Sciencemadness Discussion Board

Oxidation of ethanol

guy - 28-3-2007 at 13:44

Looking for way to oxidize ethanol (not using chromate or permaganate). Would electrolysis or oxygen do the trick? I'm sure oxygen needs some catalyst.

Magpie - 28-3-2007 at 13:52

How far do you want to go? acetaldehyde, acetic acid, or CO2? ;)

guy - 28-3-2007 at 13:55

Originally posted by Magpie
How far do you want to go? acetaldehyde, acetic acid, or CO2? ;)

Acetic acid is what I'm looking for.

I saw a paper online about Mn catalysts but they all need wierd ligands...

I'm thinking maybe we have Mn2+ salts in the alcohol then electrolyse it to some Mn4+ form which will oxidize the alcohol.

[Edited on 3/28/2007 by guy]

Levi - 28-3-2007 at 14:34

My old chemistry text mentions using a mixture of K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub> and H<sub>2</sub>SO<sub>4</sub> but it doesn't elaborate.

It says CuO and heat will take a primary alcohol all the way to the acid. If you want to stop the oxidation at the aldehyde stage you use a Cu catalyst instead of the CuO.

[Edited on 28-3-2007 by Levi]

guy - 28-3-2007 at 16:29

I would prefer something that works under mild conditions.

12AX7 - 28-3-2007 at 18:53


guy - 28-3-2007 at 19:00

Originally posted by 12AX7

Not interesting enough:P

Though I do appreciate the power of nature. Mother Nature is probably the best chemist.

not_important - 28-3-2007 at 19:19

Platinum and similar metals or oxides and air can do it. Air with acetic acid and cobalt bromide is another, although it also oxidises the acetic acid.

I'd like to hear of more options, and of ones that could oxidise ethylene glycol, the cobalt route tends to cleave the carbon-carbon bond and take it to CO2 and H2O.

Sauron - 28-3-2007 at 19:46

You want a one step, room temperature oxidation of ethanol to acetic acid, is that it? And you don't want biosynthesis.

I'll see what can be found. Don't hold your breath waiting, the conditions you imposed make this nontrivial.

(I can understand why you don't want to use Cr(VI) but what exactly do you have against alkiline permanganate and a little heat?)

[Edited on 29-3-2007 by Sauron]

Dr.3vil - 29-3-2007 at 06:29

most electrochemical oxidations of EtOH involve Pt/Ru/C catalysts and belong to direct methanol fuel cell research. The product is often water and occurs in several steps. I'll have to agree with Sauron that getting acetic acid is not trivial via ECO.

perhapses acetaldehyde as an intermediate would be possible with a divided cell.

C2H6O ---> C2H4O + 2H + 2e-

I'll keep digging as I have the same interest in electrochemical oxidations.


not_important - 29-3-2007 at 07:24

permanganate is expensive, and difficult to obtain in some areas. And for the shorter chain acids the isolation is more work. Always have to acidify with strong acids, for the lighter acids there's the problem of ending up distilling off a water-acid mix - you're back to distilling vinegar.

And converting ethylene glycol to oxalic acid with permanganate just isn't going to happen.

Strong base, heat, and air can be used to oxidise alcohols to the acids. For EG temperatures of 150 to 250 C and 25 to 100 atmospheres of air/O2 will give about a 60% yield of oxalic acid. Alcohols with alpha hydrogens can give condensation products.

This is related to those conditions

and the attacked is an oxidation that goes to the aldehyde or ketone.

Attachment: Cu_cat_oxid_alcohols.pdf (387kB)
This file has been downloaded 1520 times

XxDaTxX - 29-3-2007 at 09:32

I seem to remember coming across an old journal article a few years back .... Conditions were something like EtOH in H2O2 + Fe(III) salts in acid solvent ..... I think HCl was used. We used it in lab to oxidise a longer chain alcohol rather than wait for Fischer to come along, and it worked well.

guy - 29-3-2007 at 12:49

Originally posted by Sauron
You want a one step, room temperature oxidation of ethanol to acetic acid, is that it? And you don't want biosynthesis.

I'll see what can be found. Don't hold your breath waiting, the conditions you imposed make this nontrivial.

(I can understand why you don't want to use Cr(VI) but what exactly do you have against alkiline permanganate and a little heat?)

