JPH0236143A - Production of 2-alkyl-6-acylnaphthalene - Google Patents

Abstract

PURPOSE:To obtain the title compound useful as an intermediate for a raw material of polyester to be used for magnetic tape, etc., economically and in high yield by using a readily recoverable and reusable catalyst by acylating a 2-alkylnaphthalene in the presence of a specific catalyst. CONSTITUTION:Trifluoromethanesulfonic acid is used as a catalyst and 2- alkylnaphthalene is reacted with an acylating agent usually at -20-100 deg.C, preferably, -10-80 deg.C for 10 minutes-10 hours preferably in a solvent such as methylene chloride or benzene to give the aimed compound. Since the aimed compound and trifluoromethanesulfonic acid form a complex in the reaction product, water, ammonia, etc., are added to decompose the complex into the aimed compound and the catalyst. The amount of the catalyst used is preferably 2-20 mols based on 1 mol 2-alkylnaphthalene. Acetic acid, propionic acid, etc., are used as the acylating agent.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing 2-alkyl-6-acylnaphthalene, and specifically, acylating 2-alkylnaphthalene in the presence of trifluoromethanesulfonic acid, 2-
The present invention relates to a method for producing alkyl-6-acylnaphthalene.

[Prior Art] Conventionally, the following method is known as a method for producing 2-alkyl-6-acylnaphthalene by reacting 2-alkylnaphthalene with an acylating agent.

One is to use a Riedel-Krauch catalyst such as aluminum chloride or iron chloride as a catalyst in the above reaction (US Pat. No. 3,234,286, JP-A-61-267538). , Japanese Patent Publication No. 62-61944
Publication No.).

The other method is to carry out the above reaction in the presence of boron trifluoride, or boron trifluoride and hydrogen fluoride (JP-A-54-135756, JP-A-61-21855).
Publication No. 3, JP-A-61-271243, JP-A-6
1-277643, JP-A-62-48643).

However, in the former case, the amount of catalyst needs to be 1 mole per 1 mole of product, and since these catalysts are difficult to recover, a large amount of catalyst must be discarded, making it uneconomical. was there. On the other hand, in the latter case, when an acid fluoride is used as the acylating agent, a certain degree of selectivity can be obtained, but when acetic acid is used as the acylating agent, the selectivity for 2-alkyl-6-acylnaphthalene is low. The problem was that it was low.

[Problems to be Solved by the Invention] Under these circumstances, the present invention provides a method for producing 2-alkylnaphthalenes in high yield and in the same way as other acylating agents, even when acetic acid is used as an acylating agent. The purpose of this invention is to provide a method for producing 2-alkyl-6-au/lunaftacin with high selectivity.

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors have achieved the above object by acylating 2-alkylnaphthalene in the presence of a specific catalyst. The present inventors have discovered that it is possible to accomplish the following, and have completed the present invention based on this knowledge.

That is, the present invention reacts 2-alkylnaphthalene and an acylating agent in the presence of a catalyst to form 2-alkyl-6-
This is a method for producing 2-alkyl-6-acylnaphthalene characterized by using trifluoromethanesulfonic acid as a catalyst.

The present invention uses 2-alkylnaphthalene as a raw material. As 2-alkylnaphthalene it is possible to use all naphthalene derivatives which are substituted in the 2-position by an alkyl group or a cycloalkyl group. Specific examples of 2-alkylnaphthalene include 2-methylnaphthalene, 2-ethylnaphthalene, 2-n propylnaphthalene, 2-isopropylnaphthalene, 2-n butylnaphthalene, 2-inbutylnaphthalene, and 2-see butylnaphthalene. , 2-tertbutylnaphthalene, 2-〇pentylnaphthalene, 2-isopentylnaphthalene, 2-amylnaphthalene, 2-n hexylnaphthalene, 2-cyclopentylnaphthalene, 2-cyclohexylnaphthalene, and the like. These 2-alkylnaphthalenes may be used alone or in combination of two or more.

