Monoetherification of tert-Butylated Pyrocatechols upon Irradiation of Their Solutions in Hydrocarbons

Article abstract of DOI:10.1023/A:1024905903115

Products of reactions of tert-butylated pyrocatechols with alkyl radicals were studied. The major products formed upon γ-irradiation of deaerated solutions of 4-tert-butyl- and 3,5-di-tert-butylpyrocatechol in hexane and cyclohexane are monoalkyl ethers, which were identified by NMR spectroscopy (¹H, ¹³C, ¹H-¹H NOESY technique) and gas chromatography-mass spectrometry.

Full text of DOI:10.1023/A:1024905903115

Russian Journal of General Chemistry, Vol. 73, No. 3, 2003, pp. 394 400. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 3, 2003,
pp. 422 428.
Original Russian Text Copyright
2003 by Maslovskaya, Savchenko.
Monoetherification of tert-Butylated Pyrocatechols
upon Irradiation of Their Solutions in Hydrocarbons
L. A. Maslovskaya and A. I. Savchenko
Belarussian State University, Minsk, Belarus
Institute of Organic Chemistry, University of Gottingen, Gottingen, Germany
Received February 23, 2001
Abstract Products of reactions of tert-butylated pyrocatechols with alkyl radicals were studied. The major
products formed upon -irradiation of deaerated solutions of 4-tert-butyl- and 3,5-di-tert-butylpyrocatechol in
hexane and cyclohexane are monoalkyl ethers, which were identified by NMR spectroscopy (1H, 13C, 1H 1H
NOESY technique) and gas chromatography mass spectrometry.
Alkylated pyrocatechols belong to the class of
sterically hindered phenols and show promise as anti-
oxidants both for important biological processes initi-
ated by reactive substances and/or ionizing radiation
and for stabilization of polymers, oils, etc. [1, 2]. The
peroxy radicals are deactivated by hydrogen abstrac-
tion from the phenolic hydroxy group [1, 3]. Phenolic
inhibitors also react with alkyl radicals and, under
exposure to ionizing radiation, with H atoms and ion-
ized solvent molecules [4, 5]:
generation of radicals with the radical center at C2 and
C3, and irradiation of cyclohexane, in generation of
a single radical species [8]. Recombination of these
radicals yields isomeric dodecanes and dicyclohexyl,
respectively.
We have shown previously that 3,5-di-tert-butyl-
pyrocatechol (I) efficiently suppresses formation of
recombination products of hexyl radicals [9, 10]. To
elucidate the structure of transformation products of
pyrocatechols, we examined the influence of their
concentration on the radiation-chemical yields of
adducts in hexane and cyclohexane. This allowed
optimization of the irradiation conditions. As seen
from the table, at the maximum possible concentration
of I in hydrocarbons, equal to 1 10 2 M, the yield of
dodecanes decreases to 0.11, and that of dicyclohexyl,
to 0.20 molecule/100 eV, with the yield of decompo-
sition of I being 4.5 molecules/100 eV in hexane and
3.8 molecules/100 eV in cyclohexane. According to
GLC, the pyrocatechol is completely consumed after
irradiation for 16 20 h, with the yield of addition
products being 2.6 and 2.2 molecules/100 eV for hex-
yl and cyclohexyl radicals, respectively.
H (R ) + PhOH
RH + + PhOH [RH + PhOH +]
H2 (RH) + PhO ,
PhO + H+ + RH
This reaction is possible with both monohydric
phenols and alkylated pyrocatechols, since their ioni-
zation potential (8 9 eV) is lower than that of hydro-
carbons [6]. One of the pathways of consumption of
phenoxy radicals is their recombination with alkyl
radicals yielding various adducts. For example, it was
shown previously that -irradiation of deaerated solu-
tions of 2,6-di-tert-butyl-4-methylphenol (Ionol) in
cyclohexane results in C-alkylation of Ionol [7]. At
the same time, despite extensive use of antioxidants
based on dihydric phenols, data on their reactions with
carbon-centered radicals and on the structure of the
reaction products are lacking.
3
The optimal concentration of II was 5 10 M,
2
since at a higher concentration (10 M) the pyrocate-
chol was consumed in a considerably longer time,
which resulted in increased yield of secondary prod-
ucts.
