Hello @ x9Ev3nTh0riz0n9x
I found this from a official document
Birch reduction: this proceeds via a dissolving metal reduction of
ephedrine
or pseudoephedrine in the presence of ammonia.
The reaction involves mixing the
ephedrine or pseudoephedrine with
anhydrous ammonia gas and
either sodium or
lithium metal.
The mixture is then allowed to stand until the ammonia has evaporated. Isolation of the meth oil is carried out by direct solvent extraction and filtration.
The reaction product is further purified by formation of the hydrochloride
salt and re-crystallisation. In illicit practice, Birch reduction is usually completed in a one-step reaction using widely available ammonia, and lithium strips from batteries. Despite this, Birch reduction usually produces a very “clean”
end-product. Several route-specific impurities such as N-methyl-1-(1-(1,4-cyclohexadienyl))-
2-propanamine are reported in the literature. The reaction involving anhydrous ammonia is hazardous and explosions in clandestine laboratories are not uncommon.
