Sciencemadness Discussion Board - Miscibility between saturated H2O and Acetone

Miscibility between saturated H2O and Acetone

Luke Lively - 9-6-2016 at 13:26

Hi all, apologies if I posted in the wrong section.

Quick question, would acetone mix with H2O saturated with NaOH?

Would acetone mix with partially saturated H2O?

Thanks.

[Edited on 9-6-2016 by Luke Lively]

gdflp - 9-6-2016 at 13:32

You would get a flask full of crap. Conc. NaOH would catalyze an aldol condensation of acetone with itself, forming a tarry mess quite rapidly.

Luke Lively - 9-6-2016 at 13:35

That's terrible news. Thanks for your help gdflp.

brubei - 9-6-2016 at 13:50

aldolisaton of acetone needs heat, also excess of water displace the equilibria to hydrolysis. Then if your reaction is faster than the degradation of acetone and easy to purify, it can be performed with only little trouble

Luke Lively - 9-6-2016 at 13:53

Assuming that I can work before the Aldolization takes place, would the acetone be miscible with the saturated H2O?

aga - 9-6-2016 at 14:04

Quote: Originally posted by gdflp

You would get a flask full of crap. Conc. NaOH would catalyze an aldol condensation of acetone with itself, forming a tarry mess quite rapidly.

Now there is a proposal i can readily test.

What would the tarry mess consist of ?

Some kind of polymeric form of acetone ?

Firmware21 - 9-6-2016 at 14:15

Most probably, as a linear "poly aldol" ?

I happen to have a special erlen in which i tried that reaction. 2 whole years of reaction time...
I'll post a picture someday.

And yes, it forms 2 layers when mixed with a saturated NaOH. 9 molar NaOH is what I used.

[Edited on 9-6-2016 by Firmware21]

PHILOU Zrealone - 11-6-2016 at 05:43

Quote: Originally posted by aga

Quote: Originally posted by gdflp

You would get a flask full of crap. Conc. NaOH would catalyze an aldol condensation of acetone with itself, forming a tarry mess quite rapidly.

Now there is a proposal i can readily test.

What would the tarry mess consist of ?

Some kind of polymeric form of acetone ?

CH3-CO-CH3 + O=C(-CH3)2 --> CH3-CO-CH2-C(-OH)(-CH3)2
CH3-CO-CH2-C(-OH)(-CH3)2 --> CH3-CO-CH=C(-CH3)2 (mesityl oxyde) + H2O
(CH3-)2C=CH-CO-CH3 + O=C(-CH3)2 --> (CH3-)2C=CH-CO-CH2-C(-OH)(-CH3)2
(CH3-)2C=CH-CO-CH2-C(-OH)(-CH3)2 --> (CH3-)2C=CH-CO-CH=C(-CH3)2 (phorone) + H2O
3 CH3-CO-CH3 --> C6H3(-CH3)3 (mesitylene) + 3 H2O
...
Each C=O could react with a CH3 close to a C=O and also you could get polymerization, cyclization, crosslinking from the conjugated C=C / C=O or C=C / C=C systems.

Thus yielding upon time orange, brown, black tarry-waxy-sticky compounds of undefined structure...

Firmware21 - 11-6-2016 at 15:24

And it should look like this after 2 years...

zhiang0113 - 12-6-2016 at 04:57

Quote: Originally posted by Firmware21

And it should look like this after 2 years...

That kinda reminds me of my recent attempt to hydrolyse paracetamol into 4-aminophenol... I had no idea the latter oxidised so quickly (even under acidic conditions). Left some horrible dark green-brown sticky mess clinging to the sides of my beaker, which looked pretty much like mold gone crazy.

aga - 12-6-2016 at 05:12

Yesterday i put 2g NaOH into one beaker of 20g acetone and 2ml conc H₂SO₄ into another.

The basic flavour formed 2 layers quite quickly, the acidic one didn't do much at all.

How fast is 'quite quickly' ?

Edit:

Googling revealed the 'Aldol Condensation' which says it should form mesityl oxide from two acetone molecules and produce some water, either by an Enolate route (basic) or Enol route (acidic).

Further reaction of mesityl oxide with another acetone to give isophorone in a ' Michael addition' appears to require some kind of catalyst.

Hey ! Yesterday evening the wiki page mentioned that, yet today the page seems to be a lot shorter and with less details !

[Edited on 12-6-2016 by aga]