Anionic polymerization of an acrylonitrile trimer studied by photoelectron spectroscopy

Article abstract of DOI:10.1021/jp003143g

Anionic polymerization of an acrylonitrile trimer was discussed. Photoelectron spectrum was studied which is produced by electron impact on an acrylonitrile cluster. Results showed that the formation of stereoisomer is determined by the energetics and the entropy requirement of the reaction system.

Full text of DOI:10.1021/jp003143g

7180
J. Phys. Chem. A 2001, 105, 7180-7184
Anionic Polymerization of an Acrylonitrile Trimer Studied by Photoelectron Spectroscopy
Yuji Fukuda,†,‡ Masahiko Ichihashi, Akira Terasaki, Tamotsu Kondow, *
§
§
§,
Kazuhiko Osoda,† and Koichi Narasaka†
,|
Department of Chemistry, School of Science, The UniVersity of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-0033, Japan, and Cluster Research Laboratory, Toyota Technological Institute, in East Tokyo
Laboratory, Genesis Research Institute Inc., 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
ReceiVed: August 31, 2000; In Final Form: April 30, 2001
2 3
A photoelectron spectrum of an acrylonitrile (AN:CH dCHCN) trimer anion, (AN)
-, produced by electron
impact on an acrylonitrile cluster was measured, and was compared with that of a molecular anion of 1,3,5-
cyclohexanetricarbonitrile (c-HTCN) in the triequatorial form, which was first synthesized in the present
-
experiment. A comparison of the vertical detachment energies of (AN)
3
and the molecular anion lead us to
-
conclude that (AN)
3
is assigned as one of the stereoisomers (diaxial form) of c-HTCN (-) on the basis of
our previous studies refs 13, 14, and 20-22 [Tsukuda, T.; Kondow, T. J. Chem. Phys. 1991, 95, 6989. Tsukuda,
T.; Kondow, T. J. Am. Chem. Soc. 1994, 116, 9555. Ichihashi, M.; Tsukuda, T.; Nonose, S.; Kondow, T. J.
Phys. Chem. 1995, 99, 17354. Fukuda, Y.; Tsukuda, T.; Terasaki, A.; Kondow, T. Chem. Phys. Lett. 1995,
242, 121. Fukuda, Y.; Tsukuda, T.; Terasaki, A.; Kondow, T. Chem. Phys. Lett. 1996, 260, 423.].
+
1. Introduction
mass spectra of the cluster cation of (AN)n . They have
concluded that three AN molecules are hydrogen-bonded in a
ring geometry in (AN)m and undergo anionic polymerization
by the electron attachment. Similar intensity enhancement at n
Chemical reactions in cluster media have attracted much
attention because they are expected to provide unique reaction
products that are very different from those obtained in the usual
condensed media. Intracluster polymerization is a typical
example of such reactions. Several groups have so far investi-
gated cationic polymerization in clusters followed by ioniza-
)
3, 6, and 9 were also observed in the mass spectra of the
cluster anions of olefin molecules such as 2-chloroacryloni-
trile,
15-18
19
14,19
14
methyl acrylate, methacrylonitrile,
and styrene.
1-12
tion.
The mass spectra of cluster cations exhibit characteristic
To elucidate the mechanism of the intracluster anionic
polymerization in (AN)m by the electron attachment, systematic
studies have been conducted by using techniques of collision-
induced dissociation, photodissociation, and photoelectron
distributions in intensity. They have analyzed in such a manner
that intracluster polymerization takes place when the neutral
clusters are ionized. For instance, Garvey et al.1-6 have reported
+
the enhancement in the intensity distributions of (CH2dR)n
20
detachment. Ichihashi et al. have shown that a neutral AN
(
RdCH2, CF2, and CHCH3) produced by electron impact
trimer unit, (AN)3, is released dominantly from a parent cluster
ionization of van der Waals clusters of (CH2dR)m and inter-
preted the intensity enhancement in terms of formation of six
membered cyclic ions because of a kinetic bottleneck in the
chain propagation sequences. El-Shall et al.7 have observed
the cationic polymerization in van der Waals clusters of vinyl
chloride and isoprene. El-Sayed et al.10 have reported dissocia-
tive ionization of acrylate clusters with releasing carboxy groups
under irradiation of a laser light and suggested that intracluster
polymerization proceeds.