The goal of this study was to identify the products
formed from substituted pyrocatechols upon -irradi-
ation of their deaerated solutions in hexane and cyclo-
hexane as typical representatives of linear and cyclic
hydrocarbons. Experiments were performed with 3,5-
di-tert-butylpyrocatechol (I) and 4-tert-butylpyrocate-
chol (II).
According to GC MS analysis, irradiation of I in
hexane yielded two major products giving a molecular
1
peak at m/z 306. The H NMR spectrum of the prod-
ucts isolated by column chromatography contains
OCH proton signals (a sextet at 4.21 and a quintet at
4.37 ppm), and the 13C NMR spectrum contains the
OCH carbon signals at 75.44 and 80.17 ppm, which
It is known that -irradiation of hexane results in
1070-3632/03/7303-0394$25.00 2003 MAIK Nauka/Interperiodica

MONOETHERIFICATION OF tert-BUTYLATED PYROCATECHOLS
395
Radiation-chemical yields of addition products and yields of decomposition of 3,5-di-tert-butylpyrocatechol I and 4-tert-
butylpyrocatechol II as influenced by the solvent and pyrocatechol concentration
Yield, molecule/100 eV
Time of
Pyrocatechol
concentration, M
Pyrocatechol
Solvent
pyrocatechol
addition consumption, h
products
pyrocatechol
decomposition
products
recombination
products
Hexane
Cyclohexane
0.76
0.86
3
I
Hexane
5 10
1 10
5 10
1 10
2 10
5 10
1 10
2 10
0.14
0.11
0.28
0.20
0.20
0.15
0.13
0.40
0.40
0.30
3.0
4.5
2.8
3.8
1.3
2.6
3.0
3.0
2.7
1.8
2.2
2.6
1.8
2.2
1.2
1.6
2.2
1.4
1.6
1.6
10
16
12
20
8
18
30
8
2
3
Cyclohexane
Hexane
2
3
II
3
2
3
Cyclohexane
3
5 10
1 10
20
40
2
corresponds to the structure of 2- and 3-hexyl ethers
The tosylate and iodide were prepared according to
Ia and Ib.
[11], and ether Ib, according to [12]. Comparison of
1
the H and 13C NMR spectra of Ib with the spectra of
t-Bu
t-Bu
the products isolated after irradiation allows assign-
ment of the signals of Ia.
OH
O
OH
OH
t-Bu
t-Bu
Irradiation of I in cyclohexane, according to GC
MS analysis, yielded a complex mixture of adducts
that mainly consisted of products giving molecular
peaks at m/z 304 and 386. The mixture was fraction-
ated by column chromatography. One of the fractions
(30 mg) contained two products in a 4 : 1 ratio (mo-
lecular peak at m/z 304, intensity 6.43 and 1.51%,
respectively). The fragment peak at m/z 222, charac-
teristic of both products, suggests formation of mono-
alkyl ethers [13]. Since in cyclohexane only a single
radical species is generated, we presumed that these
products differed in the alkylation site (nonequivalent
I
t-Bu
OH
OR
t-Bu
Ia Ic
R = 2-hexyl (a), 3-hexyl (b), and cyclohexyl (c).
The structure of Ib was confirmed by independent
synthesis:
1
OH groups). The H NMR spectrum contained two
OH singlets ( 6.04 and 6.06 ppm) and a multiplet of
the OCH proton ( 4.2 4.3 ppm). The structure of
one of the products was confirmed by independent
synthesis from I and cyclohexyl bromide according to
[12]. In addition, we isolated a fraction with Rf 0.25
(20 mg), which, according to GC MS analysis, con-
sisted of three compounds giving a molecular peak at
m/z 386. This corresponds to addition of two cyclo-
hexyl radicals to I. These compounds are secondary
products; we failed to prove their structure.
OTs
OH
NaI, CH3COCH3
I
t-Bu
KOH/EtOH, I
OH
O
32%
t-Bu
C
H
Ib
Irradiation of II in hexane yielded a mixture of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 3 2003

396
MASLOVSKAYA, SAVCHENKO
, ppm
4.0
4.5
5.0
5.5
6.0
6.5
7.0
, ppm 7.0
6.5
6.0
5.5
5.0
4.5
4.0
1
1
Fig. 1. Fragment of the two-dimensional
H
H NOESY NMR spectrum of 2-(2-hexyloxy)-4-tert-butylphenol.
products. After chromatographic separation, two frac-
tions were obtained, one of which, according to GC
MS analysis, contained four compounds giving the
molecular peak at m/z 250 and the fragmentation pat-
tern typical of ethers.
