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Direct Synthesis of a Mercury Salt-Carbene Complex.

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Distribution of the butenes formed as primary products at
270 and 406 "C, respectively, was 1-butene 23.5 and 33.5 %.
trans-2-butene 21.5 and 26.5 %, and cis-2-butene 55 and 40 %.
As in similar heterogeneous eliminations more 2- than 1butene is formed (Saytzeff rule), and the cis-isomer predominates greatly. However, the relatively large proportion of
I-butene is divergent from previous results [21; it even exceeds
the amount of trans-2-butene. The thermodynamically most
stable butene (trans-2-butene) is thus primarily the most
disfavored. The deuterated and the non-deuterated alcohol
give the same primary distribution of butenes.
90 % of the deuterium present in the [2-D]-2-butanol can be
detected in the butenes. The deuterium loss is distributed as
follows among the three butenes: cis-2-butene 15 %; trans-2butene 8 %; I-butene 0 %. Thus I-butene arises by a pure
p-elimination
+
hydrogenated at room temperature and normal pressure.
Uptake of hydrogen had ceased after about 5 h. Without
having been filtered from the catalyst, the mixture was poured
into water (ca. 600 ml), and the benzaldehyde formed was
extracted with ether. The combined extracts were washed
once with water and dried over sodium sulfate. Subsequent
distillation gave 41 g (79 %) of benzaldehyde.
The procedure can be applied to other aromatic nitriles. To
what extent the inffuence of solvent or substituents must be
taken into account is the subject of further study.
Nothing is yet known about the origin of the passivation
effect. The amount of nitrile necessary for passivation depends
on the amount of Raney nickel and on the nature of the
nitrile. a,?-Unsaturated and aromatic nitriles hinder most
strongly the dissolution of the Raney nickel. Passivation may
thus perhaps arise by x-complex formation at the C N group.
Complexes of this type have already been described 111.
H~C-CDOH-C~HS + H ~ C = C D - C ~ H S HzO
Partial or-elimination (with subsequent migration of hydrogen)
cannot be excluded for the 2-butenes
H3C-CDOH-CH2CH3
+ H~C-CHZCH-CH~
+ HDO.
Presumably, however, the loss of deuterium is due to the
structure of the intermediate carbonium ion, which then
should not be considered as a classical carbonium ion.
The differences can perhaps be interpreted as follows: the
formation of I-butene occurs in a pure concerted reaction,
whereas elimination to yield 2-butene has some E-1 character
caused by the differing acidities of the protons at the end and
in the middle of the chain. Furthermore, the elimination to
give cis-2-butene must have more E-1 character than that
leading to the trans-isomer. This could indicate that the
probability of conversion into the cis-isomer increases with
the lifetime of the carbonium ion; but then chance of losing
deuterium must increase correspondingly.
Butenes with two or more deuterium atoms were not detectable.
Received: October 23, 1967; revised: December 18, 1967
[ Z 671 IEI
German version: Angew. Chem. 80, 150 (1968)
Activity of nitrile referred
to benzonitrile = 1
(average value)
Nitrile
Cinnamonitrile
Acrylonitrile
in-Tolunitrile
o-Tolunitrile
n-Hexyl cyanide
Acetonitrile
Benzyl cyanide
0.7
1.03
1.1
1.18
1.69
1.75
1.34
Received: November 9, 1961; revised: December 11, 1967 IZ 679 IE]
German version: Angew. Chem. 80, 152 (1968)
[*] Dr. P. Tinapp
Pharmazeutisches Institut der Universitat
53 Bonn, Kreuzbergweg 26 (Germany)
[I] 2. Heldt, J. organometallic Chem. 6 , 293 (1966).
[*I Licenciado en Fisica P. Bautista, Dr. M. Hunger, and
Prof. Dr. H. Noller
Escuela de Fisica y Matematicas, Universidad Central de
Venezuela
Caracas (Venezuela)
Prof. Dr. H. Noller
Physikalisch-Chemisches Institut der Universitat
8 Miinchen 2, Sophienstr. 11 (Germany)
[I] Part XVI of Mechanism of Contact Eliminations. - Part
XV: A. Correa, M . Hunger, and H. Noller, 2. Naturforsch.,
Part b, in the press.
[2] See previous communications, e.g. P. Andrdu, M . Rosa-Brusin, C. Sanchez, and H. Noller, Z . Naturforsch. 22b, 814 (1967).
