Hydrophobic Acceleration of ET Processes
J . Org. Chem., Vol. 61, No. 14, 1996 4699
Dawson.19 Spectral data of 5-n and 6-n prepared in this
laboratory are given below.
Sch em e 1
CH2CH2OH
CH2CH2O(CH2)nH
1
5
-8. H NMR (CDCl
3
): δ 7.22 (1H, d, J ) 4.0), 7.00 (1H,
1
. NaH
dd, J ) 9.0, 4.0), 6.90 (1H, d, J ) 9.0), 3.87 (3H, s), 3.80 (3H,
s), 2.97 (2H, t), 1.66 (2H, br), 1.26 (8H, m), 0.89 (3H, t). MS
2
. CH3(CH2)n–1Br
+
+
(
(
EI): m/ z (relative intensity) 265 (M + 1) (85.2), 264 (M)
3
1-n
24), 165 (100).
(
n = 1, 8, 12, 16)
-12. 1H NMR (CDCl
5
3
): δ 7.23 (1H, d, J ) 4.0), 7.01 (1H,
OMe
OMe O
OMe
dd, J ) 10.0, 4.0), 6.91 (1H, d, J ) 10.0), 3.87 (3H, s), 3.80
3H, s), 2.98 (2H, t), 1.68 (2H, br), 1.27 (16H, m), 0.90 (3H, t).
MS (EI): m/ z (relative intensity) 321 (M + 1) (92.2), 320 (M)
23.4), 165 (100).
-16. 1H NMR (CDCl
dd, J ) 8.5, 4.0), 6.90 (1H, d, J ) 8.5), 3.87 (3H, s), 3.80 (3H,
s), 2.97 (2H, t), 1.65 (2H, br), 1.25 (24H, m), 0.89 (3H, t). MS
EI): m/ z (relative intensity) 377 (M + 1) (20.2), 180 (M)
(32.3), 165 (100).
6-8. 1H NMR (CDCl
3H, s), 2.56 (2H, t), 1.57 (2H, br), 1.25 (10H, m), 0.90 (3H, t).
MS (EI): m/ z (relative intensity) 250 (M) (100), 152 (64.5).
-12. H NMR (CDCl
3H, s), 2.57 (2H, t), 1.56 (2H, br), 1.25 (18H, m), 0.88 (3H, t).
MS (EI): m/ z (relative intensity) 306 (M) (100), 152 (68.7).
-16. H NMR (CDCl
3H, s), 2.58 (2H, t), 1.58 (2H, br), 1.26 (26H, m), 0.90 (3H, t).
(
CH3(CH2)n–2CO2Cl
Pd-C/H2
(
CH2)n–1H
+
+
(
5
3
): δ 7.21 (1H, d, J ) 4.0), 7.01 (1H,
OMe
4
5-n
n = 8, 12, 16)
(
+
+
(
OMe
OH
(CH2)nH
(CH2)nH
3
): δ 6.72 (3H, m), 3.78 (3H, s), 3.77
Cl2
BBr3
(
HOAc–H2O
+
1
6
3
): δ 6.71 (3H, m), 3.78 (3H, s), 3.76
OMe
OH
(
6
-n
7-n
(n = 8, 12, 16)
+
(
n = 8, 12, 16)
1
6
3
): δ 6.75 (3H, m), 3.79 (3H, s), 3.78
O
(
+
Cl
(CH2)nH
Cl
MS (EI): m/ z (relative intensity) 362 (M) (100), 151 (72.8),
1
37 (30.2).
Cl
2-Alk ylh yd r oqu in on es (7-n ). A solution of 5 (5 mmol) and
boron tribromide (15 mmol) in dichloromethane (30 mL) was
stirred at -20 °C for 1 h and then for an additional 3 h at rt.
The mixture was hydrolyzed with water (10 mL) and extracted
with ether. The solvent was then removed in vacuo, and the
products (52.3-61.7%) were separated by flash column chro-
matography on silica gel with petroleum-EtOAc (8:2) as the
eluent.
O
-n
n = 8, 12, 16)
2
(
Molecules may associate in solution for a variety of
reasons, e.g., van der Waals forces, collision-induced weak
CT interactions, etc. However, both contributions are
quite small.17 On the other hand, previous works have
7-8. 1H NMR (CDCl
): δ 6.70 (1H, d, J ) 8.0), 6.66 (1H, d,
3
J ) 4.0), 6.51 (1H, dd, J ) 4.0, 8.0), 4.30 (2H, br, OH, D O
2
exchangeable), 2.55 (2H, t), 1.61 (4H, br), 1.28 (8H, m), 0.90
established that preassociation of chromophores greatly
+
(
3H, t). MS (EI): m/ z (relatively intensity) 222 (M) (57.2),
facilitates excimer formation.6
,7,18
We speculate that
1
24 (100).
