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Electron Spin Resonance Measurements on Irradiated Bacteriophages and Their Nucleic Acids.

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New Types of Low Molecular-Weight
Heterosiloxanes
H . Schmidbaur, Marburg (Germany)
Low molecular-weight model substances of well-defined composition were prepared for the first time in connection with an
investigation of the principles of structure and bonding in heterosiloxanes. Examples of such compounds are RiSiOXR:,
(RiSi0)2XR$ (R:Si0)3XR2, and (RiSi0)dX. where X = Si,
Ge, Sn, or Pb, R1 = CH3 or CzHs, and R2 = CH3, C2H5, etc.
Specific heterolytic cleavage reactions with Lewis acids or
nucleophilic reagents, as well as infrared and N M R
spectrosopic examinations carried out on such heterosiloxanes have shown that, within the Si-q-Xgrouping, the
X-0- bond invariably possesses the greater polarity and the
lower proportion of x-bond character. In particular, the regular changes in the chemical shifts and the coupling constants
of the N M R spectra demonstrate that this polarization is in
--
n-
accordance with +Si-O+Xt
and increases regularly in the
order X = Si < G e < Sn < Pb. This result is thus in contradiciton to the assumption that the electronegativities of these
elements alternate [I]. The N M R spectra have particularly
high numbers of peaks as a result of the presence of the magnetically active isotopes IH, 13C, 29Si, 117Sn, 119Sn, and 207Pb.
Heterosiloxanes of the trivalent elements of group V of the
periodic table, which are of the general type RiSiOYRg
(Y = P, As, or Sb) with a lone pair of electrons o n the heteroatom, are very sensitive to hydrolysis and oxidation and
belong to the thermally least stable types of heterosiloxanes. Derivatives of the same elements in the pentavalent
state [RiSiOYR: and (R:Si0)2YR$] o n the other hand exhibit
high thermal stability (in particular if Y = Sb).
Heterosiloxanes of the elements of group 111, RjSiOZRg
(2= A1 orGa), with a n electron deficiency on the hetero-atom
occur exclusively in the dimeric form. The planar four-membered ring systems ( I ) exhibit comparatively high thermal and
chemical stability on account of the stabilization which is
possible with this arrangement.
[Inorganic Chemistry Colloquium, Universitat Marburg
(Germany), December 13th, 1963, and Technische Hochschule
Aachen (Germany), November 19th, 19631 [“B 769/114 IE]
German version: Angew. Chem. 76, 234 (1964)
This system is the aliphatic analogue of a quinone/hydroquinone equilibrium for which the high stability of the semiquinone stage is characteristic. Treatment of PyH with 4
moles of T C N E in acetonitrile and subsequent dilution with
water yield crystalline pyridinium pentacyanopropenide ( I )
in approx. 90 % yield.
~ c o N H NC,
2
I
K
1. Dihydropyridines and Tetracynnoethylene: Reduced diphosphopyridine nucleotide (DPNH) and model compounds
(PyH) reduce tetracyanoethylene (TCNE) to the radical
anion TCNE-Q, which can be detected and determined
quantitatively by its characteristic “coxcomb spectrum”,
which contains twelve maxima between 350 and 500 mp. The
intensity of this absorption depends upon the apparent redox
potential of the corresponding P y @ PyH system [2]. The
transient deep coloration which occurs on mixing PyH with
TCNE can be explained by the formation of a charge-transfer complex. The reduction to a radical is interpreted as a
hydride-ion transfer. This leads to TCNEHQ, which equilibrates with TCNE.
+
TCNEHe -i TCNE
+
2 TCNE.3
+ Ha
-~
[I] Cf. also H.Schtnidbaur,Lecturedelivered at the VII. European
Congress on Molecular Spectroscopy, Budapest 1963, Abstract
“2’
=z
C
,
C-CO
N
LN ‘CN
(1)
2. Cynnoyuinones: Of the six possible cyano-substituted
benzoquinones, the compounds (2)-(6), where X = C1, Br,
I, OH, or OR, were synthetized. The electron affinity of the
halogeno- or hydrogeno-substituted compounds increases
with increasing substitution by C N ; the dissociation of the
hydroxylated quinones and hydroquinones increases correspondingly.
