Sciencemadness Discussion Board

Can i make Acetone Enolate from..

Hopeless - 15-6-2007 at 16:34

Hi ya,

what Bases can i make at home OTC to make Acetone Enolate? this is what i got so far;

a base with a pKa higher than acetone, which is 23, reacting with acetone to form an enolate

i was looking at ordinary NaOH but has a pKa of 0.2 !?

Listed are :sodium amide, lithium diisopropylamide and several alkoxides, for example potassium tert-butoxide.

so OTC style what bases can i make and how(synthesis for each base)?

Thanks..

Ozone - 15-6-2007 at 17:11

NaOH will abstract the a-proton from acetone just fine (note, in the given procedure, that a small equilibrium amount of Na ethoxide is probably involved-NaOH in EtOH).

The product will be dictated by thermodynamic control rather than kinetic (which usually involves a strong hindered base, like LDA or DIBAL-H at very low temperatures -78 and down).

Just FYI, while I'm thinking about it:

There is always the competition between the strength of the base and the strength of the nucleophile. For example, butyl lithium is a very strong base, but it is also an excellent nucleophile. The result will not be the enolate, but the product of addition (see also sodamide). To avoid this, large bulky groups are added to diminish the nucleophilicity of the base.

OK, I digress:

A nice simple bit is given here (standard sophomore Organic Chemistry lab):

http://www.chm.davidson.edu/erstevens/381aldol.pdf

Cheers,

O3

[Edited on 15-6-2007 by Ozone]

Hopeless - 15-6-2007 at 17:57

O3 Many thanks,

Thanks for you info,

So can i add the NaOH directly to the Acetone in an ice bath? instead of dissolving NaOH in EtOH?

it's my understanding (limited heehee) that H20 and Acetone and NaOH and of course the Enolate are present in the mix, so distilling to get rid of the water is understood, but how can ya seperate the leftover Acetone from Acetone Enolate? or did i read things wrong?

Taa

Ozone - 15-6-2007 at 18:58

The enolate is not usually isolated. The carbonyl compound you wish to react with the enolate is usually added in-situ. The resulting product is then worked up depending upon its nature.

I suspect the at lest a trace of EtOH is required (ethoxide, Na) since the catalyst need only be present in relatively small amounts. Try dissolving 1.8 g NaOH in 18.0 mL water and then adding 13.5 mL 95% ethanol.

Some more information is attached.

O3

Attachment: Aldol_01.pdf (412kB)
This file has been downloaded 16405 times

Hopeless - 15-6-2007 at 19:14

Thanks for that...

I'm reading the below snippet and wondering how to make the Acetone Enolate with Naoh? :(

"Reaction of Acetone Enolate (1) and Iodobenzene (2). The procedure followed was similar to that described by Bunnett Scamehorn, and Traber. 7 The deep-brown solution obtained by mixing acetone enolate (10 mmol) with iodobenzene (2.4 mmol) was irradiated for 1 h (3.8 h when filtered) with a focused high pressure mercury lamp. The reaction was quenched with 60 ml of water and extracted three times with ether.

Many thanks..

The Endless Procession of Aspiring Criminals

Sauron - 15-6-2007 at 19:56

Aw, not another clueless wannabe trying to make phenyl-2-propanone. O3, drop this guy like a hot rock. He's not interested in enolates other than as a way to make stuff with which to cook fucking meth.

[Edited on 16-6-2007 by Sauron]

Ozone - 15-6-2007 at 20:00

Thanks Sauron, I already got that, heres the source:

http://www.intellicandy.com/oldschool/chemcandy/drone/enolat...

"Reaction of Acetone Enolate (1) and Iodobenzene (2). The procedure followed was similar to that described by Bunnett Scamehorn, and Traber.7 The deep-brown solution obtained by mixing acetone enolate (10 mmol) with iodobenzene (2.4 mmol) was irradiated for 1 h (3.8 h when filtered) with a focused high pressure mercury lamp. The reaction was quenched with 60 ml of water and extracted three times with ether. The organic layer was analyzed by GLC (5% SE30 on Chromosorb P. 130-230 °C at 4°/min, biphenyl internal standard). The major product isolated was phenylacetone (88%), although a number of unidentified minor products could be detected in trace quantity.

