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Diethylmetal Thiocyanates of Aluminum Gallium and Indium.

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verted into the stable r-lactams (8a) (n1.p. 58-59') and
(86) (m.p. 85-86 ") by potassium t-butoxide. The I R spectra
(KBr discs) contain the absorption maxima for carbonyl
groups at 1820 cm-1 characteristic of aziridinones.
Heating [(C2H&AISCN]3 at 180°C in a vacuum yields
ethylaluminum dithiocyanate as a pale yellow crystalline
powder that is insoluble in benzene:
2 (C2H&AISCN
-+ C~HSAI(SCN)~
f AI(CzH5)j
Preparation of cr-CliIoro-3,5,7-trimethyl-l-adamantaneacetic
Acid:
A mixture of l-bromo-3,5,7-trimethyladamantane
(30 g) and
trichioroethylene (90 g) is added dropwise over 4 h, with
stirring, to 90 % sulfuric acid (240 ml) at 103-106 "C. Stirring
is continued for a further 2 h at the stated temperature, then
the mixture is cooled and hydrolysed with crushed ice. The
product that separates can be freed from the neutral fraction
by dissolution in dilute aqueous sodium hydroxide and
extraction with ether. Acidification of the alkaline layer with
dilute hydrochloric acid precipitates the carboxylic acid
(29.5 g; m.p. 173-175 "C). The product melts a t 175-176 O C
after recrystallization from cyclohexane.
Received: August 29th. 1967
[Z 595 IE]
German version: Angew. Chem. 79, 943 (1967)
-.
[*I Dr. K. Bolt
Forschungslaboratorium, Chemische Werke Hiils AG.
437 Marl (Germany)
[ I ] K . Bott and H. Hellinann, Angew. Chem. 78, 932 (1966);
Angew. Chem. internat. Edit. 5, 870 (1966); K. Borr, Chem. Ber.
100, 978 (1967).
[?] J . C. Sheehan and J. H. Bceson, J . Amer. chem. SOC.89, 362
(1967).
This reaction is explosive at 210°C. According to the
solubility relations and the I R spectrum, the dithiocyanate
is to be regarded as a coordination polymer in which the
aluminum atoms are linked through the sulfur atoms of the
SCN groups. Characteristic IR bands are at 2050 cm-1 (s,
vCN), 619 cni-1 (s, vCS), 601 cm-1 (vs, vCS, vAI-C), 458
cm-1 (vs, GSCN), and 393 cm-1 (vs, GSCN).
Table 1. Characteristic I R absorptions of the compounds
t(C2HshMSCNh.
Class
E
E
Az"
E
E
A2"
I Vibration I M
VCN
vcs
vaS MC2
us MCz
FSCN
6 SCN
=
A1
1
2075 vs Ibl
627 vs
627 vs
555 m
501 s
438 vs
M
=
Ga [a1
2150 vs
665 vs
578 s
534 s
476 ms
454 ms
IM
=
In Ial
2128 vs
649 vs
522 s
468 s
468 s
450 sh
Diethylmetal Thiocyanates of Aluminum, Gallium,
and Indium
By K . Dehnickei*l
Reaction of equivalent amounts of triethyl-aluminum, -gallium, and -indium with thiocyanogen occurs exothermally
and quantitatively according to the equation :
When the solvent and ethyl thiocyanate are distilled off, there
remain the diethylmetal thiocyanates (M = Al, Ga, or In)
as yellow hygroscopic oils that are very reactive and are
sensitive to oxygen. Whereas the compounds with M = Al
or In decompose at 18OoC on distillation in a vacuum, diethylgallium thiocyanate distils without decomposition at
145 "C/lO-3 mm. When pure, the gallium compound is inert
to water. When kept for some time in the cold the indium
compound forms crystals having m.p. 51 "C.
Cryoscopic determination of the molecular weight in benzene shows that the diethylmetal thiocyanates are trimeric.
The I R spectra indicate planar six-membered metal-sulfur
rings (symmetry D3h). Evidence for this is the high-frequency C N stretching vibration, which corresponds to a
C = N triple bond, the long-wave absorption due to the CS
stretching vibration, which corresponds to a C-S bond [I],
and the strictly single occurrence of these bands, which is t o
be found, for point group D3h. only with antisymmetrical
vibrations (class E') whereas for a non-planar six-membered
ring (symmetry C3.,) the symmetrical vibrations (class Al)
must also appear. The diethylmetal thiocyanates are thus
analogous to the diethylmetal azides [(C2H&MN& (M =
A1 121 or G a W .
Angew. Chem. internat. Edit. Vol. 6 (1967) J No. I 1
A'-Oxides of Imidazolyls
By K . Volkamer, H. Baumgartel, and H. ZirnmcrrnannI*1
During our work on imidazolyls we took an interest in the
N-oxides of these radicals and their ESR spectra. Imidazolyl
N-oxides ( 1 ) and N,N'-dioxides (2) are to be considered as
dehydrogenation products of imidazol-1-01 (3) and its
N-oxide (4).
0
I R
I
R'
947
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