[Edited on 29-3-2007 by Sauron]

Yeah I know its not trivial but I just want to know what the options are. I've read a few articles but they all involve these unusual ligands.

And I don't want to use permanganate because well, I don't have a lot of it and it seems that it could be put to better use than this.

I read an article on using Ni2+ catalyst and household bleach to effectively oxidize alcohols in high yields to their acids.

Attachment: Nickel-hypochlorite oxidizer.pdf (186kB)
This file has been downloaded 1031 times

sonogashira - 29-3-2007 at 13:15

If your target is acetic acid, why not just distill it from sodium acetate and sulfuric acid.
Surely this is by far the easiest way? Perhaps I am missing something?Is it the reaction rather than the product that you are interested in?

[Edited on 29-3-2007 by sonogashira]

guy - 29-3-2007 at 14:00

Originally posted by sonogashira
If your target is acetic acid, why not just distill it from sodium acetate and sulfuric acid.
Surely this is by far the easiest way? Perhaps I am missing something?Is it the reaction rather than the product that you are interested in?

[Edited on 29-3-2007 by sonogashira]

Yeah it's more of the reaction I'm interested in..

Sauron - 29-3-2007 at 19:27

Great, @guy, that is actually rather nice.

We knew that hypochlorite converts ethanol to acetaldehyde but it doesn't stop there, it then goes into the haloform rxn and produces chloral hydrate.

So, in presence of 2.5 mol% of this heterogeous nickel oxide hydroxide catalyst, it takes a different route.

The standard conditions imposed by the authors involved 45 mmol of substrate, and 300 ml of 6% NaOCl. 45 mmol of ethanol isn't much. 20 grams. So to oxidize a liter of ethanol this would call for 15 L bleach. Hmmm. A 22 L flask to make a kg of acetic acid? Is this practical?

Here is the 1973 review article from CR that is cited in ths JOC paper.

[Edited on 30-3-2007 by Sauron]

Attachment: cr60296a004[1].pdf (1.6MB)
This file has been downloaded 750 times

not_important - 29-3-2007 at 21:32

Indeed, this looks interesting, guy. Thanks much.

Sauron - is there a reference you know of that tells the conditions for ethanol and hypochlorite going to chloral hydrate vs going to chloroform and format? I've an old ochem experiments book that has the second case in it, but never have seen a discussion of what determines which path is taken.

Sauron - 29-3-2007 at 23:30

Sorry, @n_i. We had a thread going on that subject but hard references were few and far between. In fact I may have misstated matters above. Maybe ethanol and hypohalite only gives haloform via acetaldehyde whereas ethanol + chlorine gas gives chloral and/or trichloroacetic acid via same intermediate aldehyde.

Trichloroacetyl chloride breaks down to chloroform and CCl4, too. H.C. (Boron) Brown pointed this out in a 1930s paper on chlorination of trichloroacetic acid with phthaloyl chloride gave only 52% expected product, the remained was CHCl3 and CCl4. My investigation of this as a possible preparative route to those route to those halocarbons was stymied by failure to access the reference Brown gave to an older paper in Rec.Trav.Chim which apparently has not been digitized.

Klute - 30-3-2007 at 11:02

I saw a few articles related to alcohol oxidation with H2O2 and FeBr3 or Fe(NO3)3.H2O, but the goal ws to stop at the aldehyde... It was conserning benzyl alcohol to benzaldheyde I think, and they said no carboxylic formation ws noticed... might be different for ethanol though, as the aromatic ring must have a certain influence on the stability of the aldehyde..

XxDaTxX - 30-3-2007 at 11:56

J. Am. Chem. Soc.; 1926; 48(8); 2083-2091.


In all of the following experiments the volume of the solution was 172 cc.
This contained 2 cc. of pure ethanol (0.2 millimole per cc.) and concentrations
of hydrogen peroxide, catalyst and acid recorded in the tables.
The temperature of all experiments was 35’.

Before the reaction started, all of the solutions used contained an original
concentration of acid, this being furnished in part by the hydrolysis of
the catalyst and in part by acid added to the solution. As a consequence
it was necessary to correct the acid titration’s values for the concentration
of acid present before the oxidation of ethanol began. A correction was
also made for the alkali used to precipitate the catalyst as ferric hydroxide.

