Process for preparing alkyl-substituted aromatic hydrocarbons

An alkyl-substituted hydrocarbon is prepared by alkylating an alkyl aromatic hydrocarbon having at least one hydrogen atom at an alpha-position in a side chain with an olefin in the presence of a solid base which is obtainable by heating an alumina, an alkali metal hydroxide and an alkali metal hydride or an alumina containing at least 1.3% by weight of water and an alkali metal hydride in an inert gas atmosphere at a temperature of 200.degree. to 800.degree. C. as a catalyst.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for preparing an 
alkyl-substituted aromatic hydrocarbon. More particularly, the present 
invention relates to a process for preparing an alkyl-substituted aromatic 
hydrocarbon by reacting an alkyl aromatic hydrocarbon having at least one 
hydrogen atom at an alpha-position in said alkyl side chain with an olefin 
in the presence of a solid base which is prepared from an alumina, an 
alkali metal hydroxide and an alkali metal hydride or from 
water-containing alumina and an alkali metal hydride at a temperature in a 
specific range, whereby the alpha position is alkylated. 
2. Description of the Related Art 
The alkyl-substituted aromatic hydrocarbons are useful as intermediates in 
the production of fine chemicals such as agricultural chemicals, 
pharmaceuticals and other chemicals and prepared by reacting the aromatic 
hydrocarbon having the hydrogen atom at the alpha-position in the side 
chain with the olefin in the presence of a base catalyst. 
As the preparation process of the alkyl-substituted aromatic hydrocarbon, 
there are known a process which Utilizes a catalyst comprising metal 
sodium and chlorotoluene and a process which utilizes a catalyst 
comprising metal sodium supported on potassium carbonate (cf. J. Am. Chem. 
Soc., 78, 4316 (1956), GB Patent No. 1269280 and Japanese Patent Kokai 
Publication No. 53229/1986). 
However, the conventionally used catalysts have various drawbacks such as 
insufficient catalytic activities, a low yield of the alkyl-substituted 
hydrocarbon per a unit amount of the catalyst and troublesome separation 
of the catalysts from the product. Further, the conventional catalysts 
suffer from such problem that when they contact the oxygen and/or moisture 
in the air, they tend to lose their activities or they are ignited. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide a base catalyst which 
effectively catalyzes the reaction of the aromatic hydrocarbon having the 
hydrogen atom at the alpha-position in the side chain with the olefin, can 
be easily separated from the product after reaction. 
Another object of the present invention is to provide a process for 
producing an alkyl-substituted hydrocarbon by reacting the alkyl aromatic 
hydrocarbon having the hydrogen atom at the alpha-position in the side 
chain with the olefin. 
Accordingly, the present invention provides a process for preparing an 
alkyl-substituted hydrocarbon comprising alkylating an alkyl aromatic 
hydrocarbon having at least one hydrogen atom at an alpha-position in a 
side chain with an olefin in the presence of a solid base which is 
obtainable by heating an alumina, an alkali metal hydroxide and an alkali 
metal hydride or an alumina containing at least 1.3 % by weight of water 
and an alkali metal hydride in an inert gas atmosphere at a temperature of 
200.degree. to 800.degree. C. as a catalyst. 
DETAILED DESCRIPTION OF THE INVENTION 
The process of the present invention is characterized in the use of the 
specific solid base as the catalyst, which solid base is prepared by 
heating the alumina, the alkali metal hydroxide and the alkali metal 
hydride at the specific temperature. 
As the alumina, various types of aluminas except .alpha.-alumina are used. 
Preferred examples of the alumina are .gamma.-alumina, .chi.-alumina, 
.rho.-alumina and .eta.-alumina. Among them, those having a relatively 
large surface area are preferred. 
As the alkali metal hydride, a hydride of an alkali metal of Group I of the 
Periodic Table such as lithium, sodium, potassium and rubidium is used. 