The acylating agent used in the present invention is not particularly limited, and any compound that can be acylated may be used. Examples of the acylating agent include carboxylic acids, acid anhydrides, acid halides, ketenes, and carboxylic acid esters.

Note that acid anhydrides are preferable because they produce less water than carboxylic acids, so a high conversion rate can be obtained with a small amount of catalyst.

Specific examples of the acylating agent include acetic acid, propionic acid, butyric acid, isobutyric acid, acetic anhydride, propionic anhydride, a-acid anhydride, acetyl fluoride, propionyl fluoride, butyl fluoride, phenylpropionyl fluoride, Propionyl fluoride, acetyl chloride, propionyl chloride, butyryl chloride, phenylpropionyl chloride, acetyl bromide, propionyl bromide, acetyl iodide, propionyl iodide, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propion Propyl acid, methyl butyrate, ethyl butyrate, propyl butyrate, etc. can be used. These acylating agents may be used alone or in combination of two or more.

The amount of this acylating agent to be used is usually in the range of 1 to 10 mol, preferably in the range of 1.2 to 2 mol, per 1 mol of the above-mentioned 2-alkylnaphthalene. If the proportion of the acylating agent used is small, the conversion rate of 2-alkylnaphthalene will decrease, and if the proportion of the acylating agent used is too large, the selectivity of 2-alkyl-6-acylnaphthalene will decrease.

In the present invention, the 2-alkylnaphthalene and the acylating agent are reacted in the presence of trifluoromethanesulfonic acid.

The amount of trifluoromethanesulfonic acid used is generally in the range of 2 to 50 mol, preferably in the range of 2 to 20 mol, per 1 mol of 2-alkylnaphthalene. If the amount of trifluoromethanesulfonic acid used is small, the conversion rate of 2-alkylnaphthalene will be reduced, and if the amount of trifluoromethanesulfonic acid used is too large, the catalyst efficiency will be reduced and the heat generation in the product separation step will be increased. growing.

The method of adding the 2-alkylnaphthalene and acylating agent, which are the raw materials of the present invention, and the trifluoromethanesulfonic acid, which is the catalyst of the present invention, is not particularly limited, and various methods and procedures can be used.

In the present invention, the above raw materials are reacted in the presence of the above catalyst.

Conditions for this reaction may be determined as appropriate depending on the type of raw materials and the like.

The reaction temperature is not particularly limited and is usually -20 to
In the range of 100°C, preferably -10 to 80°C
is within the range of If the reaction temperature is too low, the reaction rate will be slow;
If the reaction temperature is too high, polymers will form, which is not preferable.

The reaction time is not particularly limited, and is usually carried out within a range of 10 minutes to 10 hours.

In the present invention, it is not necessary to use a solvent, but it is preferable to use a solvent because the product can be easily separated. Usable solvents include halogenated hydrocarbons such as methylene chloride and carbon tetrachloride, carbon sulfides such as carbon disulfide, aromatic hydrocarbons that are difficult to react with such as benzene, and nitro compounds such as nitrobenzene, nitromethane, nitroethane, and nitropropane. and halogenated aromatic compounds such as chlorobenzene.

The amount of solvent used is usually in the range of 1 to 1009, preferably 5 to 5, per 1 g of 2-alkylnaphthalene.
It is in the range of 09.

In the present invention, 2-
A reaction product containing alkyl-6-acylnaphthalene can be obtained. In this reaction product, 2-alkyl-6-
Since acylnaphthalene forms a complex with trifluoromethanesulfonic acid, it is necessary to decompose this complex in order to extract 2-alkyl-6-acylnaphthalene alone. This complex can usually be decomposed by adding water, ammonia gas, or the like. The amount of water added is usually in the range of 10 to 100 times the weight of the catalyst.

2-alkyl-6 obtained by decomposing the complex
-Acylnaphthalene can be separated and purified by known methods.

