Adamantyl derivatives of pyrogallol

Article abstract of DOI:10.1007/s11172-011-0093-z

4-(1-Adamantyl)-, 5-(1-adamantyl)-, and 4,6-bis(1-adamantyl)pyrogallols were obtained by the reaction of adamantan-1-ol with pyrogallol in trifruoroacetic acid. The reaction of pyrogallol with adamantan-1-ol at 200 °C in a solvent-free medium without catalysts resulted in 5-(1-adamantyl)pyrogallol.

Full text of DOI:10.1007/s11172-011-0093-z

Russian Chemical Bulletin, International Edition, Vol. 60, No. 3, pp. 593—594, March, 2011
593
Adamantyl derivatives of pyrogallol
W. A. Sokolenko,a N. M. Svirskaya,a N. I. Pavlenko,a and A. I. Rubailoa,b
aInstitute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences,
42 ul. K. Marksa, 660049 Krasnoyarsk, Russian Federation.
Fax: +7 (391) 212 4720. Eꢀmail: williamsokol@yandex.ru
bSiberian Federal University,
79 Svobodny Prosp., 660041 Krasnoyarsk, Russian Federation.
Fax: +7 (391) 244 8625. Eꢀmail: rai@icct.ru
4ꢀ(1ꢀAdamantyl)ꢀ, 5ꢀ(1ꢀadamantyl)ꢀ, and 4,6ꢀbis(1ꢀadamantyl)pyrogallols were obtained
by the reaction of adamantanꢀ1ꢀol with pyrogallol in trifruoroacetic acid. The reaction of
pyrogallol with adamantanꢀ1ꢀol at 200 °C in a solventꢀfree medium without catalysts resulted in
5ꢀ(1ꢀadamantyl)pyrogallol.
Key words: pyrogallol, adamantanꢀ1ꢀol, alkylation, trifluoroacetic acid.
In continuation of research of adamantylation of polyꢀ
atomic phenols,1 we studied the reaction of pyrogallol with
adamantanꢀ1ꢀol in trifluoroacetic acid. The adamantylꢀ
ation of pyrogallol with 1ꢀbromoadamantane has been perꢀ
formed earlier.2 According to the data of the latter publiꢀ
cation, a mixture of isomeric 4ꢀ(1ꢀadamantyl)pyrogallol
and 5ꢀ(1ꢀadamantyl)pyrogallol formed that could not be
separated. The composition and the structure of these comꢀ
pounds were tentatively established2 on the basis of Stewꢀ
art—Brigleb spatial model, IR spectra, and elemental analꢀ
ysis data. We found that heating of 1ꢀBrAd with pyrogallol
results only in 5ꢀ(1ꢀadamantyl)pyrogallol.
We also found that pyrogallol reacts with adamantanꢀ
1ꢀol in CF3COOH at 16 °С to form 4ꢀ(1ꢀadamantyl)ꢀ
pyrogallol (1a), and at 85 °С to form 5ꢀ(1ꢀadamantyl)ꢀ
pyrogallol (1b) (Scheme 1). Heating of compound 1a at
85 °С in CF3COOH results in its isomerization into comꢀ
pound 1b. This means that isomer 1a is a product of the
kinetic control and isomer 1b is a product of the thermoꢀ
dynamic control.
When the double excess of adamantanꢀ1ꢀol was used
in the reaction at 8 °С, 4,6ꢀbis(1ꢀadamantyl)pyrogallol
(1c) formed.
We obtained compound 1b also by the reaction of adaꢀ
mantanꢀ1ꢀol with pyrogallol at 200 °С using neither cataꢀ
lyst nor solvent. Apparently, the reaction is caused by the
fact that the protonating agent is pyrogallol. It is known3
that adamantanꢀ1ꢀol reacts with pyrocatechol without
a catalyst at 200 °С to form 4ꢀ(1ꢀadamantyl)pyrocatechol
(63%) and 3ꢀ(1ꢀadamantyl)pyrocatechol (17%).
Intensive absorption bands (AB) at 2904 and 2848 cm–1
were present in the IR spectra of all the obtained adaꢀ
mantyl pyrogallol derivatives pertaining to stretching
vibrations of the adamantane CH2 groups. The AB at
1600—1500 cm–1 indicates the presence of an aromatic
ring in the adamantyl derivatives. A comparison of the
spectrum of the starting pyrogallol with the spectra of
derivatives shows that the highest differences are observed
in the region of stretching vibrations of the hydroxyl groups.
In the spectrum of compound 1b, three poorly resolved
broad AB are seen in this region with distinct maxima at
3351 and 3280 cm–1, the maximum of the third highꢀ
frequency AB at 3524 cm–1 can be distinguished only upon
deconvolution of the observed complicated spectral conꢀ
tour into individual components. All the three OH groups
form fairly weak intermolecular hydrogen bonds of the
H—O...H type. We should agree with the authors of the
cited work2 that the presence of the AB at 840 cm–1 in the
spectrum indirectly proves the presence of the adamantyl
group in position 5 of pyrogallol.
Scheme 1
The spectrum in the region corresponding to vibraꢀ
tions of the hydroxyl groups of compound 1a is quite difꢀ
ferent from that described above. Two AB observed at
1
a
b
c
R1
Ad
H
R2
H
Ad
R3
H
H
3489 and 3448 cm–1 have halfꢀwidths of 36 and 40 cm–1
,
Ad
H
Ad
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 580—581, March, 2011.
1066ꢀ5285/11/6003ꢀ593 © 2011 Springer Science+Business Media, Inc.