They may be used as a mixture. Among them, sodium hydride, potassium 
hydride, or a mixture of them, particularly potassium hydride are 
preferred. The amount of the alkali metal hydride is generally from 2 to 
15 % by weight based on the weight of the alumina. 
As the alkali metal hydroxide, any of hydroxides of the above exemplified 
alkali metals may be used. Preferably, sodium hydroxide, potassium 
hydroxide and cecium hydroxide are used. Mixtures of two or more alkali 
metal hydroxides may be used. The amount of the alkali metal hydroxide is 
generally from 5 to 40 % by weight based on the weight of the alumina. 
In the preparation of the solid base, preferably the alumina is treated 
with the alkali metal hydroxide, and then the resulting product is reacted 
with the alkali metal hydride in the inert gas atmosphere. 
For example, the alumina is heated to a desired temperature and mixed with 
the alkali metal hydroxide. Thereafter, the alkali metal hydride is added 
to the resulting product and the mixture is further heated. Alternatively, 
the alumina is impregnated with an aqueous solution of the alkali metal 
hydroxide, and water in said solution is removed. Then, the dried product 
is heated to a desired temperature. Thereafter, the alkali metal hydride 
is added to the product and further heated. 
As the inert gas, nitrogen, helium, argon and the like are used. 
In the preparation of the solid base to be used in the process of the 
present invention, the reaction temperature is important. Usually, the 
reaction temperature is from 200.degree. to 800.degree. C. Preferably, the 
alumina and the alkali metal hydroxide are reacted in a temperature range 
of 250.degree. to 700.degree. C., more preferably in a temperature range 
of 260.degree. to 480.degree. C., and the alkali metal hydride is reacted 
in a temperature range of 200.degree. to 450.degree. C. 
The reaction time varies with other reaction conditions such as the 
reaction temperature. The reaction of the alumina with the alkali metal 
hydroxide may be completed within 0.5 to 10 hours, and the treatment with 
the alkali metal hydride may be completed within 10 to 300 minutes. 
By the above reactions, the solid base which has high catalytic activity, 
good flowability and handleability can be obtained. 
When water-containing alumina containing at least 1.3 % by weight of water 
is used as the alumina, the solid base having the same catalytic 
performances as above can be prepared with using no alkali metal 
hydroxide. Namely, the solid base catalyst can be prepared by reacting the 
alumina containing at least 1.3 % by weight of water with the alkali metal 
hydride in the inert gas atmosphere at a temperature of 200.degree. to 
800.degree. C. 
Various types of water-containing aluminas except for .alpha.-alumina can 
be used. 
Generally, alumina is produced by calcining aluminum hydroxide. According 
to the calcining temperature and time, alumina has various metastable 
states and a water content varies so that various type of alumina are 
produced. In the present invention, such alumina may be used. Preferably, 
water-containing alumina with a large surface area such as 
.gamma.-alumina, .chi.-alumina, .rho.-alumina and .eta.-alumina are used. 
The water content may be expressed by weight loss on heating in the heating 
step in which the alumina in its original state is converted to 
.alpha.-alumina which is considered to include no removable water. 
Usually, the water content of the water-containing alumina is 1.3 to 25 % 
by weight, preferably 2 to 10 % by weight. 
The amount of alkali metal hydride used in this preparation method is 
generally from 0.5 to 2.5 time, preferably 0.5 to 2.0 time molar 
equivalents of water contained in the alumina. 
Again, the reaction temperature is important in this preparation method of 
the catalyst. Usually, the reaction temperature is from 200.degree. to 
800.degree. C, preferably from 250.degree. to 700.degree. C., more 
preferably from 260.degree. to 480.degree. C. 
The reaction time varies with other reaction conditions such as the 
reaction temperature. The reaction of the alumina and the alkali metal 
hydride may be completed within 10 to 300 minutes. 
