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Mass-Spectroscopy of Inorganic Systems at High Temperatures.

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b) With Lewis-acids [36], e.g. BX3, where X = F or H,
T D A E forms cyclic “borazylammonium” salts ( I ) . This type
of reaction (b), together with (a), disproves the existence of a
carbene equilibrium.
methyl- I ,4,6-heptatriene (2) and 1,3,6-octatriene as main
products. Butadiene and ethylene form 1,3-hexadiene ( I ) ,
butadiene and acrylic esters give 4,6-heptadiene-l-carboxylic
esters (3). Isoprene and acrylic ester give 6-methyl-4,6heptadiene-1-carboxylic ester. 1,8-Diphenyl-l,3,5,7-octatetraene, the product of two-fold dienylation, is formed from
phenylacetylene and butadiene.
Hydrocarbons and ether are used as solvents. The preferred
reaction temperature lies between 30 and 100 ‘C.
[VB 750jl09 IE]
German version: Angew. Chem. 75, 1106 (1963)
c) A compound in which the entire electron system of TDAE
is involved in bond formation is encountered in the crystalline electron donor-acceptor complex TDAE(TNB)2, where
T N B = s-trinitrobenzene. Spectroscopic results suggest a
sandwich arrangement of the molecules.
N e w Heterocycles Containing Germanium and Silicium
M . Wieber and Max Schmidt, MarburgILahn (Germany)
Bifunctional halogenoalkyl-germanes and -silanes may be
converted practically quantitatively into the heterocycles ( I )
by means of glycol or its monothio or dithio analogue.
Catechol or its amino or thio analogue similarly furnish the
new ring-compounds fused onto a benzene ring.
z
x
=
G e or sl; x = y = 0; x = y = NH;
Y = NH; x = s, Y = NH
= 0,
o-Hydroxybenzyl alcohol yields heterocycles of type ( 3 ) .
Their isomeric molecules ( 4 ) are formed from chloromethyldimethyl-chlorogermane or -chlorosilane and catechol.
Z = G e or Si
Novel Dienylation Reactions
Isomerism of Hydroxylamine Derivatives
0. Exner, Prague (Czechoslovakia)
The infrared spectra of hydroxylamine derivatives confirm
the correctness of the formula R-CO-NHOH preferred
today for hydroxamic acids rather than R-C(N0H)OH;
however, a new formula had to be put forward for the anion.
It had previously been assumed that the hydrogen linked to
the oxygen dissociates; thus, all the 0-derivatives were called
esters. However, it was shown by comparison of the dissociation constants (in 80 % methyl cellosolve) of 0- and N-substituted benzhydroxamic acids that it is the hydrogen atom
bound to the nitrogen that is acidic. If the p K values of a
number of 0-substituted benzhydroxamic acids are plotted
against the Taft inductive constants of the substituents, the
point for the unsubstituted acid lies on the same streight line.
On the other hand, the N-derivatives are mostly much weaker
acids; their acidity depends not only on the inductive but
also on the steric effects of the substitutents. The Hammett
p-constant for benzhydroxamic acids that are substituted in
the nucleus, as well as for 0-benzoylbenzhydroxamic acid
derivatives, is about equal to that of benzoic acids, because the
acidic hydrogen atom in all of these compounds bears the
same relationship to the benzene nucleus. As expected, the pconstant for N-methylbenzhydroxamic acid derivatives is
about half as great.
The structure of the hydroxamic acid anion R-CO-NOH
was further proved by its infrared spectrum in Nujol suspension and dioxan solution. The presence of the OH-group in the
lithium salt followed from comparison with 0- and N-derivatives as well as with deuterated compounds. Finally, it appears from the ultraviolet spectra of p-nitrobenzhydroxamic
acid and its 0- and N-derivatives in neutral and alkaline
media that the structure of the unsubstituted acid and of the
0-derivatives alters in the same way on dissociation, whereas
the N-derivatives show no alteration.
[GDCh-Ortsverband Marburg (Germany),
[VB 7671113 1E]
November Sth, 19631
C i
German version: Angew. Chem. 76 (1964). in the press.
D . Wittenberg, Ludwigshafen/Rhein (Germany)
Hardly any substitution reactions on dienes have been
reported up to now. Novel types of dienylation reactions
were reported in which a 1,3-diene is added onto carboncarbon multiple bonds in the form of the dienyl and hydrogen
radical.