3. Cvanoarenes: Similar changes in the physical properties
are found with increasing substitution of the benzene ring
with cyano groups. Pentacyanotoluene shows high C-H
acidity; it forms a deep blue anion which is unstable in the
presence of water. The pyrene complexes of tetracyanom-xylene, pentacyanotoluene, and hexacyanobenzene [3] are
yellow, red, and blue-green, respectively (color of solution in
acetonitrile). In a differential thermoanalysis, hexacyanobenzene was found to be stable up to 475OC. It sublimes
rapidly without decomposition at this temperature.
[Organic Chemistry Colloquium, Universitat Basel
(Switzerland), November 29th, 19631
[VB 772/115 IE]
German version: Angew. Chem. 76, 275 (1964)
Electron Spin Resonance Measurements on
Irradiated Bacteriophages and Their Nucleic Acids
Recent Developments in Cyanocarbon Chemistry
K. Wallenfels, Freiburg/Breisgau (Germany); experimental
work with G . Bachmnnn, H . Diekmnnn, K. Friedrich, D . Hofmann, and R. Kern
c
A. Miiller, Karlsruhe (Germany)
Bacteriophages are particularly suitable for studying radiation damage because of their primitive organization, high
nucleic-acid content, and great sensitivity to radiation. Radicals were produced in dry bacteriophages and nucleic acid
prepared therefrom, by irradiation with X-rays (50 kr/min) or
y-rays (6OCo; 10 krep/min) and examined qualitatively and
quantitatively by means of their ESR absorption spectra; the
results were compared with measurements on phage proteins
and nucleic-acid components (nucleotides, nucleosides, free
bases).
I n whole phages of strains T I and T 2 , radicals which show
different ESR-spectral types are produced in high yield (G =
2-10) by irradiation. Radicals are formed in comparable
yield from T Z p h a g e nucleic acids and give ESR spectra
which correspond to those observed in whole phages. The
radical concentration in irradiated phage nucleic acid increases with dose according t o a n exponential function up to
a saturation value lying between 1018 and 1019 radicals/g
(63 % of the saturation concentration is reached after doses
of 0.4-1.4 Mr).
p. 86.
121 K . Wollenfels, H . Diekmann, and F. Kubowitz, Liebigs Ann.
Chem. 621, 174 (1959).
Angew. Cliem. internat. Edit. / VGI.3 (1964)
1 No. 3
[3] K . Wollenfels and K. Friedrich, Tetrahedron Letters 1963,
1223.
24 1
The radicals of the T2-protein are equal in concentration and
spectral frequency to those of other sulfur-free proteins (e.g .
gelatin). D-2-Deoxyribose gives a radical yield of G = 4.
The radicals produced in the nucleosides do not show a spectrum typical of ~-2-deoxyribose,but spectra which are similar
to those of the free bases.
Whilst the radical yield of irradiated nucleotides corresponds
to that from nucleic acids (G = 2-15), the radical yield in the
case of irradiated nucleosides is less (G = 0.4-1.0) and still
smaller in the case of the pure nucleic-acid bases (G = 0.1 to
1.0). The radical yield increases particularly strongly on pasing from thymine via thymidine to thymidine-5-monophosphate. Directly after irradiation, the spectrum of the phosphate, like that of thymine, has a large number of lines, but
on keeping changes into a quartet, which appears very like
that of stored nucleic acid.
The radical concentrations in the bases, nucleosides, and
nucleotides show a similar dependence on the radiation dose
as those in the nucleic acid and all the other substances investigated. It is probable that the primary radiation damage
occurs at the thymine unit of the nucleic acid.
[Physikalisches Colloquium, Heidelberg (Germany),
November 8th, 19631
[VB 763/111 IE]
Investigations on Highly Substituted Glycols
H. H . Inhoffen,Braunschweig (Germany)
Birch reduction of 3,4-di-p-anisylhexane-3,4-diol
gives a bisenol-ether which is converted into ( I ) by mild treatment with
acid. The reaction of ( I ) with alcoholic sulfuric acid aKords
a mixture from which a racemate of molecular formula
ClsH2202, m.p. 70-71 OC,and with ultraviolet maxima at
A = 303 mp. E = 19000, and 1, - 224 mp, E = 14300, can be
isolated in 30 "/, yield. This compound was shown to have
the spiro-ketone structure (2).