A sharp end-point was obtained in the acid titration at the beginning of
the reaction, but near the end, when practically all the alcohol had been
oxidized, the end-point was indistinct and the acid value less than it should
be. This was shown to be due to the oxidation of acetic acid to carbon
dioxide, a reaction that does not take place, however, until the ethanol
is almost completely oxidized, as will be shown later. As a consequence
of this reaction, the titrations made near the end of the reaction are untrustworthy


1. Hydrogen peroxide in the presence of ferric salts (Fenton's reagent)
oxidizes ethanol to acetic acid. This reaction is quantitative. This reaction
is paralleled by the catalytic decomposition of the hydrogen peroxide
by the ferric ions. The two reactions are approximately unimolecular.

Note, oxidation of EtOH is the dominant reaction until it gets very low after which it goes on to oxidize acetic acid so you will have to kill the reaction at your appropriate endpoint.

[Edited on 30-3-2007 by XxDaTxX]

Sauron - 30-3-2007 at 16:49

Back to the Ni (II) - NaOCl system. It might make more sense to everyone if we call the black insoluble active catalyst which forms immediately and quantitatively by its real name instead of nickel oxide hydroxide.

It is nickel peroxide.

And if you have 15 L or so of bleach there to process 1 Kg ethanol, do you really care whether you use 2.5 mol% Ni (II) or the more traditional 1 to 1.5 equiv. ?

Because if you read the 1975 review I posted, you will see some remarkably different results compared to the catalytic procedure in the JOC article.

In particular note that you can oxidize benzyl alcohol to benzaldehyde not benzoic acid this way if you use an organic solvent not aqueous phase.

Many of the other transformationa are also highly interesting.

It's a good read.

this just in

roamingnome - 31-3-2007 at 13:24


A Langevin-type quartz vibrator (1.7 MHz, input power 50 W) was used to produce cavitation in 500 ml of 10% ethyl alcohol solution. As a result, 40 ml of 78% acetoaldehyde solution was obtained in the reservoir 5 minutes after commencement of ultrasonic vibrations.

in the presence of Oxygen ethanol reportably will oxidize

Eclectic - 31-3-2007 at 14:30

There is a patent I read a few years ago (of course I can't find it now) that showed air oxidation of slightly acidified alcohols in stainless steel reactors with only the trace of chromium supplied by the stainless steel serving as the catalyst.

[Edited on 3-31-2007 by Eclectic]

JohnWW - 31-3-2007 at 16:23

That would tend to impact upon the fermentation and storage of wines in stainless steel tanks, as opposed to the traditional oak barrells, unless air can be totally excluded while allowing the venting of CO2 produced in fermentation.

guy - 31-3-2007 at 17:40

I have a mixture of nickel and copper salts (from US nickel coins) I dont know how to separate it! grrr

Sauron - 31-3-2007 at 17:54

Gemtlemen, let's have some documentation.

@RG, what's your snippet from?

@Eclectic, it is very well known that a number of extremely ubiquitous microbes happily consume sugars and turn them into acetic acid, these bacteria multiply much faster than do yeasts and that is whywinemeakers operate microbiology labs on premises, They can't use biocides or they'd kill the yeast as well. Fermentation is anaerobic, these bacteria require air (oxygen) while yeast does not. In short there is always some acetic acid formed in wine via these imperfectly excluded bacteria

I suspect that any contribution by Cr in the SS alloy of the vat is down in the baseline noise level of the bacterial generation of AcOH -- which in any succesful fermentation is managed to be kept to an acceptable low level anyway.

not_important - 1-4-2007 at 03:18

Originally posted by guy
I have a mixture of nickel and copper salts (from US nickel coins) I dont know how to separate it! grrr

Check the properties of NiSO4 and CuSO4, I believe copper sulfate decomposes around 650 C while nickel lasts until 840 C or thereabouts. Heating the mixture to 700 - 730 C should decompose the copper salt to the oxide, leaving the nickel salt. Having not tried this, I can't say that the mixture might behave differently that the isolated salts, or that you might need to leech out the NiSO4, dry, and heat once again.