Interesting reaction involving an ionic-radical intermediate. Unfortunately, I cannot be party to any illicit activity regarding the product.

bummer,

O3

[Edited on 15-6-2007 by Ozone]

Hopeless - 15-6-2007 at 20:03

i am actually curious and interested in all reactions..

Sauron - 15-6-2007 at 20:11

Oh, sure you are. That's why the very first thread you post, the very first reaction you ask about is preparation of penylacetone.

FYI while it is perfectly okay to read about making this compound, if you actually DO it you will be commiting a federal felony. It is a DEA Schedule 1 (not List 1) Controlled Substance and its mere possession is a federal felony, making it is a federal felony.

Hopeless - 15-6-2007 at 20:23

Sauron quoted - the very first reaction you ask about is preparation of penylacetone

yeah true, but i have no intent of making, was just curious. i'm not in America so i don't know the laws..
i was actually bored, and came across that web page, got me thinking, i suppose you don't believe me..and don't blame ya.. well curoiusity ended

i know the old proverb curiousity killed the cat.. :)

OK so point me to an interesting chem article them? need something challenging in my life, boooored as a computer programmer and like the chemistry challenge..

thanks

Ozone - 15-6-2007 at 20:34

Try the JOC article cited in the reference that brought us to this point. Regardless of the final outcome, the Chemistry involved in your "simple" transformation is elegant.

O3

Polverone - 15-6-2007 at 20:42

Quote:
Originally posted by Sauron
Oh, sure you are. That's why the very first thread you post, the very first reaction you ask about is preparation of penylacetone.

FYI while it is perfectly okay to read about making this compound, if you actually DO it you will be commiting a federal felony. It is a DEA Schedule 1 (not List 1) Controlled Substance and its mere possession is a federal felony, making it is a federal felony.

It's actually schedule 2. Interesting -- I did not know (or had forgotten) that non-psychoactive chemicals could be scheduled as well as listed.

No more legal talk in this thread now -- just chemistry talk.

not_important - 15-6-2007 at 20:47

It should be noted that tert-butoxide is a strong base than the simple primary alkoxides. Using ethoxide will give lower yields, or even failed reactions, because much less of the enolate will be formed.

Ozone - 15-6-2007 at 21:20

This is true. Adjacent EDG's increase the electron density about the central carbon and the bulky groups decrease the nucleophilicity. Result? Better base!

The trace ethoxide/NaOH system works well with acetone though (if your not too worried about control of specificity); at least well enough for the old "dibenzyl acetone trick".

Wow, maybe we need a thread specifically for enolate Chemistry.

Broad topic!

O3

Sauron - 15-6-2007 at 21:23

@Hopeless, the forum is chock full of interesting chemistry that has nothing whatsoever to do with amphetamine chemistry,

[Edited on 16-6-2007 by Sauron]

Ozone - 15-6-2007 at 21:27

No doubt! Maybe Hopeless should UTFSE and/or go to Woelen's site for some *really* well done experiments?

Cheers,

O3

vulture - 25-6-2007 at 15:18

Cut the crap and get back to the thread at hand please, both of you. No more squabbling.

Polverone - 25-6-2007 at 15:21

Are there any remaining chemistry questions/answers for this thread? I just deleted two posts about politics/legalities that I'm sure were meant for U2U, since such discussion is really off topic in a thread about acetone enolate and I already specifically said not to post it here.

drfro2 - 12-7-2009 at 21:17

O3,

If i wanted to try this on a smaller more experimental scale using say,

0.9g NaOH in 9.0 mL water and then adding 6.75 mL 95% ethanol.

