JPS61176541A - Production of alpha-alkyl-substituted naphthalene - Google Patents

Abstract

PURPOSE:To produce the titled compound useful as an intermediate raw material for pharmaceuticals, etc., by reacting a naphthalene compound with an olefin compound at a specific temperature in the presence of a specific amount of an aluminum chloride catalyst having high catalytic activity and non-corrosive to the material of the apparatus. CONSTITUTION:A naphthalene compound such as naphthalene, methylnaphthalene, etc. is made to react with an olefin compound such as ethylene, propylene, etc. to obtain an alpha-alkyl-substituted naphthalene such as isopropylnaphthalene. the above reaction is carried out in the presence of 0.05-0.5mol, preferably 0.1-0.4mol of aluminum chloride catalyst based on 1mol of the naphthalene, at 0-50 deg.C, preferably 0-40 deg.C until the conversion of naphthalene reaches 85-95%. EFFECT:Industrially advantageous. USE:Intermediate raw material for pharmaceuticals, dyes, synthetic resins, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a method for producing α-alkyl-substituted naphthalene, which is useful as an intermediate raw material for pharmaceuticals, dyes, synthetic resins, etc.

[Conventional technology]

α-Alkyl-substituted naphthalenes can be easily synthesized by reacting naphthalenes with corresponding olefins or alkyl halides in the presence of a Friedelkraff catalyst. At the same time, large amounts of its isomers, polyalkylated naphthalenes such as β-alkyl-substituted naphthalene and trialkyl-substituted products, or naphthalene polymers, etc., are produced, making it difficult to selectively produce α-alkyl-substituted naphthalenes. .

For example, there have been some attempts to alkylate naphthalene with olefins using aluminum chloride as a catalyst, but this method produces a large amount of β-alkyl substituted products, making it difficult to selectively obtain α-alkyl substituted products. It is reported that it is not possible.

Therefore, as a method for selectively producing this α-alkyl-substituted naphthalene, naphthalenes and olefins are combined with a copper compound-phosphoric acid catalyst, an iron compound-phosphoric acid catalyst, a boron fluoride, or a hydrogen-phosphoric acid catalyst. react in the presence of
α-alkyl substituent/β-alkyl substituent ratio 70-8
It has been proposed to react selectively to about 0/30 to 20% (Japanese Patent Application Laid-Open Nos. 49-14453, 49-18857, and 55-44733).

[Problem that the invention seeks to solve]

However, in a method for selectively producing α-alkyl substituted naphthalene using such a catalyst, 180°C
Since the above reaction temperature is required, there are many disadvantages from an industrial perspective, such as the need for a pressure reactor such as an autoclave as a reaction device.

[Means for solving problems]

The present invention was devised in view of this point of view, and has a high catalytic activity, is not so corrosive to the material of the equipment, and is an aluminum chloride catalyst that is most commonly used industrially. The present invention provides a method for selectively producing α-alkyl-substituted naphthalene.

That is, the present invention provides α-alkyl-substituted naphthalene, which is produced by reacting naphthalenes and olefins at a temperature of 0 to 50°C in the presence of an aluminum chloride catalyst in an amount of 0.05 to 0.5 times the molar amount of the naphthalenes. This is the manufacturing method.

In the present invention, as the naphthalenes used as raw materials, in addition to naphthalene, at least one α
Alkylnaphthalenes such as methylnaphthalene which are not substituted at the - position can be mentioned.

Further, in the present invention, there are various olefins used as alkylating agents, but specific examples include ethylene, propylene, butenes, etc., and ethylene or propylene is preferable. Olefins of butene or higher have lower α-position selectivity. The amount of these olefins used is usually 0.0% relative to naphthalene.
5 to 2 times the molar amount, preferably 0.5 to 1 times the molar amount when one alkyl group is introduced, and 1.5 to 2 times the molar amount when two alkyl groups are introduced. This is twice the molar amount. If the amount of olefins used relative to naphthalenes is too large, the by-product layer of polyalkylnaphthalene will increase, and if it is too small, the conversion rate of naphthalene will decrease.

Further, the amount of the aluminum chloride catalyst used in the present invention is usually 0.05 to 0.0% relative to naphthalenes.
5 times -E/L, amount, preferably 0.1 to 0.4 times molar amount. When the amount of the catalyst used is less than 0.05 times the molar amount, the reaction rate tends to decrease, and when it is more than 0.5 times the molar amount, the reaction selectivity for the α-position of naphthalene decreases. Note that aluminum chloride is an aromatic hydrocarbon,
It can also be used in the form of a complex with nitromethane or the like.

