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Investigations on Aromatic Systems.

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The preparation of a tricyanatosilylamine could only be accomplished as shown below.
(K,Si)?NNa .+ (R?Si)ZNSiCI3 + (R3Si)ZNSi(NCO)3( b . p . 81 'Cjl mm)
Carbon monoxide is converted into sodium cyanide, disiloxane being eliminated.
CO
I
NaN(SiR:)z
-
In the course of studies on nine-membered rings containing
nitrogen and having 10 x-electrons 1,4,7-dibenzo[b,h]triazonines were obtained (with R. Bader).
[Max-Planck-lnstitut fur Kohlenforschung,
MiilheimjRuhr (Germany), January 8th, 19641 [I]
[VB 783/124 IE]
German version: Angew. Chem. 76, 276 (1964)
(CN)-Na+ -;- O(SiR3h
A five-membered SiN ring ( I ) can be built up.
New Types of Polyenes with Cyclic
Cross-Conjugated Bond Systems
R2Si-SiR2
CISiRZSiRzCl
~~
LiNRSiRzNRLi
4
2 LiC1 I-
Rh.
AR
Sik
(1)
H. Prinzbach, FreiburgjBreisgau (Germany)
Octamethyl- 1,2,4-trisila-3,5-diazacyclopentane
melts at I8 "C
and boils at 70 'C/I 3 mm.
[GDCh-Ortsverband Gottingen (Germany), November 25th,
1963. and Marburg (Germany) November 29th, 19631
[VB 777/119 IE]
~
In the dipolar structural formulae of the hydrocarbons sesquifulvalene ( I ) . calicene (2), and phenafulvalene ( S ) , the
central single bond joins, in each case, two relatively stable
organic ions.
German version: Angew. Cheni. 76. 234 (1964)
Investigations on Aromatic Systems
H . A . Stanb, Heidelberg (Germany)
Hexa-nt-phenylene (I), which has practically the same
geometrical arrangement in its inner ring system as [18]annulene and probably possesses a practically planar
structure, has like that compound x-electrons on all the
carbon atoms of its inner ring. However, in view of the metabonding of the phenylene groups, the cyclic x-conjugation
should be suppressed. Compound ( I ) was prepared (with F.
Binnip) from the Grignard compound of 3,3'-dibromodiphenyl with CoC12 in tetrahydrofuran. It can be distilled
&
'I1
I
i1)
without decomposition at 650L'C/10-4mmH g ; m.p. 509.5 to
511 "C. Its proton resonance (in view of its low solubility,
measurements have so far only been carried out in I-methylnaphthalene at 18OoC) gave no signals at 3.7-7.7 7 and
8.5-18.0 7 ; particularly strong shielding of the six inner
protons by an aromatic ring current can thus be excluded, as
anticipated. In the ultraviolet, ( I ) absorbs practically at the
Same wavelength (251.2 mp, E = 138000 in CHCI3) as biphenyl
(251.5 m p , E = 18300).
Attempts to prepare the benzocyclopropene (-3) (with J .
Ipoktschi) by photochemical elimination of nitrogen from
(2) did not lead to the desired product. Instead, the 9-phenylfluorene derivative ( 4 ) was obtained in very good yield.
Although ( I ) exists only in solution, it may be estimated
accurately by spectrophotometry and by its chemical reactions. On the other hand, doubly annellated derivatives of
( I ) , or those containing four phenyl groups on the fivemembered ring, are stable. Simple derivatives are obtained
by prototropic rearrangement of fulvenes ( 4 ) . In contrast
to the observation in the annellated series (4n), where only
a formal 1,5-hydrogen displacement to give (50) is found, a
competition reaction occurs in the analogous rearrangement
of (4b), and with increasing acceptor-character of R3,progressively more formation o f the vinyloguous heptafulvene (66)
takes place. The chemical behavior of this class of compounds including the smooth addition of acids and bases,
the site of the electrophilic attack, and adduct formation .- is
in agreement with the x-electron delocalization favored in
the transition state.
-
(u)
1 I,CC,I
5
5
3
is)
R'R2
R'
= -CdH?;
= R2 =
H:
R3 = -CN, -CI, -H, -OCH>
--N(CH3)z
R'-
[ I ] Also reportedJanuary iOth, 1964, at
Ortsverband Koln (Germany).
Aiigew. Chem. itttermtt. Edit.
1 Vol. 3 (1964)
No. 4
-CN. -CI,
--N(CH3)r
B
- H , -OCH?
meeting or the GDCh-
3 19
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