Sciencemadness Discussion Board

preparing methanol

ionic bond - 23-6-2004 at 08:22

Hi

How can I prepare methanol from acetylene?

thanks
:)

unionised - 23-6-2004 at 15:35

Why? Methanol is a whole lot cheaper than acetylene.
Still, if you insist...
Add 2 moles of HBr to give dibromoethane stir with NaOH solution (for about a million years, I think this is a rather slow reaction) to hydrolyse this to acetaldehyde, (you might want to try the mercury-salt catalysed addition of water to the acetylene to give the aldehyde instead) oxidise it to acetic acid. .Treat this with PCl3 to get the acid chloride, react this with ammonia to give acetamide.
Then treat this with hypochlorite to give (via the Hoffman degradation) or treat the acid with hydrazoic acid and sulphuric acid (The Schmidt reaction) to give methylamine, then react this with nitrous acid to give the most expensive methanol (and in the poorest yield) ever known to mankind.

It would probably be easier to burn the acetylene to CO2, grow a tree in it, then pyrolyse the wood to get wood alcohol.:D

chemoleo - 23-6-2004 at 15:55

Well said :D
I do think, however, that preparation of acetaldehyde from acetylene is actually quite straightforward (with HgCl2), according to some preps I read.
In fact, one of my long-standing quests has been to make acetaldehyde that way. One day I will.... despite the loss of my chemical companion (doing experiments on your own is just not the same at all - I always loved sharing things :()

Reverend Necroticus Rex - 23-6-2004 at 16:24

would there be any way to go to methylamine without using hydrazoic acid, that stuff makes me nervous and I am in great need of the alkylamine bases because of a new found interest in organic chemistry :D

The_Davster - 23-6-2004 at 21:48

unionised: What isomer of dibromoethane is formed? 1,1-dibromoethane or 1,2-dibromoethane?

unionised - 24-6-2004 at 14:11

1,1