Question

How we convert methanal into propanal

Answer 1

it is ethanol...not methanal

How we convert ethanol into propanol -->

Ethanol is first treated with KCN to form ethyl cyanide. Ethyl cyanide is then treated with water to form propanoic acid. Propanoic acid gets reduced by LiAlH4 to form propanol

Answer 2

Answer:

1. Using grignard reagent with methanal, then hydrolysis.

2. The product is then oxidised to form Propanal.  

Explanation:

Ethyl Magnesium Bromide (Grignard reagent) is taken and reacted with methanal.

C2H5MgBr + HCHO ------> HCH(OMgBr)(C2H5)

Then HCH(OMgBr)(C2H5) is hydrolysed:

HCH(OMgBr)(C2H5) + H3O+ ----------->CH3CH2CH2OH

Then CH3CH2CH2OH  is oxidised by sodium dichromate (Na2Cr2O7) acidified in dilute sulphuric acid to form propanal:

                                  Na2Cr2O7

CH3CH2CH2OH ----------------------------------> CH3CH2CHO

                                  dil. H2SO4

Hope this helps!