Noncatalytic alkylation of phenol with 1,3,5-trimethyl-1Hpyrazol-4- ylmethanol

Full text of DOI:10.1134/S1070363208030286

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 3, pp. 506–507. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © O.S. Attaryan, A.A. Gevorkyan, S.K. Antanosyan, G.A. Panosyan, G.V. Asratyan, 2008, published in Zhurnal Obshchei Khimii,
2
008, Vol. 78, No. 3, pp. 521–522.
LETTERS
TO THE EDITOR
Noncatalytic Alkylation of Phenol with 1,3,5-Trimethyl-1H-
pyrazol-4-ylmethanol
a
b
b
c
b
O. S. Attaryan , A. A. Gevorkyan , S. K. Antanosyan , G. A. Panosyan , and G. V. Asratyan
a
Armenian Institute of Applied Chemistry Ariak Ltd., Artashatskoe shosse 5/2, Erevan, 375053 Armenia
b
Institute of Organic Chemistry, National Academy of Sciences of Armenia, Erevan, Armenia
c
Molecular Structure Research Center, National Academy of Sciences of Armenia, Erevan, Armenia
Received August 24, 2007
DOI: 10.1134/S1070363208030286
We previously showed that heating of 1,3,5-
aromatic ring in phenol. At a I-to-PhOH ratio
of 1 : 5 the yield of the alkylation products (a mix-
ture of ortho and para isomers) attained 67%.
trimethylpyrazol-4-ylmethanol (I) in the presence of
benzyl and hexyl alcohols leads mainly to the
formation of mixed trimethylpyrazolylmethyl ethers.
While studying the scope of application of this
transformation we examined the reaction of compound
I with phenol. We found that, instead of the expected
pyrazolylmethyl phenyl ether, the reaction gave
isomeric products II and III via alkylation of the
1
According to the H NMR data, the ratio of isomeric
phenols was 3:2. The signal from the hydroxy proton
of isomer II was located in a weaker field (δ 8.91 ppm)
than the corresponding signal of isomer III (δ 8.62
ppm). Isomer II was isolated by fractional
crystallization.
_
___________
Me
HO
N
Me
Me
N
OH
CH2
II
Me
CH OH
2
Me
Δ
+
N
Me
N
Me
N
N
Me
OH
I
CH2
Me
III
_
___________
We failed to interpret the observed behavior of
alcohol I on the basis of generally accepted views [2–
], for the presence of pyrazole heteroring should
may be given in terms of the new generalized theory of
acids and bases [5].
4
hinder heterolytic dissociation of the C–OH bond and
formation of C–O–C ether bond or C–H alkylation in
the absence of acid catalyst. A reasonable explanation
2- and 4-(1,3,5-Trimethyl-1H-pyrazol-4-ylmeth-
yl)phenols (II) and (III). A mixture of 1.4 g of 4-
hydroxymethyl-1,3,5-trimethyl-1H-pyrazole (I) and
506

NONCATALYTIC ALKYLATION OF PHENOL
507
9
.5 g of phenol was heated for 5 h under reflux. Excess
Mercury-300 instrument at 300 MHz. The IR spectra
were measured on a Specord 75-IR spectrometer from
thin films.
phenol was removed, and the residue (dark crystals)
was treated with 10 ml of water and with sodium
hydroxide. The aqueous phase was extracted with
chloroform and neutralized with hydrochloric acid, and
the precipitate was filtered off. Yield 1.45 g (67%), mp
REFERENCES
–
1
1
2
. Attaryan, O.S., Gevorkyan, A.A., Antanosyan, S.K.,
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Russ. J. Gen. Chem., 2005, vol. 75, no. 9, p. 1500.
1
1
52–201°C. IR spectrum, ν, cm : 1510 (pyrazole),
1
590 (C–Carom), 3200–3500 (OH). H NMR spectrum,
δ, ppm (J, Hz): 1.98 s (3H, 3-CH ), 2.11 s (3H, 5-
CH ), 3.52 s (2H, CH ), 3.64 s (3H, NCH ), 6.58 m
3
. Becker, H., Einführung in die Elektronentheorie
organisch–chemischer Reaktionen, Berlin: Wissen-
schaften, 1974, 3rd ed.
3
2
3
(
2H, m-H), 6.80 m (2H, o-H), 8.66 s (1H, OH).
Recrystallization of the product from ethanol gave
1
3. Dneprovskii, A.S. and Temnikova, T.I., Teoreticheskie
osnovy organicheskoi khimii (Theoretical Foundations of
Organic Chemistry), Moscow: Khimiya, 1979.
pure isomer II. mp 195°C. H NMR spectrum
(
DMSO-d ), δ, ppm (J, Hz): 2.00 s (3H, CH ), 2.12 s
6
3
(
3H, CH ), 3.53 s (2H, CH ), 3.65 s (3H, NCH ), 6.57
3
2
3
4
. Sykes, P., A Guidebook to Mechanism in Organic
Chemistry, Harlow, Essex, England: Longman, 1986, 6th ed.
t. d (1H, Harom, J = 7.4, J = 1.4), 6.70 d.d (1H, Harom,
1
2
J = 7.5, J = 1.9), 6.72 d.d (1H, H , J = 7.8, J =
1
2
arom
1
2
5
. Gevorkyan, A.A., Obobshchennaya teoriya kislot i
osnovanii. Novoe vozzrenie na reaktsionnuyu sposobnost’
atomov i molekul (Generalized Theory of Acids and
Bases. Novel Concepts of the Reactivity of Atoms and
Molecules), Erevan: Gitutyun, 2006.
1
8
.4), 6.88 d.d.d (1H, Harom, J = 7.8, J = 7.5, J = 1.9 ),
1 2 3
.90 s (1H, OH). Found, %: C 69.94; H 7.21; N 11.85.
C H N O. Calculated, %: C 72.22; H 7.41; N 12.96.
13
16
2
1
The H NMR spectra were recorded on a Varian
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008