[excuse my newbness i tried to research this myself but could not find specific amounts to use]

How much Acetone would be needed for the reaction?
How long should i take to add the solution to the acetone?
At what temperature should i make sure the reaction does not rise above in the ice bath?
How will i know when the reaction is complete?

And finally is this safe for someone relatively new to chemistry to undertake?

DJF90 - 12-7-2009 at 22:37

NaH or KH are good bases to use should they be available - hydrides are very basic and completely non-nucleophilic. Alkoxides and even hydroxide should be fine for forming an equilibrium concentration of the enolate, with addition of another carbonyl compound taking place to form the b-hydroxy ketone, which then eliminates (E1cb) to give the a,b-unsaturated ketone (the irreversible step that drives the reaction to completion). I see no problem using ethoxide as the base - everything is in equilibrium anyway. If the ethoxide adds to the ketone, it just kicks back out again. The key ideas about the reaction is EQUILIBRIUM, and the irreversible step that drives the reaction to completion.

The aldol reaction works best when only one of the carbonyl substrates can enolise (i.e. the other has no a- hydrogens, eg formaldehyde, neopentaldehyde or benzoquinone) and the other carbonyl present has to be more electrophilc than the one being deprotonated (otherwise the deprotonated carbonyl will react with itself and completely ignore the other species). Please note that this is for equilibrium conditions only.

If a strong base is used, or a specific enol equivalent then the whole of the carbonyl compound is turned into the "enolate". The other carbonyl compound is then added, and the reaction should give a clean crossed aldol condensation.

[Edited on 13-7-2009 by DJF90]

drfro2 - 12-7-2009 at 23:08

Neither of those bases are readily available to me however lithium strips from batteries are still available here, would this be a suitable base?

DJF90 - 13-7-2009 at 00:26

Lithium is not a base. You could dissolve it in liquid ammonia and wait for the solution to turn colourless and use that (i.e. preparing lithium amide, another strong base, pKa ~33 ish?) or "burn" it in an ammonia atmosphere, again forming LiNH2. You could also try the same in a hydrogen atmosphere, forming the hydride. Alternatively (and preferably - supposing you have the experience to deal with lithiation reactions and the associated control/safety - then you could form an alkyl lithium (BuLi or MeLi are standard) and then lithiate diisopropylamine to form LDA - this is then used to form the kinetic enolate. (conditions are -78C, adding the carbonyl to the LDA solution, THF as solvent). But this isnt a reaction you can do safely (and in good yield) without the low temperature and the proper technique (anhydrous conditions, inert atmosphere...).

Tell me what the substrates are and I can provide better advice. At the moment I can only guess, which is not very helpful.

[Edited on 13-7-2009 by DJF90]

drfro2 - 13-7-2009 at 15:03

I've been looking into this for some time,

I find the P2P theory and controversy all very interesting, However i have no desire to make P2P, What i am interested in though is phenylacetic acid,

I was searching through this forum when i found this thread and wondered if i could take this route to phenylacetic acid via phenylacetone OR can i get there through a similar path without even having to go to phenylacetone.

I am aware of some other methods but this seemed like a shorter path if it is possible. Any suggestions?

entropy51 - 13-7-2009 at 16:04

Quote: Originally posted by drfro2  
I've been looking into this for some time,

I find the P2P theory and controversy all very interesting, However i have no desire to make P2P, What i am interested in though is phenylacetic acid,

I was searching through this forum when i found this thread and wondered if i could take this route to phenylacetic acid via phenylacetone OR can i get there through a similar path without even having to go to phenylacetone.

I am aware of some other methods but this seemed like a shorter path if it is possible. Any suggestions?


You're going to make phenylacetic from phenylacetone? That's a new twist. LOL

drfro2 - 13-7-2009 at 16:17

I know it sounds sort of ridiculous but could it work?

Otherwise is there a relatively short way to synthesize phenylacetic acid?

stygian - 13-7-2009 at 18:18

Well you could possibly haloform the above-mentioned ketone. Or perhaps some form of Willgerodt reaction.