ISSUE:

Hello,

what a problem, how do I synthesize ethylamine starting from acetylene as the only carbon source, try to convert it to ethanal and then to amide for its reduction and get the amine, but I have propylamine left...???

What can you advise me?

Man, it seems clear that there is no interest in a carbonyl group from what you say, then you can't load it, just add + carbons and that doesn't matter.

A simple idea, perhaps would be the reduction of acetylene to ethylene with H2/Lindlar's catalyst, then brominate the alkene with HBr and finally add NH3 (SN2 nucleophilic substitution).

Let's see if it works for you

Thank you, I did not take this reaction into account due to chemoselectivity, in this I do not have such a high efficiency due to the competition of ammonia or the primary amine, to continue substituting secondary and tertiary amines.

I see the reductive amination of ethanal as very possible.

Reductive amination is the proper method to obtain amines from aldehydes and ketones.

The reaction between haloalkanes and ammonia is not a good method, it produces a mixture of primary, secondary, tertiary amines and ammonium salts.

Greetings to all

You can do the reaction that oxk told you but instead of ammonia use sodium azide and then reduce it!
obtaining the primary amine Greetings,
I just flew, I was in some trouble...

Following the initial reasoning of acontreras, you arrived at acetamide which, by conventional reduction, becomes propylamine.
I have been reviewing the subject of amines, with which I have come across Hoffmann's reaction that seems to be perfect; Treating the acetamide with Br2 in a basic aqueous medium, ethylamine + CO2 would be formed, so we can remove the carbonyl group. The mechanism of the reaction is complex.