If you overheat the NiSO4 also decomposes into the oxide. The mixed oxides can be extracted with hot dilute H@SO4, with dissolves the copper oxide. I don't know what 'dilute' is exactly, consult a text on nickel mining.

Other wet methods include precipitation of CuS from an acid solution, precipitation of cuprous iodide and iodine by adding a soluble iodide (only for countries where the element iodine and its compounds have not been outlawed), using dimethylgloxime to precipitate the nickel (only for people with deep pockets).

I would have tried starting with the metal alloy, and electro-refine it by plating copper from the alloy to a copper electrode in an acid solution, using a low voltage. The nickel would go into solution as the copper dissolves to be plated out on the other electrode.

Another method, when you have a mix that is mostly nickel, the finely divided metals (from reducing the oxides) can be treated by the Mond process to extract the nickel. As this involves carbon monoxide (toxic) and nickel carbonyl (more toxic) it is not a process for the amateur or to do at home, unless your home is very isolated and your will is up to date. But it is a elegant method.

unionised - 1-4-2007 at 09:32

Just a thought, add iron filings or steel wool to give metalic copper and a mixture of nickel and iron salts.
Filter and add excess ammonia and bubble air through it. The iron ppts as Fe(OH)3 and the Cu stays in solution as the ammine complex.

Eclectic - 1-4-2007 at 12:21

@Sauron: The patent was teaching a catalytic O2 oxidation to esters with Cr as the catalyst, either added, or leached with HCl from the SS. No fermentation involved.

chemrox - 3-4-2007 at 06:59

chromatography? countercurrent extraction?

Sauron - 3-4-2007 at 22:26

@Eclectic, someone else (@JohnWW I believe) brought up the connection to viniculture in SS vats, it was not interjected by me. I was merely responding that that post.

It's hard to address the patent when you haven't posted it or remembered the number, isn't it?

guy - 5-4-2007 at 16:30

Another Nickel Peroxide article

Information on preparation of catalyst and procedures for oxidizing various alcohols. This example is for oxidizing saturated aliphatic alcohols.



Preparation of Nickel Peroxide.
-A mixture of 300 ml. of
6% sodium hypochlorite solution and 42 g. of sodium hydroxide
was added dropwise to 130 g. of nickel sulfate hydrate
in 300 ml. of water, and stirred for 0.5 hr. at 20".
The resulting black nickel peroxide was collected by filtration,
washed with enough water to remove active chlorine,
and, after crushing the cake to powder, dried over anhydrous
calcium chloride under reduced pressure.

Renewal of Nickel Peroxide.-After the oxidation reaction, nickel peroxide was collected by filtration, washed
with water, stirred with 6% sodium hypochlorite solution
(about ten times the quantity of nickel peroxide) for 20 min.,
filtered, washed with water, and dried.

Determination of Oxidation Rates for Saturated Aliphatic
-To a solution of 0.04 mole of each alcohol and 2
g. of sodium hydroxide in 100 ml. of water, nickel peroxide
(1.5 times the theoretical amount) was added under stirring
on a magnetic stirrer, and the heterogeneous mixture was
allowed to react for the given times at various temperatures.
The solid was then separated from the reaction solution by
suction filtration and washed with water. The combined
filtrate was acidified with dilute sulfuric acid and a portion
accurately weighed out from the solution was steam distilled.
The volatile carboxylic acid in the distillate was
titrated with 0.1 N sodium hydroxide solution

Also, NiOOH can be used to oxidize chloroform to hexachloroethane in 72% yield

[Edited on 4/5/2007 by guy]

Attachment: jo01052a026.pdf (571kB)
This file has been downloaded 703 times

Sauron - 5-4-2007 at 17:45

Yes, I noticed that, however it is not an exidation. It is a free radical initiation and dimerization. It implies that nickel peroxide might be useful as initiator for other FR reactions (in place of benzoyl peroxide or AIBN/SO2Cl2 systems for example)

However it is a little OT for this thread (like many of the other transformations described in the review).

Also, for many of us, CHCl3 is more valuable than hexachloroethane, unless you have an all consuming need to make Zn-based smoke bombs.

Magpie - 5-4-2007 at 18:48

It may be useful to know that nickel peroxide, NiOOH, also known as nickelic hydroxide, is the black material of the positive (+) electrode of a charged NiCd battery.

