Schuetzenberger and Schiffert, the coloring matters of madder
are alizarin, purpurin, pseudopurpurin, purpuroxanthin, and an orange
matter, which M. Rosenstiehl considers identical with hydrated purpurin.
Subsequently, there have been added to the list an orange body,
purpuroxantho-carbonic acid of Schunck and Roemer, identical with the
munjistin found by Stenhouse in the madder of India. It was known
that purpuroxanthin does not dye; that pseudopurpurin is very easily
transformed into purpurin, and the uncertainty which was felt concerning
hydrated purpurin left room merely for the hypothesis that Turkey-red
is obtained by the concurrent action of alizarin and purpurin. In the
meantime, the manufacture of artificial alizarin became extended, and a
compound was sold as "alizarin for reds." It is now known, thanks to the
researches of Perkin, Schunck, Roemer, Graebe, and Liebermann, that in
the manufacture of artificial alizarin there are produced three distinct
coloring matters--alizarin, iso or anthrapurpurin, and flavopurpurin,
the two latter being isomers of purpurin. We may remark that purpurin
has not been obtained by direct synthesis. M. de Lalande has produced
it by the oxidation of alizarin. Alizarin is derived from
monosulphanthraquinonic acid, on melting with the hydrate of potassa or
soda. It is a dioxyanthraquinone.
Anthrapurpurin and flavopurpurin are obtained from two isomeric
disulphanthraquinonic acids, improperly named isoanthraflavic and
anthraflavic acids, which are converted into anthrapurpurin and
flavopurpurin by a more profound action of potassa.
Pages:
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129