2 G. A. Jeffrey, An Introduction to Hydrogen Bonding, Oxford Univer-
sity Press, New York, 1997, ch. 11.
3 G. R. Desiraju and T. Steiner, The Weak Hydrogen Bond in Structural
Chemistry and Biology, Oxford University Press, Oxford, 1999,
ch. 3.
4 O. R. Wulf, U. Liddel and S. B. Hendricks, J. Am. Chem. Soc., 1936,
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5 R. S. Brown, Can. J. Chem., 1976, 54, 3206–3209.
6 R. S. Brown and R. W. Marcinko, J. Am. Chem. Soc., 1977, 99,
6500–6505.
7 K. Kowski, W. Lu¨ttke and P. Rademacher, J. Mol. Struct., 2001,
567–568, 231–240.
8 L. Claisen, Ber. Dtsch. Chem. Ges., 1912, 45, 3157–3166.
9 L. Claisen and O. Eisleb, Liebigs Ann. Chem., 1913, 401, 21–119.
10 A. M. M. Castro, Chem. Rev., 2004, 104, 2939–3002.
11 P. Rademacher, L. Khelashvili and K. Kowski, to be published.
12 A. W. Baker and A. T. Shulgin, J. Am. Chem. Soc., 1958, 80, 5358–
5363.
Experimental
Photoelectron (PE) spectra were recorded on a UPG200 spec-
trometer of Leybold-Heraeus equipped with a He(I) radiation
source (21.21 eV). Samples were evaporated directly into the
target chamber. In order to obtain sufficient vapour pressure
temperatures between 25 and 150 ◦C were used. The energy
scale was calibrated with the lines of xenon at 12.130 and
13.436 and of argon at 15.759 and 15.937 eV. The accuracy
of the measurements was approximately 0.03 eV for ionisation
energies, for broad and overlapping signals it was only 0.1 eV.
Infrared (IR) spectra were recorded at ambient temperature
on a BIORAD FTIR spectrometer FTS135. The samples were
dissolved in CDCl3 in cells with a length of 0.1, 1.0, and 10 mm
with concentrations of 0.7, 0.07 and 0.007 mol, respectively. The
accuracy of the measurements is about 1 cm−1.
1H and 13C NMR spectra were recorded on a Bruker
Avance DRX 500 spectrometer. The following frequencies were
used: 500.13 MHZ (1H), 125.76 MHz (13C). The spectra were
measured as solution in a 5 mm tube at 25 ◦C in the solvent
CDCl3.
13 A. W. Baker and A. T. Shulgin, Spectrochim. Acta, 1964, 20, 153–
158.
14 M. Oki and H. Iwamura, Bull. Chem. Soc. Jpn., 1960, 33, 717–721.
15 T. Schaefer, R. Sebastian and T. A. Wildman, Can. J. Chem., 1979,
57, 3005–3009.
16 S. K. Kim, S. C. Hsu, S. Li and E. R. Bernstein, J. Chem. Phys., 1991,
95, 3290–3301.
17 M. T. Bosch-Montalva, L. R. Domingo, M. C. Jimenez, M. A.
Miranda and R. Tormos, J. Chem. Soc., Perkin Trans. 2, 1998, 2175–
2179.
18 A. D. Becke, J. Chem. Phys., 1993, 98, 5648–5652.
19 C. Lee, W. Yang and R. G. Parr, Phys. Rev. B, 1988, 37, 785–789.
20 L. H. Bjerkeseth, J. M. Bakke and E. Uggerud, J. Mol. Struct., 2001,
567, 319–338.
Becke3LYP (B3LYP)18,19 calculations were performed with the
program GAUSSIAN 98.33 The basis set 6-31+G** was used,
if not stated otherwise. Prior to quantum chemical calculations,
molecular geometries were pre-optimised by molecular mechan-
ics calculations using the MMX34 force field with the program
PCMODEL.35
pKa values of phenols 1–9 have been retrieved from Chemical
Abstracts using SciFinder Scholar. The data have been calcu-
lated using ACD software.31
21 P. Rademacher, L. Khelashvili, R. Boese and D. Bla¨ser, to be
published.
22 H. G. Korth, M. I. de Heer and P. Mulder, J. Phys. Chem. A, 2002,
106, 8779–8789.
Materials
23 P. Rademacher and L. Khelashvili, Mendeleev Commun., 2004, 14,
286–287.
2-Allylphenol (1) and 4-acetyl-2-allylphenol (8) were purchased
from Lancaster Synthesis GmbH, Mu¨hlheim am Main, Ger-
many. 4-Substituted 2-allylphenols have been prepared from the
corresponding allyl-phenylethers by Claisen rearrangement.8,9
Syntheses of compounds 2,9,36 3,37 5,36 6,38 7,39 and their spectro-
scopic characterisation have been described in the literature.
24 T. Koopmans, Physica, 1934, 1, 104–113.
25 W. Koch and M. C. Holthausen, A Chemist’s Guide to Density
Functional Theory, Wiley-VCH, Weinheim, 2000.
26 R. Stowasser and R. Hoffmann, J. Am. Chem. Soc., 1999, 121, 3414–
3420.