3-hexyl iodide. The mixture of two isomers was chro-
matographed on a silica gel column (eluent hexane
CH2Cl2, 2 : 1). The signals in the H NMR spectra of
1
4- and 5-tert-butyl-2-(2-hexyloxy)phenols were as-
1
1
signed using two-dimensional H H NOESY NMR
spectroscopy. The observation of cross peaks between
the OCH multiplet ( 4.10 ppm) and the doublet of
the H3 proton of the ring ( 6.95 ppm, J 2.15 Hz)
corresponds to the structure of 2-(2-hexyloxy)-4-tert-
butylphenol IIIa (Fig. 1). In the case of 2-(2-hexyl-
oxy)-5-tert-butylphenol IVa, a cross peak is also ob-
served between the OCH multiplet ( 4.25 ppm) and
an H3 doublet ( 6.66 ppm), but in this case the cou-
pling is vicinal, and J is as high as 8.55 Hz (Fig. 2).
OH
OH
OH
OR
t-Bu
t-Bu
II
IIIa IIIc
OR
OH
IVa IVc
+
t-Bu
OH
t-Bu
OH
6
3
R = 2-hexyl (a), 3-hexyl (b), cyclohexyl (c).
6
3
5
4
1
2
5
4
1
2
O
O
t-Bu
1
C4H9
CH3
The H NMR spectrum contained the OH signals at
C4H9
CH3
H
H
H
5.58, 5.60, 5.66, and 5.69 ppm and OCH multiplets
H
at 4.18 4.29 and 4.32 4.45 ppm. The 13C NMR
IIIa
IVa
spectrum contained the ether carbon signals at
C
75.41 and 80.15 ppm, confirming the presence of
ethers in this fraction. The structure of compounds
IIIa, IIIb, IVa, and IVb was confirmed by their com-
parison with the respective authentic samples prepared
by the reaction of 4-tert-butylpyrocatechol with 2- and
-Irradiation of 4-tert-butylpyrocatechol II in cyclo-
hexane also yielded, according to GC MS analysis, a
complex mixture of adducts of II with cyclohexane.
The mixture was fractionated by column chromatog-
raphy; one of the fractions contained two products,
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MONOETHERIFICATION OF tert-BUTYLATED PYROCATECHOLS
397
, ppm
4.0
4.5
5.0
5.5
6.0
6.5
7.0
, ppm 7.0
6.5
6.0
5.5
5.0
4.5
4.0
1
1
Fig. 2. Fragment of the two-dimensional
H
H NOESY NMR spectrum of 2-(2-hexyloxy)-5-tert-butylphenol.
both giving a molecular peak at m/z 250 and a frag-
ment peak at m/z 166. The H NMR spectrum of this
Solvents were purified to remove unsaturated impuri-
ties according to [14].
1
fraction showed the presence of two compounds. The
spectrum contained the signals of aromatic and OH
( 5.58 and 5.65 ppm) protons and a multiplet of the
OCH group in two compounds at 4.20 4.27 ppm.
In the 13C NMR spectrum, the OCH carbon signals
from both compounds coincided and were observed
The reaction progress was monitored by TLC on
Macherey Nagel, Alugram sil G/UV-254 plates with
fluorescent indicator. The plates were developed in I2
vapor or in alcoholic solution of phosphomolybdic
acid, with subsequent heating to 120 C. The products
were separated on a column packed with silica gel
(Merck, Kieselgel 60 and Baker analyzed, 20 45 m).
The IR spectra were recorded on a Perkin Elmer
Spektrum IR-1000FT spectrophotometer (thin film).
1
at 76.5 ppm. The coincidence of the signals in the H
and 13C NMR spectra of the compounds obtained by
independent synthesis (reaction of II with cyclohexyl
bromide [12]) with those of the compounds isolated
chromatographically allows identification of the prod-
ucts as IIIc and IVc.
