A violet coloring matter is formed, together with other substances, by
boiling for 100 hours in a reflux apparatus a mixture of morphine
(seven grammes), p-nitrosodimethylaniline hydrochloride (five
grammes), and alcohol (500 c.c.). The solution gradually assumes a red
brown color, and a quantity of tetramethyldiamidoazobenzene separates
in a crystalline state. After filtering from the latter, the alcoholic
solution is evaporated to dryness, and the residue boiled with water,
a deep purple colored solution being so obtained. This solution, which
contains at least two coloring matters, is evaporated almost to
dryness, acidulated with hydrochloric acid, and then rendered alkaline
with sodium hydrate, the coloring matters being precipitated and the
unchanged morphine remaining in solution. The precipitate is collected
on a filter, washed with dilute sodium hydrate, dried, and extracted
in the cold with amyl alcohol, which dissolves out a violet coloring
matter, and leaves in the residue a blue coloring matter or mixture of
coloring matters. The violet coloring matter is obtained in a pure
state on evaporating the amyl alcohol. Its platinochloride has the
formula PtCl_{4}.C_{25}H_{29}N_{3}O_{4}.HCl, and has the
characteristic properties of the platinochlorides of the majority of
alkaloids. The coloring matter, of which the free base has the
formula--
(C_{6}H_{4}N(CH_{3})_{2})--N==(C_{17}H_{19}NO_{4})
forms an amorphous mass with a bronze-like luster; it is sparingly
soluble in water, freely so in alcohol, its alcoholic solution being
strongly dichroic; its green colored solution in concentrated
sulphuric acid becomes successively blue and violet on dilution with
water; it dyes silk, wool, and gun cotton, but is not fast to light.
Morphine violet is the first true coloring matter obtained from the
natural alkaloids, the morphine blue of Chastaing and Barillot (Compt.
Rend., 105, 1012) not being a coloring matter properly so called.
--_P. Cazeneuve, Bull. Soc. Chim._
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