Zeitschrift für Naturforschung / B / 25 (1970) - Max-Planck

Zeitschrift für Naturforschung / B / 25 (1970) - Max-Planck

K. K. BRANDES AND R. J. GERDES
176
aufgenommen. Zur Aufnahme der Heterokernspektren
(14N, 31P) wurde ein Spektrenakkumulator benutzt
(C-1024 der Firma Varian).
Die untersuchten Verbindungen wurden nach F. A.
C o tto n 12 und, soweit noch nicht bekannt, analog dar­
gestellt.
C34H51CoJ3NP
Ber. C 43,25 H 5,45 N 1,48,
Gef. C 43,49 H 5,54 N 1,26.
C34H51NiJ3NP
Ber. C 43,25 H 5,45 N 1,48,
Gef. C 44,11 H 5,07 N 1,29.
C34ff5lCoJ3P2
Ber. C 42,40 H 5,31,
Gef. C 42,46 H 5,25.
Experimenteller Teil
C3,lH51NiJ3P 2
Die KMR-Spektren wurden mit einem HA 100 KMRBer. C 42,40 H 5,31,
Spektrometer der Firma Varian, Palo Alto, Kalifornien,
Gef. C 42,64 H 5,03.
nis der Verschiebungsänderung zu dem der Konzen­
trationsänderung unterschiedliche Werte annimmt.
Dieses Verhalten ist ebenfalls nicht mit der An­
nahme von „Ionenpaaren“ in Lösung zu vereinbaren
und deutet auf das Vorliegen höherer Aggregate
(Assoziate) hin. Tatsächlich kann man solche Asso­
ziationen in Lösungsmitteln mit niedrigen Dielektri­
zitätskonstanten bei relativ hohen Salzkonzentratio­
nen erwarten 11. Es fällt auf, daß mehrere definierte
Aggregatanordnungen zu existieren scheinen, die
sich offenbar in ihrer Stabilität unterscheiden und
jeweils in einem bestimmten Konzentrationsbereich
beständig sind.
10 H. P. F r i t z , H. J. K e l l e r u . K . E. S c h w a r z h a n s , Z. Na­
turforsch. 23 b, 298 [1968].
11 C. W. D
, “Ion Association”, Butterworth and Co. Ltd.,
London 1962.
A. C
, O. D. F
u. D. M. L.
Amer. chem. Soc. 83, 344 [1961].
12 F .
otton
aut
Goodgam e,
J.
a v ie s
Formation and Electrolytic Dissociation of the Potassium Compounds
of Monohydronaphthalene and Monohydroanthracene
K. K. B r a n d e s la and R. J. G er d e s lh
b, 176 — 178 [1970] ; eingegangen am 23. O ktober 19 6 9 )
(Z. N aturforsch. 23
The molar heats of dissociation of the potassium compounds of monohydronaphthalene and
monohydroanthracene (MHQK®) in 1,4-dioxane have been determined. Furthermore it has been
shown that even high-purity solvents will eventually act as proton donors for dinegative ions of
aromatic hydrocarbons.
The molar conductance of alkali salts of aromatic
hydrocarbons has frequently been found to be lower
than the molar conductance of the unprotonated
compounds in the same solvent, methyl-tetrahydrofuran (M THF). This was shown, in particular, by
H oijTlN K and co-worker2 in their studies of the
formation of the primary proton adduct (carbanion
M He ) of the dinegative ions of alternant aromatic
hydrocarbons. These authors used either stearyl
alcohol or the dihydro compounds of the hydrocar­
bons as proton donors. From the above mentioned
conductivity behavior it was concluded that the
charge density is greater for ions of the type M H£
than M 9 .
A greater charge density for the carbanion would
also mean that one should expect the heats of disso­
ciation to be more positive for the protonated than
for the unprotonated compounds. Therefore, the
heats of dissociation were determined for the potas­
sium compounds of naphthalene, anthracene and
monohydronaphthalene and monohydroanthracene,
respectively.
la Department of Chemistry, Newberry College, Newberry,
S.C., U.S.A.