-12. 1H NMR (CDCl
): δ 6.68 (1H, d, J ) 8.0), 6.65 (1H,
enhancement of fluorescence quenching might also be
facilitated by HLI-driven coaggregation of a donor and
7
3
2
d, J ) 4.0), 6.57 (1H, dd, J ) 4.0, 8.0), 4.35 (2H, br, OH, D O
exchangeable), 2.56 (2H, t), 1.62 (4H, br), 1.28 (16H, m), 0.91
-
5
an acceptor at very low concentrations (ca. 10 M).
Furthermore, the efficiency of fluorescence quenching
should depend on the chain length of the substituent
groups of the acceptor quenchers (2-n) or the donor probes
+
(3H, t). MS (EI): m/ z (relatively intensity) 279 (M + 1)
+
(66.1), 278 (M) (35.9), 124 (100).
7
-16. 1H NMR (CDCl
d, J ) 4.0), 6.48 (1H, dd, J ) 4.0, 8.0), 3.24 (2H, br, OH, D
exchangeable), 2.55 (2H, t), 1.60 (4H, br), 1.29 (24H, m), 0.90
(
1
3
): δ 6.65 (1H, d, J ) 8.0), 6.60 (1H,
1-n) and on the solvent aggregating power (SAgP)13 of
2
O
(
the reaction media. These speculations have been found
to be true.
+
3H, t). MS (FAB): m/ z (relatively intensity) 334 (M) (42),
23 (45), 41(100).
-Alk yl-3,5,6-tr ich lor o-1,4-ben zoqu in on es (2-n ). A sus-
2
pension of 6 (2 mmol) in glacial acetic acid (80% aqueous, 35
mL) was refluxed under chlorine gas for 5 h. A yellow solid
was formed, and the product (7.2-9.1%) was separated by
flash column chromatography on silica gel with petroleum-
Exp er im en ta l Section
Rea gen ts a n d Su bstr a tes. 1H NMR spectra were ob-
tained at 200 and 90 MHz on Varian XL-200 and FX-90Q
spectrometers, with TMS as an internal standard. Chemical
shifts are expressed in ppm (δ), and coupling constants (J ) are
quoted in hertz ((0.3 Hz). Mass spectra (MS) were taken on
a Finnigan-4201 spectrometer (EI, 70 eV or FAB). Flash
column chromatography was performed on silica gel with
EtOAc (100:1) as eluent.
1
2
-8. H NMR (CDCl
3
): δ 2.73 (2H, t), 1.69-1.24 (12H, m),
+
0
(
.90 (3H, t). MS (EI): m/ z (relatively intensity) 324 (M + 2)
19.1), 225 (100). Anal. Calcd for C14 Cl : C, 51.95; H,
H
17
O
2
3
5
.30. Found: C, 52.13; H, 5.42.
2
-12. 1H NMR (CDCl
3
): δ 2.73 (2H, t), 1.70-1.25 (20H, m),
petroleum-EtOAc as the eluent. 1-R-Naphthyl-3-oxa-alkanes
+
7
0.90 (3H, t). MS (EI): m/ z (relatively intensity) 380 (M + 2)
(
1-n) are known compounds. The general procedures for the
(4.7), 225 (30.7), 43(100). Anal. Calcd for C18 Cl : C,
H
25
O
2
3
synthesis of 2-alkyl-3,5,6-trichloro-1,4-benzoquinones (2-n) are
shown in Scheme 1 and described as below.
5
6.93; H, 6.64. Found: C, 57.06; H, 6.81.
-16. 1H NMR (CDCl
): δ 2.71 (2H, t), 1.67-1.24 (28H, m),
.91 (3H, t). MS (EI): m/ z (relatively intensity) 436 (M + 2)
Cl : C, 60.59; H,
2
3
2
-Alk a n oylh yd r oq u in on e Dim et h yl E t h er s (5-n) and
-Alk ylh yd r oqu in on e Dim eth yl Eth er s (6-n) were pre-
pared from hydroquinone dimethyl ether by the method of
+
0
2
(13.3), 227 (100). Anal. Calcd for C22
H
33
O
2
3
7
.62. Found: C, 60.90; H, 7.39.
Electr on ic Sp ectr a . All aquiorgano solutions used for
(
17) (a) Foster, R. Molecular Association; Academic Press: London,
979; Vol. 2, p 3 and 25. (b) Foster, R. Molecular Association; Academic
Press: London, 1975; Vol. 1, p 217.
18) (a) Chandross, E. A.; Dempster, C. J . J . Am. Chem. Soc. 1970,
spectroscopic measurements were prepared from deionized
water and dioxane (DX) that was purified by a standard
1
(
9
2
2, 3586. (b) Doler, E.; Foster, T. H. Z. Phys. Chem., NF 1962, 31,
74.
(19) Wassermaan, D.; Dawson, C. R. J . Am. Chem. Soc. 1950, 72,
4994.