This alkaloid was found by Hesse in Papaver rhoeas Linn (red poppy) and its
reputed existence in opium now appears doubtful. The base crystallizes from a
mixture of CHCl3 and Et20 and sublimes at 21 5-225°C/0.02 mm. It has
[α]17.5D + 232° (CHCI 3) or [α]19D + 243° (CHCl3). It behaves as a weak base and
is sparingly soluble in H20, alkaline solutions and most organic solvents. It
dissolves in mineral acids giving an intensely red solution but investigation shows that only a small proportion of the alkaloid is used to produce the colour, the
major part being converted into a colourless, crystalline substance, Rhoeagenine,
a much stronger base, non-volatile, and stable to acids. This base is not isomeric
with the alkaloid as first thought but has the formula C2oH1906N, m.p. 236-8°C; [α]19D + l68° (AcOH).).
Rhoeadine itself contains two methylenedioxy groups, one methoxy group
and an N-methyl group. The salts are not easy to prepare but a crystalline
hydriodide dihydrate is formed by addition of KI to a solution of the alkaloid in
AcOH. The ultraviolet spectrum of the alkaloid shows absorption maxima at 205,
240 and 292 mμ.
