KR0144346B1 - Process for production of sec-butylbenzene - Google Patents

Abstract

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Description

Process for the preparation of secondary-butylbenzene

The present invention relates to a process for preparing secondary-butylbenzene from benzene and n-butenes.

Secondary-butylbenzene prepared by the present invention is particularly useful for use as starting material for the preparation of phenol and methyl ethyl ketone through each stage of air oxidation and decomposition. Phenol can be used as a starting material for the preparation of synthetic resins and antioxidants, and methylethyl ketone can be used for solvents or dewaxing of lubricating oils.

The use of liquid aluminum chloride complex catalysts in the preparation of secondary-butylbenzene from benzene and n-butene is now known. For example, JP-A-50-137933 (term JP-A means Japanese Patent Application, published unexamined herein) refers to a liquid aluminum chloride complex catalyst in which the amount of aluminum chloride Described is a method used in an amount of 0.05 to 0.25% by weight on the basis of.

In the preparation of secondary-butylbenzene from benzene and n-butene by alkylation, the products are mainly secondary-butylbenzene (SBB), isobutylbenzene (IBB), dibutylbenzene (DSBB) and tributylbenzene (TSBB). ) It is a mixture containing.

Of these compounds, dibutylbenzene and tributylbenzene are separated from the reaction mixture, respectively, and then subjected to alkyl-exchange reaction with secondary-butylbenzene. This reaction can be described as follows:

The boiling points of isobutylbenzene and secondary-butylbenzene are approximate to each other at 172.8 ° C and 173.5 ° C, respectively. Therefore, it is difficult to separate these two compounds from each other by distillation. The isobutylbenzene produced as a by-product during the reaction is sent to the air oxidation stage with secondary-butylbenzene by itself. However, it was found that when the secondary-butylbenzene contains isobutylbenzene, the reaction rate is significantly reduced during the air oxidation step (JP-A-48-80524). For example, when secondary-butylbenzene contains 1% by weight of isobutylbenzene, the oxidation rate of secondary-butylbenzene is about 91 when secondary-butylbenzene contains no isobutylbenzene at all. Decreases in% Similarly, when the content of isobutylbenzene is 1.65% by weight, the oxidation rate is reduced to about 86%; when the content of isobutylbenzene is 2% by weight, the oxidation rate is reduced to about 84%: isobutylbenzene When the content of is 3.5% by weight, the oxidation rate is reduced to about 82%.

Thus, in order to efficiently pass through the air oxidation step, the use of secondary-butylbenzene in which the isobutylbenzene content is reduced as much as possible is necessary. For this reason, it is necessary to minimize the amount of isobutylbenzene produced as a byproduct in the preparation of secondary-butylbenzene from benzene and n-butene.

However, in the conventional alkylation method, since the reaction is performed in a low concentration aluminum chloride catalyst, the reaction must be kept at a high temperature to sufficiently proceed with the reaction. In this case, the amount of isobutylbenzene produced as a by-product reaches 1 to 4% by weight of the produced secondary-butylbenzene, and a problem arises in that a large amount of isobutylbenzene is inevitably supplied to the air oxidation step.

The present invention has been made to solve the above problems, and an object of the present invention is therefore to provide a method for producing secondary-butylbenzene in high yield while keeping the amount of isobutylbenzene produced as a byproduct at low concentrations.

It has now been found that this object is achieved by optimizing the amount of catalyst and the reaction temperature.

The present invention relates to a process for preparing secondary-butylbenzene from benzene and n-butene in the presence of a liquid aluminum chloride complex catalyst, wherein the amount of aluminum chloride used as a component of the complex catalyst is based on the weight of benzene to be used during the reaction. 0.3 to 5% by weight, the reaction temperature is 20 to 90 ℃, the amount of isobutylbenzene produced as a by-product is adjusted to be 1% by weight or less of the secondary-butylbenzene produced.

