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Light Absorption and Relative Electron Densities of Carbocyanine Dyestuffs.

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(intense cis-double bond absorption at 740 cm-1) was synthetized independently by reduction of cis-cyclonona-l,2,6triene (6) [2] with sodium in liquid ammonia [3]. When (3)
was heated to 22OoC,it gave an equilibrium mixture identical
with that formed from ( I ) .
The formation of (3) indicstcs that thc Cope rcarrangement
3f cis-l,2-divinyIcyclopentai~eproceeds via a six-centred
transition state (2) [4] in which the carbon atoms of the dially1 system are arrangedsimilar to a boat-form. A chair-type,
four-centred transition state ( 4 ) would be expected to give
cis,iruns-cyclonona- 1,5-diene (5) as rearrangement product;
according to Dreiding and Stuart models, (5) is more strained
than the cis,cis-isomer (3).
Compound ( 5 ) . n'fi 1.4949 (cis- and trans-double bond absorptions at 720 and 971 cm 1, respectively) [5] was prepared
from both homopseiidopcilctiei-ine (analogous to the preparation of the labile homologuc cis,/~o/i.s-cycioocta-I ,5-dienc)
(by Hofinann deand 6-dimethylarnino-c~i.~\-cyclononcne
gradation) [6]. Like its eight-membered homologue, the
new hydrocarbon tends to polymerize; it can nevertheless
By Prof. Dr. K. Hafncr and cand. chem. K. Wagner
Instittit fur Organische Clicrnic dcr Universitiit Miinchen
Alkylation of dimethylnitrosamine with dimethyl sulfate
affords trimethylnitrosimmonium niethylsulfate ( l ) [I].
This compound reacts with cyclopcntadienylsodium (2) i n
tetrahydrofuran to give monomeric cyclopentadienone
N,A7-dimethylhydrazone (3). orange leaflets, imp. 14"C,
b.p. 107.- 108 'C/lC mm, Am;,x (log E)
267.7 (3.31), 326.5
(4.41) m p in n-hexane.
Conipobnd ( 3 ) is thc first cyclopentadienone derivative tinsubstituted i n the five-memhcred ring that is stable as the
monomer. It can be distilled iir v(rcwo without decomposition,
and even at 200°C shows no tcndency to dimerize o r to react
with dicnophiles. Its dipole moment of 3.3 D indicates
definite participation of thc dipolar structure (3u) in the
ground state of this aza-analogue of 6-dimethylaminofulvene 121.
Hydrolysis of (3) with 2 N t12SO4 leads immediately via ( 4 )
to dimeric cyclopentadienonc (5) [3]. Electrophilic reagents
substitute (3) i n the five-membercd ring. For example, Vilsnieier formylation of (3) with dimethylformamide a n d
be isomerized in the gas phase at 130°C under reduced pressure. Like the process starting from (3), this gave gas-chromatographically pure ( I ) [7].
As is the case with an isocyanate group [8], the allene system
can also take part in a valence isomerization of the type of
the Cope rearrangement. In a reaction analogous to the rearrangements of (3) and (5), ( 6 ) isomerizes at 140°C in the
gas phase to give 1,5-divinylcyclopentcne (7), b.p. 53 OC/125
mm, n: = 1.4972, as sole product.
Received, October 7th, 1963
[Z 5991430 IE]
German version: Angew. Chem. 75, 1103 (1963)
[ I ] E. Vogel, K . - H . O t t , and K. Gti;ck, Liebigs Ann. Chem. 644,
172 (1961).
[2] L. Skat/ehd, 'Tetrahedron Letters 5, I67 (I96 I).
[3] This reduction was also cffcctcd by D . Devaprahlrrrktrra and
P . D . G a r h e r , J . Amer. chem. Soc. 85, 648 (1963).
[4] Cf. W. v. E. Doering and W. R. Roth,Telrahcdron l8,67( 1962).
[ S ] We have not yet had sufticient substance available for an
accurate boiling-point determination.
[ 6 ] We obtained this amine from thc cis-cyclononen-6-one
described by D. DrvrrprahAnkorti and P . D. Gnrdncr, J. Arner.
chern. SOC.85, 1458 (1963).
[7] For the analogous isomcrization of cyclodeca-I,S-diencs see
C. A. Grob, H. Link, and P. W . Schicss, Hclv. chirn. Acta 46, 483
(1963); G. Wilke, Angew. Chern. 75, 10 (1963); Angew. Chem.
internat. Edit. 2, 105 (1963).
[Sl E. Vogel, Angew. Chcrn. 74, 829 11962): hngew. Chcn. inlernat. Edit. 2, I (196%.
phosphorus oxychloride yield\ the stable aldehyde (7), orange
(log c ) 25 I.8 (4.18), 373.5 (4.35) mp
needles, m.p. 65 "C,A,,
in methanol, via the immoniuni salt ( 6 ) , which can be isolated
as its perchlorate, orange nccdles, m.p. I35 "C (decomp.).
Received, October 8th, 1963
[Z 596/428 IE]
German vcrsion: Angew. Chem. 75, 1104 (1963)
[l] Cf. S. Hiinig et al., Angew. Chcm. 75, 476 (1963); Angew.
Chem. internat. Edit. 2, 327 (1963).
[2] K. Hafner et al., Angew. Chcm. 75, 35 (1963); Angew. Chern.
internat. Edit. 2, 123 (1963).
[3] K. Hajner and K. Goliasch, <:hcrn. Ber. 94,2909 (1961); C. H.
De Puy et al., J. Amer. chem. Soc. 81, 4629, 4920 (1959).
