Is pseudoephedrine likely to disassociate from it's acid before the melting temperature is reached? by a far margin, or just before the m.p?
Here:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/comparison.ephedrines.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/comparison.ephedrines.html)
https://www.thevespiary.org/rhodium/Rhodium/chemistry/ephedrine.chou-jbc.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/ephedrine.chou-jbc.html)
'Pseudoephedrine Hydrochloride. C10H15ON·HCl.
Crystallized from alcohol in stout needles; mp 179-181°C, [á]D22 +58.75°; very soluble in water and in alcohol (see Fig. 5).
Pseudoephedrine Sulfate. C10H15ON·H2SO4 .
Prismatic needles; no sharp mp; [á]D22 +52.5°; easily soluble in water and in alcohol.
Pseudoephedrine Oxalate. 2 C10H15ON·C2H2O4
Needles;
mp 218°C with decomposition; difficultly soluble in alcohol; very soluble in cold H2O; neutral to litmus (see Fig. 6).'