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Intramolecular Conformational Isomerism of the Cyclohexane Rings in Crystalline 2 3-Di-(cis-4-chloro-1-methylcyclohexyl)-trans-2-butene.

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products having retention times very close to that of (2).
A combined analysis of the mixture by gas chromatography
and time-of-flight mass spectroscopy in conjunction with an
evaluation of the N M R spectra of samples in which the
volatiles were substantially enriched suggested the structures
(3) to (7)-
are in the chair form, but in one ring the chlorine atom is
equatorial and the methyl group axial and in the other ring
this relation is reversed. The cause of this intramolecular
conformational isomerism is to be sought in a n energetically
more favorable packing of the molecule into the crystal
lattice.
Table 1. Volatile products from the debromination of 1,3-dihromo-l,3-dimethylcyclohutane
with lithium amalgam.
Product
Retention time
Molecular
Characteristic fragment ions (m/e)
(mid [a1
131
(2)
(41
(6)
+ (5)
+ (7)
4.05
4.10
4.25
4.60
4.2
87.5
5.8
2.3
84 (GH12)
82 (GH10)
82 (GH10)
80 (CsHs)
69 (M - CH3); 56 (C4H8); 42 (C3H.5)
81 (M - H); 67 (M - CH3); 41 (C3Hs)
81 (M - H); 67 (M - CH3); 54 (C4Ha)
79 (M - H); 65 (M CHd; 39 (C3H3)
[Z 491 IE]
Received: April 14th. 1967
German version: Angew. Chem. 79,467 (1967)
[*I Dr. K. Griesbaum and Dr. P. E. ButIer
Enjay Polymer Laboratories
P. 0. Box 45
Linden, New Jersey 07036 (U.S.A.)
[I] Based on the recovered starting material the yield was higher,
e.g. 13% in the reaction of diazomethane with 1,Z-dimethylcyclopropene.
E. Doering and J . F. Coburn jr., Tetrahedron Letters
[2] W.V.
1965, 991. and J . F. Coburn jr., Dissertation, Yale University,
1963; Diss. Abstr. 64-7137.
[3] K. Griesbaum, J. Amer. chem. SOC.86, 2301 (1964); Angew.
Chem. 76, 782 (1964) and Angew. Chem. internat. Edit. 3, 697
(1964); K. Griesbaum, W. Naegele, and G. G. Wanless, J. Amer.
chem. SOC.87, 3151 (1965).
[4] Based on NMR analysis of the mixture before and after the
reaction, using the solvent (dioxane) peak as internal standard.
The result of this analysis (87 % of (2)) is remarkably close to
that of the gas-chromatographic analysis (Table 1) which gave
a value of 87.5 %.
[51 The NMR spectrum of (4) showed a quintet for the CH;!
group at 6 = 4.68, downfield from TMS as internal standard.
The NMR signal of the olefinic proton of (S) occurs at 6 =
5.70. The mixture of compounds (6) and (7) was identified by
gas-chromatographic comparison with an authentic mixture.
Intramolecular Conformational Isomerism of the
Cyclohexane Rings in Crystalline 2,3-Di-(cis-4chloro-l-methylcyclohexyl)-trans-2-butene
-
The conformation of the bonds between the rings and the
butene part of the molecule can also be determined from
the electron density distribution; the methyl groups attached to the rings lie o n the same side of the plane of the
trans-butene group.
1719 independent structure amplitudes were collected for
the structure determination. The reflection intensities (copper
radiation, integrated Weissenberg photographs) were estimated. visually.
Received: January 30th, 1967
[Z 437 IE]
German version: Angew. Chem. 79, 408 (1967)
Publication delayed at the authors' request
[*I Dr. D. Mootz and Dr. E. Mootz
Institut fur Molekulare Biologie, Biochemie und Biophysik,
Abteilung fur Rontgenstrukturanalyse
3301 Stockheim uber Braunschweig (Germany)
[l] We thank Professor Znhoffen for the substance.
By D. Mootz and E. Mootz[*l
2,3-Di-(cis-4-chloro-l-methylcyclohexyl)-trans-2-butene(I)111
crystallizes from petroleum ether in a triclinic form having
m.p. 97-98 "C.
The identity of the two cyclohexane rings that one would
expect from the method of preparation is confirmed by X-ray
analysis in respect of configuration and substitution. However, as shown by the electron density distribution (Figure),
this identity does not apply to the conformation. Both rings
Angew. Chem. internat. Edit.
Vol. 6 (I967) No. 5
Stable Anion Radicals from
2,4,6-Triphenylphosphabenzene
By K. Dimroth and F. W. Steuberr*]
2,4,6-Triphenylphosphabenzene( I ) gives stable radicals on
oxidation[ll as well as on reduction. We here report three
reduction stages, which are produced by the action of
metallic potassium, as a potassium mirror, or of potassium/
445
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conformational, methylcyclohexyl, crystalline, intramolecular, butene, isomerism, chloro, cyclohexane, ring, transp, cis
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