Passivation of Raney Nickel by Nitriles.
Hydrogenation in Acid Solution
-
By P.Tinapp [ * I
In connection with a study of the possibilities of hydrogenating nitriles at various p H values it has been found that
dissolution of Raney nickel in dilute non-oxidizing mineral
acids can be prevented by addition of a nitrile. The activity
of the Raney nickel is retained in this very acid medium.
Contrary to previous assumption, hydrogenations with
Raney nickel are thus, in general, possible in the presence of
dilute mineral acid.
Experimental:
Benzonitrile (51.5 g, 0.5 mole) was dissolved in a mixture of
tetrahydrofuran (180 ml), water (20 ml), and 96 % sulfuric
acid (50 g) and, after addition of ca. 10 g of Raney nickel, was
Angew. Chem. internat. Edit. 1 Vol. 7 (1968) 1 No. 2
Direct Synthesis of a Mercury
Salt-Carbene Complex 111
By H.- W . Wanzlick and H.-J. Schonherr[*I
Transition-metal-carbene complexes have hitherto been
obtained only indirectly: suitable ligands are converted into
carbene ligands with retention of the existing bond to the
central atom [2,31. Nucleophilic carbenes, which are similar
to isocyanides[41, should be suitable for direct synthesis of
such complexes. That is the case, as we have shown by a
first example: In view of the results obtained by Schoilkopf
l , treated 1,3-diet a!., with Hgzc as central a t o m [ 3 ~ 3 ~we
phenylimidazolium perchlorate ( I ) with mercury(i1) acetate
in dimethyl sulfoxide (DMSO) and obtained the carbene
complex (3) 151. It was unnecessary to add a base to produce
the carbene in situ. Bis(l,3-diphenylimidazolio)mercury diperchlorate (3) [crystallizes from DMSO as colorless plates,
m.p. ca. 370 "C (decomp.), which darken above ca. 250 "C] is
formed with liberation of acetic acid in almost quantitative
yield. It is stable to acids but is immediately reconverted into
1
+ H2S
c---
-
+ H~(OAC)~
- 2 AcOH
141
(I) by hydrogen sulfide (in DMSO) with separation of
mercury sulfide. The carbene fragment forms the base peak
(mje = 220) in the mass spectrumt61.
The NMR spectra (measured in [D6]-DMSO as solvent) of
( I ) and (3) prove the structure of (3). The “rneta-coupling”
shown by the salt ( I ) [71 naturally is absent for the complex
(3). The signals of the phenyl protons, and particularly of the
protons on C-4 and C-5, are shifted upfield on conversion of
( I ) into (3).
Hphenyl
(I)
13)
1
1
-0.29 (t)
( J = 1.5)
T=
-
-. _~-1.95-2.5
1.47 (d)
( J = 1.5)
T = 1.71 (s)
7 =
T=
We have obtained compounds with the hitherto unknown
Si-Ti linkage by treatment of triphenylsilylpotassium with
titanium halides.The stability of the Si-Ti bond is appreciably
increased by neopentane structures, which are particularly
stable in compounds of elements of the fourth main group,
or by substituents that are x-bonded to the titanium.
A characteristic example is the formation of tetrakis(triphenylsi1yl)titanium from TIC4 and ( C ~ H S ) ~ S ~ K :
2.2-2.7 (m)
$tiH,
Experimental:
A mixture of N-(2,2-diethoxyethyl)aniline and phenyl isothiocyanate (molar ratio l:l.l), when kept for 4 days at
room temperature, gave the thiourea derivative (4), m.p.
94OC (yield 88 %), which afforded the thione (5), m.p.
161 O C (yield 66 %), when heated with conc. hydrochloric
acid. Heating (5) with 36 % nitric acid (d = 1.220) gave an
almost quantitative yieId of the nitrate (6) (very hygroscopic),
which was converted into ( I ) , m.p. 169’C (yield 94%), by
dissolution in dilute nitric acid and addition of alcoholic
sodium perchlorate solution.
Complex salt ( 3 ) : 4 g of the salt ( 1 ) and 2 g of mercury(I1)
acetate were shaken in ca. 7.5 ml of DMSO at 8OoC for 10
min. When the solution cooled to room temperature crystals
separated; crystallization was completed by addition of tertbutyl alcohol. When recrystallized from a little DMSO the
complex is obtained in well-formed rectangular plates.