1
The H and 13C NMR spectra were taken on a Bruker
AM-250 spectrometer (working frequencies 250 and
62.9 MHz, respectively) in CDCl3 and C6D6. The
proton chemical shifts were determined relative to
In the isolated fractions, the compounds giving a
molecular peak at m/z 330 were present in significant
amounts. This molecular weight corresponds to addi-
tion of two hexyl or cyclohexyl radicals. Thus, these
are the secondary transformation products of the
ethers.
chloroform ( 7.26,
77.0 ppm) and C6D6 ( 7.15,
C
C 128.0 ppm). Isomers IIIa, IIIb, IVa, and IVb were
identified independently on the basis of direct obser-
vation of the Overhauser effect for sterically proxi-
1
1
mate protons. The two-dimensional H H NOESY
NMR spectra were measured in CDCl3 and C6D6
(Bruker AMŒ-300). The 13C NMR signals were as-
signed using the DEPT technique: CH and CH3 (+),
CH2 ( ), C (0). Identification of products by retention
times was performed with a Shimadzu GC-17A gas
liquid chromatograph (SE-54 25000 0.25-mm
quartz capillary column) directly connected to a
QP-5000 mass spectrometer. The column was heated
Thus, the major products formed upon -irradiation
of pyrocatechols I and II in hydrocarbons are the cor-
responding monoalkyl ethers.
EXPERIMENTAL
Compound I was prepared as described in [8].
Compound II was recrystallized from petroleum ether.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 3 2003

398
MASLOVSKAYA, SAVCHENKO
1
from 100 to 280 C at a rate of 5 deg min . The carri-
er gas was helium (0.8 ml min ).
spectrum, C, ppm: 9.57 (+) (CH3), 14.19 (+) (CH3),
18.65 ( ) (CH2), 26.67 ( ) (CH2), 29.48 (+) (t-Bu),
31.66 (+) (t-Bu), 34.51 (0), 34.84 (0), 35.70 ( )
(CH2), 80.23 (+) (OCH), 108.22 (+) (C5), 115.43 (+)
(C3), 134.41 (0) (C6), 140.98 (0) (C4), 142.73 (0) (C2),
144.55 (0) (C1). Mass spectrum, m/z (Irel, %): 306
(7.8) [M]+, 222 (38.0) [M C6H12]+, 207 (100) [M
1
Sample preparation and irradiation. Alkylated
pyrocatechol I or II was dissolved in hexane (or cyclo-
hexane); the solution was deaerated and irradiated in
sealed glass ampules with 137Cs radiation from an
1
LMB- -1M installation at a dose rate of 0.35 Gy s
C6H12
CH3]+.
to a dose of 25 kGy (20 h). The solvent was removed
on a rotary evaporator, and the remaining yellow oil
was chromatographed on a column (silica gel, hex-
ane AcOEt, 40 : 1).
2-(2-Hexyloxy-4,6-di-tert-butylphenol Ia. Rf 0.60
1
(hexane AcOEt, 10 : 1). IR spectrum, , cm : 3650,
1
1260. H NMR spectrum, , ppm (J, Hz): 0.94 t (3H,
CH3, J 6.8), 0.96 t (3H, CH3, J 7.4), 1.29 s (9H, t-Bu),
1.40 s (9H, t-Bu), 1.25 1.78 m (6H, CH2), 4.37 sextet
(1H, OCH, J 6.0), 5.99 s (1H, OH), 6.77 d (1H, ArH,
J 2.08), 6.89 d (1H, ArH, J 2.08). 13C NMR spectrum,
C, ppm: 14.05 (+) (CH3), 20.03 (+) (CH3), 22.68 ( )
(CH2), 27.73 ( ) (CH2), 29.45 (+) (t-Bu), 31.65 (+)
(t-Bu), 34.51 (0), 34.83 (0), 36.29 ( ) (CH2), 75.44
(+) (OCH), 108.26 (+) (C5), 115.50 (+) (C3), 134.42
(0) (C6), 141.09 (0) (C4), 142.74 (0) (C2), 144.18 (0)
(C1). Mass spectrum, m/z (Irel, %): 306 (6.8) [M]+,
222 (37.6) [M C6H12]+, 207 (100) [M C6H12
CH3]+.
Isolation of hexyl ethers Ia and Ib after -irra-
diation. From 40 mg of I and 20 ml of hexane, we
obtained 32 mg (43%) of a mixture of two products in
a 52 : 48 ratio (GLC). Since we failed to separate
these compounds by column chromatography, they
were characterized by independent synthesis.
