3730 J . Org. Chem., Vol. 64, No. 10, 1999
Notes
was obtained in 91% yield: mp ) 75-7 °C (from methanol); 1H
NMR δ 1.50 (6H, s), 2.35 (3H, s), 4.45 (2H, s), 7.07 (2H, bd, J )
8.1 Hz, A part of AA′BB′), 7.26-7.45 (4H, m), 7.49 (2H, bd, J )
8.1 Hz, B part of AA′BB′), 7.73 (1H, bd, J ) 8.0 Hz), 7.84 (1H,
dd, J 1 ) 8.2 Hz, J 2 ) 1.5 Hz), 7.95 (1H, bd, J ) 8.8 Hz); MS m/z
(rel inten) 354 (M+, 13), 182 (15), 169 (100), 141 (20), 91 (10);
HRMS calcd for C21H22O3S 354.1290, found 354.1286. Anal.
Calcd for C21H22O3S: C, 71.16; H, 6.26; S, 9.04. Found: C, 71.20;
H, 6.23; S, 9.07.
2-Met h yl-2-(2-n a p h t h yl)-1-p r op yl p -Tolu en esu lfon a t e.
Following the procedure of Hixson and Tausta,8 from the
corresponding propanol (9.48 g, 47.4 mmol) we obtained the title
tosylate: 10.6 g (65%); mp ) 102-4 °C (from methanol); 1H NMR
δ 1.39 (6H, s), 2.31 (3H, s), 4.07 (2H, s), 7.10 (2H, bd, J ) 8.1
Hz, A part of AA′BB′3, 7.32-7.84 (9H, m, B part of AA′BB′ and
ArH); MS m/z (rel inten) 354 (M+, 100), 182 (8), 169 (44), 141
(8), 91 (5); HRMS calcd for C21H22O3S 354.1290, found 354.1293.
Anal. Calcd for C21H22O3S: C, 71.16; H, 6.26; S, 9.04. Found:
C, 71.14; H, 6.29; S, 9.07.
2-Meth yl-2-(2-n a p h th yl)-1-br om op r op a n e. With the same
procedure described above for the 1-naphthyl isomer, starting
from the corresponding tosylate (8 g, 22.5 mmol) we obtained
the title bromide: 4.1 g (70%); bp ) 116-8 °C (0.019 mbar); 1H
NMR δ 1.61 (6H, s), 3.70 (2H, s), 7.47-7.59 (3H, m), 7.80-7.92
(4H, m); 13C NMR (50 MHz) δ 27.9, 40.0, 47.2, 124.8, 125.1,
126.4, 126.7, 128.0, 128.6, 128.7, 132.7, 133.9, 143.9; MS m/z
(rel inten) 264 (M+ + 2, 15), 262 (M+, 16), 183 (10), 169 (100),
141 (27), 127 (7); HRMS calcd for C14H15Br 263.0357, found
263.0360. Anal. Calcd for C14H15Br: C, 63.89; H, 5.74; Br, 30.36.
Found: C, 63.87; H, 5.71; Br, 30.37.
Kin etic Mea su r em en ts. Competitive kinetic measurements
were performed in samples consisting of 300 µL of benzene
solutions containing the reactants and the radical initiator.
Deoxygenated samples were sealed under nitrogen atmosphere
in a quartz tube and irradiated for 30-90 min in a thermostated
((0.2 °C) photoreactor equipped with a 125 W high-pressure
mercury lamp. The crude reaction mixture was analyzed by gas
chromatography for quantitative measurements and by GC-
MS for preliminary experiments and for the identification of
reaction products.
Ca libr a tion of th e Ra d ica l Clock s. Measurements were
performed in the temperature range 293-358 K on samples
containing the radical clock precursor (typically (3-5) × 10-2
M), 2,4,6-trimethylphenol (0.15-0.8 M), and bis(tributyltin)
(typically (2-3) × 10-2 M). Concentrations of the reactants were
chosen so as to avoid significative consumption of the phenol
during the experiment. At each temperature, five to eight
experiments were performed with different phenol concentra-
tions, and the product ratio [UH]/[RH] was plotted against the
initial phenol concentration to obtain the rate constant ratio kH/
kr.
2-Meth yl-2-(1-n a p h th yl)-1-br om op r op a n e. The tosylate
prepared above (8 g, 22.6 mmol), lithium bromide (1.9 g, 22.0
mmol), anhydrous hexamethylphosphorictriamide (20 mL), and
water (25 drops) were heated at 90 °C under stirring for 5 h.