E.E.S., Georgia Institute of Technology, Atlanta, Ga.,
U.S.A.
2 N.
87, 4529 [1965].
H . V e lt h o r st a n d
G. I.
H o ijt in k ,
J. Amer. chem. Soc.
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FORMATION AND ELECTROLYTIC DISSOCIATION OF POTASSIUM COMPOUNDS
Experimental Section
Dipotassium compounds of naphthalene were pre­
pared by solid state reaction under ultrahigh vacuum
conditions (10-8 to 10~9torr). The detailed experi­
mental procedure was reported earlier3. The specific
conductivity of the solvent, 1,4-dioxane, after purifica­
tion in ultrahigh vacuum was 0.8 x 10~14 cm-1. A
detailed description of the purification of solvents for
work with these compounds is given elsewhere 4.
Water was used as proton donor and approximately
10-4 mole// were added to the 1,4-dioxane. When solid
dipotassium naphthalene or anthracene was treated
with this mixture, a yellow solution was obtained at
once. The solid dicompound had reacted with the pro­
ton donor according to
K2®M2G +HOH = K®MH0 +KOH.
The electronic spectra of these solutions agree well
with those reported by others2 [Fig. 1, solid curve,
Fig. 2 in tetrahydrofuran) dashed curve].
177
Results and Discussion
The electric conductance of the ion pairs M He K®
of naphthalene and anthracene in 1,4-dioxane was
measured as a function of temperature. The contri­
bution of KOH, formed through reaction of the
dipotassium compounds with water as proton donor,
to the specific conductance of the pure solutions is
negligible because of the very low solubility of KOH
in 1,4-dioxane (less than 10~6 mole/Z). The small
conductivity of the pure solvent (0.8 x 10“ 14
Q~l cm-1 ) was subtracted.
The logarithms of the corrected molar conductivi­
ties of the potassium salts of monohydronaphthalene
(c = 8.0 X 10 5 mole/Z) and monohydroanthracene
(c = 6.4 x 10-5 mole//) were plotted vs. 1/71 (Fig. 3
and 4). From the slopes of these curves and from
X
10
15
20
25
30
35
40
45
50
----- xW3cm-l
Fig. 1. Electronic spectrum of the potassium compound of
monohydronaphthalene (M H®K®).------ Spectrum obtained
through reaction of solid dipotassium/naphthalene with 1,4-dioxane-water mixture. - — Spectrum obtained through con­
tact of solid dipotassium compound with high-purity 1,4-dioxane after four days.
v
v ----- *-
x jo3 cm~i
Fig. 2. Electronic spectra of dipotassium anthracene and the
protonated compound in (MH®K®) in tetrahydrofuran.
—— Spectrum of dipotassium anthracene in tetrahydrofuran.
— — Spectrum of dipotassium anthracene in tetrahydrofuran
after two days. — - Spectrum of protonated compound, ob­
tained through reaction of solid dipotassium anthracene with
tetrahydrofuran-water mixture.
3 K. K. B
508 [1967].
randes
and R. J.
G e r d e s,
J. physic. Chem. 71,
Fig. 3. Logarithm of the molar conductance of the potassium
compound of monohydronaphthalene i n 1,4-dioxane (c =
8.0 x 10-5 mole/Z) as a function of 1jT.
Fig. 4. Logarithm of the molar conductance of the potassium
compound of monohydroanthracene in 1,4-dioxane (c =
6.4 x 10—5 mole/Z) as a function of 1/7*.
the gradients of the curves of the vicosity vs. l/T
the molar enthalpies of dissociation were determined
according to
log Ac + log r\= const —log e AH(\j2 RT
4
K. K. B
[1968].
randes
and R. J.
G e r d e s,
J. prakt. Chem. 37, 1
178
H. BUDZIKIEWICZ, V. KRAMER UND H. H. PERKAMPUS
(see also reference 3). In the temperature range con­
sidered ( + 12 to + 3 5 °C) log Ac is a linear func­
tion of 1/T and, therefore, the activity coefficients
as well as AHd were assumed to be constant. The
molar enthalpies of dissociation of the protonated
and unprotonated ion pair complexes (MHeK®
and M 0K®) are given in Table I.
