Chemistry help!!

[hegeland]

I am about to write about how to transform 2-propanole into 2-propanone with oxidation.

The thing I'm wondering is:

Does the actual transferring of electrones take place during the distillation or before, when the mixture of chemicals is under stirring?

Any serious help would be MUCH appreciated!

[Semih_Sayginer]

i would say "before" as distillation is normally just the separation of factions.

isnt it?

[hegeland]

Yeah, well maybe I should refine my question a little:

Do you need to add heat (such as the heat you use in distillation) or can you produce this specific redox reaction with just stirring the chemicals together?

[Semih_Sayginer]

ill pass on that one hegers

(at a guess id say yes, add heat)

[Robert602]

This is possibly the most off topic thread I've ever seen in off topic. Congrats

I swear I used to know this kind of thing but whatever chemistry I once studied seems to have left me. May be an obvious suggestion (or may be a stupid one, depending on how much I've forgotten ) but perhaps you could draw an enthalpy diagram? If the reaction is hugely endothermic then you'll know, if not, possibly time to hit the books, or flip a coin.

(Actually, if you are struggling, I can point you in the direction of some decent forums good at this stuff, they'll probably be happy to help)

Good luck anyway.

[hegeland]

Well, I don't blame you Semih! Wish I could say the same myself!

The thing is:

The aim is to create 2-propanone out of 2-propanole. To do this, you use the redox reaction.

You mix 2-propanole with ethanoic acid. Then you add some NaClO as the oxidation "starter" (pardon my English, Im short of time).

Let the mixture stand under stirring for about 15-20 mins.

Then you heat the mixture to free the 2-propanole from the other substances (distillation).

My quiesion is really whether the redox reaction starts as you mix the substances together or if it starts as you turn on the heat during the distillation?

[hegeland]

Thank you Robert!

Calculating on enthalpy might be a way of understanding the reaction, but the thing is our teacher have not mentioned enthalpy and the like when lecturing about oxidation of alcohols. So I don't think it's the way go in this case. Thanks anyway.

Will check here again tomorrow morning before I go to school!

[April madness]

hege, NaClO being the catalyst - does it start the reaction or just accelerate it? I'd imagine that would require heating. anyway, don't rely on me

[Robert602]

Ok, it was a stab in the dark anyway to be honest. There's quite possibly a general trend for oxidation of alcohols to be endothermic which might proclude the need to do any calculations, but if there is I've forgotten about it. If you need the answer for tomorrow the best place to go for a quick response might be the student room - it's a huge and very helpful board which usually has people online at all levels, from gcse to phd.

The science section is here http://www.thestudentroom.co.uk/forumdisplay.php?f=51 , but there's also a chemistry section under that which I failed to spot before posting a quick thread for you. Might be worth checking back there too before you head off tomorrow.

Failing that, a US based forum should be at its most active when us europeans are in bed. I'm not a member of any personally but googling reveals that about.com has one which looks reasonably alive: http://forums.about.com/n/pfx/forum....g=ab-chemistry

Hope some of that helps. Who knows, a chemist might just turn up from among TSF's ranks.

[hegeland]

Thanks a lot, Robert, your a really helpful man!

I don't think it's necessary for me to ask on those forums this time, but your links will certainly come in handy in the future!

[snookersfun]

Hege,
you got some good answers already I see.
I am not an organic chemist (blaeh), but some general observations:
in order to let two substances react you usually have to overcome the activation energy, even if a reaction is exothermic (a catalyst reduces that activation energy btw). If a reaction is endothermic, heat needs to be supplied for the reaction to take place. Otherwise heat simply accelerates a reaction.
Now to the distillation part, you are forming a ketone (acetone btw.) from 2-propanol. The acetone has a lower boiling point than the alcohol, therefore, you can distill it off the mixture. That way you not only separate the product but you also remove the product effectively from the equilibrium (you can write the reaction as an equilibrium (forward and backward reaction)) and as you probably know, if you remove a product from an equilibrium, you'll shift that equilibrium to the side of the removed product.

[hegeland]

Yes, I see. Ph.D. chemist and all, good to have you on the board!

But cannot stirring be a way of creating energy to start a process like this? Or is it always "heat energy" that is required?

Well, thank you all for your good answers! Will discuss it with my teacher later, but for now case closed.

[snookersfun]

Stirring nearly never produces enough extra energy. So stirring is just needed to mix uniformly or let the reactants meet. On the other hand, room temperature is enough for a lot of reactions to proceed (once reactants are dissolved and mixed).
Other energy possibilities are out there (photochemistry, ultrasound, radiation etc. but these usually involve different mechanisms, e.g. higher excited states of molecules or radicals respectively). By the way there is a very impressive reactions, which we all did in first year chemistry, which involves dropping a hammer or weight on a mixture of substances (great effect-boom, fire, etc.).
Perchlorates explode sometimes on slightest scratching.
So, yes, one can use other sources of energy.