2-(3-Hexyloxy)-4,6-di-tert-butylphenol (Ib). To-
syl chloride (2.06 g) was added to a solution of 1.00 g
of 3-hexanol in 8 ml of pyridine, cooled to 0 C. The
mixture was stirred for 2 h at 0 C and then for 3 h at
room temperature. After that, 150 ml of cold water
was added, and the liquid was extracted with ether
(4 50 ml). The combined ether extracts were washed
with 10% HCl (2 50 ml) and saturated NaHCO3
solution (3 50 ml) and dried over MgSO4. The sol-
vent was distilled off, the remaining oil (3.95 g) was
dissolved in 61 ml of acetone, and 6.1 g of NaI was
added. The reaction mixture was stirred for 18 h at
room temperature, after which the precipitate was fil-
tered off, the filtrate was poured into 100 ml of H2O,
and the mixture was extracted with ether (4 50 ml).
The combined extracts were washed with 50 ml of
10% Na2SO3 and dried over MgSO4. The solvent was
distilled off, and the remaining oil (1.17 g) was added
to a mixture obtained in a nitrogen atmosphere from
a solution of 0.27 g of KOH in 2.8 ml of 96% ethanol
and 0.247 g of 3,5-di-tert-butylpyrocatechol. The mix-
ture was refluxed for 3 h, diluted with water, acidified
with HCl, extracted with ethyl acetate (3 20 ml),
and dried over MgSO4. After removing the solvent
in a vacuum, the remaining dark oil was chromato-
graphed on SiO2 (eluent hexane AcOEt, 40 : 1). The
main fraction (0.128 g) was distilled in a vacuum
(150 C, 0.01 mm Hg, Kugelrohr), and 0.108 g of
ether Ib was isolated (yield 32% based on I).
Isolation of 2-cyclohexyloxy-4,6-di-tert-butyl-
phenol Ic after -irradiation. After -irradiation of a
deaerated solution of 40 mg of I in 20 ml of cyclohex-
ane, removal of the solvent on a rotary evaporator,
and chromatography of the residue (60 mg; silica gel,
hexane AcOEt, 40 : 1), we obtained 24 mg (43%) of
ether Ic (Rf 0.56) and 6.0 mg (10%) of an isomer with
Rf 0.47 (hexane AcOEt, 10 : 1).
2-Cyclohexyloxy-4,6-di-tert-butylphenol (Ic). In a
nitrogen atmosphere, 0.50 g of I was dissolved in a
solution of 0.27 g of KOH in 2.8 ml of 96% EtOH.
Cyclohexyl bromide (1.06 g) was added; the mixture
was refluxed with stirring for 4 h and worked up as
described above for Ib. After chromatography (silica
gel, hexane AcOEt, 40 : 1), 0.12 g (18%) of Ic was
obtained. Rf 0.56 (hexane AcOEt, 10 : 1). IR spec-
1
1
trum, , cm : 3513, 1299. H NMR spectrum,
,
ppm (J, Hz): 1.29 s (9H, t-Bu), 1.40 s (9H, t-Bu),
1.20 2.17 m (10H, CH2), 4.19 4.29 m (1H, OCH),
6.04 s (1H, OH), 6.80 d (1H, ArH, J 2.1), 6.90 d (1H,
ArH, J 2.1). 13C NMR spectrum, C, ppm: 23.70 ( )
(CH2), 25.51 ( ) (CH2), 29.45 (+) (t-Bu), 31.66 (+)
(t-Bu), 32.08 ( ) (CH2), 34.48 (0), 34.83 (0), 77.10
(+) (OCH), 108.69 (+) (C5), 115.67 (+) (C3), 134.50
(0) (C6), 141.09 (0) (C4), 142.89 (0) (C2), 143.94 (0)
(C1). Mass spectrum, m/z (Irel, %): 304 (6.4) [M+],
222 (32.1) [M C6H10]+, 207 (100) [M C6H10
CH3]+.
