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H. Shimakoshi et al. / Journal of Organometallic Chemistry xxx (2017) 1e7
Fig. 6. ESR spectra of 1 during the electrolysis of styrene at ꢀ0.7 V vs. Ag/AgCl in CH3CN under N2; [1] ¼ 5 ꢁ 10ꢀ4 M; [styrene] ¼ 5 ꢁ 10ꢀ2 M; [TFA] ¼ 5 ꢁ 10ꢀ1 M;
[DMPO] ¼ 5 ꢁ 10ꢀ1 M; [n-Bu4NClO4] ¼ 1 ꢁ 10ꢀ1 M in the presence of TFA (a) and in the presence of TFA-d1 (b).
J ¼ 7.2Hz, 6H, CH3), 1.28e1.44 (m, 4H, CH2), 2.60e2.62 (m, 2H, CH),
7.21e7.36 (m, 10H, Ph), 13C NMR (CDCl3,
d/ppm), 12.55, 27.80, 54.65,
126.37, 128.58, 128.83, 144.95.
4.3.2. DH (racemic)
Colorless liquid. GC-MS, Mþ ¼ 238; 1H NMR (CDCl3,
d/ppm), 0.77
(t, J ¼ 7.6Hz, 6H, CH3), 1.54e1.66 (m, 4H, CH2), 2.74e2.76 (m, 2H,
CH), 6.88e7.21 (m, 10H, Ph), 13C NMR (CDCl3,
d/ppm), 12.76, 26.24,
Fig. 7. Structure of the imine/oxime type cobalt complex, [Co(III){(C2C3)(DO)(DOH)pn}
Br2].
53.68, 126.00, 127.83, 129.46, 143.46.
4.3.3. 1,1-Diphenylethane
Colorless liquid. GC-MS, Mþ ¼ 182; 1H NMR (CDCl3,
d/ppm), 1.74
using a BAS CV 50W electrochemical analyzer. A three-electrode
cell equipped with a 1.6-mm diameter glassy carbon rod and
platinum wire as the working and counter electrodes, respectively,
was used. An Ag/AgCl (3.0 M NaCl) electrode served as the refer-
ence. The E1/2 value of the ferrocene-ferrocenium (Fc/Fcþ) was
0.40 V vs. Ag/AgCl with this setup.
(d, J ¼ 7.3Hz, 3H, CH3), 4.27 (q, J ¼ 7.3Hz, 1H, CH), 7.25e7.39 (m,10H,
Ph), 13C NMR (CDCl3,
146.92.
d/ppm), 22.44, 45.33, 126.58, 128.19, 128.92,
4.3.4. Butyl propionate (4a)
Colorless liquid. GC-MS, Mþ ¼ 130; 1H NMR (CDCl3,
d/ppm), 0.95
(t, J ¼ 7.3Hz, 3H, CH3), 1.16 (t, J ¼ 7.6Hz, 3H, CH3), 1.38e1.41 (m, 2H,
4.3. General bulk electrolysis
CH2), 1.60e1.66 (m, 2H, CH2), 2.35 (q, J ¼ 7.6Hz, 2H, CH2), 4.09 (t,
J ¼ 7.0Hz, 2H, CH2), 13C NMR (CDCl3,
d/ppm), 9.45, 13.98, 19.47,
The controlled-potential electrolysis of the alkene was carried
out in a divided cell equipped with a carbon felt cathode and a zinc
plate anode (1 ꢁ 3 cm2) at ꢀ0.7 V vs. Ag/AgCl in the presence of 1 at
room temperature in 0.1 M n-Bu4NClO4 containing acetonitrile. The
applied potential between the working and reference electrodes
during the electrolysis was maintained constant using a Hokuto
Denko HA BF-501A potentiostat, and the electrical quantity was
also recorded by it. The concentrations of the catalyst and substrate
were 5.0 ꢁ 10ꢀ4 M and 5.0 ꢁ 10ꢀ2 M, respectively. After the elec-
trolysis, the electrolyte solution was passed through silica gel with
the CHCl3 eluent, then analyzed by GC-MS. Authentic samples of
the products from the catalytic reactions (Tables 1 and 2) except for
those listed below were purchased from Aldrich or Tokyo Kasei
Kogyo (TCI). The 2,3-diphenylhexanes (racemic and meso) (DH)
were synthesized by reported methods [30], and the mixture of the
racemic and meso compound was separated by preparative TLC
using hexane as the eluent. 1,1-Diphenylethane, butyl propionate
(4a), and octyl propionate (4c) were synthesized by hydrogenation
of 1,1-diphenylethylene, butyl acrylate (3a), and octyl acrylate (3c)
using Pd/C under 1atm H2, respectively. Ethyl 2-phenylacrylate was
synthesized by the acid-catalyzed esterification of 2-phenylacrylic
acid in ethanol.
27.94, 31.07, 64.47, 174.86.
4.3.5. Octyl propionate (4c)
Colorless liquid. GC-MS, Mþ ¼ 186; 1H NMR (CDCl3,
d/ppm),
0.89e0.92 (t, J ¼ 7.3Hz, 3H, CH3), 1.15e1.18 (t, J ¼ 7.6Hz, 3H, CH3),
1.30e1.31 (m, 10H, CH2), 1.63e1.66 (m, 2H, CH2), 2.33e2.37 (q,
J ¼ 7.6Hz, 2H, CH2), 4.07e4.10 (t, J ¼ 6.9Hz, 2H, CH2), 13C NMR
(CDCl3, d/ppm), 9.54, 14.44, 23.01, 26.31, 28.02, 29.05, 29.55, 29.60,
32.16, 64.87, 174.97.
4.3.6. Ethyl 2-phenylacrylate
Colorless liquid. GC-MS, Mþ ¼ 176; 1H NMR (CDCl3,
d/ppm), 1.33
(t, J ¼ 7.2Hz, 3H, CH3), 4.3 (q, J ¼ 7.2Hz, 2H, CH2), 5.89 (s, 1H, CH),
6.35 (s, 1H, CH), 7.34e7.41 (m, 5H, Ph), 13C NMR (CDCl3,
d/ppm),
14.62, 61.51, 126.86, 128.48, 128.51, 128.69, 137.19, 141.99, 167.23.
4.4. Spin-trapping experiment by ESR
The ESR spectra were obtained using a Bruker EMX-Plus X-band
spectrometer at room temperature. The ESR spectra for the DMPO
spin-trapping products were observed during the electrolysis of
styrene (5.0 ꢁ 10ꢀ2 M) at ꢀ0.7 V vs. Ag/AgCl using a carbon felt
electrode in the presence of DMPO (5 ꢁ 10ꢀ1 M), 1 (5.0 ꢁ 10ꢀ4 M)
and TFA (5.0 ꢁ 10ꢀ1 M) in dry acetonitrile under nitrogen. The
settings for the ESR measurements were a frequency of 9.87 GHz,
4.3.1. DH (meso)
White solid. GC-MS, Mþ ¼ 238; 1H NMR (CDCl3,
d/ppm), 0.55 (t,
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