CH?=CH-CH=CHz
+ RCH=CHR’
+
CHz=CH-CH=CH-CHR-CH?R’
( 1 ) : R = H, R = H
(2): R
=
-CH=CHz,
(3): R
=
H, R = -COOR’
R =H
The brown solutions of “cobalt - diene complexes” formed
on reduction of cobalt compounds with metal alkyls in the
presence of 1,3-dienes are used as catalysts.
Butadiene is converted into a mixture of straight-chain
oligomers. The reaction can be controlled so as to give 3__- [36]N. Wiberg and J. W . Buchler, J. Amer. chem. SOC. 85, 243
(1963);Chem. Ber. 96,3000 (1963).
Angew. Chem. internat. Edit. [ Vol. 3 (1964) 1 No. 2
Mass-Spectroscopy of Inorganic Systems
at High Temperatures [l]
P . Goldfinger, Brussels (Belgium)
The vaporization equilibria of numerous inorganic substances
have been examined by mass spectroscopy during the last ten
years [la].
A narrow molecular beam of the vapor under examination
effuses from a Knudsen cell of a few ml volume, in which
a solid/gas or liquid/gas equilibrium is established. The
[ I ] Sponsored in part by the Aeronautical Systems Division,
AFSC, through the European Office, Aerospace Research, U. S.
Air Force.
[la] M . G. Ingram and J . Drowart: High TemperatureTechnology.
McGraw-Hill, New York 1960;P . Goldfinger: Compound Semiconductors. Reinhold, New York 1962;J. Drowart and P . Goldfinger, Annual Rev. Phys. Chem. 13, 459 (1962).
153
molecules are ionized in the ion source of a mass spectrometer by electrons of variable energy, accelerated to about
2000 volt, submitted to magnetic mass analysis in a 6 0 ”
sector instrument (radius of curvature: 20 cm), and the
intensities measured with a secondary electron amplifier.
The qualitative composition of the gaseous phase in the
Knudsen cell is determined from the mass of the ions,
their isotope distribution, and their appearance potentials.
The quantitative composition and absolute pressure are obtained from the ion intensities, the total quantity of substance
effused, and the relative ionization cross-sections [2].
Our results are summarized in Table 1. It was possible to
determine the dissociation energies of S2 and Sen [3], which
have been the subject of long-standing controversy, from the
equilibrium values (a) and (b); M = Ca, Sr, or Ba. The results
can be corroborated by means of the equilibrium values (r) to
(u) and other data. The equilibrium values (f) to (h) and (i) to
(I) yield the dissociation energy of SO.
Table I . Energies of formation of gaseous compounds
I
I
Equilibrium
_I
213 MS(sol) + 2 S
- + 213 M + 4/3 S z [*I
a
h
MtS2:’MStS
d
e
f
MOi-0
h
__
MO+S
k
I
-
m
-
BaS(so1) t B a s
o
MO(so1)
+ BazS:
n
Sez + 2 S e
P
rl
r
MS(so1)
T\
MS
MSe(so1)
T-
MSe
U
v
W
MgO
CaO
SrO
77+ 5
83+ 5
92 -5 5
I51
-
_
_
CaO
SrO
BaO
845 6
92.t 6
130* 6
BazSz
I I4 5 5
GeO
SnO
PbO
SnS
I51
141
I41
L41
[**I
75*2
157
I27
91
_151 -
+. 2.5
+3
141
__
I61
[71
171
:-2
171
______
111
.I
2.5
171
PhS
79 = 2.5
171
___-___-__
S
-
t
141
141
[41
[41
I41
Sez
MO
7.
’
55
74;t 4.5
74 e 4 . 5
95 r’ 4 . 5
~
MfSO-
- 9 7 . 5 ! 4.5
MgS
CaS
SrS
Bas
___MIO1-
z
i
S2
______-
MTe(so1)
-2
SnSe
PbSe
95 :: 1.5
71 2 2 . 5
[71
[71
SnTe
93 .’ 2.5
80:. 1.5
(71
[71
MTe
and 2. the glass constituents are not homogeneously distributed in the glass, but form clusters. There is even occasional
mention of complete phase separation. Examination of
Zc~chorinsen’swork shows that he did not postulate a threedimensional lattice, nor did he make any assertions on the
homogeneity of the distribution of glass constituents. Criticism of his views on that score is therefore unfounded.