By the above reaction, the solid base which has the same properties as that 
prepared from the alumina, the alkali metal hydroxide and the alkali metal 
hydride, such as high catalytic activity, good flowability and 
handleability can be obtained. This may be because a part of the alkali 
metal hydride reacts with the water contained in the alumina to form the 
corresponding alkali metal hydroxide and as the result, the alumina, the 
alkali metal hydroxide and the alkali metal react with each other. 
In the process of the present invention, the aromatic hydrocarbon having 
the hydrogen atom at the alphaposition in the side chain is reacted with 
the olefin in the presence of the above described solid base as the 
catalyst. 
As such aromatic hydrocarbon, not only monocyclic aromatic hydrocarbons but 
also condensed polycyclic aromatic hydrocarbons may be used. In the 
aromatic hydrocarbons, the side chains may be closed to form a ring. 
Specific examples of the aromatic hydrocarbon are toluene, ethylbenzene, 
isopropylbenzene (cumene), n-propylbenzene, n-butylbenzene, 
sec.-butylbenzene, isobutylbenzene, xylene, cymene, diisopropylbenzene, 
methylnaphthalene, tetrahydronaphthalene, indan and the like. Among them, 
toluene, ethylbenzene and isopropylbenzene are preferred. 
As the olefin, those having 2 to 20 carbon atoms are usually used. The 
olefin may be straight or branched. The carbon-carbon double bond may be a 
terminal or internal double bond. Preferably, the olefin having the 
terminal double bond is used. Specific examples of the olefin are 
ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 
2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, 
octene, nonene, 3-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-pentene, 
3methyl-2-pentene and the like. Among them, ethylene, propylene, 1-butene 
and 2-butene are preferred. 
The alkylation reaction according to the present invention may be carried 
out batchwise or continuously with the use of a fluidized bed or a fix 
bed. 
The reaction temperature for the alkylation is usually from 0.degree. to 
300.degree. C., preferably from 10.degree. to 200.degree. C. 
The reaction pressure is from atmospheric pressure to 200 kg/cm.sup.2, 
preferably from 2 to 100 kg/cm.sup.2. 
The molar ratio of the olefin to the aromatic hydrocarbon is usually from 
0.1 to 10, preferably from 0.2 to 5. 
In the batchwise reaction, the amount of solid base catalyst to be used is 
from 0.01 to 20 % by weight, preferably from 0.2 to 5 % by weight based on 
the weight of the aromatic hydrocarbon. The reaction time is generally 
from 0.05 to 50 hours, preferably from 1 to 25 hours. 
In the continuous reaction, the mixture of the aromatic hydrocarbon and the 
olefin in the above molar ratio is supplied at LHSV of 0.1 to 600 
hr.sup.31 1, preferably 0.5 to 400 hr.sup.-1. 
According to the present invention, the alkyl-substituted hydrocarbon is 
effectively prepared in the presence of the solid base catalyst in a small 
amount under the mild conditions. Further, the catalyst to be used 
according to the present invention is easily handled and post-treated 
after the reaction.

PREFERRED EMBODIMENTS OF THE INVENTION 
Practically and presently preferred embodiments of the present invention 
will be illustrated by following examples. 
Preparation of Solid Bases 
Solid Base A 
An activated alumina of 42-200 mesh (NKHD-24, a trade name of Sumitomo 
Chemical Co., Ltd.) (26.5 g) was stirred in an atmosphere of nitrogen at 
510.degree. C. for one hour and cooled to 380.degree. C. Then, potassium 
hydroxide (2.5 g) was added to the alumina and the mixture was stirred at 
380.degree. C. for 3 hours followed by cooling to 310.degree. C. 
To the mixture, potassium hydride (2.33 g) was added and the mixture was 
stirred at 310.degree. C. for 0.2 hour followed by cooling to room 
temperature to obtain Solid Base A. 
Solid Base B 
In the same manner as in the preparation of Solid Base A but using 1.78 g 
of potassium hydride, Solid Base B was prepared. 
Solid Base C 
In the same manner as in the preparation of Solid Base A but adding 
potassium hydroxide at 550.degree. C. and using 1.81 g of potassium 
hydride, Solid Base C was prepared. 