594
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 3, March, 2011
Sokolenko et al.
and a third broad AB at 3351 cm–1 has a halfꢀwidth of
160 cm–1. The lowꢀfrequency shift of the latter and its
significant halfꢀwidth indicates the involvement of the
hydroxyl group in the formation of an intermolecular
hydrogen bond. In our opinion, the highestꢀfrequency AB
at 3489 cm–1 characterizes stretching vibrations of the
"free" hydroxyl group (it is identical to that in pyrogallol).
We believe that the AB at 3448 cm–1 pertains to the stretchꢀ
ing vibration of the OH group bound by an intermolecular
hydrogen bond. The observed spectral pattern in the conꢀ
sidered region is virtually analogous to that of paraꢀsubstiꢀ
tuted phenols.4 The AB observed at 820 cm–1 confirms the
substitution of adamantanꢀ1ꢀyl for hydrogen in position
4 of pyrogallol.5 In the 1H NMR spectrum of compound 1а,
the signals for the aromatic protons appear as two douꢀ
blets at δ 6.33 and 6.51 with J5,6 = 8.63 Hz; this shows that
the protons are located in orthoꢀposition to each other. In
the spectrum of compound 1b, there is a singlet at δ 6.44
which was ascribed to H(4) and H(6) with J4,6 = 2.22 Hz
(determined from 13C satellites), such spin—spin coupling
is typical of protons in metaꢀposition. The signal for the
proton H(5) of the aromatic part of compound 1c appears
as a singlet at δ 6.64.
Thus, convenient and selective methods for the synꢀ
thesis of adamantyl derivatives of pyrogallol were develꢀ
oped. It was shown that at 130 °С, the reaction of 1ꢀbroꢀ
moadamantane with pyrogallol resulted in the product of
the thermodynamic control, viz., 5ꢀ(1ꢀadamantyl)pyroꢀ
gallol.
The reaction of pyrogallol with adamantanꢀ1ꢀol withꢀ
out a solvent and a catalyst at 200 °С gives the same 5ꢀ(1ꢀ
adamantyl)pyrogallol, water being a byꢀproduct. This is
a typical example of a "green" chemistry reaction.
(C(2)); 145.27 (C(1)); 145.12 (C(3)) (pyrogallol). Found (%):
C, 73.92; H, 7.69. C16H20O3. Calculated (%): C, 73.82; H, 7.74.
5ꢀ(1ꢀAdamantyl)pyrogallol (1b). A. A mixture of pyrogallol
(1 mmol) and 1ꢀAdOH (1 mmol) in CF3COOH (2 mL) was
heated for 3 h at 85 °С. The acid was removed, the reaction
mixture was washed with water and dried. The yield was 0.17 g
(66%), m.p. 213—215 °C.
B. A mixture of pyrogallol (3 mmol) and 1ꢀAdOH (1 mmol)
was heated in a sealed tube at 200 °С for 4 h, cooled, washed
with water to remove pyrogallol, and dried. The yield was 0.185 g
(71%), m.p. 213—215 °С.
C. A mixture of pyrogallol (3 mmol) and 1ꢀBrAd (1 mmol)
was heated for 15 min at 130 °С, cooled, washed with water to
remove pyrogallol, and dried. The yield was 0.240 g (90%), m.p.
213—215 °С.
IR, ν/cm–1: 3524, 3351, 3280 (OH); 2904, 2848 (CH2, Ad).
1H NMR (δ, J/Hz): 1.78 (6 H, Нδ); 1.84 (6 H, Нβ); 2.05 (3 H,