Since the reaction in the method of the present invention is carried out in a liquid phase, a solvent is used if the reaction mixture becomes solid in the reaction system. The solvent used for this purpose may be one that dissolves naphthalenes and is not alkylated in the presence of an aluminum chloride catalyst, specifically n-hexane,
Examples include paraffin or cycloparaffin solvents such as cyclohexane, n-hebutane, iso-hebutane, n-octane, isooctane, n-nonane, and decalin.

Regarding the amount of these solvents to be used, it is sufficient that the amount is sufficient to dissolve at least a portion, preferably all, of the raw naphthalenes, and it is not preferable to use a large amount. Note that when the raw material is something liquid at the reaction temperature, such as methylnaphthalene, a solvent may or may not be used.

In the method of the present invention, the reaction temperature is 0 to 50°C, preferably 0 to 40°C, and the reaction time is preferably kept at a time such that the reaction does not reach equilibrium.
Usually 5 to 20 hours, preferably 6 to 15 hours. If the reaction temperature is lower than 0°C, the reaction rate will be slow;
If it becomes higher, the α-position selectivity decreases. In addition, when the number of alkyl groups to be introduced in the alkylation is one, it is preferable to carry out the reaction so that the conversion rate of naphthalenes is 40 to 70%, and when the number of alkyl groups is two, it is preferably 85 to 70%.
It is preferable to cause the reaction to reach 95%.

The α-alkyl-substituted naphthalene produced in the method of the present invention can be separated and purified from the reaction mixture by common operations such as extraction and distillation.

〔Example〕

Hereinafter, the method of the present invention will be specifically explained based on Examples.

Example 1 0.3 mol naphthalene and 4.5 mol n-
Hebutane and 0.09 mol of aluminum chloride were added thereto, and the reaction was carried out at 0° C. while blowing propylene from the inlet of the reaction vessel. This injection of propylene gas was carried out under such conditions that a small amount of propylene gas was detected in the exhaust gas at the outlet of the reaction vessel.

During the reaction, a small amount of the reaction mixture was taken out at regular intervals and analyzed to determine the naphthalene conversion rate and the composition of isopropylnaphthalene and diisopropylnaphthalene. The naphthalene conversion after 6 hours of reaction was 10.2%, and the yields of isopropylnaphthalene and diisopropylnaphthalene were 6.7 mol% and 1.7 mol%, respectively.

In addition, the ratio of the α-position substituted product in isopropylnaphthalene is 10%, 20%, 63%, and 89% in naphthalene conversion.
%, respectively 83.5%, 83%, 83% and 8
It was 3%.

Further, the proportion of the 1,×-substituted product having at least one α-position substituent in diisopropylnaphthalene is 99% or more when the naphthalene conversion rate is 20% or less, and 95% when the naphthalene conversion rate is 89%. Met. Also, 1
．． The proportions of X-diisopropylnaphthalene are 1.4 54-59%, 1.7 19-21%, 1.5
2-14%, 1,6 unit 9-10% and 1,3 unit 1%
1,4 as the naphthalene conversion rate increases.
There was a tendency for the monomer to decrease and other isomers to increase.

Example 2 A reaction between naphthalene and propylene was carried out under the same conditions as in Example 1 above, except that the reaction temperature was 30°C. The results are shown in Table 1.

Table 1 also shows that the proportions of the α-substituted product in isopropylnaphthalene were 74.5% and 76% when the naphthalene conversion rates were 20% and 93%, respectively. The proportion of 1, It was constant. 1. The proportion of x-diisopropylnaphthalene varies slightly depending on the naphthalene conversion rate, but it is 35% for 1,4 and 24% for 1,7.
, 20% for 1°5, 19% for 1,6, and 2% for 1.3, which were almost constant.

Example 3 0.3 moles of naphthalene and 4.5 moles of n-
Hebutane and 0.15 mol of aluminum chloride were added thereto, and the reaction was carried out at 30° C. while blowing propylene from the inlet of the five reaction vessels. The results are shown in Table 2.

(Effects of the Invention) According to the present invention, α-alkyl-substituted naphthalene can be selectively produced using an aluminum chloride catalyst that has high catalytic activity and is less corrosive to equipment materials. , α-alkyl-substituted naphthalene can be produced industrially advantageously.

Claims (3)

[Claims] (1) α-alkyl substitution characterized by reacting naphthalenes and olefins at a temperature of 0 to 50°C in the presence of an aluminum chloride catalyst in a molar amount of 0.05 to 0.5 times that of the naphthalenes. Method for producing naphthalene. (2) The method for producing α-alkyl-substituted naphthalene according to claim 1, wherein the olefin is ethylene or propylene. (3) The method for producing α-alkyl-substituted naphthalene according to claim 1 or 2, wherein the reaction is carried out until the conversion of naphthalene reaches 85 to 95%.