The liquid aluminum chloride complex catalyst (hereinafter referred to as the complex catalyst) used in the present invention refers to a homogeneous complex catalyst comprising aluminum chloride, hydrogen chloride and aromatic hydrocarbons. As aromatic hydrocarbons, secondary-butylbenzene, ethylbenzene, di-tert-butylbenzene and tri-tert-butylbenzene can be used alone or in mixture of two or more. Of these, secondary-butyl benzene is most suitable.

Regarding the relative amounts of aluminum chloride, hydrogen chloride and aromatic hydrocarbons, hydrogen chloride and aromatic hydrocarbons are used in amounts of about 1 mole and 2 to 10 moles per mole of aluminum chloride, respectively.

In the preparation of the complex catalyst, it is sufficient for the components to be mixed and stirred in a homogeneous solution. This is accomplished by stirring at room temperature for about 20 minutes to 3 hours. The complex catalyst thus prepared can be used as such during the reaction of benzene and n-butene.

Once used during the reaction, the complex catalyst can be separated from the reaction mixture and reused in the reaction.

N-butenes to be used in the present invention include 1-butene, cis-2-butene and trans-2-butene. It is also possible to use mixtures of these compounds, and mixtures of compounds (eg butane) which are inert to the reaction with n-butene.

In the production of secondary-butylbenzene from benzene and n-butene according to the process of the invention, benzene, n-butene and the complex catalyst are mixed and stirred.

The amount of n-butene used is preferably 0.1 to 1.2 moles, more preferably 0.4 to 1.1 moles per mole of benzene. If the amount of n-butene used is too small, the volumetric efficiency of the reaction decreases and the cost of separating secondary-butylbenzene from the reaction mixture increases. On the other hand, if the amount of n-butene used is too high, by-products of alkylbenzenes having two or more butyl groups undesirably increase.

Regarding the amount of complex catalyst used, the amount of aluminum chloride in the complex catalyst is 0.3 to 5% by weight, more preferably 0.3 to 1% by weight, based on the amount of benzene used in the reaction. The amount of complex catalyst used is less than the range defined above. This reaction should be carried out at elevated temperature to allow the reaction to proceed sufficiently. In this case, the production of isobutylbenzene, an undesirable byproduct, increases. On the other hand, if the amount of complex catalyst used exceeds the above defined range, the catalyst cost undesirably increases. Also in this case the production of isobutylbenzene, an undesirable byproduct, increases.

Reaction temperature is 20-90 degreeC, Preferably it is 20-70 degreeC. If the reaction temperature is higher than this range, the production of isobutylbenzene increases. On the other hand, when the reaction temperature is lower than the above defined range, the reaction for the production of secondary-butylbenzene does not proceed completely. In this case, increasing the amount of catalyst used to fully advance the reaction leads to an undesirably increased production of isobutylbenzene.

The most prominent feature of the present invention is its success in the most suitable combination of relatively low reaction temperature and relatively large amount of catalyst compared to reaction temperature and amount of catalyst in the conventional art, and suppresses the formation of undesirable by-products. As well as to complete the desired reaction.

The reaction pressure is not important.

The amount of isobutylbenzene produced as a by-product in the reaction mixture obtained by the present invention can be maintained at less than 1% by weight, preferably less than 0.8% by weight of the resulting secondary-butylbenzene. The significance of keeping the ratio of isobutylbenzene to the resulting secondary-butylbenzene at a low level is as described below.

The reaction can be carried out batchwise or continuously.

In the present invention, the separation and recovery of the secondary-butylbenzene from the reaction mixture obtained by the reaction of benzene and n-butene can be carried out by conventional techniques. For example, after separating the complex catalyst from the reaction mixture by a liquid-separation operation, or without separating the complex catalyst from the reaction mixture, the reaction mixture is washed with water to deactivate the complex catalyst. After removing the inactivated complex catalyst, the residue is further washed with an aqueous sodium hydroxide solution to completely remove the complex catalyst and then separated into an oil layer and an aqueous layer. The oil layer thus obtained is then taken into fractions containing mainly secondary-butylbenzene, fractions containing mainly dibutylbenzene and tributylbenzene, fractions containing mainly heavy material and fractions containing mainly unreacted benzene. Distill. Thereafter, if necessary, the fractions containing dibutylbenzene and tributylbenzene are recycled to the abovementioned alkyl exchange groups in which they are converted to secondary-butylbenzene. Unreacted benzene is returned to the stage where secondary-butylbenzene is prepared from benzene and n-butene.

