produced an alkyl amine of some sort , or is this similar to the aroma of of 4amino 2butanone , I can't find an aroma description anywhere ,

vannylaholic - 17-5-2018 at 06:51

Or could the amino ketone cyclize to 1methyl piperidine from the excessive heat,

Assured Fish - 17-5-2018 at 22:39

I was actually thinking it would instead polymerize and form black tar, as the heat would be enough to drive off water and dehydrate the product.
If it were cyclizing i would instead expect some kinda distillate.
The presence of an ammonia or alkyl amine aroma would more likely indicate decomposition of the product, but this is far from a qualitative way of determining any kinda reaction.
If the reaction you attempted were successful then i would expect the following product. 1,5-diamino-3-pentanone.


Proposed product.png - 1kB

http://www.chemspider.com/Chemical-Structure.11373728.html

According to that reference this compound should have a boiling point of 243*C.
However the temperature for the reaction might be too high for the compound to be stable, what temperature did you manage to get your boiling flask too?

Also did you see any water condensation at all in your flask?

If you weren't able to roughly determine the temp of your pot then i would suggest trying again and using at the very least one of those laser pointer thermometer things to get a rough idea of the pot temp.
Most thermocouples can handle temps that high but those laser dot thermometers are relatively accurate and should work fine for those kinda temperatures.

It might also be a good idea to try this in a steel distillation set up, if i recall watching NileRed's video when he made acetone, where he managed to melt his flask to the heating element.

Ive never attempted the reaction myself but it looks like it requires some pretty high temps to drive the reaction forward.

At the end of the day though it could just be that this reaction is incompatible with primary amines.
Can i ask, what is your goal with this experiment?
Because if you are trying to get to an end product there are likely several other way to get there.