When adding water to decompose the above complex, the decomposition yields +
The trifluoromethanesulfonic acid is present as an aqueous solution. This trifluoromethanesulfonic acid can be recovered from the aqueous solution and used as a catalyst in the reaction of the present invention to acylate 2-alkylnaphthalenes.

As a method for recovering trifluoromethanesulfonic acid from an aqueous solution containing trifluoromethanesulfonic acid, for example, the aqueous solution is heated under reduced pressure to remove as much water as possible, and then 100% sulfuric acid or fuming sulfuric acid is added and distilled.
There are methods for obtaining trifluoromethanesulfonic acid.

Thus, the recovered trifluoromethanesulfonic acid can be used as a catalyst in the reactions of the present invention any number of times.

[Examples] Next, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples in any way.

Example 1 5.0 g of 2-methylnaphthalene was dissolved in benzene 409, and 25 g of trifluoromethanesulfonic acid was added. Gradually add 2.5 g of acetic acid while heating the solution to 60°C.
Stirred for 5 hours. The reaction mixture was poured into ice water to decompose the catalyst and products, and the products were analyzed by gas chromatography. The conversion rate was 97%, and the selectivity for 2-methyl-6-acetylnaphthalene was 88%.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that methanesulfonic acid 259 was used as the catalyst, but no acetylated product was observed.

Comparative Example 2 In a 2.00 cc autoclave, 5.0 g of 2-methylnaphthalene, 409 benzene, 2.5 g of acetic acid, H
When F59, BF, and 109 were charged and reacted at 11'O, the conversion rate was 99% and the selectivity of 2-methyl-6-acetylnaphthalene was 25%.

Example 2 500 ml of the trifluoromethanesulfonic acid aqueous solution obtained in Example 1 was heated at 60° C. under reduced pressure to remove moisture. 100% concentrated sulfuric acid was added to the obtained CF, 5O3H-H2O and distilled to 331111H9110~113°C.
239 fractions were obtained. Using this as a catalyst, Example 1
When the reaction was carried out in the same manner as above, the conversion rate was 96% and the selectivity of 2-methyl-6-acetylnaphthalene was 88%.

Example 3 The same reaction as in Example 1 was carried out except that 6.09% of 2-isopropylnaphthalene was used instead of 2-alkylnaphthalene. The conversion rate was 98%, and the selectivity for 2-isopropyl-6-acetylna-7talene was 90%.

Example 4 10.09 g of 2-methylnaphthalene was dissolved in 409 g of benzene, and after cooling to 0° C., 1125 g of trifluoromethanesulfone was added. While maintaining the solution at 0°C, 4.6 g of acetic anhydride was gradually added and stirred for 3 hours. The following analysis was conducted in the same manner as in Example 1, and the conversion rate was 75%.
The selectivity of -methyl-6-acetylnaphthalene was 87%.

[Effects of the Invention] As explained above, according to the configuration of the present invention, 2-alkyl-6-acylnaphthalene can be obtained from 2-alkylnaphthalene with high selectivity and high yield. Furthermore, the catalyst used in the reaction of the present invention can be recovered by a simple method, and the recovered catalyst can be used in the reaction of the present invention any number of times. This is an extremely advantageous method for industrially producing 6-acylnaphthalene. The 2-alkyl-6-acylnaphthalene produced according to the present invention can be used as an intermediate for raw materials for polyester used in magnetic tapes and the like.

Claims (1)

[Claims] 1. A method for producing 2-alkyl-6-acylnaphthalene by reacting 2-alkylnaphthalene and an acylating agent in the presence of a catalyst, characterized in that trifluoromethanesulfonic acid is used as the catalyst. 2-alkyl-
Method for producing 6-acylnaphthalene. 2. The manufacturing method according to claim 1, wherein the acylating agent is acetic acid or acetic anhydride. 3. The manufacturing method according to claim 1, wherein the trifluoromethanesulfonic acid is recovered from a reaction product obtained by reacting a 2-alkylnaphthalene and an acylating agent in the presence of trifluoromethanesulfonic acid.