Solid Base D 
To a solution of potassium hydroxide (2.5 g) and water (50 g), the same 
activated alumina as used in the preparation of Solid Base A (26.5 g) was 
added. Then, the mixture was dried with removing water at 70.degree. C. 
under reduced pressure while stirring to obtain a solid material. 
The solid material was stirred in an atmosphere of nitrogen at 250.degree. 
C. for 3 hours and heated to 310.degree. C. Then, potassium hydride (3.18 
g) was added to the solid material and the mixture was stirred at the same 
temperature for 0.2 hour followed by cooling to room temperature to obtain 
Solid Base D (24.8 g). 
Solid Base E 
In the same manner as in the preparation of Solid Base D but stirring the 
solid material at 380.degree. C. and using 3.15 g of potassium hydride, 
Solid Base E was prepared. 
Solid Base F 
In the same manner as in the preparation of Solid Base D but stirring the 
solid material at 550.degree. C. and using 3.25 g of potassium hydride, 
Solid Base F was prepared. 
Solid Base G 
In the same manner as in the preparation of Solid Base D but stirring the 
solid material at 700.degree. C. and using 3.15 g of potassium hydride, 
Solid Base G was prepared. 
Solid Base H 
In the same manner as in the preparation of Solid Base A but using 2.5 g of 
sodium hydroxide in place of potassium hydroxide and 2 g of potassium 
hydride, Solid Base H was prepared. 
Solid Base I 
The same manner as in the preparation of Solid Base A but using 2.5 g of 
sodium hydroxide in place of potassium hydride, Solid Base I was prepared. 
Solid Base J 
In the same activated alumina used in the preparation of Solid Base A (26.5 
g) and potassium hydroxide (2.5 g) were ground and mixed and then placed 
in a crucible and heated at 1,200.degree. C. for 3 hours in a muffle 
furnace. The mixture was cooled to 200.degree. C. and further to room 
temperature in a desiccator in an atmosphere of nitrogen to obtain a fine 
powder. 
The fine powder was heated to 310.degree. C. Then, to the heated powder, 
sodium hydride (2.6 g) was added while stirring. The mixture was further 
stirred at 310.degree. C. for 0.2 hour followed by cooling to room 
temperature to obtain Solid Base J. 
Solid Base K 
To 40-200 mesh activated alumina containing 3.6 % of water (21.7 g) in an 
atmosphere of nitrogen, potassium hydride (2.6 g) was added. The mixture 
was heated to 360.degree. C. while stirring and further stirred at the 
same temperature for 0.2 hour followed by cooling to room temperature to 
obtain Solid Base K (23.9 g). 
Solid Base L 
In the same manner as in the preparation of Solid Base K but using 1.8 g of 
potassium hydride, Solid Base L was prepared. 
Solid Base M 
In the same manner as in the preparation of Solid Base K but using 1.55 g 
of potassium hydride, Solid Base M was prepared. 
Solid Base N 
In the same manner as in the preparation of Solid Base K but using 1.4 g of 
potassium hydride, Solid Base N was prepared. 
Solid Base O 
To the same water-containing alumina as used in the preparation of Solid 
Base K (21.7 g) heated at 360.degree. C. in an atmosphere of nitrogen, 
potassium hydride (0.95 g) was added while stirring and the mixture was 
further stirred at the same temperature for 0.2 hour. Then, the mixture 
was heated to 700.degree. C. and further stirred at the same temperature 
for 3 hours and cooled to 360.degree. C. To the mixture, potassium hydride 
(0.95 g) was added and the mixture was stirred at 360.degree. C. for 0.2 
hour followed by cooling to room temperature to obtain Solid Base O. 
