CH3OH + 2CuO Which reaction is true?

[katarina]

Which reaction is true? Or maybe both?
CH3OH + 2CuO = HCOOH + 2 Cu + H2O
CH3OH + 2CuO = HCHO + Cu2O + H2O
How to explain this since the ratio of substrates in both reactions is the same.

 

link removed

[DrP]

I'm guessing at the second one. I can't see the alcohol reducing the CuO back to the metal. The Cu1 going to Cu2 though looks feasible with the production of the ketone.

 

I bet hypervalent_iodide will be able to explain why.

 

Edited May 15, 2019 by DrP

[katarina]

Thank you 

[DrP]

no problem... although I would check the reasoning behind it, I could be wrong.

Also, sorry, it's formaldehyde not a ketone (which is very similar with the c=o) obviously.  

[studiot]

Have you considered the solubilities (not necessarily in water) of cuprous v cupric oxides?

 

eg in Fehling's solution/test.

Edited May 15, 2019 by studiot

[hypervalent_iodine]

I’m not overly familiar with using copper in this way, but I believe that you would typically use CuO catalytically in the presence of O₂ (rather than stoicheometrically) to give the aldehyde. I don’t think you would get the acid, but I am not 100% sure. 

[DrP]

OK - Typing the LHS of the equation into google gives links only to the formaldehyde as a result from what I can see. I don't have time to read through the results, but if you type 'CH3OH + 2CuO ' into google there should be some reading for you... at first glance it's all giving the aldehyde as the product.

[studiot]

1 hour ago, DrP said:

OK - Typing the LHS of the equation into google gives links only to the formaldehyde as a result from what I can see. I don't have time to read through the results, but if you type 'CH3OH + 2CuO ' into google there should be some reading for you... at first glance it's all giving the aldehyde as the product.

Better  to type in "methanol and cupric oxide"

https://www.google.com/search?client=firefox-b&ei=NwvcXPe7AbHzxgOs8obgBA&q=methanol+and+cupric+oxide+&oq=methanol+and+cupric+oxide+&gs_l=psy-ab.3..0i22i30.152328.177874..181186...0.0..0.146.3558.37j6......0....1..gws-wiz.....0..0i67i70i251j0i67j0i131i67j0j0i131j0i10i67j0i13j0i8i7i30j0i13i30j33i22i29i30.9Pr9Xyq7Wh4

This gives lots of stuff including the comaprison of copper and chrome oxides as catalysts

https://www.researchgate.net/publication/231366160_Complete_oxidation_of_ethanol_acetaldehyde_and_ethanolmethanol_mixtures_over_copper_oxide_and_copper-chromium_oxide_catalysts

 

It does seem you have to heat the methanol over the oxide.

 

Unfortunately so many sites these days want to collect personal data an put up a barrier until you agree.
So I leave and never return.

[John Cuthber]

Hot copper oxide is used in classical chemical analysis to convert organic compounds to carbon dioxide and water.

 

What mixture of products you get will depend on temperature, contact time, proportions and other stuff.

Passing methanol vapour over hot copper (metal- not oxide) will produce formaldehyde.

The commercial synthesis uses silver, rather than copper.