Received: November 20, 1967
[ Z 680 IE]
German version: Angew. Chem. 80, 154 (1968)
[*I Prof. Dr. H.-W. Wanzlick and Dip].-Chem. H.-J. Schonherr
Organisch-Chemisches Institut der Technischen Universitat
1 Berlin, Hardenbergstr. 34 (Germany)
[l] Part XIV of Chemistry of Nucleophilic Carbenes. - Part
XIII: H.-W. Wanzlick and H. Steinmaus, Chem. Ber. 101, 244
(1968).
121 E. 0. Fischer and A . Maasbol, Chem. Ber. 100,2445 (1967),
where previous literature is cited.
[3] U.SchoNkopf and F. Gerhart, Angew. Chem. 79, 819 (1967);
Angew. Chem. internat. Edit. 6, 805 (1967), where previous
literature is cited.
[3a] U.Schoflkopf and F. Gerhart, Angew. Chem. 79,990 (1967);
Angew. Chem. internat. Edit. 6, 970 (1967).
[4] Cf. W. Kirmse: Carbene Chemistry. Academic Press, New
York, London 1964.
[S] Formulation of the complex by analogy with the symbolism
used for other carbene-metal complexes [2,31.
[6] We thank Dr. D. Schumann for the measurement of the
spectrum. Apparatus: AEI MS 9, 70 eV, 350 “C.
[7] Cf. G. S. Reddy, R. T . Hobgood, and J . H . Goldstein, J. Amer.
chem. SOC.84,336 (1962).
142
By E. Hengge and H. Zimmermann[*I
(m)
The salt (1) was prepared as follows:
VsH5
Compounds with Si -Ti Linkages
Ethereal solutions of (C6H5)3SiK and Tic14 are simultaneously added dropwise to ether at 0°C with stirring. Stirring
is continued overnight, then the mixture is poured on ice plus
2 N HCI; the water and ether are then separated off and the
precipitate is washed with methanoljwater and ether and
recrystallized from xylene (yield 44 %).
Tetrakis(triphenylsily1)titanium is a pale yellow substance
that melts a t 395-40O0C with decomposition. It is very
sparingly soluble in xylene, toluene, or benzene, and insoluble in all other solvents. Its particular stability may
depend above all o n the strong shielding of the phenyl groups
in the neopentane structure, and on the high symmetry.
Aqueous alkali decomposes the compound slowly, causing
evolution of hydrogen:
The amount of hydrogen evolved corresponds t o theory
(Si: H2 = 1:l).
The IR spectrum shows, besides the usual CH, phenyl, and
Si-phenyl bands, a new band at 900-940 cm-1. This vibration
may be associated with the neopentane skeleton since similar
bands appear for similar compounds such as [(CH&Si]4Si.
(C6HS)3SiK reacts also with CI2Ti(x-CsH& forming a Si-Ti
bond:
(X-CSH&TiC12
+ 2 KSi(C6H&
+ (~-CSHS)~T~[S~(C~HS)~]Z
The reaction is carried out in diglyme (diethylene glycol dimethyl ether) with ice cooling. The resulting reddish-brown
solution is evaporated and the resulting residue is extracted
with chloroform. On addition of pentane t o the extract,
is
yellow bis(triphenylsilyl)di(x-cyclopentadienyl)titanium
precipitated and is purified by sublimation at 280OC (yield
35 %).
Received: November 30, 1967
[ Z 682 IE]
German version: Angew. Chem. 80, 153 (1968)
[*] Prof. Dr. E. Hengge and Dip1.-Ing. H. Zimmermann
Institut fur Anorganische Chemie
der Technischen Hochschule
A-8010 Graz, Rechbauerstr. 12 (Austria)
Synthesis of Methyl 4,6-0-Benzylidene-2,3(2’-hydroxyethylidene)-ol-D-mannopyranoside,
a Cyclopropane Sugar
By W. Meyer zu Reckendorf and U. Kamprath-Scholta~*l
PO-Activated olefination, as described by Horner [I], has
seldom been used for the preparation of sugars with a
branched carbon skeleton. Its applicst ion t o the preparation
of cyclopropane derivatives from epoxides of the sugar series
has not previously been described.
We treated the epoxide ( I ) 121with ethyl diethoxyphosphorylacetate [3J, (CzH50)2PO-CH2COOC2H5, and N a H in diAngew. Chem. internat. Edit, VoI. 7 (1968) J No. 2
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