-
anion (AN)n by Kr-atom impact. They have interpreted this
-
result in such a manner that (AN)3 is present in (AN)n as a
21
stable trimer unit. Fukuda et al. have undertaken the photo-
-9
-
dissociation measurement of (AN)n (2 e n e 9) at photon
-
energies of 1.17 and 2.33 eV and have observed (AN)3 and
-
(
AN)6 as the main products. They concluded that the parent
-
-
anion (AN)n (n g 3) consists of an anionic trimer unit, (AN)3 ,
a neutral trimer unit, (AN)3, and AN molecule(s). They have
also measured the vertical detachment energies of (AN)n (2
e n e 11) and showed that the core ion of (AN)n (n g 3) is
an anionic trimer unit, (AN)3 , in a ring geometry. In summary,
previous studies have revealed that (AN)n (n g 3) consists of
a polymerized cyclic trimer core ion, (AN)3 , solvated with a
22
-
On the other hand, Tsukuda et al.13,14 have investigated
Rydberg electron attachment onto an acrylonitrile (AN:CH2d
CHCN) cluster, (AN)m, and observed intensity enhancements
-
-
-
-
-
in the mass spectra of (AN)n and [(AN)n-X] (X ) H, H2,
-
-
HCN, and H2 + HCN) at n ) 3, 6, and 9, where [(AN)n-X]
represents an anion produced by eliminating a neutral species,
X, from (AN)n ; no intensity enhancements are observed in the
polymerized cyclic neutral trimer unit, (AN)3, and AN mol-
-
-
ecule(s). The polymerized cyclic trimer core ion, (AN) , is
3
regarded to be one of the four stereoisomers of the molecular
*
To whom correspondence should be addressed.
The University of Tokyo.
Present address: Advanced Photon Research Center, Kansai Research
anion of 1,3,5-cyclohexanetricarbonitrile (c-HTCN; see Table
†
1
). The final goal of this series of studies is to identify the
‡
-
isomeric structure of (AN)3 . In the present study, a photoelec-
tron spectrum of (AN)3 was measured and compared with that
Establishment, Japan Atomic Energy Research Institute, 8-1 Umemidai,
Kizu-cho, Souraku-gun, Kyoto 619-0215, Japan.
-
§
Toyota Technological Institute.
Present address: Fujisawa Pharmaceutical Co., Ltd., Medicinal Chem-
of the molecular anion of c-HTCN in a triequatorial form, which
|
was first synthesized in the present study. An ab initio MO
istry Research Laboratories, 5-2-3 Toukoudai, Tsukuba, Ibaraki 300-2698,
Japan.
2
3
method based on Gaussian 94 was employed to calculate the
1
0.1021/jp003143g CCC: $20.00 © 2001 American Chemical Society
Published on Web 07/07/2001

Anionic Polymerization of an Acrylonitrile Trimer
J. Phys. Chem. A, Vol. 105, No. 30, 2001 7181
TABLE 1: Relative Energies and Vertical Detachment Energies for Four Stereoisomers of 1,3,5-Cyclohexanetricarbinitrile (-)
Calculated with HF/6-31+G//MP2/6-31++G(d,p)a
a
The values shown in parentheses were calculated with HF/6-31+G//MP2/3-21+G. b Relative energy with respect to the stereoisomer a which
c
has the most stable structure. Relative energy with respect to the stereoisomer c which has the structure of the synthesized sample.
Figure 1. Schematic diagram of the experimental apparatus equipped with a magnetic-bottle-type TOF photoelectron spectrometer.
vertical detachment energies of the four stereoisomers of
electric field and accelerated up to 500 eV in a field-free path
of 2.7 m. The anion, c-HTCN (-), was selected out from
spatially separated ion bunches by using a mass gate and was
decelerated down to 50 eV by a potential switch located in front
of the magnetic-bottle-type TOF photoelectron spectrometer.
Then, at the photodetachment region, c-HTCN (-) was irradi-
ated by the output of unfocused second harmonics of a Nd:
YAG laser (Quanta Ray DCR-11). Laser fluence was maintained
c-HTCN (-) for the sake of comparison with the vertical
-
detachment energy of (AN)3 .
2
. Experimental Section
Figure 1 shows a schematic diagram of the experimental setup
employed for the measurements of both the mass and the
photoelectron spectra. The apparatus consists of a pulsed cluster
ion source, a time-of-flight (TOF) mass spectrometer, and a
magnetic-bottle type TOF photoelectron spectrometer.