[GDCh-Ortsverband Siid-Wiirttemberg, Tubingen (Germany)
December 13th, 19631
[VB 774/122 IE]
German version: Angew. Chem. 76, 233 (1964)
German version: Angew. Chem. 76, 235 (1964)
SELECTED ABSTRACTS
Tetracyanoethylene oxide has been synthetized by A . Rieche
and P . Dietrich. Tetracyanoethylene reacts with hydrogen
peroxide in ether at room temperature to give tetracyanoethylene oxide ( I ) , m.p. 174 OC (sealed tube), in quantitative
yield. Compound ( I ) is also formed from tetracyanoethylene
and alkyl hydroperoxides in warm benzene. Hydrolysis of
( I ) readily affords a black product (polymeric hydrocyanic
acid). With pyridino bases, ( I ) forms crystalline pyridinium
(4): R
CHz=CH-CZC--CECH
(I)
CHEC-CH=CH-CZCH
(2b)
co2c2I15
betaines, e. g . (2). Ethanolic hydrogen chloride converts
(2) into ( S ) , which gives (4) on heating with ethanolic
H2S04. / Chem. Ber. 96, 3044 (1963) / -Ma. [Rd 857/218IE]
The most potent animal venom known is found in the skin of
the Columbian arrow-poison (kokoi) frog Phyllobufesbicolor.
F. Marki and B. Witkop found that 0.05 y of the 60-fold enriched poisonous principle was sufficient to kill a mouse of
10 g weight. The poison is a chloroform-soluble base with a
mol. weight of 399240. Molecular weight and elemental
composition have recently been determined on a sample of only 40 y with the aid of a double-focussing mass
spectrometer. / Experientia 19, 329 (1963) / -W.
[Rd 794/214 IE]
The isolation, identification, and synthesis of isomeric hexenediynes from electric-arc acetylene is reported by T. BohmGossl, W . Hunsmunn, L . Rohrschneider, W. M . Schneider, and
W. Ziegenbein. The condensate obtained from the countercurrent condenser, which contains the higher boiling byproducts formed together with electric-arc acetylene, was
submitted to gas chromatography, and three c,5 acetylenic
hydrocarbons, which where present in amounts of about 0.1
to 1.0 %, were isolated. Ultraviolet, infrared, and mass
spectra showed that triacetylene was present. The main
component (1.3 %) (Amax = 270, 255, and 242 mp) had a
mass spectrum corresponding t o CsH4. It contained a vinyl
double bond in conjugation with an acetylenic bond, a
242
central and a terminal acetylenic group, and two types of
protons, bound to doubly and triply bonded carbon.
The ratio of acetylenic to olefinic protons was 1:3
and corresponds to the formula of 1-hexene-3,5-diyne ( I ) .
The N M R spectrum excludes all other possible constitutions.
The third c6 acetylene (0.1 %) was separated on polypropylene
glycol as stationary phase. Structures ( 2 u ) and (2b) were
possible according to infrared and mass spectra. Compound
(2u) was synthetized from 1,4-pentadiyne-3-01, and (2b)
from 1,5-hexadiyne-3-01 ( 3 ) . The results obtained indicated
that truns-3-hexene-l,5-diyne(26) is present in electric-arc
acetylene.
SOBrr
(3)
~~
-+
CHEC-C-CECH
ll
12al
CHI
quinoline (-HBr)
3-bromo-1,s-hexadiyne __
s, (2b)
200mm N2, 100 C
cis-3-Hexene- 1,5-diyne could not be isolated from crude
acetylene. It may occur in traces and be removed with the
triacetylene during gas chromatography. / Chem. Ber. 96,
2504 (1963) / -Ma.
[Rd 791/210 IE]
Five-membered heterocyclics containing Si, Ge, or Sn, and
sulphur in the ring have been synthetized by M . Wieber and
M. Schmidt, who have previously built up the corresponding
six-membered rings. Dithioglycol reacts with equivalent
quantities of triethylamine and dimethylchloro-silane, -germane, and -stannane in boiling benzene to form 2,2-dimethyl2-sila-1,3-dithiacyclopentane,b.p. 75-77 "C/12 mm, 2,2dimethyl-2-germa-l,3-dithiacyclopentane,b.p. 87-93 "(712
b.p.
mm, and 2,2-dimethyl-2-stanna-l,3-dithiacyclopentane,
113-115 "Cj5 mm, m.p. 82-83 OC, respectively.
Yields are satisfactory. The compounds have unpleasant
odors and are rapidly decomposed by hot water. / 2. Naturforsch. 186, 846 (1963) / -Ma.
[Rd 789/207 IE]
Angew. Chem. internut. Edit. 1 Vol. 3 (1964) / No. 3
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acid, measurements, spina, thein, nuclei, bacteriophages, irradiated, electro, resonance
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