27 A. J. Arduengo, H. Bock, H. Chen, M. Denk, D. A. Dixon, J. C.
Green, W. A. Herrmann, N. L. Jones, M. Wagner and R. West,
J. Am. Chem. Soc., 1994, 116, 6641–6649.
28 H. S. Aaron, Top. Stereochem., 1979, 11, 1–52.
29 G. C. Pimentel and A. L. McClellan, The Hydrogen Bond, W. H. Free-
man, San Francisco, CA, 1960.
◦
2-Allyl-4-ethoxyphenol (4). Bp 114 C 2mbar−1 (lit.40 184–
◦
185 C 67mbar−1); H-NMR (500 MHz, CDCl3): d 1.36 (t, J
1
= 7.0 Hz, 3H, ArOCH2CH3), 3.35 (dt, J = 6.4 Hz, 1.5 Hz,
=
2H; ArCH2CH CH2), 3.95 (q, J = 7.0 Hz, 2H; ArOCH2CH3),
30 J. Shorter, Correlation Analysis of Organic Reactivity, ResearchStud-
=
4.61 (s, 1H; ArOH), 5.11–5.16 (m, 2H; ArCH2CH CH2), 5.98
ies Press, Chichester, 1982.
=
(m, 1H, ArCH2CH CH2), 6.64 (d, J = 8.2 Hz, 1H, ArH),
31 Solaris, Version 4.67, Advanced Chemistry Development, Inc.
(ACD/Labs), Toronto, ON, www.acdlabs.com, 1994–2004.
32 C. Hansch, A. Leo and R. W. Taft, Chem. Rev., 1991, 91, 165–195.
33 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, V. G. Zakrzewski, J. A. Montgomery, Jr.,
R. E. Stratmann, J. C. Burant, S. Dapprich, J. M. Millam, A. D.
Daniels, K. N. Kudin, M. C. Strain, O. Farkas, J. Tomasi, V. Barone,
M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford,
J. Ochterski, G. A. Petersson, P. Y. Ayala, Q. Cui, K. Morokuma,
D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J.
Cioslowski, J. V. Ortiz, A. G. Baboul, B. B. Stefanov, G. Liu, A.
Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, R. L. Martin,
D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara,
C. Gonzalez, M. Challacombe, P. M. W. Gill, B. G. Johnson, W. Chen,
M. W. Wong, J. L. Andres, M. Head-Gordon, E. S. Replogle and J. A.
Pople, GAUSSIAN 98 (Revision A.7), Gaussian, Inc., Pittsburgh,
PA, 1998.
6.66 (s, 1H, ArH), 6.71 (d, J = 8.2 Hz, 1H, ArH); 13C–NMR
(126 MHz, CDCl3): d 14.93 (CH3), 35.29 (–CH2–), 63.97 (O–
=
CH2) 113.34 (C-5), 116.44 (C-3), 116.51 (C-6), 116.72 ( CH2),
126.40 (C-2), 136.18 (allyl-CH), 147.88 (C-1), 153.10 (C-4); IR
(CDCl3): mmax/cm−1 3535 (OHass), 2982 (C–H), 1653 (C C ),
al
=
ar
=
1505 (C C ), 1203 (C–O).
◦
◦
2-Allyl-4-nitrophenol (9). Mp 77 C (lit.9 79 C); H-NMR
1
=
(500 MHz, CDCl3): d3.45 (d, J = 6.4 Hz, 2H; ArCH2CH CH2),
=
5.18–5.25 (m, 2H; ArCH2CH CH2), 5.74 (s, 1H; ArOH), 5.99
=
(ddt, J = 16.9 Hz, 10.4 Hz, 3.9 Hz, 1H, ArCH2CH CH2),
6.86 (d, J = 7.2 Hz, 1H, ArH), 7.24 (s, 1H, ArH), 8.05 (d, J
= 7.2 Hz, 1H, ArH); 13C-NMR (126 MHz, CDCl3): d 34.71 (–
=
CH2–), 115.86 ( CH2), 118.08 (C-6), 124.03.(C-3), 124.87 (C-5),
126.39 (C-2), 134.57 (allyl–CH), 141.72 (C-4), 159.65 (C-1); IR
34 J. J. Gajewski, K. E. Gilbert and J. McKelvey, Adv. Mol. Model.,
(CDCl3): mmax/cm−1 3433 (OHass), 1609 (C C), 1522 (NO2), 1342
=
1990, 2, 65–92.
(NO2), 1165 (C–O).
35 PCMODEL, Version 7.0, Serena Software, Bloomington, IN, 1999.
36 M. Yodo and H. Harada, Chem. Pharm. Bull., 1989, 37, 2361–
2368.
Acknowledgements
37 F.-T. Hong, K.-S. Lee, Y.-F. Tsai and C.-C. Liao, J. Chin. Chem. Soc.
(Taipei), 1998, 45, 1–12.
Assistance by Prof. Dr H. W. Siesler, Essen, with IR measure-
ments is gratefully acknowledged.
38 K. Nakashima, R. Ito, M. Sono and M. Tori, Heterocycles, 2000, 53,
301–314.
39 H. Sekizaki, K. Itoh, E. Toyota and K. Tanizawa, Heterocycles, 2003,
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