JPH0447654B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 1-acetylnaphthalene by acetylating naphthalene. 1-Acetylnaphthalene is an important chemical as a precursor of α-(1-naphthyl)ethylamine, which is often used as an optical resolution agent. It is desired to develop a new manufacturing method. So far, naphthalene has been acetylated and 1-
The following methods are known as methods for obtaining substituted products as main products. (1) A solution of equimolar acetyl chloride and aluminum chloride dissolved in ethylene dichloride is added to a solution of naphthalene in ethylene dichloride at 35°C to perform an acetylation reaction,
Treat the reaction product solution with dilute hydrochloric acid (F.Chem.
Soc., 99 (1949). (2) To a solution of equimolar acetyl chloride and aluminum chloride dissolved in ethylene dichloride, naphthalene is dissolved in ethylene dichloride, and the solution is added at 30°C to perform an acetylation reaction, and the reaction product solution is treated with dilute hydrochloric acid. (Chem.Abstr.,
47, 3286d (1953)). It is stated that these methods achieve a conversion rate of 88 to 93% to acetylnaphthalene and a selectivity of 1-substituted product of 98%, but in both methods, calculation of the selectivity of 1-substituted product is The reliability is not high because it relies on the method of inducing a substance into picrate and estimating its melting point. By the way, when the inventors retried methods (1) and (2) and recalculated the 1-substituted selectivity using gas chromatography, they found that both methods (1) and (2) showed 1-substituent selectivity. The substitution selectivity was only about 92%. However, when 1-acetylnaphthalene is used as a precursor for an optical resolution agent, it is required to have a purity of about 97% or higher, and in this case, the 2-substituted product must be removed from 1-acetylnaphthalene by distillation or the like. Since it is extremely difficult to achieve this, it is necessary to reliably achieve a 1-substituted selectivity of approximately 97% or higher in the acetylation of naphthalene. Therefore, the present inventors conducted extensive studies on a method for achieving a 1-substituted product selectivity of 97% or more in the acetylation of naphthalene, and determined the quantitative ratio of aluminum chloride and acetyl chloride, the mixing method of the reactants, the reaction temperature, and the reaction temperature. The inventors have discovered that this object can be achieved only when the conditions such as temperature when treating the product with dilute hydrochloric acid are specified, and have arrived at the present invention. That is, the present invention provides a method for producing 1-acetylnaphthalene by acetylating naphthalene with acetyl chloride using an aluminum chloride catalyst in a chlorinated hydrocarbon solvent, in which acetyl chloride, 1.0 to 1.2 times the mole of chloride relative to acetyl chloride, is used. A solution of approximately equimolar naphthalene as acetyl chloride dissolved in a chlorinated hydrocarbon solvent is added to an acetylation reaction solution consisting of aluminum and a chlorinated hydrocarbon solvent at a temperature of 10°C or less, and the temperature of the mixture with the acetylation reaction solution is
Acetylnaphthalene produced by the acetylation reaction is carried out by gradually adding and mixing while cooling to maintain the temperature below 10°C, and then bringing the reaction product into contact with dilute hydrochloric acid at below 10°C. This is a method for producing 1-acetylnaphthalene, which is characterized by decomposing an aluminum chloride complex to liberate acetylnaphthalene. The method of the present invention will be specifically explained below. As the chlorinated hydrocarbons used as the solvent in the present invention, chlorinated products of lower saturated aliphatic hydrocarbons such as dichlorinated ethane, trichlorinated ethane, tetrachlorinated ethane, and dichlorinated methane can be used. Ethylene dichloride, which has a high ability to dissolve the acetyl chloride-aluminum chloride complex, is a particularly preferred solvent.
The amount of chlorinated hydrocarbon solvent to be used is approximately 2.5 to 5 times the weight of aluminum chloride as a solvent for dissolving aluminum chloride and acetyl chloride, and approximately 2.5 to 5 times the weight of naphthalene as a solvent for dissolving naphthalene. It is preferable to use about 2.5 to 5 times the amount by weight. As the acetylating agent, acetyl chloride is used in an approximately equal molar ratio to naphthalene. As a catalyst, anhydrous aluminum chloride is used in moles of 1.0 to 1.2 times the amount of acetyl chloride. When the amount of aluminum chloride used is less than 1.0 mole times, both the yield of acetylnaphthalene and the selectivity of 1-substituted product decrease. On the other hand, when the amount of aluminum chloride used increases by 1.2 moles or more, high-boiling point by-products tend to increase, and the required amount of dilute hydrochloric acid and the amount of heat removed in the dilute hydrochloric acid treatment performed to decompose the complex after the acetylation reaction become unreasonable. This is not preferable because it increases the catalyst cost. In the present invention, an acetylation reaction solution is prepared by dissolving the above amounts of aluminum chloride and acetyl chloride in a chlorinated hydrocarbon solvent and maintaining the temperature at 10°C or lower, preferably from 0 to 5°C. On the other hand, a solution of naphthalene dissolved in the above-mentioned chlorinated hydrocarbon solvent is prepared, and the acetylation reaction of naphthalene is carried out by slowly adding and mixing the solution to the above-mentioned acetylation reaction solution over a period of about 0.5 to 2 hours. The acetylation reaction mixture is then cooled so that the reaction temperature is maintained below 10°C, preferably in the range of 0 to 5°C. If the reaction temperature exceeds 10°C, the