[pixie]

What chemical tests can be used to distinguish between methylamine and ammonia?

Can you please help because both methyl amine and ammonia turn red litmus blue and fom white clouds with HCl!

[Mitch]

HPLC should do it.

[pixie]

Is there no chemical test you can do?

[Dude]

Two possibilities:

1.  Scrape off some of the residue of the white cloud with HCl (salt) and check it's melting point.  There is about a 100 C difference between the methylamine HCl and ammonium chloride.

2.  If you have a IR gas cell, collect some off gas in a bag and then flush it through the cell and look for the CH stretch.

[Garneck]

I think I know.. so you have ammonium chloride, right? Try to look for Nessler's reagent somewhere.. it's some mercury compound, that has a characteristical reaction with NH₄⁺

Edit: Ok, I found it, it's potassium tetraiodomercurate(II)

http://en.wikipedia.org/wiki/Nessler's_solution

[Karakth]

There are two chemical tests, one is the reaction with HNO₂ and the other is burning.

1.  Scrape off some of the residue of the white cloud with HCl (salt) and check it's melting point.  There is about a 100 C difference between the methylamine HCl and ammonium chloride.

2.  If you have a IR gas cell, collect some off gas in a bag and then flush it through the cell and look for the CH stretch.

A little too complicated, and aren't these physical tests?
   

[movies]

Proton NMR would tell you right away.

IR would too.

You should also be able to smell the difference.

[CLUB387]

I think you would have a heck of a time trying to take a proton of ammonia or methyl amine since they are both gases.  Smelling them is certainly not recommended since ammonia is toxic and methyamine is a lachrymator. I suggest the addition of benzoyl chloride and characterization of the product by 1H-NMR or melting point.

[movies]

Both ammonia and methylamine are totally stable as aqueous solutions which you could definitely get an NMR of those solutions.  You can also buy solutions on methyl amine in THF, MeOH, and EtOH and ammonia solutions in MeOH, EtOH, iPrOH, or dioxane, all of which are fine NMR solvents.  Shouldn't be a problem.  The smell thing should be obvious because it's pretty tough to deal with significant amounts of either of these chemicals without smelling them.

It's also possible to do gas phase NMR, incidentally.

The chemical derivitization is definitely a good way as well, it's just less direct and would take more time.

[Garneck]

Yeah, but you have to have access to a NMR spectrometer..  

besides, in this case it's like driving 10 meters by car rather than walking the same distance..

[movies]

True, but if you have an NMR, then the whole process would take 10 minutes.  If not, it would take a lot longer to do the derivitization and then the MP.