Helium gas of 4-8 atm was expanded from a pulsed nozzle
of 0.8 mm in diameter. Electrons having a kinetic energy of
-
2
-1
in the range of 50 mJ cm pulse . Photoelectrons, created in
a strong inhomogeneous magnetic field (∼1000 G) generated
by a pulsed electromagnet located outside the vacuum chamber,
were guided in a 2 m drift tube applied with a weak magnetic
field (∼10 G) and detected by a tandem microchannel plate
∼
300 eV were introduced at the distance of 2 mm downstream
from the nozzle. The diameter of the electron beam was 1 mm.
A powder sample of c-HTCN in the triequatorial form (see the
Appendix for its synthesis) was heated in a stainless steel oven
at 160 °C, and c-HTCN vapor was effused into the vacuum
through a 0.5 mm orifice on a lid of the oven. The supersonic
expansion from the nozzle was allowed to mix with the effusive
beam of the sample vapor at the distance of 7 mm downstream
from the nozzle. The anions produced in the expansion region
were extracted by applying a pulsed electric field and accelerated
up to 1500 eV in a field-free path of 2.7 m. After passing
through the ion optics, the anions were detected by a tandem
microchannel plate (Hamamatsu F2223-21S), and the mass
spectrum of the product anions was obtained.
(Hamamatsu F2223-21S). The signal was recorded by a 1 GHz
time-to-digital converter (LeCroy TDC4208) interfaced with a
personal computer (NEC PC-9801 VX). The data were ac-
cumulated for 30 000-60 000 laser shots so as to obtain one
photoelectron spectrum of c-HTCN (-) with a good signal-to-
noise ratio. Energy calibration was performed by measuring the
-
- 24-27
known photoelectron spectra of O and O2 .
of this photoelectron spectrometer was determined to be 30 and
50 meV fwhm (full width at half-maximum) at Ec.m. ) 1.148
The resolution
1
and 2.79 eV, respectively, from the measurement of the
-
photoelectron spectrum of Cu .
The photoelectron spectrum of (AN)3- was also measured
under the same experimental condition by using the same
procedure as stated above. A detailed description of the
The photoelectron spectrum of c-HTCN (-) was measured
as follows: The anions were extracted by applying a pulsed

7182 J. Phys. Chem. A, Vol. 105, No. 30, 2001
Fukuda et al.
Figure 2. Mass spectrum of anionic species produced by electron
impact on c-HTCN. The peak indicated by a vertical arrow (m/z )
1
2
59) was assigned to c-HTCN (-). Peaks with m/z ) 177, 195, and
-
3
Figure 3. Photoelectron spectra of (AN)
(upper trace) and 1,3,5-
2
13 were assigned to c-HTCN (-) solvated with H O molecule(s). The
cyclohexanetricarbonitrile (-) in the triequatorial form (lower trace)
at a photon energy of 2.33 eV. The vertical arrows represent the vertical
detachment energies of both anionic species.
peak indicated by an asterisk (m/z ) 132) was assigned to an anion
produced by eliminating one HCN unit from c-HTCN (-).
measurement of a photoelectron spectrum of (AN)3- was shown
in one of our previous papers.22
detachment energies of (AN)3- and c-HTCN (-) were deter-
mined to be 0.85(3) and 1.14(3) eV, respectively; the vertical
-
detachment energy of (AN)3 is smaller by 0.29(6) eV than
3. Results
that of c-HTCN (-) in the triequatorial form.
13,14,20-22
3
.3. Ab Initio MO Calculation. Previous studies
3
.1. Anionic Products by Electron Impact on c-HTCN.
-
have shown that (AN)3 is one of the stereoisomers of c-HTCN
Figure 2 shows a typical TOF mass spectrum of anions produced
by electron attachment on c-HTCN (1,3,5-cyclohexanetricar-
bonitrile). The peak indicated by a vertical arrow (m/z ) 159)
was assigned to c-HTCN (-). The peaks with m/z ) 177, 195,
and 213 were assigned to c-HTCN (-) solvated with H2O
molecule(s). On the other hand, the peak indicated by an asterisk
(
-) as described in section 1. This conclusion is actually
-
supported by the photoelectron spectra of (AN)3 and c-HTCN
(-) in the triequatorial form; the spectral profile is almost same
but only the peak energy is different by 0.29(6) eV. The
molecular anion, c-HTCN (-), is known to have four stereo-
isomers as listed in Table 1: They are (a) the diaxial form in
which two -CN groups are oriented axially and the other one
equatorially with respect to the average plane of the chair-form
cyclohexane ring, (b) the diequatorial form in which two -CN
groups are oriented equatorially and the other one axially, (c)
the triequatorial form in which all of the three -CN groups are
oriented equatorially, and (d) the triaxial form in which all of
the three -CN groups are oriented axially.
