T.M. Bockman et al. / Journal of Organometallic Chemistry 586 (1999) 41–47
43
phase-transfer catalyst) was allowed to react, with stir-
ring, until the temperature reached 50°C, when 25 ml
additional dichloromethane was added. After stirring
for 1 h, the temperature was increased to 60°C and held
for an additional 1 h. Cooling, separating the organic
layer, extracting of the aqueous layer with diethyl ether,
For a CIDNP experiment, an NMR tube charged
with HCo(CO) or DCo(CO) solution was allowed to
4
4
warm to room temperature. The pressure cap was
pulled back to allow ingress of a syringe needle and the
substrate (neat or in solution) was added down the side
of the tube, after which the cap was replaced. Reaction
was initiated by vigorous shaking, the tube placed
immediately in the probe of the spectrometer (usually a
Varian EM-390), and a stopwatch started. The spectral
region of interest was scanned repeatedly at 10 ppm
drying the combined organic layers (MgSO ), filtering,
4
concentrating, and distilling led, after a forerun, to 45 g
(
1
48%) 1,1-dichloro-2-phenylcyclopropane. B.p.: 105–
10°C (8 mm). NMR (CCl ): l 7.11 (br s, 5 H), 2.85 (br
4
−
1
min . Finally, the entire spectrum was obtained with
scanning at a slower rate. The entire experiment lasted
about 10 min.
t, 1 H), 1.65–1.98 (complex m, 2 H) ppm.
,1-Dichloro-2-phenylcyclopropane (9.3 g, 0.050
1
mol), ethanol (70 ml), and 50% aqueous NaOH (10 ml)
were refluxed for 18 h, poured onto 150 g ice, and
extracted three times with 25 ml portions of petroleum
ether. The combined extracts were dried, stripped of
solvent, and distilled under reduced pressure (oil
pump), collecting 5.0 g (fractions boiling 70–100°C (2.0
mm)) of impure diethyl acetal of 2-phenylpropenal.
When a Jeol-FX90Q spectrometer was used, its open
architecture allowed a slightly different procedure. The
charged sample tube was first placed in the probe and a
reference spectrum recorded. Substrate (neat or solu-
tion) was added to the slightly-withdrawn tube and it
was recapped, shaken, and replaced, leaving it between
the poles of the magnet at all times during this proce-
dure. The spectrum was recorded and stored at fixed
subsequent time intervals.
NMR (CCl ): l 7.0–7.4 (m, 5 H) ppm, 5.66 (s, 2 H),
4
5.18 (s, 1H), 3.53 (m, 4 H), 1.18 (t, 6H). Contamina-
tion, ꢀ20%, was evident in the NMR spectrum.
After the acetal (5.0 g) was swirled for 60 s at 0°C
with a solution of formic acid (5 ml) and water (2 ml),
a mixture of water (20 ml) and petroleum ether (10 ml)
was added and the aqueous phase was removed with a
Pasteur pipette. The combined organic phases (includ-
ing two 5-ml petroleum-ether extracts of the aqueous
2
For H-NMR experiments, a Jeol-FX90Q spectrome-
ter was used. The procedure was like that for CIDNP
experiments except that a sealed 5 mm tube containing
0
.5 ml 4.0 M LiBr in H O was placed inside the 10 mm
2
tube containing the sample. The spectrometer was
7
2
locked on the Li signal. During the reaction, H-NMR
spectra were recorded in sets of 16 transients and
stored. Finally, a product spectrum was obtained from
phase) were dried (MgSO ), stripped of solvent (rotary
4
evaporator without heat), and dissolved in a mixture of
1
00–400 transients. Where only the product spectrum
was desired, the NMR tube was held in a water bath
instead of the probe) until reaction was judged
10 ml petroleum ether and 5 ml diethyl ether. The
crystals that formed after 20 min of cooling at −50°C
were washed with cold petroleum ether and dried in
vacuo, giving 2.2 g (34% from 1,1-dichloro-2-phenylcy-
lopropane) 2-phenylpropenal. NMR (C D ): l 9.23 (s,
(
complete.
Kinetic measurements on the reaction of HCo(CO)4
with phenylacetylene used the Jeol-FX90Q NMR spec-
trometer, solvent C D , and added internal standard
6
6
1
H), 6.8–7.3 (m, 5 H), 6.65 (s, 1 H), 5.05 (s, 1 H) ppm.
6
6
C H . The procedure above was followed, except that
the HCo(CO)4 concentration was measured before
adding excess phenylacetylene (molar ratio
6
6
2
.8. Reactions in an NMR spectrometers ( for CIDNP,
product spectra, and kinetics)
PhCꢀCH:HCo(CO) of 3–14) and initiating the reac-
4
A sample was prepared in a 5 or 10 mm (outer
diameter) NMR tube. The tube was dried overnight in
an oven and placed in a side-armed test tube covered
with a rubber septum. Through the side arm, the ap-
paratus was evacuated and filled with CO several times,
after which the NMR tube was charged (through the
tion. Spectra were recorded as sets of four transients at
3
6 s intervals. HCo(CO) was monitored by its signal at
4
l −11.6 ppm (normalized by the signal from C H ).
6
6
Three runs of varying concentrations of HCo(CO)4
gave consistent results when fitted using a second-order
plot.
septum, using a gas-tight syringe) with stock HCo(CO)4
Similar procedures were used to determine the time
required for the equilibration of cis- and trans-b-deu-
or DCo(CO) solution that had been allowed to warm
4
1
to room temperature. For H-NMR studies, C D was
the solvent; for H-NMR, heptane. An internal stan-
teriostyrenes under the influence of HCo(CO) .
6
6
4
2
dard was added (optionally) at this time (C H6 for
6
HCo(CO) in C D or heptane; C D for DCo(CO) in
3. Results and discussion
4
6
6
6
6
4
heptane). Under a fast flow of CO, the septum was
removed and the NMR tube capped, after which it was
kept immersed in a dry-ice bath until used.
1
H-NMR spectra of product solutions from reactions
of phenylacetylene with excess HCo(CO)4 reveal