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Chemiluminescence of Cyclic Diacylhydrazides and Diazaquinones.

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Chemiluminescence of Cyclic Diacylhydrazides
and Diazaquinones
luminescence of luminol and related compounds, which
postulated decomposition of a peroxide of type ( I S ) as energy-releasing step.
By K . - D . Gundermann[*l
Dialkylamino groups in the 3-position of the phthalhydrazide
system are sterically resonance-hindered, and thus compounds
of type ( I ) show only very weak chemiluminescence o n hemin-cataIyzed oxidation in aqueous-alkaline H202.
Lecture at Gottingen (Germany) on February 1 , 1968 [VB 150 IEI
German version: Angew. Chem. 80,494 (1968)
[*] Prof. Dr. K.-D. Gundermann
Institut fur Organische Chemie der Technischen Universitat
3392 Clausthal-Zellerfeld, Leibnizstr. 6 (Germany)
[l] K.-D. Gundermann, Angew. Chem. 77, 572 (1965): Angew.
Chem. internat. Edit. 4, 566 (1965).
[2] K.-D. Gundermann, Lecture at GDCh-Hauptversammlung
Berlin, September 1967.
[31 M . M . Rauhut, A . M . Semsel, and B. C. Roberts, J. org.
Chemistry 31, 2431 (1966).
Compounds of type ( 2 ) [vinylogs of ( I ) in the wider sense]
are more effective than luminol (3-aminophthalhydrazide) in
purely aqueous systems. However, in mixtures of DMSO and
water, hydrazides of type (3) [I] and (4) [vinylogs of ( I ) in,
respectively, the wider and the narrower sense] are much
superior t o luminol and hydrazides of type (2). Compound
( 4 ) with R' = cyclohexyl and n-pentyl was synthesized from
dimethyl 3-methylphthalate (5) by way of the steps (6)-(11].
(10): R =
0-CH,
CH,C<
I
0-CH,
(9): R
0-CH,
= CH~CH:
I
0-CH,
(11): R = CHzCHO
Dehydrogenation of the monosodium salts of the corresponding hydrazides with fert-butyl hypochlorite in dimethyl ether
leads t o the azaquinones (12)-(14).
Compounds ( 1 3 ) and (14) are deep violet in the crystalline
state and chemiluminesce when their acetone solutions are
mixed with aqueous sodium hydroxide. The light yield is a
function of the amount of H202 present, which, however,
can also be replaced by oxygen 121. The quantitative findings
support the mechanism proposed b y Rauhut 131 for the chemi-
480
The Behavior of Modifications of Arsenic
Sesquioxide
By I . N. Stranski[*]
The behavior of arsenolite (cubic) and claudetite (monoclinic)
offends against some of the rules for polymorphic substances,
e.g., against the rule that crystals cannot be heated above
their transition point (or melting point) and also against
Ostwald's stepwise rule. The fundamental assumption [1-51,
which has been confirmed by structural analysis of claudetite,
is that the two forms differ basically in the nature of the
lattice components and in their mode of union: claudetite has
a layer lattice with cross-linkage by primary valences within
the layers and by van der Waals bonding between the layers;
arsenolite, however, contains a molecular lattice of diamond
type formed from saturated, isolated As406 molecules.
All the anomalies in the phase transitions (evaporation,
condensation, dissolution, crystallization, melting, and solidification) are caused by the fact that the units of the initial
phase must be rearranged t o units of the product phase.
Appreciable activation energies are required in practice for
this process, and particularly so when primary valences have
to be cleaved.
The condensation as arsenolite instead of as the stable
claudetite that is observed above and below the transition
point (ca. -3O'C) results because u p to ca. 800°C arsenic
oxide vapor consists almost exclusively of saturated As406
particles, whose bonding must be at least partly destroyed before incorporation into the claudetite lattice. Correspondingly,
the evaporation of claudetite is hindered in comparison with
that of arsenolite, and its rate of evaporation at comparable
vapor pressure is lower by many powers of ten, because only
secondary valences need to be broken during destruction of
the claudetite lattice.
For dissolution and for crystallization from solutions the
decisive factor is whether the solvent can (e.g., HzO) or cannot
(e.g., AsBr3) set up a n equilibrium between the units composing the various phases. In the negative case measurements of solubility can lead to totaliy false conclusions about
the transition point. That arsenolite can be heated unchanged,
not merely above its transition point, but even above its
melting point, arises because the melt has a claudetite-like
structure, so that cleavage of the lattice is necessary also for
conversion into the molten state. Whereas in many cases
the activation energy can be lowered catalytically (e.g., by
entry of H 2 0 into the action), it is often added as thermal
energy or ion impact in enforced condensations. However, in
such cases amorphous, glassy condensates usually result, and
Angew. Chem. internat. Edit.
/ Vol. 7 (1968) 1 No. 6
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