Common, cheap and green reducing agents

[Elite Engineer]

what are som relatively cheap, and environmentally safe reducing agents that could be used to reduce olefins /alkenes?

 

Looking to reduce propene to propane

 

[John Cuthber]

Is there a problem with using hydrogen?

[hypervalent_iodine]

Is there a problem with just buying propane? Or is this just to see if you can?

[Enthalpy]

With the growing success of polypropylene, oil cracking doesn't suffice to provide propene, which is additionally produced from other short olefins - so economics can't be a good reason.

[Elite Engineer]

Is there a problem with just buying propane? Or is this just to see if you can?

yea, just to see if I can.

Is there a problem with using hydrogen?

I dont have any platinum, and i dont really want to try raney nickel reduction. I was jsut hoping someone on here knew of some unknown cheap reduction agent that no one knows about and that was cheap...bit of a long shot.

With the growing success of polypropylene, oil cracking doesn't suffice to provide propene, which is additionally produced from other short olefins - so economics can't be a good reason.

I was just going to dehydrate propanol

[Enthalpy]

Things like cyclohexadiene (and polycycles) are a techological hydrogen carrier, as the compound turns easily into benzene.

 

No idea whether it's any useable, what kind of catalyst it takes, nor if sensible chemists would consider it instead of hydrogen...

 

Lithium (?) helps move double bonds within a molecule and make metathesis. Would it move hydrogen from cyclohexadiene to propene? Please take with much skepticism, until chemists give an opinion.

[hypervalent_iodine]

Things like cyclohexadiene (and polycycles) are a techological hydrogen carrier, as the compound turns easily into benzene.

 

No idea whether it's any useable, what kind of catalyst it takes, nor if sensible chemists would consider it instead of hydrogen...

It wouldn't work.

 

Lithium (?) helps move double bonds within a molecule and make metathesis. Would it move hydrogen from cyclohexadiene to propene? Please take with much skepticism, until chemists give an opinion.

You should probably avoid giving this sort of advice if you don't know what you're talking about.

 

There are a lot of reducing agents that could potentially work, but it depends on what the OP has access to and what they consider cheap. Really, hydrogen / Pt or Pd would have been my go-to and it's possible that getting 5 or 10% Pt/C is more doable than purchasing one of the many pyrophoric reagents that would work (such as sodium or sodium borohydride), even if it is a little more expensive (you only need a catalytic amount, anyway).

[Enthalpy]

You are right. Saturation of alkenes by 1,4-cyclohexadiene needs a catalyst like palladium that the OP wanted to avoid.

[Elite Engineer]

NaBH4 is out of the question. Things that ignite with water scare me and I don't want to store anything like that. What is an average portion of catalytic Pt? How how much would it cost. Long shot here...can could it be obtained from catalytic converters? I'm more concerned with disposing of the waste in a green fashion.

[hypervalent_iodine]

NaBH4 really isn't that scary and it doesn't react too violently with water. It fizzes and gets a little warm, but it won't catch fire the way that Na or LiAlH4 would. You would have to store it in a desiccator, but it's not difficult to keep over long periods of time. In any case, I understand your caution with pyrophorics. However, if you do ever find yourself having to use them for whatever reason, I would strongly urge you not to be scared of them. Be cautious, wear lots of PPE and have appropriate measures in place to avoid and extinguish any fires (if they occur), but never be afraid. People make more mistakes when they're nervous and that's clearly not something you want when dealing with dangerous chemicals.

 

I don't know how much the Pt would cost you. It would vary from supplier to supplier and I don't know which ones sell to hobbyists. How much depends on the scale. IIRC, I used to use about 3-5 mol% and the work up and purification was very easy as far as my compounds were concerned. The trickiest part was degassing my solvent to get rid of any oxygen, but even that is not difficult.

[Elite Engineer]

NaBH4 really isn't that scary and it doesn't react too violently with water. It fizzes and gets a little warm, but it won't catch fire the way that Na or LiAlH4 would. You would have to store it in a desiccator, but it's not difficult to keep over long periods of time. In any case, I understand your caution with pyrophorics. However, if you do ever find yourself having to use them for whatever reason, I would strongly urge you not to be scared of them. Be cautious, wear lots of PPE and have appropriate measures in place to avoid and extinguish any fires (if they occur), but never be afraid. People make more mistakes when they're nervous and that's clearly not something you want when dealing with dangerous chemicals.

 

I don't know how much the Pt would cost you. It would vary from supplier to supplier and I don't know which ones sell to hobbyists. How much depends on the scale. IIRC, I used to use about 3-5 mol% and the work up and purification was very easy as far as my compounds were concerned. The trickiest part was degassing my solvent to get rid of any oxygen, but even that is not difficult.

This was wonderfully helpful! I really thought NABH4 was a dangerous no no chemical you shouldn't use around the house. Your words and knowledge give me confidence, thank you! I also believe this is the best financial choice...a chem supply company I looked up is selling 1 gram of Pt catalyst for $65-$75

[Enthalpy]

Search for:

platinum catalyst

at eBay.com or elsewhere.

[Enthalpy]

For my personal information:

could one go from propanol to propane, without the propene step, but through propanol formate instead?

Esterification first, then let a CO₂ leave to get propane? Can this work just by heating?

Thanks!

[rktpro]

For my personal information:

could one go from propanol to propane, without the propene step, but through propanol formate instead?

Esterification first, then let a CO₂ leave to get propane? Can this work just by heating?

Thanks!

I think you mean oxidation and then reduction? You can oxidise propanol to carboxilic acid and then get propane using strong LiAlH4 or diborane/borane. If oxidation is not stron and you get aldehyde then HCl and Zn are used in the reduction. I dont clearly know the pathway reduction would follow and if alkene would be an intermediate. Edited February 27, 2014 by rktpro

[Enthalpy]

Thank you!

 

I meant esterification, from (Smiles) CCCO and OC=O to CCCOC=O

and then heat to let O=C=O leave CCC.

 

Is that any sensible?

[rktpro]

Thank you!

 

I meant esterification, from (Smiles) CCCO and OC=O to CCCOC=O

and then heat to let O=C=O leave CCC.

 

Is that any sensible?

Such esterification would happen in highly acidic medium with very poor yield. And no, CO2 can't be made to leave just by heating (edit) in this case. Edited February 28, 2014 by rktpro

[Enthalpy]

Thanks!