After cooling, the reaction mixture was poured into water and
extracted three times with 50 mL portions of diethyl ether. The
combined organic layers were dried (MgSO4) and concentrated
under vacuum to give an oily residue that was chromatographed
on silica gel. Elution with light petroleum furnished an oil that
was distilled under vacuum to give 5.10 g (85%) of the title
1
compound: bp ) 114-5 °C (0.019 mbar); H NMR δ 1.85 (6H,
s), 4.15 (2H, s), 7.48-7.70 (4H, m), 7.85 (1H, bd, J ) 8.3 Hz),
7.86-8.06 (1H, m), 8.43 (1H, m); 13C NMR (50 MHz) δ 29.4, 41.2,
46.2, 125.5, 125.8, 125.9, 126.1, 129.1, 130.6, 131.9, 135.7, 141.5;
MS m/z (rel inten) 264 (M+ + 2, 15), 262 (M+, 15), 183 (5), 169
(100), 141 (25), 127 (8); HRMS calcd for C14H15Br 263.0357,
found 263.0354. Anal. Calcd for C14H15Br: C, 63.89; H, 5.74; Br,
30.36. Found: C, 63.87; H, 5.77; Br, 30.31.
Meth yl 2-m eth yl-2-(2-n a p h th yl)-p r op a n oa te. A 10.4 g
portion of a 60% NaH (260 mmol) dispersion in mineral oil was
added to 200 mL of anhydrous dimethylformamide. The mixture
was kept under N2, stirred, and cooled at ca. 10 °C, and 37.0 g
(260 mmol) of MeI and subsequently 13.0 g (65 mmol) of methyl
2-naphthyl acetate20 were added dropwise. The mixture was
warmed at room temperature, stirred for 10 h, and then poured
into ice-cooled diluted HCl and extracted three times with 80
mL portions of diethyl ether. The combined organic phases were
dried (MgSO4), and the solvent was removed under reduced
pressure. The oily residue was distilled under vacuum to give
12.1 g (80%) of the desired ester: bp ) 100-2 °C (0.04 mbar);
1H NMR δ 1.7 (6H, s), 6.68 (3H, s), 7.44-7.56 (3H, m), 7.78-
7.90 (4H, m); νmax 1730 cm-1; MS m/z (rel inten) 228 (M+, 33),
169 (100), 153 (9), 152 (9), 141 (40); HRMS calcd for C15H16O2
228.1150, found 228.1153. Anal. Calcd for C15H16O2: C, 78.92;
H, 7.06. Found: C, 78.97; H, 7.08.
Deter m in a tion of kH for Tr ip h en ylsila n e. Six measure-
ments were performed at 298 K on samples containing the
radical clock precursor (typically (4-5) × 10-2 M), di-tert-
butylperoxide (5 × 10-2 M), and different concentrations of
triphenylsilane in the range 0.3-1.0 M.
2-Meth yl-2-(2-n a p h th yl)-1-p r op a n ol. A solution of methyl
2-methyl-2-(2-naphthyl)propanoate (11.85 g, 51.9 mmol) in
anhydrous diethyl ether (20 mL) was added dropwise to a
suspension of LiAlH4 (1.98 g, 51.9 mmol) in anhydrous diethyl
ether (100 mL) with stirring at room temperature under N2
atmosphere. After the reaction was complete (ca. 2 h), the
mixture was hydrolyzed with ethyl acetate and subsequently
with dilute HCl. The organic layer was separated and dried
(MgSO4), and the solvent was removed under vacuum to give
the title propanol as an oil that solidified upon standing: 9.9 g
(95%); mp ) 56-8 °C (from light petroleum); 1H NMR δ 1.40
(6H, s), 1.70 (1H, bs), 3.63 (2H, s), 7.48-7.61 (3H, m), 7.81-
7.93 (4H, m); νmax 3600 cm-1; MS m/z (rel inten) 200 (M+, 20),
Ack n ow led gm en t. Financial support from MURST,
CNR, and the University of Bologna “Progetto d’Ateneo
1997-1999: Processi a basso impatto ambientale” is
gratefully acknowledged. We also thank Dr. Federica
Monti for technical assistance.
Su p p or tin g In for m a tion Ava ila ble: Tables of kinetic
data and a detailed Experimental Section describing the
kinetic measurements and the data treatment. This material
169 (100), 153 (8), 152 (8), 141 (25); HRMS calcd for C14H16
O
200.1201, found 200.1205. Anal. Calcd for C14H16O: C, 83.96;
H, 8.05. Found: C, 83.94; H, 8.02.
J O9813179