[strider]

hi, i was wondering as to how can Ethyl bromide be converted into Methane. I'm all puzzled 

[Dan]

here's an idea.

1. Eliminate HBr to give ethene
2. Ozonolysis to give formaldehyde
3. NaBH₄ to give methanol
4. TsCl to give MeOTs
5. LiAlH₄ to give methane

It's a bit long though, so there is probably an easier way...

[strider]

thanks man, u saved me much time  if u somehow manage to find an easier way to carry the conversion please do let me know 

[Dan]

sorry, i meant formaldehyde, not acetone, I have corrected it...

[Dan]

Actually, from formaldehyde you could do W-K reduction, Mozingo reduction, or Clemmenson reduction. That's more obvious and has fewer steps...

[strider]

hmmm...cant we just convert ethyl bromide into ethane and then through thermal cracking obtain methane. If so, what would be the exact chemical reaction..

[Dan]

I don't know enough about cracking to answer that confidently, but I don't think you can crack ethane into two methane (not enough H).

To get ethane from ethyl bromide, you could use Bu₃SnH with AIBN initiator (this is a radical reaction).

I think the best bet is to get to formaldehyde and then reduce with Wolff-kischner, Mozingo or Clemmenson.

[strider]

yup, ure right. Thanks for helping me out 

[lavoisier]

There's in fact a simpler way (in terms of chemistry involved and reagents used), even though nobody would ever use it to make methane, I guess.

EtBr + LiOH --> EtOH + LiBr
EtOH + KMnO4 --> CH3COOH
CH3COOH + NaOH --> CH3COONa + H2O
CH3COONa --> CH4 + CO2

I remember reading somewhere that acetates are the only simple fatty acid salts undergoing decarboxylation on heating.

[HP]

And what happen with your Na, where H coming from 
I suggest the path to H3CCOOH and after that:
2CH3COOH + Ag2O--> 2CH3COO:-Ag+
CH3COO:-Ag+  + Br2 --> CH3Br (Borodin reaction)
CH3Br + Mg--> CH3MgBr (Grignard)
CH3MgBr + H2O or alcohol --> CH4...
Also from acetic acid-->bromacetic acid-->nitromethane-->Me-NH3-->Hoffman elimination-->CH4
Do you think bromacetic acid may thermally decompose to CH3Br?
Thats what i can suggest now

[lavoisier]

And what happen with your Na, where H coming from

J. March, Advanced Organic Chemistry, 4th edition Wiley Interscience, page 627:

"An exception is acetic acid, which as the acetate, heated with base, gives good yields of methane".

But I have no idea of the mechanism.

In either way, this would be the most expensive methane on Earth!

[HP]

Heating with base is another thing Here we are discussing only possible on blank sheet synthesis with about no practical cost. But its always useful to think about how can prepare some compound from others in the lab as we all know how rich Sigma&Aldrich are from the same kind of thinking )

[lavoisier]

HP,

apparently the fact that they use a 'base' tells you something more about how it works and where this 'H' comes from. Could you please explain it to everybody? Thanks

[HP]

I am not sure but may be so:
CH3COONa + NaOH heat--> CH4 + Na2CO3
So H comes from OH from sodium hydroxyde...

[HP]

Oh, yes this is the so known method of Duma: heating sodium salt carboxylic acid with melted NaOH.
Another similar method is the Kolbe method for electrolysis sodium salt carbo acid in water solution...