(
m/z ) 132) was assigned to an anion produced by eliminating
one HCN unit from c-HTCN (-). This anion is regarded as
-
[
(AN)3-HCN] , which was also produced by electron attach-
13,14
ment on (AN)m.
The production of the anion (m/z ) 132)
-
lends a further support that (AN)3 is one of the stereoisomer
of c-HTCN (-), because the product anions from (AN)3 and
c-HTCN (-) are same.
-
.2. Vertical Detachment Energies of (AN)3- and c-HTCN
3
-
-
To identify the isomeric structure of (AN)3 , the vertical
(-). Figure 3 shows typical photoelectron spectra of (AN)3
detachment energies of these stereoisomers were calculated as
shown below:
and c-HTCN (-) measured at the photon energy of 2.33 eV
under the same experimental conditions, where the abscissa
represents the electron binding energy. The small hump at ∼0.2
eV is an artifact caused by a multiphoton process. The peak
(1) Geometry optimization was carried out for a given isomer
of c-HTCN (-) possessing a predetermined -CN conformation
by using the 6-31+G basis set at the Hartree-Fock level.
-
energy of (AN)3 is smaller than that of c-HTCN (-), whereas
(2) The energies of c-HTCN (-) and c-HTCN (defined as
the spectral width of both the spectra is almost the same; a slight
difference in spectral width is explained by a difference in
Eanion and Eneutral, respectively) were calculated at the second-
order Møller-Plesset (MP2) level with the 6-31++G(d,p) basis
set on the premise that both c-HTCN (-) and c-HTCN have
the same geometrical structure calculated in procedure 1.
-
internal energy between (AN)3 and c-HTCN (-).
The vertical detachment energy, Vexp, of an anion, is derived
from the peak energy of the photoelectron spectrum of the anion
by using the relation
(3) The vertical detachment energy, Vcal, for the isomer was
obtained as
2
Eb - V
exp
Vcal ) Eneutral - Eanion
(2)
I(E ) ) C exp -
(1)
b
{ (
) }
δ
In the calculation, the spin-restricted Hartree-Fock (RHF) and
the spin-unrestricted Hartree-Fock (UHF) methods were em-
ployed for the closed-shell and the open-shell systems, respec-
tively. Let us define the relative energy ∆Eanion for a given
isomer anion with respect to the energy of isomer a which is
the most stable structure of c-HTCN (-). On the other hand,
where 2δ ln2 is the full width at a half-maximum of the
spectrum, Eb is the electron binding energy, and C is a constant.
The parameters Vexp and δ were obtained by a least-squares
fitting of the rising portions of the (AN)3 and c-HTCN (-)
spectra with the Gaussian function given by eq 1. The vertical
x
-

Anionic Polymerization of an Acrylonitrile Trimer
J. Phys. Chem. A, Vol. 105, No. 30, 2001 7183
Figure 4. Conformational inversion in 1,3,5-cyclohexanetricarbonitrile
(
-). The topomerization gives rise to the interconversion of two
diastereomers.
the relative vertical detachment energy, ∆Vcal, is defined with
respect to the vertical detachment energy of isomer c, because
the synthesized c-HTCN (-) corresponds to isomer c. The
methods and the basis sets employed in the present calculation
are reliable enough to predict the relative energy, ∆Eanion, and
the relative vertical detachment energy, ∆Vcal, but not suf-
ficiently accurate to reproduce the absolute energy and the
observed vertical detachment energy. The ∆Eanion and ∆Vcal
obtained from the calculations are listed in Table 1. As shown
in Table 1, the order of the magnitudes of ∆Eanion and ∆Vcal
does not change by reducing the number of the basis functions,
although ∆Eanion and ∆Vcal themselves change slightly.
Figure 5. Synthetic scheme for 1,3,5-cyclohexanetricarbonitrile.
other hand, the preferential formation of isomer a can also be
predicted by an argument based on an entropy point of view.
As each -CN group can be oriented either equatorially or
axially, there exist eight possible combinations for three -CN
groups. Two combinations out of the eight give rise to
triequatorial (isomer c) or triaxial (isomer d) stereoisomers, and
the rest provide diaxial (isomer a) and diequatorial ones (isomer
b). This implies that a probability for producing isomer a or b
is three times larger than that for producing isomer c or d. In
addition, isomer b is readily inverted to isomer a as discussed
above. These considerations lead us to conclude that the
intracluster anionic polymerization favors the formation of
stereoisomer a on the basis of the energetics and the entropy
requirement.