When the details of the glass structure that are known with
certainty are assembled, and the reliability of the analytical
procedures employed is investigated, it soon becomes apparent that the evidence derived from the results obtained up to
now has been highly overrated. Using X-ray crystallographic
analysis, for instance, it is not possible to determine the coordination number of Si in silica glass more closely than “as
lying between 3 and 5”. Other procedures are equally uncertain, with the possible exception of the chromatographic
method for the determination of the length of the phosphate
chains in high-alkali P2O5 glasses. Most promising are feasibility studies in which glasses are compared with crystals of
corresponding composition.
Electron micrographs of glass-fracture planes are often cited
as evidence for inhomogeneity and phase separation. There
are glasses which will actually give complete phase separation
after sufficiently long time intervals, but statistical experiments show that even a completely random distribution of the
different kinds of particles in the glass leads to relatively great
inhomogeneity. It is not known how the fracture planes of
such glasses would appear. Furthermore, cluster formation
can already occur above the critical separation point, that is,
certainly in the uniphase region, without phase separation
ever taking place. It is at present not possible to distinguish
~ certainty between such a tendency to separate and statistiwith
cal distribution or incipient separation.
Certain far-reaching assertions on the structure of the vitreous
state, which are frequently encountered, should therefore be
viewed with considerable caution. New and unexpected
results ( e . g . with glasses in the system Pb2SiO.$/PbS04, examined in conjunction with L. Merker, or with the P b ~ S i 0 4 /
PbHalz glasses found by Merker) show again how uncertain
predictions in the field of glass chemistry can often be.
[GDCh-Ortsverband Saar (Germany),
November Sth, 19631
[VB 761/110 IE]
German version: Angew. Chem, 76 (1964), in the press.
The Constitution of Rifamycins
V. Prelog, Zurich (Switzerland)
The Structure of Silicate Glasses
H. Wondrotschek, Freiburg/Breisgau (Germany)
It has been customary for some time to consider the hypotheses of Zachariasen on the structure of glasses as outmoded.
Two assertions always seem to recur; 1. a three-dimensional
(Si,AI)-0 lattice is not necessarily present in silicate glasses,
__ __
[ 2 ] R. Colin, Ind. chim. belge 26, 51 (1961).
[3] P. Goldfinger, 14.‘ Jeunehomme. and B. Rosen, Nature (London) 138, 205 (1936).
[4] R. Colin, P . Goldfinger, and M . Jeunehomme, Trans. Faraday
SOC.,in the press.
[5] G . Verhaegen, J . Drowrrrt, and G . Exsteen, Trans. Faraday
SOC.,in the press.
[6] D . Derry, Ind. chim. belge 28, 752 (1963).
[7] R. Colin and J. Droivort, Technical Note No. 10, contract A F
62 (052)-225 (1963); available from ASTIA, Arlipgton Hall
Station, Arlington, Virginia (U. S . A,).
154
Rifamycins (formerly known as rifomycins) are metabolic
products isolated from cultures of StreptomJJces mediterranei. Under certain growth conditions, riftamycin B is the
main product of this group of compounds. It is, however,
unstable and is oxidized in buffered neutral solutions by mild
oxidizing agents, or even in air, to rifamycin 0 with loss of
two hydrogen atoms. Rifamycin S is obtained from rifamycin
0 by treatment with acid in aqueous solution, one molecule
of glycolic acid being removed hydrolytically. Rifamycin 0
is transformed by mild reducing agents, e.g. ascorbic acid,
into rifamycin B; rifamycin S undergoes the same reaction
to give rifamycin SV, the sodium salt of which has found
clinical application under the commercial name rifocin@.
Extensive investigations by W . v. Oppolzer in our laboratory
have led to the constitutional formulae ( I ) - ( 4 ) for the four
rifamycins mentioned above. These are based mainly on the
results of chemical degradations of rifamycin S (methanolysis of the iminomethyl ether of rifamycin S; degradation
of rifamycin S by ozone and subsequent treatment with
performic acid ; oxidation of tetrahydrorifamycin S with
nitric acid) and on the analysis by N M R spectroscopy
of the molecule and its degradation products obtained by
these and other reactions.
Angew. Chem. internot. Edit. 1 Vol. 3 (1964)
No. 2
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