Sauron - 5-4-2007 at 20:03

For oxidation of ethanol, to acetaldehyde it is useless.

To acetic acid, in inert organic solvent it is very efficient.

For benzyl alcohol to benzaldehyde (in inert solvent) it is very efficient. 92%

For toluene to benzaldehyde and benzoic acid, it is claimed but no yield given.

For some other oxidations where we normally use KMnO4 it may be superior. Methylpyridines to nicotinic and isonicotinic acids for example.

Nickel peroxide's claim to fame is a very high ratio of available O2 to weight as compared to MnO2 etc. The potential of harvesting the powder from NiCd batteries rather than having to prepare it from bleach and soluble nickel salts is interesting and attractive. The applicability to numerous other transformations is also tantalizing.

[Edited on 6-4-2007 by Sauron]

KMnO4 + EtOH + NaOH ---> Sodium acetate --> Acetic acid

Dr.3vil - 10-4-2007 at 18:09

I need some help with the oxidation of ethanol in the presence of KMnO4 and NaOH to yield sodium acetate. There is plenty of info on “put the alcohol, oxidant, and base into a flask and you will get the carboxylic salt), but little info on how much and for how long. And what type of work-up is required


A 250ml Erlenmeyer flask was charged with 50ml of 95% EtOH and ~.60g KMnO4 with stirring. The KMnO4 was allowed to dissolve upon to which 75ml of 3M NaOH was added. Immediately upon adding NaOH, the solution turned from deep pink to dark brown. A precipitate was noticed on the bottom of the flask. The solution was then heated to boiling for approximately 15 minutes. The solution was then gravity filtered to separate the precipitate.

The filtrate is clear orange and strongly basic, the precipitate is muddy brown.

I would like to issolate the sodium salt...but have no idea if any of the reagents were used in correct proportion.

- 3vil

fwangj - 18-4-2007 at 16:13

Activated DMSO can oxidize ethanol to aldehyde.
I have an article of review for that.
If you need it, Please contact me.

not_important - 18-4-2007 at 17:32

Originally posted by Dr.3vil

I would like to issolate the sodium salt...but have no idea if any of the reagents were used in correct proportion.

- 3vil

Stoichiometry is your friend, and a good starting point. Sometimes an excess of a reactant is needed or helpful, but starting with balanced equations.

So start with balanced equations, use formula weights and liquid density values to determine the physical amount of the the reactants to use, and you most of the way there.

guy - 27-5-2007 at 19:03

Ok..I didnt want to use bleach because that would be too dilute. So I got a bunch of sodium dichloro-s-Triazinetrione (sodium dichloroisocyanurate)

Is there anyway to make a "bleach' solution out of this in situ. Like can I mix sodium dichloro-s-Triazinetrione, NaOH, NiCl2 and EtOH in one pot?

[Edited on 5/27/2007 by guy]

Sauron - 27-5-2007 at 20:23

The S in that name is not capitalized. If you capitalize it it means SULFUR of which there is none in this compound. The small s stands for sym. as in symmetrical, and the compound you are talking about is merely the monosodium salt of TCCA.

guy - 27-5-2007 at 20:38

Ok. so I tested it by adding some of the NaDCC with NaOH and hypochlorite is definietly formed. Ok good to go!

[Edited on 5/27/2007 by guy]

I added 68g NaOH to 100mL H2O and added that to an alcoholic solution of NiCl2*6H2O (10.17g) and 100mL of EtOH. The solution turned to a thick green sludge.
Then I added in portions, 158g of sodium dichlorocyanurate dihydrate. Each addition formed a brown coloration but quickly turned back to green along with a lot of heat! I foolishly did not use an ice bath (just plain water). I added the last portion too quickly and had a runaway reaction with ethanol and water boiling off vigorously.

Now I am left with the solids and tommorow I will try adding acid to see if acetic acid has formed.

[Edited on 5/28/2007 by guy]

guy - 28-6-2007 at 22:18

Indirect alcohol oxidation by electrolysis with Ni(OH)2 catalyst?

I have read a few journal articles on this method but they all used a NiOOH electrode. I am wondering if I can just electrolyze a slurry of Ni(OH)2 in alcohol? I have tried electrolyzing Ni(OH)2 by itself and it does indeed make NiOOH.