selectivity of 1-acetylnaphthalene will decrease, which is not preferable. Note that when the reaction temperature becomes extremely low, such as 0° C. or lower, the reaction liquid becomes a highly viscous slurry, which may make stirring difficult. Since the rate of the acetylation reaction is fast, the conversion to acetylnaphthalene is almost complete when the addition of naphthalene is completed, but stirring is continued for several minutes to an hour after the addition is completed to complete the acetylation reaction. This is also a preferred embodiment of the present invention. Note that if a solution in which aluminum chloride and acetyl chloride are dissolved in a chlorinated hydrocarbon solvent is added to a solution in which naphthalene is dissolved in a chlorinated hydrocarbon solvent, the selectivity of 1-acetylnaphthalene tends to decrease. Undesirable. In the reaction product solution after the acetylation reaction, acetylnaphthalene forms a complex with aluminum chloride.Next, the reaction product solution is brought into contact with dilute hydrochloric acid at 10℃ or below to decompose the complex and acetylnaphthalene is released. Release. It is preferable to use dilute hydrochloric acid at a concentration of about 3 to 10%, about 5 to 25 times the weight of aluminum chloride. In this case, it is necessary to ensure that the temperature of the mixture of the reaction product liquid and dilute hydrochloric acid does not exceed 10°C, and the reaction product liquid is gradually added to the cooled dilute hydrochloric acid. If the temperature of the mixture rises to 10℃ or more before the decomposition of the complex is completed,
The selectivity of 1-acetylnaphthalene tends to decrease. After the complex has been decomposed, the mixed liquid is separated to collect the oil layer, thoroughly washed with water, and then distilled to recover the chlorinated hydrocarbon solvent, and then the residue is distilled under reduced pressure to obtain 1-acetylnaphthalene. Let go. The purity of the 1-acetylnaphthalene thus obtained is 97% or more, and the amount of 2-acetylnaphthalene mixed in is only 3% or less. By the method of the present invention detailed above, it has become possible to economically produce highly pure 1-acetylnaphthalene by acetylating naphthalene. The present invention will be specifically described below with reference to Examples. Example 1 18.4 g (0.138 mol) of aluminum chloride and 10.5 g of acetyl chloride are placed in a 200 ml four-necked flask equipped with a stirrer, thermometer, gas outlet, and dropping funnel.
(0.134 mol) and 50 ml of ethylene chloride were mixed and dissolved, and then cooled to 0°C to prepare an acetylation reaction solution. On the other hand, a solution of 16 g (0.125 mol) of naphthalene dissolved in 50 ml of ethylene chloride was added to the acetylation reaction solution and mixed over 1 hour. At this time, the reaction mixture was cooled so that the temperature was maintained at 0 to 5°C. After the addition was completed, stirring was continued for another 30 minutes, and then the reaction product solution was gradually added to 300 g of 6% aqueous hydrochloric acid solution. At this time, the temperature of the mixed liquid is 0 to 10℃.
so that it is kept at After collecting the lower oil layer and thoroughly washing it with water, the composition was analyzed by gas chromatography and found to contain 19.4 g of 1-acetylnaphthalene and 0.6 g of 2-acetylnaphthalene. (Acetylnaphthalene reaction yield 94.1%, 1-acetylnaphthalene selectivity 97.1%). Collect ethylene chloride with an evaporator,
The residue was then distilled under reduced pressure to obtain 17.5 g of 1-acetylnaphthalene (purity 97.7%). Comparative Example 1 In Example 1, when adding and mixing naphthalene to the acetylation reaction solution, the temperature was increased to 25 to 30°C, and 18.9 g of 1-acetylnaphthalene and 2-acetylnaphthalene were found in the resulting oil layer. 1.6g
Contains 1-acetylnaphthalene selectivity of 92.1
%. Comparative Example 2 In Example 1, when the reaction product liquid was added to a 6% aqueous hydrochloric acid solution, the temperature of the mixed liquid was raised to 15 to 25°C, and the resulting oil layer contained 19.2 g of 1-acetylnaphthalene and 2 -Acetylnaphthalene 1.6g
Contains 1-acetylnaphthalene selectivity of 92.3
%. Comparative Example 3 In Example 1, when the amount of aluminum chloride used was reduced to 17.5 g (0.131 mol) and the same reaction was carried out, 18.3 g of 1-acetylnaphthalene and 1.0 g of 2-acetylnaphthalene were found in the obtained oil layer. contained, the acetylnaphthalene yield decreased to 90.8%, and the 1-acetylnaphthalene selectivity decreased to 94.8%. Comparative Example 4 In Example 1, when a solution of aluminum chloride and acetyl chloride dissolved in ethylene chloride was added to a solution of naphthalene dissolved in ethylene chloride, a reaction was carried out, and 14.8% of 1-acetylnaphthalene was found in the oil layer. g and 4.1 g of 2-acetylnaphthalene were contained, the acetylnaphthalene reaction yield was 88.9%, and the 1-acetylnaphthalene selectivity was reduced to 78.3%.

Claims (1)

[Claims] 1 In a method for producing 1-acetylnaphthalene by acetylating naphthalene with acetyl chloride using an aluminum chloride catalyst in a chlorinated hydrocarbon solvent,
Add a solution of acetyl chloride and approximately the same mole of naphthalene dissolved in a chlorinated hydrocarbon solvent to an acetylation reaction solution of 1.0 to 1.2 moles of aluminum chloride and a chlorinated hydrocarbon solvent at 10°C or lower. The acetylation reaction is carried out by gradually adding and mixing the mixture while cooling it so that the temperature of the mixture is kept below 10℃, and then the reaction product is brought into contact with dilute hydrochloric acid at a temperature below 10℃ to perform acetylation. 1. A method for producing 1-acetylnaphthalene, which comprises decomposing an acetylnaphthalene-aluminum chloride complex produced in the reaction to liberate acetylnaphthalene.