Нγ, Ad); 6.44 (2 H, Н(4), Н(6)); 7.05 (1 H, 2ꢀOH); 7.56 (2 H, 1ꢀOH,
3ꢀOH) (pyrogallol). 13C NMR (δ): 29.03 (Сγ); 35.28 (Сα); 36.98
(Сγ); 43.27 (Сβ, Ad); 103.83 (С(4), С(6)); 130.30 (С(2)); 142.89
(С(5)); 145.26 (С(1), С(3)) (pyrogallol). Found (%): C, 73.54;
H, 8.96. C16H20O3. Calculated (%): C, 73.82; H, 8.79.
4,6ꢀBis(1ꢀadamantyl)pyrogallol (1c). A mixture of pyrogallol
(4 mmol) and 1ꢀAdOH (2.5 mmol) in CF3COOH (3 mL) was
kept for 10 days at 8 °С. The precipitate was filtered off, washed,
and dried. The yield was 0.277 g. Then compound 1a was reꢀ
moved by washing with aqueous acetone (0.140 g, (63%)). The
residuum was compound 1c, 0.137 g (35%), m.p. 227—228 °С.
IR, ν/cm–1: 3534, 3503, 3342 (OH); 2904, 2848 (CH2, Ad).
1H NMR (δ): 1.80 (12 H, Hδ); 2.05 (6 H, Нγ); 2.15 (12 H, Hβ, Ad);
6.64 (1 H, Н(5)); 6.90 (2 H, 1ꢀOH, 3ꢀOH); 7.00 (1 H, 2ꢀOH)
(pyrogallol). 13C NMR (δ): 29.24 (Сγ); 36.44 (Сα); 37.02 (Сδ);
40.86 (Сβ, Ad); 115.13 (С(5)); 126.99 (С(4), С(6)); 132.21 (С(2));
144.30 (С(1), С(3)) (pyrogallol). Found (%): C, 79.24; H, 8.75.
C26H34O3. Calculated (%): C, 79.15; H, 8.69.
References
Experimental
1. W. A. Sokolenko, N. M. Svirskaya, T. I. Kogai, M. S. Karꢀ
pova, N. I. Pavlenko, Zh. Prikl. Khim., 2008, 81, 524 [Russ.
J. Appl. Chem. (Engl. Transl.), 2008, 81, 509].
2. G. Yu. Stepanova, Ya. I. Bleikher, Ukr. Khim. Zhurn. [Ukr.
Chem. J.], 1973, 39, 1176 (in Russian).
3. W. A. Sokolenko, L. N. Kuznetsova, N. F. Orlovskaya,
Izv. Akad. Nauk, Ser. Khim., 1996, 505 [Russ. Chem. Bull.
(Engl. Transl.), 1996, 45, 485].
IR spectra were recorded on a BrukerꢀVectorꢀ22 Fourierꢀ
spectrometer in KBr pellets. 1H and 13C NMR spectra
were recorded on a Bruker—Avance IIIꢀ600 spectrometer (1H,
600 MHz; 13C, 150 MHz) (Scientific Center of SB RAS Krasnoꢀ
yarsk) in acetoneꢀd6. The reaction products were purified by
preparative TLC on Silufol (benzene : acetone, 9 : 1).
4ꢀ(1ꢀAdamantyl)pyrogallol (1a). A mixture of pyrogallol
(4 mmol) and 1ꢀAdOH (1 mmol) in CF3COOH (3 mL) and
water (0.3 mL) was stirred for 15 min at 16 °С. The precipitate
that formed was filtered off, washed with water, and dried. The
yield was 0.190 g (73%), m.p. 220—221 °С. IR, ν/cm–1: 3489,
3448, 3351 (OH); 2904, 2848 (CH2, Ad). 1H NMR (δ, J/Hz):
1.80 (6 H, Hδ); 2.05 (3 H, Hγ); 2.14 (6 H, Hβ, Ad); 6.33 (d, 1 H,
H(6)); 6.51 (d, 1 H, H(5), J5,6 = 8.63); 6.37, 6.96, 8.02 (3 H,
OH). 13C NMR (δ): 29.15 (Cγ); 35.95 (Cα); 36.98 (Cδ); 40.82
(Cβ, Ad); 105.73 (C(6)); 116.16 (C(5)); 128.11 (C(4)); 132.37
4. G. C. Pimentel, A. L. McClellan, The Hydrogen Bond, W. H.
Freeman and Company, San Francisco—London, 1960, 462 pp.
5. K. Nakanishi, Infrared Absorption Spectroscopy, HoldenꢀDay,
Inc., San Francisco; Nankodo Company Limited, Tokyo,
1962, 220 pp.
Received June 28, 2010;
in revised form February 7, 2011