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A. J. MENDONC¸ A ET AL.
1
70 eV; H and 13C NMR spectra were recorded on a Bruker AC 250P spectrometer
or a Bruker Avance II, at 600 MHz (1H NMR) and 150.9 MHz (13C NMR) in
CDCl3. Chemical shifts are given in parts per million (ppm) and were measured
versus residual peak of the solvent, 7.26 ppm for 1H and 77.0 ppm for 13C.
Two-dimensional experiments (1H–1H COSY, HSQC, HMBC) were performed with
standard Bruker software and were carried out for complete assignment of proton
and carbon signals in the NMR spectra.
Constant-Current Electrolysis
Electrolyses were carried out in a single-compartment glass cell with two Pt foil
electrodes separated by 5 mm, under magnetic stirring at a constant current of
15 mA=cm2 using a dc power supply (Good Will Instruments GSP-3030D). Electro-
lyte solution volumes were 25 cm3 or 50 cm3, using 1.1 ꢃ 1.1 cm2 or 2.5 ꢃ 2.5 cm2 elec-
trodes, respectively. The carboxylic acid was dissolved in MeOH=Py (4:1) and
partially neutralized with NaOMe. The electrolysis was carried out at room tempera-
ture, until the pH of electrolyte solution was approximately 8. During the reaction,
every 30 min, the polarity inversion was performed to avoid electrode passivation.
After the electrolysis, the reaction mixture was extracted with chloroform
(3 ꢃ 20 cm3) and washed with water. The combined organic extracts were dried
(Na2SO4) and concentrated. The crude residue was submitted to column chromato-
graphy over silica gel G (230–400 mesh) using n-hexane=ethyl acetate gradients of
increasing polarity as solvent.
1,2-Diphenylethane (2)
White crystals; mp 50.1–51.3 ꢀC; IR (nujol) 3086, 3064, 3031 (t arC-H), 2960,
2927, 2856 (t C-H), 1947, 1881, 1810, 1775 (comb monosubst.), 1599, 1487 (t
arC-C), 1146, 1027, 968 (dip arC-H), 909, 752, 699 (doop) cmꢂ1 1H NMR
;
(250 MHz, CDCl3), d 2.95 (s, 4H, H-1 and H-2), 7.15–7.24 (m, 7H, H aromatic),
7.28–7.35 (m, 3H, H-aromatic); 13C NMR (63 MHz, CDCl3), d 38.1 (C-1 and
C-2), 126.4 (C-40 and C-400), 128.6 (C-20, C-60, C-200 and C-600), 128.9 (C-30, C-50,
C-300 and C-500), 141.9 (C-10 and C-100).
1,2-Di(Bicyclo[2.2.1]heptan-2-yl)ethane (4)
White crystals; mp 98.3–99.2 ꢀC; IR (nujol) 2952, 2933, 2873, 2854 (t C-H),
1
1455 (d CH2) cmꢂ1; H NMR (600 MHz, CDCl3), d 1.17–1.21 and 0.97–1.04 (m,
4H, H-60 and H-600), 1.23–1.28 (m, 2H, H-20 and H-200), 1.24–1.28 (m, 4H, H-1
and H-2), 1.34–1.41 and 0.93–1.00 (m, 4H, H-70 and H-700), 1.39–1.46 and
1.04–1.10 (m, 4H, H-30 and H-300), 1.42–1.46 and 1.08–1.12 (m, 4H, H-40 and
H-400), 1.89–1.94 (m, 2H, H-10, H-10), 2.11–2.16 (m, 2H, H-50, H-500); 13C NMR
(150.9 MHz, CDCl3), d 28.9 (C-30 and C-300), 30.2 (C-40 and C-400), 35.3 (C-60 and
C-600), 35.3 and 35.4 (C-1 and C-2), 36.6 (C-50 and C-500), 38.4 (C-70 and C-700),
41.2 (C-10 and C-100), 42.5 (C-20 and C-200); EIMS (%) m=z 218 (5) [M]þ, 190 (11),
135 (8), 121 (10), 108 (15), 95 (100).