Russian Journal of Applied Chemistry, Vol. 76, No. 4, 2003, pp. 558 560. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 4, 2003,
pp. 579 581.
Original Russian Text Copyright
2003 by Agaev, Nazarova.
CATALYSIS
Catalytic Alkylation of 1-Naphthol with Methanol
A. A. Agaev and M. K. Nazarova
Sumgait State University, Sumgait, Azerbaijan
Received January 9, 2003
Abstract The reaction of 1-naphthol with methanol in the presence of mordenite catalysts was studied.
The synthesis conditions ensuring high yields of methylnaphthols, methylnaphthalenes, or methoxynaphthalene
were determined.
Catalytic methylation of naphthols with methanol
has been poorly studied. Both C-alkylation yielding
methylnaphthols and O-alkylation yielding methoxy-
naphthalenes are possible. However, it has been re-
ported [1, 2] that the reaction of naphthol with an ex-
cess of methanol mainly yields isomeric alkylnaph-
thalenes. Apparently, the reaction pathway and the
composition of the products depend on the reaction
conditions and catalysts used.
mations, the naphthol conversion on H-mordenite is
significant.
The reaction of 1-naphthol with methanol follows
three major pathways: etherification, ring methylation,
and self-condensation. In the reaction products, we
detected 1-methoxynaphthalene, 2- and 4-methyl-1-
naphthols, methylnaphthalenes, and high-carbon com-
pounds.
At low temperatures (320 380 C), the major path-
way is electrophilic methylation of the 1-naphthol
core at 2- and 4-positions to form the correspond-
ing methylnaphthols. At higher temperatures (380
420 C), the contribution of dehydroxylation accom-
panying ring methylation increases in the presence of
H-mordenite, and methylnaphthalenes become the
major products. At moderate temperatures, appreci-
able amounts of 1-methoxynaphthalene are formed,
apparently by the competing O-methylation pathway:
To examine the effect exerted by zeolite composi-
tion and reaction conditions on alkylation of 1-naph-
thol with methanol, we studied the catalytic properties
of synthetic mordenites containing 0.1 5.0 wt% Ni(II).
EXPERIMENTAL
H-Mordenite was prepared by treatment of Na-
mordenite (SiO2 : Al2O3 = 10) with 1 N NH4Cl and
then with eight portions of 2 N HCl, followed by
washing and drying. The nickel-containing zeolite was
prepared by impregnation of H-mordenite with a cal-
culated amount of an Ni(NO3)2 solution. The optimal
content of Ni(II) in H-mordenite was 1.5 wt %.
OCH3
The catalytic activity of zeolites was evaluated on
a flow-through installation at atmospheric pressure.
A 10-cm3 portion of the catalyst was charged into re-
actor and heated for 5 h at 450 C in a flow of dry air
and then for 3 h at 450 C in a hydrogen flow. The ex-
periments were performed at 300 425 C, molar ratio
1-naphthol : CH3OH = 1 : 7, and space velocity of
OH
OH
CH3
OH
CH3
+ CH3OH
H2O
1
0.8 1.4 h . The reaction products were analyzed on
a Chrom-5 chromatograph; 3600 4-mm columns
were packed with Chromosorb W containing 15 wt %
Apiezon M as the stationary phase. The relative error
of the analysis did not exceed 3.0%. The IR spectra
of individual reaction products were measured on
an M-80 spectrometer.
The table shows that introduction of Ni(II) into
H-mordenite noticeably enhances its catalytic proper-
ties in alkylation of 1-naphthol with methanol. In the
range 320 360 C, the major reaction products are
1-methoxynaphthalene and 2- and 4-methylnaphthols;
the total selectivity of their formation is 91.3 96.4%.
In contrast to the initial Na-mordenite, on which
1-naphthol undergoes virtually no chemical transfor-
1070-4272/03/7604-0558 $25.00 2003 MAIK Nauka/Interperiodica