Oxidation of Ethanol to Ethanal?

Hi guys,
I NEED HELP! I have a presentation tommorow on the oxidation of ethanol to ethanal and I'm lost :/

Firstly, I need to know the reaction mechanism involved. Does anyone know the steps on how to get from ethanol to ethanol?

I know the reaction is something along the lines of:
3CH3CH2OH + CR2O7 + BH --> 3CH3CHO + 2CR3 + 7H20

but I need to know what's happening step by step. I've searched everyone on the internet and I cant find anything!

Not only that, I need to know the curly arrows involved too!

Can someone please help me out

Quote: Originally posted by mnick12

This took me a gut-wrenching 3 minutes to find: http://www.springerlink.com/content/u14n74051g547p07/ .

Quote: Originally posted by madscientist

That is the mechanism!

I'm so confused

what's a mechanism? Like a catlyst? or something...

ahhhhhhhh

Quote: Originally posted by madscientist

Is this the first time you looked at any of the material for your class? You already were given the answer. If you can't recognize that, you're going to have to do some reading. If explanations are not given in your textbook, which I find hard to believe, here's some helpful articles: http://en.wikipedia.org/wiki/Reaction_mechanism http://en.wikipedia.org/wiki/Arrow_pushing http://www.chem.wisc.edu/areas/reich/handouts/elecpush/epush... You're on your own until you can show you learned something. Sciencemadness is not Academic Dishonesty 911 - no one here is going to make a presentation for you.

Thanks for the help everyone!

I have one more question, does anyone know what enviormental conditions must be in place for oxidation to occur?

EthanOL can be converted to it's aldehyde (ethanAL) by passing it over hot copper as a catalyst.

This is called dehydrogenation, as a pair of hydrogens are removed by the copper.

Count all the hydrogens on ethanOL in this picture. The O-H on the right is the functional group, and here it is an alcohol group. You can have alcohols of lots of different things, so long as they have this O-H group sticking off them.


This is ethanAL. The left side carbon of the molecule has stayed the same, but the one on the right has changed, there is now only one hydrogen left and the oxygen has double bonded to the carbon on the right - this is because carbon likes having four bonds and oxygen can make two. With two of the hydrogens missing, the oxygen makes up for the lack. If you count the number of bonds to the right hand carbon in ethanOL and then ethanAL, you'll see they're the same; four. The only thing that's changed is the number of hydrogens present.


This catalytic method is very simple. Ethanol is blown into solid copper turnings, wire, powder or (far more effective) copper that's deposited on a type of sponge (zeolite - which is also used in kitty litter and washing powder).

The copper is heated to around 300C.

The two hydrogens that get removed from each molecule of ethanOL come out of the process as hydrogen, H2.

Zeolite is a mineral you find in rock. If you roast it, it becomes microporous. When you look at it under a microscope, it will be full of billions of tiny holes. When the copper is deposited on that, it gives the copper a gigantic surface are.

Both the bulk production methods for ethanAL use catalysts. But this copper one is not how ethanal is typically produced on a bulk scale, but bulk quantities of it have been made from surplus grain alcohol (ethanol), using this process.

The alternative method starts from ethylene and uses a palladium (platinum) catalyst and oxidation, as it's cheaper when you're running huge plants that can handle stranger materials.

There are, I suppose, three main stages to your level of knowledge in chemistry.

To begin with, you'll be mixing things and only know very roughly what is happening.

By the time you're 16-18, you should know what functional groups are and be starting to understand how they swap and why they're important.

As you're going from 17 to 18 to university, you should know what mechanisms are and have studied at least one of them. The mechanism tells you precisely how the things are swapping electrons and parts of the molecules around.

Mechanisms aren't chemical by chemical things, they apply to broad spectrums, since the specific chemical doesn't matter so much as what functional groups are on it; and there aren't anywhere near as many functional groups as there are different molecules with different combinations of them present.

They are called functional groups because they are the part of the molecule that is typically involved in a reaction; that gives it it's main characteristics.

E.g. EthanOL and ethanAL are very similar, the only change is in their functional group. One makes you drunk and the other makes you feel very sick if you drink it.

YOUR BODY ENZYMATICALLY CONVERTS ETHANOL TO ETHANAL WHEN YOU DRINK ALCOHOL, AS IT TRIES TO BREAK DOWN THE CHEMICAL

Which is part of the reason for feeling so nasty once the ethanol is gone.

These are called tautomers. The molecules are virtually identical. The only change is the state of their functional group. And it's also a simple change. The functional group is being oxidised, from ethanOL to ethanAL (a higher oxidation state).

If it oxidises a step further, it because ETHANoic acid.

This is what's in vinegar. And wine that hasn't been sealed up properly, or that's been left open for too long, will sometimes smell a bit like vinegar, as this is what's happened.

The ethanOL has oxidised to the higher oxidation state, the acid. There are some bacteria that will do this if they get into the wine, and it's one way of making vinegar (dilute ethanoic acid).

Ethanoic acid;


Here is some zeolite. It looks pretty boring, but is used for a lot of chemistry work due to it's special microscopic pore structures. It can do some amazing things given how simple it is.


Pure, specific forms of zeolite are usually used to carry catalysts like copper, and they are powdered by grinding them, to give them an even larger surface area. Here's what the grains look like under an electron microscope.


The topic of making ethanAL, and the various different methods, has been discussed a lot on this forum. You can find them by searching for ethanal and aldehyde (although the latter will bring up things related to other aldehydes as well). Here is a link to one such thread, showing people actually trying the different ideas

[Edited on 8-2-2011 by peach]