2-(3-Hexyloxy)-4,6-di-tert-butylphenol Ib. Rf 0.63
1
(hexane AcOEt, 10 : 1). IR spectrum, , cm : 3650,
1
1260. H NMR spectrum, , ppm (J, Hz): 0.97 t (3H,
CH3, J 7.1), 0.99 t (3H, CH3, J 7.1), 1.32 s (9H, t-Bu),
1.43 s (9H, t-Bu), 1.25 1.78 m (6H, CH2), 4.23 quin-
tet (1H, OCH, J 7.3), 6.04 s (1H, OH), 6.79 d (1H,
ArH, J 2.08), 6.92 d (1H, ArH, J 2.08). 13C NMR
Isolation of hexyl ethers IIIa, IIIb, IVa, and IVb
after -irradiation. After -irradiation of a deaerated
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MONOETHERIFICATION OF tert-BUTYLATED PYROCATECHOLS
399
solution of 40 mg of II in 50 ml of hexane, removal
of the solvent on a rotary evaporator, and chromatog-
raphy of the residue (52 mg) on silica gel (eluent hex-
ane AcOEt, 40 : 1), 27 mg of a fraction with Rf 0.56
was obtained. According to GC MS analysis, the
fraction consisted of four products giving a molecular
peak at m/z 250; it was a mixture of four monoalkyl
ethers. The total chemical yield of IIIa, IIIb, IVa,
and IVb was 43%. Since we failed to separate these
compounds by column chromatography, they were
characterized by independent synthesis.
9.54 (+) (CH3), 18.65 ( ) (CH2), 26.60 ( ) (CH2),
31.44 (+) (t-Bu), 34.19 (0), 35.66 ( ) (CH2), 80.17 (+)
(OCH), 112.03 (+) (C3), 112.34 (+) (C6), 116.35 (+)
(C5), 142.94 (0) (C2), 144.55 (0) (C1), 145.81 (0) (C4).
Mass spectrum, m/z (Irel, %): 250 (5.2) [M]+, 166
(20.8) [M C6H12]+, 151 (100) [M C6H12 CH3]+.
Isolation of 4-tert-butylpyrocatechol cyclohexyl
ethers IIIc and IVc after -irradiation. After -irra-
diation of a deaerated solution of 40 mg of II in 50 ml
of cyclohexane, solvent evaporation on a rotary evap-
orator, and chromatography of the residue (67 mg) on
silica gel (eluent hexane AcOEt, 40 : 1), a fraction
(22 mg) with Rf 0.56 was isolated. According to GC
MS analysis, the fraction consisted of two compounds
giving a molecular peak at m/z 248 and was a mixture
of monoalkyl ethers IIIc and IVc (total yield 35%).
2-(2-Hexyloxy-5-tert-butylphenol IVa and 2-(2-
hexyloxy)-4-tert-butylphenol (IIIa). From compound
II and 2-hexyl iodide [15], we obtained a mixture of
IIIa and IVa according to [12] in a total yield of 45
mg (45%). The ethers were separated by column chro-
matography (Baker silica gel, eluent hexane CH2Cl2,
1
2 : 1) and characterized by 1H, 13C, and 1H H
A mixture of IIIc and IVc was independently ob-
tained from II and cyclohexyl bromide according to
[12] in 17% yield after column chromatography (SiO2,
hexane AcOEt, 40 : 1). The signals in the spectra of
IIIc and IVc were assigned by comparison with the
spectra of pure IIIa and IVa.
NOESY NMR spectroscopy.
2-(2-Hexyloxy)-5-tert-butylphenol (IVa). 1H NMR
spectrum, , ppm (J, Hz): 0.92 t (3H, CH3, J 6.8),
1.29 s (9H, t-Bu), 1.30 d (3H, CH3, J 6.3), 1.25
1.78 m (4H, CH2), 1.80 2.12 m (2H, CH2), 4.37 sex-
tet (1H, OCH, J 5.7), 5.67 s (1H, OH), 6.76 d (1H,
Ar H3, J3,4 8.6), 6.82 d.d (1H, Ar H4, J3,4 8.6 and
J4,6 2.1), 7.00 d (1H, Ar H6, J4,6 2.2). 13C NMR spec-
trum, C, ppm: 9.54 (+) (CH3), 18.65 ( ) (CH2), 26.60
( ) (CH2), 31.44 (+) (t-Bu), 34.19 (0), 35.66 ( )
(CH2), 80.17 (+) (OCH), 112.03 (+) (C3), 112.34 (+)
(C6), 116.35 (+) (C5), 142.94 (0) (C2), 144.55 (0)
(C1), 145.81 (0) (C4). Mass spectrum, m/z (Irel, %):
250 (5.9) [M]+, 166 (21.0) [M C6H12]+, 151 (100)
2-Cyclohexyloxy-5-tert-butylphenol (IVc). Rf 0.56
1
(hexane AcOEt, 10 : 1). IR spectrum, , cm : 3513,
1
1299. H NMR spectrum, , ppm (J, Hz): 1.27 s (9H,
t-Bu), 1.20 2.10 m (10H, CH2), 4.20 4.27 m (1H,
OCH), 5.65 s (1H, OH), 6.80 s (2H, ArH), 7.00 s (1H,
ArH). 13C NMR spectrum, C, ppm: 23.80 ( ) (CH2),
26.37 ( ) (CH2), 31.44 (+) (t-Bu), 32.02 ( ) (CH2),
34.20 (0), 76.50 (+) (OCH), 112.09 (+), 112.99 (+),
116.38 (+), 142.14 (0), 144.41 (0), 146.02 (0).