4
. Discussion
.1. Identification of (AN)3- Structure. In c-HTCN (-),
4
the pair of isomers a and b and that of c and d are mutually
invertible (see Figure 4 parts 1 and 2),2
8,29
whereas all of the
other two pairs are not mutually invertible in a thermal condition
because of a high energy barrier for the conformational change,
which involves the rupture of chemical bonds. According to
the calculation, the energy differences between the pair of
isomers a and b and that between c and d are found to be
sufficiently large (0.91 and 0.63 eV, respectively) that the
equilibrium favors formation of isomer a through the intercon-
version reaction between isomers a and b and isomer c through
that between isomers c and d. Furthermore, the calculation
shows that the vertical detachment energy of isomer a is smaller
by 0.29 eV than that of isomer c (see Table 1). In summary,
c-HTCN (-) has stable isomers a and c, where the vertical
detachment energy of isomer a is calculated to be smaller by
5
. Conclusion
A characteristic feature of intracluster polymerization reac-
tions was investigated by using such a bench mark system that
three acrylonitrile molecules assembled in a ring form undergo
anionic polymerization by electron attachment. The formation
of the most preferable stereoisomer was found to be determined
by the energetics and the entropy requirement of the reaction
system.
Acknowledgment. The authors thank Center for Computa-
tional Material Science of IMR in Tohoku University, The
Institute of Physical and Chemical Research (RIKEN), and
Institute for Molecular Science (IMS) for using their computers.
The authors also thank Professors T. Nagata, T. Tsukuda, K.
Yamanouchi, and K. Someda for their fruitful discussion. One
of the authors (Y.F.) is grateful for the Research Fellowship of
the Japan Society for the Promotion of Science for Young
Students. This research was supported by a Grant-in-Aid for
Scientific Research by the Ministry of Education, Science and
Culture of Japan and by a special cluster project of Genesis
Research Institute Inc.
0
.29 eV than that of isomer c.
Note the experimental result that the vertical detachment
energy of (AN)3- is smaller by 0.29(6) eV than that of c-HTCN
(
-) having the structure of isomer c. In comparison with the
-
calculation described above, it is concluded that (AN)3 holds
the structure of isomer a, whereas the synthesized c-HTCN (-)
holds the structure of isomer c.
4
.2. Preferential Stereoisomer Formation. The formation
-
of (AN)3 in isomer a by intracluster polymerization in (AN)m
initiated by electron attachment can be explained as follows:
As discussed in our previous paper,13-22 prealigned hydrogen-
bonded three AN molecules in (AN)m are polymerized into the
six-membered ring molecule, c-HTCN (-), when one electron
attached to it. In the intracluster polymerization, chain propaga-
tion is likely to proceed so as to seek a product having the most
stable structure among the four stereoisomers. As mentioned
previously, the most stable structure is isomer a, so that the
product of the intracluster polymerization must be isomer a as
a natural consequence on the basis of the energetics. On the
Appendix
Synthesis of 1,3,5-Cyclohexanetricarbonitrile. The com-
pound 1,3,5-cyclohexanetricarbonitrile was synthesized by the
following procedures and was examined by H NMR, C NMR,
and IR spectroscopy. The synthetic scheme is shown in Figure
5.
1,3,5-Cyclohexanetricarbonyl Chloride (2). A solution of
a triequatorial 1,3,5-cyclohexanetricarboxylic acid (1; 737 mg,
3.41 mmol) and benzyltriethylammonium chloride (23.3 mg,
0.102 mmol) in 1,2-dichloroethane (5 mL) was refluxed while
1
13

7184 J. Phys. Chem. A, Vol. 105, No. 30, 2001
Fukuda et al.
dropping thionyle chloride (5 mL) at 100 °C for 1.5 h under
argon atmosphere. After cooling to room temperature, the
solvent was distilled out under reduced pressure. The solid thus
obtained was washed twice by tetrahydrofuran (THF; 1 mL)
and dried off under reduced pressure, and then 1,3,5-cyclohex-
anetricarbonyl chloride (2; 859 mg, 3.16 mmol, 93%) was
obtained.
(2) Coolbaugh, M. T.; Vaidyanathan, G.; Peifer, W. R.; Garvey, J. F.
J. Phys. Chem. 1991, 95, 8337.
(3) Whitney, S. G.; Coolbaugh, M. T.; Vaidyanathan, G.; Garvey, J.
