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New Syntheses of Pyrylium Salts.

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The following observations confirm this course of reaction:
1 . Reduced pyridine nucleotide (DPNH) is formed only in
presence of cis-p,y-enoyl hydrase, racemase and HOADH.
D-( -)-$-Hydroxylauroyl-CoA (2) is dehydrogenated to ( 4 )
only in presence of racemase and HOADH.
2. After incubation of 35 pmoles of [5-14C]-cis-3-dodecenoylCoA ( I ) with cis-$,y-enoyl hydrase and racemase, 3.0 mg
of methyl rat.$-hydroxylaurate (m.p. 27 "C) were isolated
by saponification, esterification and gas-chromatographic
separation. The optical rotation of methyl D+)- or L-(+)-$19.5'; c = 1 in CHCl3)did not
hydroxylaurate ([a]ko =
change in the blank under the conditions of isolation.
Through these reactions the unsaturated fatty acids are
connected with the metabolic cycle of the saturated fatty
acids [4], so that o u r knowledge of the $-oxidation of all the
fatty acids occurring in the animal kingdom is thereby
complete.
Received, March 25th. 1964
[Z 717/542 I € ]
German version: Angew. Cheni. 76, 4 4 0 (1964)
[I] J . R. Stern and A . Del Caiiipillo, J. biol. Chemistry 218, 985
( 1956).
[2] S . J. Wakil and H. R. Malpler, J. biol. Chemistry 207, 215
(1954).
[3] D. E. Green in: Progress in the Chemistry of Fats and other
Lipids. Pergamon Press, London 1963, p. 102.
[4] W . Seiibert, G. Greull, and F. Lynen, Angew. Chem. 69, 359
( 1 957).
New Syntheses of Pyrylium Salts
By Dr. Richard Schmidt
lnstitut fur Organische Chemie
und Organisch-Chemische Technologie
der Technischen Hochschule Stuttgart (Germany)
Dedicuted to Professor H . Rredereck
on the occrrsioti of his 60th birthday
By reacting phenylacetylene with aromatic acid chlorides i n
the presence of Lewis acids, pyrylium salts ( I ) could be
obtained i n good yields:
The reactions went best with excess acid chloride acting as
both reactant and diluent at -5 to + 15 "C. The pyrylium
salts prepared are shown in Table 1.
Table I. Properties of the pyryliurn salts i l l .
I
I Hexachlorostannatel
Ar
m. p. [ ' C ]
yield
(decornp.)
1 %I
Phenyl
290-298
73
0-C hloro phenyl
p-Chlorophenyl
p-Tolyl
294-298
290-294
273-277
72
81
55
Perchlorate
log
Emax
~
287-290
360
(288-290 [I]) 408 [2]
209
3 I4
200-202
320
230--232
325
415
(224 131)
SnC14 has been the most suitable Lewis acid. The hexachlorostannates could be converted to perchlorates with perchloric
acid in dimethylformamide/water. The pyrylium salts are
yellow and fluoresce strongly in solution. The ultraviolet
spectra were taken in methanol. By comparison of ( I n ) with
authentic 2,4,6-triphenylpyrylium perchlorate [I] and by
conversion of ( I n ) to 2,4,6-triphenylpyridine [4] the course
of the reaction was clarified.
Received, March 31st. 1964
[Z 711/537 IE]
German version: Anpew. Chenl. 76. 437 (1964)
[ I ] C. G. LeF3vre and R. J . IY. LeFi.iw, I . chem. SOC.(London)
1932, 2894.
121 R . Wizinger, S. Losinyer, and P. Ulrirli, Helv. chim. Act3 3Y,
5 (1956).
[3] K. Diinroth, G. Neiibauer, H . Mollenkamp, and G. Oosterloo.
Chem. Ber. 90, 1668 (1957).
[4] W . Difthey, J . prakt. Chem. (2) 94, 53 (1916).
C O N F E R E N C E REPORTS
Colloquium in Honor of G. Scheibe
On thc occasion of Prof. G . Scheibe's 70th birthday a colloquium was held in Munich (Germany) on November 29th
and 30th, 1963. The following is a selection from the papers
read.
Influence of Heavy Atoms on the Polarization of
Triplet/Singlet Phosphorescence of Organic C o m p o u n d s
F. D 6 w , H . Gropper, and N . M i k a , Miinchen (Germany)
The triplet/singlet phosphorescence of organic molecules in
isotropic solid solution, when excited with linearly polarized
light, is itself partially polarized. On theoretical grounds, a
degree of polarization p = 0.5 is to be expected in the plane
perpendicular to the electric vector of the exciting light
source, if the absorbing and the emitting transition moments
in the molecule are parallel. If they are perpendicular to each
other, p = 0.33 [l]. The x-TCabsorption transitions of planar
molecules are all polarized in the plane of the molecule. For
numerous aromatic hydrocarbons, the triplet/singlet phosphorescence consists essentially of only one intense com[I
1
W . L. Leivschin, Z . Physik 32, 307 (1925).
Arigen;. Chem. internut. Edit.
Vol. 3 (1964)
No. 5
ponent, which is polarized perpendicularly to the plane of
the molecule [2]. However, halogeno substituents, r . g . in
naphthalene, intensify other components of the phosphorescence that are polarized in the plane of the molecule. The
resulting intensification of emission is known as the heavy
atom effect [ 3 ] . The superimposition of differently polarized
components is also manifest in the degree of polarization.
which becomes increasingly positive with increasing atomic
number of the substituting element [4]. A similar influence
has now been observed in the series fluorene, dibenzofuran,
carbazole, and dibenzothiophene, i n which i; rises from --0.32
to +0.04.
The theory of triplet/singlet transitions [51 provides selection rules for the mixing of singlet and triplet states via
[21 H. Cropper and F. Diirr, Ber. Bunsenges. physik. Chem. 67,
46, 193, 202 (1963).
[31 D. S . McClure, N. W. Blake, and P. L. Hanyt, J . chem.
Physics 22, 255 (1954).
[41 F. Di;rr, H . Cropper, and N. Mika, Z. Naturforsch. 18tr. 1025
(1963).
[51 D.S. McCliire, J . chem. Physics 17, 665 (1949); 20, 682 (1952).
387
3.90
3.98
4.09
2.89
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