[M
C6H12
CH3]+.
2-(2-Hexyloxy)-4-tert-butylphenol (IIIa). 1H NMR
spectrum (C6D6), , ppm (J, Hz): 0.8 t (3H, CH3,
J 6.6), 1.0 d (3H, CH3, J 6.0), 1.00 1.60 m (6H,
CH2), 1.25 s (9H, t-Bu), 4.10 sextet (1H, OCH, J 6.0),
5.50 s (1H, OH), 6.81 d.d (1H, Ar H5, J5,3 2.2, J5,6
8.3), 6.94 d (1H, Ar H3, J3,5 2.2), 7.07 d (1H, Ar H6,
J6,5 8.3). 13C NMR spectrum, C, ppm: 9.54 (+)
(CH3), 18.65 ( ) (CH2), 26.60 ( ) (CH2), 31.44 (+)
(t-Bu), 34.19 (0), 33.56 ( ) (CH2), 80.17 (+) (OCH),
112.03 (+) (C3), 112.34 (+) (C6), 116.35 (+) (C5),
142.94 (0) (C2), 144.55 (0) (C1), 145.81 (0) (C4).
Mass spectrum, m/z (Irel, %): 250 (6.2) [M]+, 166
(19.4) [M C6H12]+, 151 (100) [M C6H12 CH3]+.
2-Cyclohexyloxy-4-tert-butylphenol IIIc. Rf 0.56
1
(hexane AcOEt, 10 : 1). IR spectrum, , cm : 3513,
1
1299. H NMR spectrum, , ppm (J, Hz): 1.29 s (9H,
t-Bu), 1.20 2.10 m (10H, CH2), 4.20 4.27 m (1H,
OCH), 5.58 s (1H, OH), 6.87 s (2H, ArH), 6.91 s (1H,
ArH). 13C NMR spectrum, C, ppm: 23.73 ( ) (CH2),
25.49 ( ) (CH2), 31.57 (+) (t-Bu), 32.06 ( ) (CH2),
34.29 (0), 77.5 (+) (OCH), 111.44 (+), 113.77 (+),
118.04 (+), 143.12 (0), 143.82 (0), 144.72 (0). Mass
spectrum, m/z (Irel, %): 248 (6.5) [M]+, 166 (24.0)
[M
C6H10]+, 151 (100) [M
C6H10
CH3]+.
2-(3-Hexyloxy)-5-tert-butylphenol (IVb). 1H NMR
spectrum, , ppm (J, Hz): 0.92 t (3H, CH3, J 7.2),
0.95 t (3H, CH3, J 7.4), 1.34 1.53 m (2H, CH2),
1.57 1.74 m (4H, CH2), 4.19 quintet (1H, OCH, J
5.8), 5.67 s (1H, OH), 6.74 d (1H, Ar H3, J3,4 8.6),
6.82 d.d (1H, Ar H4, J3,4 8.6 and J4,6 2.1), 6.98 d
(1H, Ar H6, J4,6 2.2). 13C NMR spectrum, C, ppm:
ACKNOWLEDGMENTS
The authors are grateful to A. de Mejere (Institute
of Organic Chemistry, University of Gottingen) for
the offered opportunity for NMR studies and to
R. Machinek for measurement of two-dimensional
NMR spectra and participation in their discussion.
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400
MASLOVSKAYA, SAVCHENKO
(Liquid-Phase Radiolysis of Hydrocarbons), Moscow:
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