Non-catalytic alkylation of phenol and aniline with 1-hydroxymethylpyrazole

Full text of DOI:10.1134/S1070363212070274

ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 7, pp. 1319–1321. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © H.S. Attaryan, V.I. Rstakyan, S.S. Hayotsyan, G.V. Asratyan, 2012, published in Zhurnal Obshchei Khimii, 2012, Vol. 82, No. 7,
pp. 1222–1224.
LETTERS
TO THE EDITOR
Non-Catalytic Alkylation of Phenol and Aniline
with 1-Hydroxymethylpyrazole
H. S. Attaryan, V. I. Rstakyan, S. S. Hayotsyan, and G. V. Asratyan
Institute of Organic Chemistry of Scientific-Technological Center of Organic and Pharmaceutical Chemistry,
National Academy of Sciences of the Republic of Armenia, Azatutyan ave. 26, Yerevan, 0014 Armenia
e-mail: vrstakyan@gmail.com
Received February 21, 2012
DOI: 10.1134/S1070363212070274
We have previously shown that the reaction of
(1,3,5-trimethyl-1H-pyrazol-4-yl)methanol with hexyl
and benzyl alcohols, phenol, and aniline in the absence
of catalysts and solvents results in the corresponding
O-, C-, and N-alkylated products [1–3].
ture was proved by the IR and 1H NMR spectroscopy.
The IR spectrum of compound IV contains charac-
teristic absorption bands of the hydroxy group and
aromatic ring at 3100–3300 and 1600 cm–1,
respectively.
In this work we studied the non-catalytic alkylation of
phenol and aniline with 1-hydroxymethylpyrazoles I–III.
In the 1H NMR spectrum of compound IV there is a
signal of OH proton in a weak field (9.46 ppm), which
indicates that the C-alkylation of the aromatic ring
occurs. The integral intensities of the benzene ring pro-
tons show the formation of the ortho-substituted iso-
We found that only (1H-pyrazol-1-yl)methanol I
reacted with phenol. The reaction occurs as the C-
alkylation of aromatic ring by analogy with (1,3,5-tri-
methyl-1H-pyrazol-4-yl)methanol [1]. When the ratio
compound I:phenol is equal to 1:9, the yield of the
alkylation product IV reaches 57%. The product struc-
1
mer. In the H NMR spectrum of compound IV there
are also the signals of the pyrazole ring protons (6.15,
7.33, and 7.55 ppm).
R1
R1
I
OH
OH
N
N
N
R2
N
II, III
R2
CH2OH
I−III
I, IV, R1 = R2 = H; II, R1 = CH3, R2 = H or R1 = H, R2 = CH3; III, R1 = R2 = CH3.
IV
The presence of the electron-donor methyl groups
The alkylation of aniline with hydroxy-1-methyl-
pyrazoles II and III under the same conditions (in the
absence of the catalysts and solvent) was not observed.
As in the case of phenol derivatives, the oxy-
methylpyrazole derivatives II and III converted into
the corresponding pyrazoles.
in the pyrazole ring does not allow to obtain in similar
conditions the corresponding substituted pyrazoles. In
these cases, the oxymethyl pyrazole derivatives are
converted into the corresponding pyrazoles [4, 5].
The difference in the reagents behavior in the
alkylation of 1-pyrazolyl-carbinoles I–III in the
absence of the catalyst can be attributed to the different
electrophilicity of the carbon atoms of hydroxymethyl
groups [6].
In the reaction of aniline with compound I the main
product is N-(2-aminobenzyl)aniline V and polymer
VII of 1,3,5-triphenyl-1,3,5-triazine VI.
1319

