вход по аккаунту


New Sulfides of Metals.

код для вставкиСкачать
In an heterogeneous system with liquid B 2 0 , the accompanying gaseous phase is, in accord with the supposition
of the method of calculation (sliding equilibrium), in equilibrium with gaseous boron oxides, so that the proportion
of liquid B,O, can be calculated by difference.
If the total composition is known then the enthalpies of
the combustion products at given temperatures and pressures are also known, and an enthalpy-entropy curve can
be plotted after calculation of the respective entropy values.
The thrust chamber isobars each intersect the isenthalpic
lines of the calorific value of the mixture at a point from
which the isentropically assumed expansion occurs.
The intersection of these isentropic lines with the expansion
isobar (e.g. 1 bar under ambient conditions) afford the
enthalpy difference which is convertable into kinetic
energy and from which the emission velocity of combustion
products after having passed the nozzle of the second
thrust chamber can be calculated. For a mixture of boron
air, h= l.lL3],
the discharge rate for an expansion ratio
20: 1 is 1893 m/s, the thrust chamber temperature under a
pressure of 20 bar is 2717"K, and the expansion temperature (20: I)
tions with ring closure, e. g., the reaction of diphenylamine
to give carbazole, and of hydroxybiphenyl to give dibenzofuran illustrate interesting possible applications of plasma
Plasma reactions take place mainly through radicals. The
electrons transfer the energy of the external field to the
molecules. This yields excited molecules, ionized molecules,
or negative ions, which give the products either directly or
after decomposition to radicals. Different mechanisms are
found with individual classes of compound ;some resemble
those of pyrolysis, others those of photolysis or the processes in the mass spectrometer, and yet others have no relation
to known mechanisms.
The reactions of organic molecules in the plasma offer
interesting preparative possibilites. Several processes have
been worked out on a laboratory scale ; application on an
industrial scale is certainly a possibility.
Lecture at Tiibingen on January 22,1971 [VB 284 IE]
German version: Angew. Chem. 83,413 (1971)
Lecture at Miinchen on February 14,1971 [VB 283 IEJ
German version: Angew. Chem. 83,412 (1971)
[I] I . Husrnann, Diplomarbeit, Technische Universitat Miinchenl969.
[ 2 ] K.Schadow, A. I. A. A. Journal Vol. 7, No. 10, 1870 (1969).
[3] h = l when equivalent quantities of fuel and oxidizer are reacting;
when h = l . l there is an excess of air. h=coeffcient of oxidizer.
Organic Reactions in the Plasma of Glow Discharges
By Narald Suhr"]
When electrons with an energy of a few eV impinge on
organic molecules, the latter are partially altered and
rearrangements, fragmentations, or, at high pressures,
bimolecular processes can occur. Some of these processes
have long been known but were not suitable for preparative
purposes because in previous work the substances were
largely destroyed with formation of low-molecular gases
and tar. A procedure has now been worked out by which
electron impact processes can be utilized preparatively.
The apparatus is similar to that for vacuum distillation in
which a high-voltage or high-frequency glow discharge is
produced in the vapor space. Simple laboratory apparatus
(with about 100 watts) produce 0.1-1 mole of product per
A number ofreactions occur particularly well in the plasma.
They were worked out first with the parent compounds,
but can be extended to substituted compounds. High yields
are obtained in dehydrogenating dimerization, e. g., of
benzene to biphenyl and of methylated aromatic compounds to 1,2-diarylethanes. Rearrangement of alkyl aryl
ethers and N,N-dialkylanilines to respectively, alkylphenols and N-alkyl derivatives of alkylated anilines, and cistrans-isomerizations, are also among favored plasma reactions. Among eliminations, particularly good yields are
obtained in decarbonylations, e. g., of benzophenone to
biphenyl, of camphor to trimethylbicyclohexane, and of
naphthols to indenes, and in decarboxylations of carboxylic
acids and their anhydrides to hydrocarbons. Dehydrogena[*) Prof. Dr. H. Suhr
Chemisches Institut der Universitat
74 Tiibingen, Wilhelmstr. 33 (Germany)
New Sulfides of Metals
By Welf Bronger"]
If the binary metal sulfides are considered in relation to
their positions in the Periodic Table it is noticeable that
very marked changes in properties occur near where the
transition metals are inserted. The structure shows this
particularly clearly : thus sulfides crystallize in salt-like
structural types when derived from metals that have empty
or completely filled d shells-to a smaller extent this is
true also for metals with half-occupation- whereas sulfides
ofmetals with partially filled d shells crystallizein structural
arrangements where metal-metal interaction can be recognized. In this connection it appeared interesting to synthesize and study the structure of sulfides that contain both a
main-group metal and a transition metal in ternary compounds.
Sulfides with heavy alkali metals on the one hand and with
d elements on the other, were prepared by reactions in a
melt under an inert gas. The starting materials were
mixtures of alkali-metal carbonates or sulfides, transition
metal, and sulfur. The following phases were thus synthesized :
X-ray investigation of single crystals showed that the
ferrates have a structure characterized by edge-junction of
the sulfur tetrahedra surrounding the iron atoms1'. 21 to
form chains. In the manganates and cobaltates these sulfur
polyhedra were joined by edges two-dimensionally into
In the pall ad ate^^^^ and platinateL6'(the structure
of the nickelate is still unknown) the ligands surround the
transition metal in a planar arrangement, and the sulfur
rectangles are joined by sides to give here too either layers
or chains. In general, the structures of these compounds
[*I Prof. Dr. W. Bronger
Institut fur Anorganische Chemie der Technischen Hochschule
51 Aachen, Templergraben 55 (Germany)
Angew. Chem. internat. Edit.