Solid Base P 
To the same water-containing alumina as used in the preparation of Solid 
Base K (21.7 g) heated at 290.degree. C in an atmosphere of nitrogen, 
potassium hydride (0.89 g) was added while stirring and the mixture was 
further stirred at the same temperature for one hour. Then, the mixture 
was placed in a crucible and heated at 1,200.degree. C. for 3 hours in a 
muffle furnace. The mixture was cooled to 200.degree. C. and further to 
room temperature in a desiccator in an atmosphere of nitrogen. 
After heating the mixture to 360.degree. C. in an atmosphere of nitrogen, 
sodium hydride (1.02 g) was added and the mixture was stirred at 
360.degree. C. for 0.2 hour followed by cooling to room temperature to 
obtain Solid Base P. 
EXAMPLE 1 
In a 600 ml autoclave equipped with a magnetic stirrer, Solid Base A (0.45 
g) and cumene (240 g) were charged under nitrogen, heated to 160.degree. 
C. while stirring at 1,000 rpm and then reacted at the same temperature 
for 3 hours while supplying ethylene gas under pressure of 10 kg/cm.sup.2 
G. to produce tert.-amylbenzene (hereinafter referred to as "TAB"). 
After the reaction, the autoclave was cooled, and the catalyst was filtered 
off. The reaction mixture was analyzed with gas chromatography. The 
results are shown in Table 1. 
The selectivity of TAB is calculated according to the following equation: 
##EQU1## 
EXAMPLES 2-16 AND COMATIVE EXAMPLES 1-2 
In the same manner as in Example 1 but carrying out the reaction under the 
conditions shown in Table 1, the alkylation was carried out. The results 
are shown in Table 1. 
In Examples 1 through 16, the catalyst was still active at the end of the 
reaction and the alkylation could be further carried out by using the same 
catalyst. 
TABLE 1 
______________________________________ 
Reac- Conver- 
Exam- Solid Reaction tion sion of 
Selec- 
ple Base Temp. time cumene tivity of 
No. (g) (.degree.C.) 
(hrs) (%) TAB (%) 
______________________________________ 
1 A (0.45) .uparw. 3.0 98.9 99.2 
2 B (0.51) .uparw. .uparw. 
95.7 99.1 
3 C (0.49) .uparw. .uparw. 
91.3 95.2 
4 D (0.49) 160 1.5 99.4 99.6 
5 E (0.38) .uparw. .uparw. 
93.7 99.4 
6 F (0.40) .uparw. .uparw. 
91.5 99.3 
7 G (0.39) .uparw. .uparw. 
36.4 98.7 
8 H (0.41) .uparw. 3.0 99.7 99.2 
9 I (1.26) .uparw. .uparw. 
32.0 95.5 
10 K (0.48) .uparw. 1.5 97.8 97.6 
11 L (0.32) .uparw. 3.0 83.9 99.4 
12 M (0.37) .uparw. .uparw. 
84.9 98.6 
13 N (0.42) .uparw. .uparw. 
63.5 99.4 
14 O (0.41) .uparw. .uparw. 
95.7 95.6 
15 A (0.32) 100 1.5 98.7 99.7 
16 L (0.39) .uparw. 3.0 99.8 99.2 
C. 1 J (1.98) 160 .uparw. 
5.7 98.9 
C. 2 P (1.38) .uparw. .uparw. 
0.18 99.0 
C. 3 Mixture .uparw. .uparw. 
19.4 73.9 
(8.49) 
______________________________________ 
COMATIVE EXAMPLE 3 
To a 200 ml autoclave equipped with a magnetic stirrer, anhydrous potassium 
carbonate which had been calcined at 400.degree. C. for 2 hours in a 
nitrogen atmosphere (8.19 g), metal sodium (0.3 g) and cumene (26.7 g) 
were charged under nitrogen, heated to 190.degree. C. while stirring at 
1,000 rpm then stirred at the same temperature for 2 hours. 
After cooling the autoclave, additional cumene (53.3 g) was added and the 
mixture was heated to 160.degree. C. while stirring at 1,000 rpm and then 
reacted at the same temperature for 3 hours while supplying ethylene gas 
under pressure of 10 kg/cm.sup.2 G. 