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ATTARYAN et al.
N
N
N
H
+
H
NH2
V
NH2
N
Δ
+
N
HOH2C
I
N
N
N
H
N
N
H
n
VII
VI
The formation of the anhydroformaldehydeaniline
trimer VI and its polymer VII was described earlier
[7], but the formation of N-(2-aminobenzyl)aniline V
was unexpected since aniline is known to be unable to
form the corresponding carbocation in the reaction
with formaldehyde in the absence of acid [8], which
would lead to the formation of compound V.
The formation of compound V proceeds pre-
sumably as follows:
N
N
CH2
NH2
N
H2C
NH2
N
I
H
N
N
H
NH2
N
H
X
XI
IX
V
Compound I reacts with the aniline excess ap-
parently forming compound IX followed by transform-
ing it into X, which eventually reacts with an excess of
aniline. In the case of pyrazoles II and III only a
polymer is formed from the aniline trimer that also
supports this hypothesis.
was refluxed for 4–5 h. The phenol excess was
distilled off, and the residue was refluxed in water
(30 ml). After cooling, the crystalline precipitate
formed was filtered off. Yield 3 g (57%), mp 125°C.
1
IR spectrum ν, cm–1: 1590 (Ar), 3100–3300 (OH). Н
NMR spectrum δ, ppm: 5.24 s (2H, CH2), 6.15 d.d
(1H, H4, J1 2.2, J2 1.8 Hz), 6.69 d.d.d (1H, CH, Ar, J1
7.6, J2 7.2, J3 1.1 Hz), 6.82 d.d (1H, CH, Ar, J4 8.1, J3
1.1 Hz), 6.91 d.d (1H, CH, Ar, J1 7.6, J5 1.7 Hz), 7.05
d.d.d (1H, CH, Ar, J4 8.1, J2 7.2, J5 1.7 Hz), 7.33 d.d
(1H, H3, J2 1.8, J3 0.7 Hz), 7.51 d.d (1H, H5, J2 2.2, J3
0.7 Hz), 9.46 s (1H, OH). Found, %: С 68.47; Н 5.32;
N 16.32. С10Н10N2O. Calculated, %: С 68.96; Н 5.74;
N 16.09.
The structure of compounds V and VII was con-
firmed by the IR and 1H NMR spectroscopy. In the IR
spectra of these compounds there are the characteristic
absorption bands of NH- and NH2-moieties at 3300–
3350 cm–1 and of the benzene ring at 1500–1600 cm–1.
1
The H NMR spectrum of compound V contains the
proton signals of CH2-, NH-, and NH2-groups at 4.10–
4.82 ppm and of benzene ring at 6.92–7.11 ppm.
2-(1H-Pyrazol-1-yl)methylphenol (IV). A mixture
of 28 g of phenol and 3 g of 1H-pyrazol-1-ylmetanol I
N-(2-Aminobenzyl)aniline (V). A mixture of 27 g
of aniline and 3 g of 1H-pyrazol-1-ylmetanol I was
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 7 2012

NON-CATALYTIC ALKYLATION OF PHENOL AND ANILINE
refluxed for 4–5 h. After removing the aniline excess,
1321
REFERENCES
the residue was distilled in a vacuum to give 1.3 g
(22.1%) of compound V, bp 193°C (2 mm Hg), mp
83°C (hexane). IR spectrum, ν, cm–1: 1590 (Ar), 3300,
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1
3350 (NH, NH2). Н NMR spectrum, δ, ppm: 4.10
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(5H, Ar), 6.92–7.11 m (4H, Ar). Found, %: C 78.85, H
7.38; N 14.37. С13Н14N2. Calculated, %: C 78.78; H
7.07; N 14.14. The residue after distillation was
dissolved in 20.0 ml of DMF. Polymer VII (0.8 g) was
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position point 80–120°C [7]. IR spectrum, ν, cm–1:
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1
3300 (NH), 1600, 1630 (Ar). Н NMR spectrum δ,
ppm: 4.0–4.8 m (CH2), 5.0–5.6 m (NH), 6.2–7.4 m
(Ar). An insoluble cross-linked polymer (0.5 g) was
also isolated from the distillation residue.
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(thin layer) and Nicolet Avatar 330 Sci IR spec-
trometers. The NMR spectra were registered on a
Varian Mercury spectrometer (300 MHz) in DMSO-d6.
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