Sciencemadness Discussion Board

Ethanol oxidation

Ramiel - 27-8-2004 at 17:17

I may as well hang my head and ask what's bothering me.

I've been trying to make ethanoic acid from ethanol... pretty simple compared to the other stuff a mad-for-science-scientist [thank you orgie :D] does, right?

NO! and it's hurting my brain. :mad:

first I tried the acidic permanganate oxidation at ~~10*C. I am greeted with an exceptionally 'estery' smell... and I think to myself - the acid catalysed esterfication? surely not in these quantities? So I leave it to react at near freezing and after about a week, the solution is the dark brown sludge of MnO<sub>2</sub>. The smell of baileys became more and more apparent as I was decanting the liquid from the white insoluble salt. Strange, but I had to stop myself drinking this beautiful smelling nectar.

So I'll distill that later for the ester and forget about the EtOOH.

Next stop is hypochlorite. I added stoichiometric amounts of 96% EtOH to 99% CaOCl.

No reaction.

I walk away and in my absence the reaction runs away, and I'm standing there scratching my head at a dry crater of hypochlorite in my beaker.

I try it again with more ethanol - just as a proof of concept. Nothing happens.

Why won't the hypochlorite give up it's oxygen... my sparse reading suggests it's a straightforward reaction.

Any help is much appreciated
Sincerely
- Ramiel

The_Davster - 27-8-2004 at 18:05

From ethanol_reactions on the FTP.
"The action of bleaching powder on alcohol was reported by Schmitt and Goldberg in 1879. These compounds reacted spontaneously after a lapse of 7-10 minutes; acetaldehyde and acetal distilled off, together with a greenish yellow oil which was believed to be ethyl hypochlorite. Goldberg studied the effects of diluting the alcohol with water. In equialent ammounts of water and alcohol there was no dilutent effect in evidence, but above this ratio water acted as an inhibitor. The presence of chloroform among the products was noted with these diluted reactants."

The PDF mentioned above is really informative, I hope to have a go at oxidizing ethanol to acetaldehyde via an ammoniacal solution of CuO in the near future.