12. QUINONES: STRUCTURE AND DISTRIBUTION
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about pH 9. It can be reduced with alkaline sodium dithionite, forming
a yellow solution which returns to green on shaking in air. It appears
to be a polyhydroxypolycyclicquinone.
The second pigment is hallachrome (192a), an acidic red coloring
matter present in the integument of the polychete worm Holla parthenopeia (Delia Chiaje) originally thought to have the structure, 2,3dihydroindole-5,6-quinone-2-carboxyhc acid. It gives a green solution in
alkali, changing reversibly to blue violet with acid, and is readily reduced to a yellow leuco compound, the original color being restored in
air. Beyond this, it is doubtful if any of the original work is reliable,
but recent work by Bielig and Möllinger (192b) suggests that hallachrome, C21H24-25NO9S, may be a hydroxyquinone sulfonic acid. A
closely related vermilion pigment, hallorange, is also present.
3. Arthropoda
In this phylum a group of simple benzoquinones has been identified
in Myriapoda, Insecta, and Arachnida. In the order Hemiptera (Insecta), a few Coccidae secrete anthraquinones, and complex aphin pigments (extended quinones) are found in a number of Aphididae. Once
again there is great diversity of structure, and as the number of species
examined is relatively trivial, little correlation can be attempted. No
quinones have yet been found in the Crustacea. This section deals only
with quinones that have been isolated as such and is not concerned
with the intermediate formation of quinones involved in the hardening
of the cuticle of arthropods. This subject has been reviewed recently
(193).
a. Benzoquinones. The simplest of all quinones are found in insects
and millepedes. The discharge of obnoxious gases by certain insects
has been well known for a long time, but only in the last few years,
through the application of modern techniques, has the presence of
quinones been definitely established, mainly by the work of Roth,
Lederer, Pavan, and Schildknecht. Many observers have noted that
millepede secretions are yellow or brown and have an odor likened to
that of the halogens or nitrogen peroxide (194). Such exudates probably
contain benzoquinones. p-Benzoquinone itself has been positively identified in the beetle Brachinus crepitans (Linn.) (195), in the cockroach
Diploptera punctata (Eschscholtz) (196), and in the millepede Spirostreptus castaneus Attems (197). Earlier claims that benzoquinone is
also emitted by the millepede Julus terrestris (198) and the cockroach
Blaps gigas Fischer (199) were not supported by adequate evidence.
Nevertheless it is fairly certain that a simple quinone (or quinones)
does occur in those species. Reference to Table V shows that methylbenzoquinone (toluquinone) occurs most frequently, both in Insecta
677
about pH 9. It can be reduced with alkaline sodium dithionite, forming
a yellow solution which returns to green on shaking in air. It appears
to be a polyhydroxypolycyclicquinone.
The second pigment is hallachrome (192a), an acidic red coloring
matter present in the integument of the polychete worm Holla parthenopeia (Delia Chiaje) originally thought to have the structure, 2,3dihydroindole-5,6-quinone-2-carboxyhc acid. It gives a green solution in
alkali, changing reversibly to blue violet with acid, and is readily reduced to a yellow leuco compound, the original color being restored in
air. Beyond this, it is doubtful if any of the original work is reliable,
but recent work by Bielig and Möllinger (192b) suggests that hallachrome, C21H24-25NO9S, may be a hydroxyquinone sulfonic acid. A
closely related vermilion pigment, hallorange, is also present.
3. Arthropoda
In this phylum a group of simple benzoquinones has been identified
in Myriapoda, Insecta, and Arachnida. In the order Hemiptera (Insecta), a few Coccidae secrete anthraquinones, and complex aphin pigments (extended quinones) are found in a number of Aphididae. Once
again there is great diversity of structure, and as the number of species
examined is relatively trivial, little correlation can be attempted. No
quinones have yet been found in the Crustacea. This section deals only
with quinones that have been isolated as such and is not concerned
with the intermediate formation of quinones involved in the hardening
of the cuticle of arthropods. This subject has been reviewed recently
(193).
a. Benzoquinones. The simplest of all quinones are found in insects
and millepedes. The discharge of obnoxious gases by certain insects
has been well known for a long time, but only in the last few years,
through the application of modern techniques, has the presence of
quinones been definitely established, mainly by the work of Roth,
Lederer, Pavan, and Schildknecht. Many observers have noted that
millepede secretions are yellow or brown and have an odor likened to
that of the halogens or nitrogen peroxide (194). Such exudates probably
contain benzoquinones. p-Benzoquinone itself has been positively identified in the beetle Brachinus crepitans (Linn.) (195), in the cockroach
Diploptera punctata (Eschscholtz) (196), and in the millepede Spirostreptus castaneus Attems (197). Earlier claims that benzoquinone is
also emitted by the millepede Julus terrestris (198) and the cockroach
Blaps gigas Fischer (199) were not supported by adequate evidence.
Nevertheless it is fairly certain that a simple quinone (or quinones)
does occur in those species. Reference to Table V shows that methylbenzoquinone (toluquinone) occurs most frequently, both in Insecta