Compound
Temperature
Range [°C]
AH u (Kcal/mole)
12 to 35
12 to 35
12 to 35
12 to 35
+ 2.7 3
+5.2
+ 3.1 3
+ 5.5
(Naphth.) ©K®
(Naphth.H) ©K®
(Anth.) ©K®
(Anth.H) ©K®
Table 1. Molar enthalpies of dissociation of the protonated
and unprotonated potassium naphthalene and anthracene in
1,4-dioxane.
Dipotassium naphthalene is not soluble in 1,4dioxane 3. However, after shaking solid dipotassium
naphthalene with anhydrous 1,4-dioxane for several
hours the solvent turned slightly yellow. Finally,
after four days an orange solution was obtained. The
electronic spectrum (Fig. 1, dashed curve) is very
similar to the one obtained through reaction with
water. The reaction with 1,4-dioxane is surprising
because of the great stability of this solvent against
potassium.4
Other solvents, such as tetrahydrofuran, reacted
in a similar way. After two days the absorption band
characteristic for the carbanion M He appeared
distinctly in the spectrum of dipotassium anthracene
dissolved in THF (Fig. 2 solid curve). This effect
explains the frequently reported “killing” of dilute
solutions of alkali metal compounds of aromatic
hydrocarbons in tetrahydrofuran after twelve hours
or more.5
The heats of dissociation of the protonated ion
pair complexes show indeed the expected increase
and indicate a greater charge density of ^-electrons
at the carbanion. A preferred localization of the
The authors wish to thank Prof. Dr. R. S u h r m a n n
additional electron at a carbon atom in para position of the
T.U. Hannover, Germany, for helpful suggestions.
to the CHo group would also contribute to a stronger Work supported in part by the LCA Education Fund
ionic bond between the counterions.
and by the Georgia Tech E.E.S.
5 R. V.
S lates
and M.
Sw arc,
J. physic. Chem. 69, 4124 [1965].
Unterschiede im Fragmentierungsverhalten isomerer Phenanthroline
H. B u d z ik ie w ic z , Y. K r am er * und H.-H. P e r k a m pus
Institut für Organische Chemie der Technischen Universität 3300 Braunschweig
und Institut für Physikalische Chemie der Universität 4000 Düsseldorf
(Z. N aturforsch. 25
b, 1 7 8 — 180 [197 0] ; eingegangen am 1 . Dezem ber 196 9)
Characteristic differences in the fragmentation pattern of 12 isomeric phenanthrolines are
discussed.
Die Molekülionen unsubstituierter aromatischer
N-Heterocyclen können sowohl durch Verlust von
H' als auch von HCN und CoH2 zerfallen. Da uns
zehn isomere Phenanthroline (bezüglich der C.A.Numerierung s. Tab. 1) zur Verfügung standen1,
sollte an diesen Beispielen untersucht werden, ob die
Moleküle vor dem Zerfall ihre Struktur beibehalten
oder sich zu einer gemeinsamen Sekundärspezies
umlagern und, wenn das erste zutrifft, ob eine ein­
fache Korrelation zwischen Struktur und bevorzug­
tem Verlust einer der drei genannten Partikeln
möglich ist.
Die Ergebnisse sind zusammen mit Literaturdaten
für zwei weitere Isom ere2,3 in den Tabn. 1 und 2
zusammengestellt. Im unteren Massenbereich sind
die Spektren sehr ähnlich, was darauf hindeutet, daß
* Ständige Anschrift: Institut Jozef Stefan, Ljubljana.
1 H.-H. P
. G. K
, Liebigs Ann. Chem.
696,1 [1966].
2 W. W. P
. T. J. K
, J. org. Chem. 32, 2616
[1967].
3 J. H. B
, G. E. L
. J. A. R
, Austral. J. Chem.
21, 1233 [1968],
erkam pus
u
a sse b e e r
audler
o w ie
u
re ss
e w is
u
e iss