acetaldehyde from ethanol using PtCl6H2

[noche]

Chloroplatinic acid selectivly catalyzes the liquid phase of ethanol to acetadehyd giving yelds exeeding 95%.
The reaction takes place in the absence of free oxygen at
80 deg. C and at atmospheric pressure.

Preperation of chloroplatinic acid can be found at Rhodiums in the document "Largescale methamphetamine production via catalytic hydrogenation"

This method  should also be suiltable for other alcohols includindg propyl alcohol wich can be used to make propylbenzene by chloropropylation of benzene followed
by a "dechlorination" with NaOH and KHSO4 giving 60% yeld.

The only thing I could find on this subject was psyloxys post: "benzodioxole --> isosaffy - totally easy - *maybee* ..." but that was olso kind of enough for me.

references.
Encyclopedia of chemical technolegy by Kirk Othmer
p. 845  vol.9  fourth edition.

[Osmium]

> Chloroplatinic acid selectivly catalyzes the liquid phase
> of ethanol to acetadehyd giving yelds exeeding 95%.
> The reaction takes place in the absence of free oxygen at
> 80 deg. C and at atmospheric pressure.

What will the oxidant be if not oxygen?

I'm not fat just horizontally disproportionate.

[foxy2]

Looks like Os is right.

Photoactivated oxidation by alcohols by oxygen.      
J. Am. Chem. Soc.  (1985),  107(21),  6116-17. 
Ab.
A wide variety of alcs. can be selectively oxidized by two electrons at room temp. by O2 if a H2PtCl6/CuCl2 photocatalyst is used.  The catalyst responds to visible light and is active in excess of 150 turnovers.  Quantum yields for product formation as high as 0.1 have been obsd. using 488nm light.  When primary alcs. are used as the substrate, aldehyde is formed in high yield with no appreciable overoxidn. to the acid.  The catalytic cycle involves a Pt(III) species, which undergoes a redox reaction with Cu(II) to regenerate the Pt(IV) catalyst. 


Photocatalytic dehydrogenation of liquid alcohols by platinized anatase.          
J. Chem. Soc., Faraday Trans. 1  (1987),  83(5),  1631-9.  Ab.
The photocatalytic dehydrogenation of liq. MeOH, EtOH, PrOH, and 2-PrOH was investigated using platinized anatase and 366 nm radiation over the range 278-303 K.  Activities and activation energies for carbonyl-compd. formation were effectively identical for the alcs. on Pt(0.5)/TiO2 prepd. by photodeposition.  The activation energy of 20 kJ mol-1 is assocd. with photoelectron transport through the anatase to the Pt particles.  With Pt(0.5)/TiO2 prepd. by impregnation and H2 redn., identical activities for the 4 alcs. were achieved after O treatment.


Electrogenerative oxidation of dissolved alcohols with platinum-graphite packed bed catalysts.          
Electrochim. Acta  (1993),  38(2-3),  221-34.


GB Patent 1520513

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[foxy2]

Ethanol Dehydrogenation with a Palladium Membrane Reactor: An Alternative to Wacker Chemistry.    
Raich, B. A.; Foley, Henry C.   
Ind. Eng. Chem. Res.  (1998),  37(10),  3888-3895.  Abstract
The use of a palladium membrane to remove hydrogen in conjunction with a catalyst leads to a shift further to the right in the acetaldehyde-forming step before the product can react deleteriously with ethanol, and thereby increase the yield of acetaldehyde substantially over the conventional reactor case.  With the membrane, ethanol conversion increased from 60% to nearly 90% with a commensurate rise in selectivity to acetaldehyde from 35% to 70%, moving the yield from 21% to 63%.


Ethanol dehydrogenation catalysts - a developmental approach.    
Chhabra, M. S.; Naidu, S. R.   
Chem. Ind. Dig.  (1996),  9(3),  118-122. 
Abstract
Dehydrogenation of EtOH is the most important process in the syntheses of aldehydes, ketones, and esters, since it is used for the manuf. of MeCHO.  This article discusses a Cu/SiO2 catalyst developed for this purpose, which can operate at low temps. and does not need any regeneration as it has a long onstream life.  The discussion is backed by plant and lab. performance data.

[PrimoPyro]

Why couldn't chlorine serve as the oxidant? (from the chloroplatinic acid)
The Water Will Be Your Only Mirror

[Osmium]

Well, it sorta could. Meaning, the chloroplatinic acid could, but that would be a rather expensive method.
I'm not fat just horizontally disproportionate.

[PrimoPyro]

Ah, excuse me, I think I may be mistaken.

Chloroplatinic acid selectivly catalyzes the liquid phase of ethanol to acetadehyd giving yelds exeeding 95%

Unless there is a way for the chlorine to be reduced back to revert back to the chloroplatinic acid, then the chloroplatinic acid cannot be considered a catalyst, by definition.

So, something either has to suck up the hydrogen from the chlorine/system, or chlorine is not the oxidant.

                                                   PrimoPyro

The Water Will Be Your Only Mirror

[foxy2]

A wide variety of alcs. can be selectively oxidized by two electrons at room temp. by O2 if a H2PtCl6/CuCl2 photocatalyst is used.

Ever hear of a Wacker Oxidation?

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[PrimoPyro]

Of course I have. Reread the first post: "In the absence of oxygen." That is what I was using as the criteria for this reaction. All I was saying is that logically there is more to it than being stated, or chloroplatinic acid is not a catalyst by definition, as it would be decomposed.

Correction: there is more than I inferred from the abstract, not more than stated.

                                                    PrimoPyro
The Water Will Be Your Only Mirror

[terbium]

What will the oxidant be if not oxygen?
Alcohol to aldehyde does not require any oxygen. The alcohol just has to lose H₂. If you are just looking to make aldehyde, as opposed to getting a paper published, then copper chromite does an admirable job as a dehydrogenation catalyst albeit one that requires higher temperatures.

[Osmium]

Well, I guess the chloroplatinic would be reduced by the H2 (or not???), so unless there is a re-oxidation of the catalyst happening in situ it would still be a rather costly way.
Or will the catalyst survive the H2 presence unchanged?
I'm not fat just horizontally disproportionate.

[Rhodium]

It is proably a dehydrogenation similar to the butanediol -> GBL reaction, as long as the H2 is vented away, the catalyst will go on like it used to...

[noche]

It is an oxidation. Unfourtunantly i forgot to write the key word in the text "Chloroplatinic acid selectivly catalyzes the liquid phase OXIDATION of ethanol to acetadehyd giving yelds exeeding 95%." Sorry about that.

[terbium]

Yes, any conversion of ethanol to acetaldehyde is, ipso facto, an oxidation. What we have been discussing is the second sentence of your first post: The reaction takes place in the absence of free oxygen .

[halfapint]

My impression: at the end of this Wacker oxidation chain is the cupric chloride, which is reduced to its cuprous state, or in some circumstances to the free metal. It is sacrificed to regenerate the oxidation state of the chloroplatinic acid, though I'm a bit vague on just what species may bee involved. I can conceive this all happening in the absence of free oxygen. Not sure if the liberated H2 actually plays any reducing role here, or just merrily bubbles away.

What was that foxy2 said about copper on silica? For some reason, I find that of even greater interest than chloroplatinic acid...
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.