Vol. I0 (1971) J No. 6
permit differentiation into sulfides with a greater similarity
to alloys and the more salt-like complex compounds of the
transition metals. The more metallic structural units are
distinctly separated from the ionic ones by formation of
layers or chains.
account, Corasil and Zipax appear to be equal as regards
the possible speed of analysis at equal pressure drop.
Comparable values were obtained for the Corning glass
beads only with substances that were very strongly retarded
on the other carriers.
Lecture at Aachen on January 22,1971 [VB 286 IE]
German version : Angew. Chem. 83,413 (1971)
Corasil and Zipax are active adsorbents because a silica
gel with a large specific surface area is used for the porous
surface layer. This activity is evidenced in a variety of ways:
The relative retention is a function ofthe amount of stationary phase on the support. The uncoated carrier adsorbs
stationary phase from the solvent saturated with the
stationary phase until a steady state is reached. Reproducible results cannot be obtained with loadings lower than
that corresponding to this steady state. Only with the
Corning glass beads are the values of relative retention
independent of the amount of loading.
[l] J . W Boon and C. H . Mac Gillary, Recl. Trav. Chim. Pays-Bas 61,
910 (1942).
[Z] W Bronger, 2. Anorg. Allg. Chem. 359,225 (1968).
[3] W Bronger, Angew. Chem. 78,113 (1966); Angew. Chem. internat.
Edit. 5, 134 (1966).
[4] W Bronger and P . Bottcher, unpublished work.
[5] W Bronger and J . Huster, J. Less. Common Metals 23, 67 (1971).
[6] W Bronger and 0.Giinther, unpublished work.
Problems of High Speed Liquid Chromatography
By Heinz Engelhardt“
The theoretical relations derived for gas chromatography
are valid also for liquid chromatography. However, the
differences in the relative numerical values of the physical
quantities (viscosity, diffusion coefficient, etc.) concerned
in, for instance, the equation for zone spreading as a function of flowrate cause a shift in the relative influences of
the various terms of this equation.
Thus the longitudinal diffusion term (the B term) has very
little influence in liquid chromatography, since the rate of
diffusion in the mobile phase is slower than in gases by a
factor of lo4. On the other hand, this same slow diffusion
leads to preponderance of the term (the C , term) for resistance to mass transfer in the mobile phase,‘namely that
between the moving mobile phase between the particles
and the stagnant mobile phase in the pores of the carrier.
This band broadening can be overcome to some extent by
decreasing the depth of the pores; this can be effected by
decreasing the diameter of the particles (< 10 Fm), since
then the pore depth also becomes smaller, or by using
thin-layer particles (porous layer beads) in which a thin
porous surface layer (- 1 pm) is placed on an inpenetrable
core. This surface layer can be produced either by etching
the surface of the particles, as in the carrier material Corning GLC 100 (Corning Glass Works, Coming, N. y.)or by
precipitating a thin porous layer of silica gel as in the
carrier materials Corasil (Waters Assoc., Framingham,
Mass.) and Zipax (Dupont, Wilmington, Del.). If the
particle diameter is increased, then, in order to obtain the
same flowrate, a higher pressure must be applied, the
limits being set by the apparatus. Such particles were compared by observing the band broadening in relation to
velocity (H. vs. velocity) and the number of effective plates/
sec (measure of the speed of analysis).
The carriers differ in their loading capacity for the stationary phase. Surface-etched particles give sticky fillings even
with light loading (0.4%of 3,3’-oxydipropionitrile),whereas
the others can be much more heavily loaded (up to 2.6% of
3,3’-oxydipropionitrile)without appearing sticky. The
number of effective plates/sec created is largest with Zipax.
If, however, the difference in particle size is taken into
If all of the pores on a porous carrier are almost completely
filled with stationary phase (e.g., Porasil A with 100% wjw
of 3,3’-oxydipropionitrile),band broadening in the stationary phase preponderates and lower plate heights are found
for strongly retarded substances than for those eluted at
the beginning. With these heavily loaded columns there is
no reasonable loss of stationary liquid phase (using completely saturated eluants) due to mechanical erosion which
limits the life of columns with porous layer beads. On
these columns the sample size can be very large without
Lecture at Erlangen on January 22,1971 [VB 285 IE]
German version: Angew. Chem. 83,411 (1971)
By Hans Grundke and P. I . Paetzold (lecturer)[‘’
o-Cyclopentadienyl compounds XCp are subject to, inter
a h , two types of equilibration, namely, valence tautomerism (I) and sigmatropic hydrogen shift (2):
WhenX=R,AI only reaction(l)isobserved, whenX=R,Si
both reactions occur, but when X =R,C only reaction (3)
takes place. How do cyclopentadienylboranes R,BCp
We prepared cyclopentadienyldiethylborane Et,BCp ( I )
[and analogously diethyl(methylcyclopentadieny1)borane
(211 by reaction of chlorodiethylborane-pyridine with
NaCp and subsequent removal of the pyridine by BF, :
The by-way through the pyridine adduct is necessary since,
in the presence of Lewis acids such as free Et,BCl, ( I )
rapidly dimerizes by a Diels-Alder reaction ;this dimeriza-
[*] Dr. H. Engelhardt
Institut fur Organische Chemie der Universitat
852 Erlangen, Henkestrasse 42 (Germany)
Angew. Chem. internat. Edil. / Vol. I0 (1971) 1 No. 6
p] Dr. H. Grundke and Prof. Dr. P. I. Paetzold
Institut fur Anorganische Chemie der Technischen Hochschule
51 Aachen, Templergraben 55 (Germany)
Без категории
Размер файла
256 Кб
sulfide, metali, new
Пожаловаться на содержимое документа