F. J. Phys. Chem. 1991, 95, 9625.
(4) Coolbaugh, M. T.; Garvey, J. F. Chem. Soc. ReV. 1992, 21, 163.
(5) Coolbaugh, M. T.; Whitney, S. G.; Vaidyanathan, G.; Garvey, J.
F. J. Phys. Chem. 1992, 96, 9139.
(6) Lyktey, M. Y. M.; Rycroft, T.; Garvey, J. F. J. Phys. Chem. 1996,
1
00, 6427.
1
,3,5-Cyclohexanetriamide (3). A solution of 1,3,5-cyclo-
(7) El-Shall, M. S.; Marks, C. J. Phys. Chem. 1991, 95, 4932.
hexanetricarbonyl chloride (2; 859 mg, 3.16 mmol) in 28%
aqueous ammonia (50 mL) was stirred at 0 °C for 1 h and was
allowed to react at room temperature for 2 h. The solvent was
filtered out. The solid thus obtained was washed by acetone
and dried off under reduced pressure. Then 1,3,5-cyclohexane-
triamide (3; 626 mg, 2.93 mmol, 93%) was obtained.
(8) El-Shall, M. S.; Schriver, K. E. J. Chem. Phys. 1991, 95, 3001.
(
9) El-Shall, M. S.; Daly, G. M.; Yu, Z.; Meot-ner (Mautner), M. J.
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(
9
5, 1664.
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9
(
(
(
(
The physical properties of product 3 are given below:
1
H NMR (d6-DMSO) δ ) 1.30-1.33 (1H, dd), 1.73-1.76
(
1H, d, J ) 11.4 Hz), 2.11 (1H, dd), 6.69 (1H, s), 7.18 (1H, s).
1
3
C NMR (d6-DMSO) δ ) 176.3, 42.5, 31.5.
-
1
IR (KBr): 3346, 3180, 1676, 1620, 1480 cm .
,3,5-Cyclohexanetricarbonitrile (4). A solution of 1,3,5-
(
1
cyclohexanetriamide (3; 626 mg, 2.93 mmol) in chloride
phosphate in excess was refluxed for 8 h under argon atmo-
sphere. The reaction was terminated by adding a saturated
aqueous solution of sodium hydrogencarbonate. The organic
portion of the solution was extracted, washed by a saturated
aqueous solution of sodium chloride, and dehydrated by sodium
sulfate anhydride. The solvent was distilled out under reduced
pressure. The solid thus obtained was refined by thin chroma-
tography (ethyl acetate) to prepare 1,3,5-cyclohexanetricarbo-
nitrile (4; 230 mg, 1.45 mmol, 49%).
(
(
(
(
Lett. 1996, 260, 423.
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Gordon, M.; Gonzalez, C.; Pople, J. A. Gaussian 94, revision E.2; Gaussian,
Inc.: Pittsburgh, PA, 1995.
(24) Breyer, H. F.; Frey, P.; Hotop, H. Z. Physik A 1987, 286, 133.
(25) Celotta, R. J.; Bennett, R. A.; Hall, J. L.; Siegel, M. W.; Levine, J.
Phys. ReV. A 1972, 6, 631.
26) Posey, L. A.; DeLuca, M. J.; Johnson, M. A. Chem. Phys. Lett.
986, 131, 170.
The physical properties of product 4 are given below:
White-colored solid at room temperature.
Melting point ) 156.0-156.5 °C.
1
H NMR (CDCl3) δ ) 1.80-1.87 (1H, dd, J ) 25.9, 13.0
Hz), 2.45-2.48 (1H, m), 2.53-2.59 (1H, dddd, J ) 12.6, 12.6,
3
.5, 3.5 Hz).
1
3
C NMR (CDCl3) δ ) 118.5, 30.9, 26.2.
-
1
IR (KBr): 2250 cm .
The NMR spectra show that product 4 has a triequatorial
form; all of the three -CN groups are oriented equatorially with
respect to the average plane of chair-form cyclohexane ring.
(
1
(27) Posey, L. A.; Johnson, M. A. J. Chem. Phys. 1988, 88, 5383.
(
28) Carey, F. A.; Sundberg, R. J. AdVanced Organic Chemistry; Plenum
Press: New York, 1990.
29) Eliel, E. L.; Wilen, S. H. Stereochemistry of Organic Compound;
John Wiley & Sons: New York, 1994.
References and Notes
(
(1) Garvey, J. F.; Bernstein, R. B. Chem. Phys. Lett. 1986, 126, 394.