Question

Describe the method of preparation of ?Ethanol.How will we obtain ethanol from methanol

Answer 1

Method 1

First lets react the methanol with PCl3 or HCl …(in case of HCl) the H+ gonna attack the OH bond to give a final result of Chloromethane

Do either Wurtz Reaction(Na with dry ether ) or Frankland Reaction (Zn) with 2 moles of Chorlomethan to get a final product of Ethane

Reaction of Ethane with Cl2 in presence of Sun light will give Chloroethane

Reaction of Chloroethane with Aq KOH will take up Cl to add OH to give a final product Ethanol

Method 2{Shorter}

First React Methanol with PCC to give a final product of HCHO

Reaction of Grignard Reagent (RMgX) take R=CH3 so reaction of CH3MgX in “acidic” medium will directly give you Ethanol

Method 3

CH3-OH + HBr ------> CH3Br + H2O

2CH3Br + (alc) KOH----->CH2=CH2

Reaction of of CH2=CH2 with H2SO4 ————→ CH3CH2OH

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Josh Velson, Lapsed Chemical Industry Consultant

Updated Apr 25, 2017

Most of the time there is absolutely no reason to make that conversion. However, there are two proposed industrial routes (as opposed to laboratory synthesis).
The first is indirect catalytic homologation, where you transform the methanol into an ester with acetic acid, catalytically carbonylate the methanol portion of the ester to acetic acid, and then hydrogenate. There's a rather energy intensive separating step in between each of these operations, but the advantage is that it's highly selective in comparison to direct homologation; the main side reaction is from the carbonylation forming acetals.
A second direct homologation basically adds methanols using a catalytic chain growth mechanism. However, there's no good way to stop at ethanol. Instead you get a product distribution based on the length growth mechanism.
Both of these are synthesis methods I came across while reviewing patent material for various processes proposed for production of fuel ethanol from syngas. Needless to say, they're not particularly likely to succeed in those forms.