1104
Chemistry Letters 2002
Alkylation-Acylation of Aromatics with ꢀ-Butyrolactone Catalyzed by Heteropolyacids
Supported on Silica
Jianxin Mao, Tetsuo Nakajo,y and Toshio OkuharaÃ
Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810
yShowa Denko K. K., 5-1 Ohgimachi, Kawasaki-ku, Kawasaki 210-0867
(Received July 12, 2002; CL-020585)
Silica-supported H4SiW12O40 catalyzed efficiently alkyla-
air. The products were analyzed with a GC (Shimadzu 14B) with a
capillary column (5%PHME silane), 1H NMR spectrometer, GC-
MS, and IR spectrometer.
tion/acylation of 1,3,5-trimethylbenzene or p-xylene with ꢀ-
butyrolactone to 4-(2,4,6-trimethylphenyl) butyric acid or to
dimethyl-ꢁ-tetralone (5,8-dimethyl-3,4-dihydro-2H-naphtalen-
1-one), while other typical solid acids such as zeolites and
SiO2-Al2O3 were much less active.
Table 1 summarizes the catalytic data for the reaction of
1,3,5-trimethylbenzene with ꢀ-butyrolactone over various solid
acids. The main product was identified to 4-(2,4,6-trimethylphen-
yl) butyric acid (1 in Eq. (1)) with the GC, IR spectrometer, 1H
NMR spectrometer, and GC-MS, showing that the alkylation took
place. A possible product by the acylation, 4-hydroxy-1-(2,4,6-
trimethylphenyl)-butan-1-one and derivatives were little formed
under these reaction conditions. Table 1 demonstrates that the
heteropolyacids and their SiO2-supported catalysts exhibited
high conversions of ꢀ-butyrolactone and the yields of 1. On the
contrary, zeolites (H-ꢂ, H-Y, H-ZSM-5, and H-mordenite), and
SiO2-Al2O3 gave poor activities for the formation of 1. While H-
ꢂ gave a high conversion of ꢀ-butyrolactone, the product was
only the oligomers. The superiority of these heteropoly
compounds in the yield suggests that their strong acidities6{8
are responsible for the acceleration of the reaction.
Derivatives of ꢁ-tetralone (3,4-dihydro-2H-naphtalen-1-
one) areimportant rawmaterials formedical supplies. Practically,
ꢁ-tetralone has been synthesized from benzene and succinic
anhydride via multi-steps.1;2 While one-step synthesis of ꢁ-
tetralone from benzene using ꢀ-butyrolactone was proposed,
until the present day, only a system using an excess amount of
AlCl3 has been reported.3;4
Here we wish to report the catalytic synthesis of dimethyl-ꢁ-
tetralone from ꢀ-butyrolactone by using the supported hetero-
polyacids. The catalytic activities for 1,3,5-trimethylbenzene
with ꢀ-butyrolactone (Eq. (1)) were first examined over various
solids. Then the reaction of p-xylene with ꢀ-butyrolactone (Eq.
(2)) was performed with the selected solid acid catalysts.
Table 1. Catalytic data for reaction between 1,3,5-trimethyl-
benzene and ꢀ-butyrolactone
Conv. Yield
/%
Sb
/%
M.B.c
/%
Catalyst
TONa
/%
10 wt%HSiW/SiO2 44.9
30.7
25.1
33.5
46.6
23.5
2.6
1.7
0.0
0.0
0.0
49.1 97.1
56.2 100.0
87
84
49
56
66
91
91
53
94
82
10 wt%HPW/SiO2
H4SiW12O40
H3PW12O40
Cs2:5H0:5PW12O40
H-Y
41.6
85.1
91.0
60.9
11.7
4.1
5.4
10.4
34.9
0.2
1.2
0.0
97.6
96.3
88.9
67.9
40.4
0.0
H-ZSM-5
H-ꢂ
H-mordenite
SiO2-Al2O3
47.2
5.9
17.7
0.0
0.0
0.0
0.0
The reactions of 1,3,5-trimethylbenzene and p-xylene with
ꢀ-butyrolactone were performed ina stainless autoclave (volume,
100 or 40 cm3) using a mixture of 1,3,5-trimethylbenzene
(40 cm3, 288 mmol) and ꢀ-butyrolactone (2.6 cm3, 34 mmol)
and a mixture of p-xylene (81 mmol) and ꢀ-butyrolactone
(0.74 mmol), respectively. The following solid acids were used;
H3PW12O40 (6 m2gÀ1) and H4SiW12O40 (5 m2gÀ1, Nippon
Inorganic Color and Chemical) and their silica (Aerosil 300,
274 m2gÀ1)-supported catalysts (abbreviated as HSiW/SiO2 and
HPW/SiO2, respectively) calcined at 523 K in air.
Cs2:5H0:5PW12O40 was prepared as described previously.5;6 H-ꢂ
zeolite (Si/Al = 12.5, Sud Chem.), H-ZSM-5 (Tosoh, HSZ-
860HOA, Si/Al = 37), H-Y (JRC-Z-HY 4.8, Si/Al = 2.4), H-
mordenite (JRC-Z-HM-20, Si/Al = 10), and SiO2-Al2O3 (JRC-
SAL2, 546 m 2gÀ1) were also used after the calcination at 773 K in
aTurnover number defined by the ratio of the amount of
product to the total amount of acid sites. bSelectivity was
defined as the percent of 1 among all the products detected by
GC. cMass balance on the basis of ꢀ-butyrolactone. Reaction
conditions: 1,3,5-trimethylbenzene 288 mmol, ꢀ-butyrolac-
tone 34 mmol, catalyst weight: 1.5 g, 453 K and 6 h.
Table 1 further shows that the supported heteropolyacids
exhibited high selectivities and mass-balances (=84%). When the
loading amount of H4SiW12O40 was varied, the yield gave a
maximum (about 51%) at 40 wt% of the loading, while the mass
balance decreased as the loading amount of H4SiW12O40
increased.
Figure 1 shows the results of repeated runs over
10 wt%HSiW/SiO2. Between the runs, the solid catalyst was
Copyright Ó 2002 The Chemical Society of Japan
Mao, Jianxin