It is also preferable to return the fraction containing mainly dibutylbenzene and tributylbenzene back to the reaction zone of benzene and n-butene together with the separated benzene.

After completion of the reaction, it is also preferred that the complex catalyst used during the reaction is separated and recovered from the reaction mixture by a liquid-separation operation, and the complex catalyst thus separated is recycled to the reaction zone of benzene and n-butene.

Secondary-butylbenzene obtained by the process of the present invention can be suitably used as a starting material for the production of phenol. For the production of phenol from secondary-butylbenzene, for example, see JP-A-. 48-80524. That is, secondary-butylbenzene is oxidized to secondary-jutylbenzene hydroperoxide at about 75 to 140 ° C. The secondary-butylbenzene hydroperoxide is then concentrated and broken down with an acid catalyst to produce phenol and methyl ethyl ketone.

According to the invention, as described above, there is provided a process for the preparation of secondary-butylbenzene from benzene and n-butene, which maintains the ratio of isobutylbenzene to the secondary-butylbenzene produced at a low level. And the degree of reaction can be sufficiently increased.

Although the present invention is described in more detail with reference to the following examples, the present invention is not limited thereto.

Example 1

61.64 g of secondary-butylbenzene and 26.79 g of aluminum chloride are placed in a 200 ml three-necked flask equipped with a stirrer and a gas inlet tube. Through the gas inlet tube, the hydrogen chloride gas is blown over 2 hours with stirring. Over time, aluminum chloride is dissolved in secondary-butylbenzene and a liquid aluminum chloride complex catalyst (95 g, aluminum chloride concentration: 28% by weight) is obtained as a homogeneous solution.

Separately, 78 g (1 mol) of benzene and 1.43 g (3.0 mmol) of the complex catalyst are placed in a 200 ml three-necked flask containing a stirrer and a gas inlet tube. While controlling the flow rate with a mass flow controller, 1-butene is blown with stirring through the gas inlet tube over 1 hour at a rate of 1 mole per hour. The flask is then cooled on a water bath and the reaction temperature is adjusted to 36 ° C. After completion of the reaction, the reaction mixture is cooled to room temperature, half is taken out of the flask and washed with 30 g of 30% by weight aqueous sodium hydroxide solution to inactivate the catalyst, and then the liquid is separated. The reaction mixture is then analyzed by gas chromatography under the conditions shown below to determine the composition. The results are shown in Table 2. Analysis condition

Column: DB-1 capillary column, 60m

Temperature: Hold at 100 ° C. for 10 minutes and raise from 100 ° C. to 200 ° C. at a rate of 10 ° C. per minute.

[Examples 2 to 5]

The method of Example 1 is repeated with varying amounts of complex catalyst and reaction temperature as shown in Table 2. The results are shown in Table 2.

Example 6

The amount of the complex catalyst and the reaction temperature were varied as shown in Table 2, and the method of Example 1 was repeated except using the mixed butenes shown in Table 1 instead of 1-butene. The results are shown in Table 2.

The total amount of 1-butene, cis-2-butene and trans-2butene used is 1 mole.

Comparative Examples 1 and 2

The method of Example 1 is repeated except changing the amount of complex catalyst and the reaction temperature as shown in Table 2.

The results are shown in Table 2.

Example 7

78 g (1 mol) of benzene and 1.43 g (3.0 mmol) of the same complex catalyst as used in Example 1 are placed in a 200 ml eluent three-necked flask equipped with a stirrer and a gas inlet tube. Stir under atmospheric pressure and blow the 1-butene at a rate of 0.67 moles per hour over 1 hour at a reaction temperature of 50 ° C. through a gas inlet tube while controlling the flow rate with a mass flow controller. After blowing is complete, stirring is carried out at 50 ° C. over 30 minutes. After the reaction was completed, the reaction mixture was cooled to room temperature, taken out of the flask, washed with 30 g of 30% by weight aqueous sodium hydroxide solution to inactivate the catalyst, and then separated. The composition of the reaction mixture is analyzed by gas chromatography. The results are shown in Table 2.