Light Absorption and Relative Electron
Densities of Carbocyanine Dyestuffs
By Dr. S. Dahne and Dr. J . Ranft [*]
lnstitut fur Optik und Spektroskopie der Deutschen
Akademie der Wissenschaften zu Berlin (Germany) and
Physikalisches lnstitut der Universitlt Leipzig (Germany)
The relative electron densities at the cc-methylene protons of simple pentamethine dyestuffs ( I ) decrease with
increasing bathochromic shift of the longest-wavelength
The Preparation of Quinolones by Condensation of
Acetylenecarboxylic Esters with Aromatic Amines
By Dr. J. Reisch
I 1)
RI,R2= Alkyl groups which may also be attached together as part of a
pyrrolidine or a piperidine ring; ( l a ) : R1 = R2 = C2HS.
lnstitut fur Pharmazie und Lebensmittelchemie
der Universitiit Munster/Westfalcn (Germany)
electron excitation bands [I].This relationship is largely confirmed by the proton-resonance spectra of the carbocyanine
dyestuffs (2) which exhibit considerably greater variations
in light absorption.
When a-acetylenic esters are heatcd without solvent at 230 to
250’C for 10-15 min with aromatic amines in the presence
of a small amount of cuprous chloride or cuprous oxide,
10 - 20 X 2-quinolones and 60--70 4-quinolones are formed. These can be separated by their different behaviors
towards alkali.
(ta): X = 0
(tb): X = S
The chemical shifts determined at 100 Mc/sec [2], which are
a measure of the relative electron densities at the nucleus, are
given in Table 1 together with the positions of the longestwavelength electron excitation bands of the appropriate dyestuffs.
Table 1. Correlation between the chemical shifts T and the position of
the longest-wavelength electron excitation bands (Amax) for
carbocyanine dyestuffs.
~ [ P P ~[a1I
~ [ P P ~ I
of the 3.3’-r-
of the 8,smethine
of the 9methine
’ protons
[a] Based on 7 for tctramethylsilane - 10.0.
[b] 13)
3,CMethylenedioxyphen yl
(253 -254 [2j)
128- 129
(290-291 [I])
1 :;lb
-260 121)
Received, November 6th, 1963 [Z 612/439 IE]
German version: Angew. Chem. 75, 1203 (1963)
[I] H. R. Ar//rrrr and L. Y. S. Ldr, .I. chem. SOC.(London) 1961,
121 Ch. H. Harrser and G‘. A. ReynoMs, J. Amer. chem. SOC.70,
2402 (1 948).
Nitrosamine Boron Trifluoride Complexes [l]
Remarkably, the relative electron densities at the 8,8’- and 9methine protons diminish in the same order as those at the
3,3’-a-methylene protons, but with greater irregularity. It must
be assumed that the electron densities at the remaining atoms
(1,l’-, 2,2’-, or 3,3’-), which are part of the chromophoric
system, are increased to a greater or lesser extent with inc:easing bathochromicity. This result is in agreement with
the relationship between the light absorption and the basicity
of the cyanine dyestuffs, discovered by G. Scheibe et al. [3,4],
as an increased electron density at a given site corresponds to
an increased basicity. However, Scheibe’s suggestion [4] that
the increased basicity is localized at the 8- and 8’-methine
carbon atoms is not confirmed for these dyes.
Received, October loth, 1963
[Z 6001431 lE]
German version: Angew. Chem. 75, 1175 (1963)
[*] Present bddress: CERN, Geneva (Switzerland).
[ I ] S. Diihne and J. Ranff, Z. physik. Chem. (Leipzig), in the
press; S. Diihrzc, Mber. dtsch. Akad. Wiss. 5 , 567 (1963).
[2] A detailed account oC the proton-resonance spectra of the
dyestuffs, and their interpretation will appear in Z. physik. Chem. (Leipzig). We would like to take this opportunity
to express our sincere thanks to Dr. A. Malera, Research Laboratory, Varian AG. Zurich (Swit~erland),who determined the
proton-resonance spectra.
13) G. Scheihe and D. Briick, Z. Elcktrochem. Ber. Bunsenges.
physik. Chcm. 54,403 (19501.
[4] G. Schcibe, Chimia IS, 10 (1961).
Arrgew. Clwm. interrlrrt. Edit. / Vol. 2 (1963)
( 1)
/ N o . 12
By Priv.-Doz. Dr. D. Klamann and Dr.
On mixing equimolar solutions ol‘aliphatic nitrosamines and
boron trifluoride etherate, or on passing gaseous boron trifluoride into solutions of the nitrosamines in ether or
benzene at room temperature or 0 “C, colorless, crystalline
complexes of 1 : I composition are obtained. The N-nitrosamines can be recovered from these complcxes with alkali.
R’ = alkyl. aryl:
R2 = alkyl;
R* = cyclic residue
The stability of the HF3-nitrosamine complexes increases
with the electron-donating properties of the residues attached
to the amino nitrogen and thereby, according to theory, with
increasing electron density of Ihe >N- N-0-system. Provided moisture is excluded, the BF3-complexes of aliphatic
and heterocyclic nitrosamines can be kept for months without alteration. The nitrosamine of N-methylaniline forms a
quantitative yield of a bright yellow BF3-complex; however,
this rearranges after a Fhort timc into p-nitroso-N-methy-l
aniline with formation of a dark green color. The N - N bond
is so strongly influenced by the benzene ring that the NO-
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carbocyanine, densities, relative, dyestuffs, light, electro, absorption
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