After the reaction, the product was analyzed in the same manner as in 
Example 1. The results are also shown in Table 1. 
EXAMPLE 17 
In a 300 ml autoclave equipped with a magnetic stirrer, Solid Base A (0.99 
g) and cumene (80 g) were charged under nitrogen and then liquid propylene 
(100 ml) was injected under pressure. The reaction was then carried out at 
160.degree. C. for 24 hours while stirring to produce 
1,1,2-trimethylpropylbenzene (hereinafter referred to as "TMPB"). 
After the reaction, the autoclave was cooled, and the reaction mixture was 
analyzed in the same manner as in Example 1 to find that the conversion of 
cumene was 71.1 % and the selectivity of TMPB was 85.7 %. 
The selectivity of TMPB is calculated according to the following equation: 
##EQU2## 
EXAMPLE 18 
In the same manner as in Example 18 but using Solid Base L in place of 
Solid Base A, the alkylation was carried out. 
After the reaction, the autoclave was cooled, and the reaction mixture was 
analyzed in the same manner as in Example 1 to find that the conversion of 
cumene was 46.0 % and the selectivity of TMPB was 85.4 %. 
In Examples 17 and 18, the catalyst was still active at the end of the 
reaction and the alkylation could be further carried out by using the same 
catalyst. 
COMATIVE EXAMPLE 4 
In a 200 ml autoclave equipped with a magnetic stirrer, anhydrous potassium 
carbonate which had been calcined at 400.degree. C. for 2 hours in a 
nitrogen atmosphere (8.86 g), metal sodium (0.3 g) and cumene (81.2 g) 
were charged under nitrogen, heated to 190.degree. C. while stirring and 
then stirred at the same temperature for 2 hours. 
After cooling the autoclave, liquid propylene (70 ml) was injected under 
pressure and the mixture was stirred at 160.degree. C. for 24 hours. 
After the reaction, the product was analyzed in the same manner as in 
Example 1 to find that the conversion of cumene was 8.0 % and the 
selectivity of TMPB was 81.5 %. 
EXAMPLE 19 
In a 300 ml autoclave equipped with a magnetic stirrer, Solid Base A (2.81 
g) and toluene (80 g) were charged under nitrogen and then liquid 
propylene (70 ml) was injected under pressure. The reaction was carried 
out at 160.degree. C. for 6 hours while stirring to produce 
isobutylbenzene (hereinafter referred to as "IBB"). 
After the reaction, the product was analyzed in the same manner as in 
Example 1 to find that the conversion of toluene was 22.9 % and the 
selectivity of IBB was 91.0 %. The selectivity of IBB was calculated 
according to the following equation: 
##EQU3## 
EXAMPLE 20 
In the same manner as in Example 20 but using Solid Base K in place of 
Solid Base A, the alkylation was carried out. 
After the reaction, the product was analyzed in the same manner as in 
Example 1 to find that the conversion of toluene was 21.2 % and the 
selectivity of IBB was 91.5 %. 
In Examples 19 and 20, the catalyst was still active at the end of the 
reaction and the alkylation could be further carried out by using the same 
catalyst. 
COMATIVE EXAMPLE 5 
In a 200 ml autoclave equipped with a magnetic stirrer, anhydrous potassium 
carbonate which had been calcined at 400.degree. C. for 2 hours in a 
nitrogen atmosphere (8.45 g), metal sodium (0.3 g) and toluene (26.6 g) 
were charged under nitrogen, heated to 190.degree. C. while stirring at 
1,000 rpm and then stirred at the same temperature for 2 hours. 
After cooling the autoclave, additional toluene (53.2 g) was added and 
liquid propylene (70 ml) was injected under pressure. Then the mixture was 
stirred at 160.degree. C. for 6 hours. 
After the reaction, the product was analyzed in the same manner as in 
Example 1 to find that the conversion of toluene was 3.5 % and the 
selectivity of IBB was 88.2 %.