[HP]

One more aproach with industrial hint:
C2H5-Br + Mg--> C2H5MgBr
C2H5MgBr + C2H5Br--> C4H10 (butan)
Butan gas is industrially oxidized to acetic acid with Co catalyst, at T=150C and 55atm presure:
C4H10 + O2 --> 2CH3COOH
Then using Kolbe or Duma methods or Borodin-Grignard you may transfer acetic acid to methane...

[swati]

   I think another method that can be used is :

1.)   Elimination of HBr from C₂H₅Br  to form  H₂C=CH₂
2.)   Ozonolysis of H₂C=CH₂ to form formaldehyde  HCHO
3.)   reduction of HCHO with HI in presence of red phosphorus to give CH₄

         

[HP]

Can you explain us the mechanism reaction CH2O + HI with red P to CH4?
Its really posible to obtain ethylen fron EtBr by dehydrobromination at heat and some basic catalyst or by dehydrobromination with ethanolic KOH at mild conditions. Then ethylene may be transformed  to acetic acid by industrial Wacker proces..

[swati]

Can you explain us the mechanism reaction CH2O + HI with red P to CH4?
Its really posible to obtain ethylen fron EtBr by dehydrobromination at heat and some basic catalyst or by dehydrobromination with ethanolic KOH at mild conditions. Then ethylene may be transformed to acetic acid by industrial Wacker proces..

   Sorry but I dont know its mechanism .
   The only thing I know about it is that on heating an aldehyde or a ketone with HI in presence of red P at 150 ^oC , it is reduced to corresponding alkane .


                                                 Red  P
                     HCHO + 4HI  -------------------->  CH₄ + H₂O + 2I₂
                                                  150 ^oC

[HP]

Yah it seems possible as HI is known reductive compound. But i think the formed elemental I2 will react with red P to PI3 which can hydrolyze with H2O to H3PO3 or H3PO4 and 3HI regenerated..Again at 150C HI can be farely god reductive agent similar to nascent H generators used at Clemenson reduction for example

[HP]

Also possible Wolf-Kishner reduction of CH2O with hydrazine:
CH2O + H2N-NH2 --> CH2=N-NH2 + NaOH --> CH4 + N2

[Alberto_Kravina]

My idea:

1.)C₂H₅Br -----> H₂C=CH₂ + HBr
2.)H₂C=CH₂ ------- Ozonolysis -----> CH₂O
3.)CH₂O -------LiAlH₄---> CH₃OH
4.)CH₃OH + HCl -----> CH₃Cl + H₂O
5.)CH₃Cl + Mg -----Grignard reaction ---> CH₃MgCl
6.)CH₃MgCl + H2O --------> CH₄ + MgClOH