Example 8

The reaction is carried out as follows, assuming that dibutylbenzene separated from the reaction mixture is recycled.

339.0 g (4.34 mole) benzene, 50.6 g (0.27) di-tert-butylbenzene and 6.59 g (0.0138 mole) complex catalyst are placed in a 1 L three-necked flask equipped with a stirrer and gas inlet tube. While stirring under atmospheric pressure, 1-butene is blown through a gas inlet tube at a flow rate of 1.81 moles per hour at a reaction temperature of 66 ° C. for 1 hour. After blowing is complete, stirring is carried out at 66 ° C. for 4 hours. After the reaction is complete, it is post-treated and analyzed in the same manner as in Example 1.

Composition of reaction mixture

Benzene: 39.81 wt%: SBB: 47.28 wt%: IBB 0.39 wt%

DSBB: 10.76% by weight: TSBB: 0.53% by weight

Benzene conversion rate: 41.6%

SBB selectivity =

IBB / SBB = 0.0083

TBB / SBB = 0

In all embodiments where the reaction is carried out with complexes, amounts of catalyst and reaction temperatures defined in the present invention, the reaction proceeds sufficiently (benzene conversion is high) and the undesirable by-product isobutylbenzene is less present and therefore The object is fully achieved.

On the other hand, in Comparative Example 1, where the amount of the complex catalyst is less than the range defined in the present invention, the reaction proceeds insufficiently. (Low benzene conversion is low) In addition, in Comparative Example 2 in which the amount of the complex catalyst is greater than or equal to the range defined in the present invention, isobutylbenzene, which is an undesirable by-product, is produced significantly.

(1) SBB: Secondary-Butylbenzene

(2) IBB: Isobutylbenzene

(3) TBB: tert-butylbenzene

(4) DSBB: Dibutylbenzene

(5) TSBB: tributylbenzene

(6) Benzene Conversion = Reacted Benzene (mol) / Benzene Used (mol) x 100

(7) SBB selectivity = generated SBB (mol) / reacted benzene (mol) × 100

While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope thereof.

Claims (9)

Produced as a byproduct at a reaction temperature of 20 to 90 ° C. in the presence of a liquid aluminum chloride complex catalyst, wherein the amount of aluminum chloride used as component of the complex catalyst is 0.3 to 5% by weight based on the weight of benzene used. A process for producing secondary-butylbenzene from benzene and n-butene, such that the weight ratio of isobutylbenzene to secondary-butylbenzene produced is not greater than 0.01: 1. The process according to claim 1, wherein the amount of aluminum chloride used as a component of the complex catalyst is 0.3 to 1% by weight based on the weight of benzene used. The process of claim 1 wherein the molar ratio of benzene to n-butene to be reacted is from 1: 0.1 to 1: 1.2. The process of claim 3 wherein the molar ratio of benzene to n-butene to be reacted is from 1: 0.1 to 1: 1.1. The reaction mixture obtained by reacting benzene with n-butene is a fraction mainly containing benzene, a fraction mainly containing secondary-butylbenzene, and a fraction mainly containing dibutylbenzene and tributylbenzene. And separating into a fraction containing mainly heavy material and recycling the fraction containing mainly benzene and the fraction containing mainly dibutylbenzene and tributylbenzene into the reaction zone of benzene and n-butene. 2. Process according to claim 1, wherein the secondary-butylbenzene obtained is secondary-butylbenzene used as starting material for the preparation of phenol. The process according to claim 1, wherein the reaction temperature is 20 to 70 ° C. The process of claim 1 wherein the complex catalyst is a homogeneous complex catalyst comprising aluminum chloride, hydrogen chloride and aromatic hydrocarbons. The process of claim 1 wherein the amount of isobutyl benzene produced as a by-product is such that the weight ratio of resulting isobutylbenzene to secondary-butylbenzene is no greater than 0.008: 1.