JPH01197449A - Production of 2,6-diisopropylnaphthalene - Google Patents

Abstract

PURPOSE:To attain high yield in obtaining the title compound by isopropylating naphthalene with propylene or further transalkylation, by efficiently circulating 2,7-diisopropylnaphthalene isomer, mono- and triisopropylnaphthalenes as by- products. CONSTITUTION:A mixture containing 2,7-diisopropylnaphthalene isomer obtained by separating 2,6-diisopropylnaphthalene isomer from a mixture of diisopropylnaphthalene isomers (2,6-diisopropylnaphthalene isomer and 2,7- diisopropylnaphthalene isomer) and naphthalene are transalkylated (A), then to isopropylated (IP) and further transalkylated (B) to give a reaction product, from which a diisopropylnaphthalene fraction is taken out (I) and then 2,6- diisopropylnaphthalene isomer is separated. The 2,7-diisopropylnaphthalene isomer prepared in the separation and a high-boiling fraction prepared as a by-product in the above-mentioned process are circulated to the transalkylation process and at least part of the reaction product of the process A is circulated to at least one process of the process IP, the process B and the process I to give the title compound. The compound is useful as a polyester raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an industrially advantageous method for producing 2,6-diituprobylnaphthalene.

[Prior art]

Conventionally, in order to obtain polyester, terephthalic acid, 2,
It is widely known that 6-naphthalene dicarboxylic acid is subjected to a polymerization reaction with glycol. Polyester obtained from 2,6-naphthalene dicarboxylic acid has superior physical properties such as heat resistance compared to those obtained from terephthalic acid, so 2,6-naphthalene dicarboxylic acid is used industrially as a raw material for polyester. It is desired to establish an advantageous manufacturing method.

2,6-diisopropylnaphthalene can be converted into 2,6-naphthalene dicarboxylic acid by oxidizing it, and is therefore useful as a material for 2,6-naphthalene dicarboxylic acid. Such 2,6-diitubropylnaphthalene is
It can be produced by isopropylating naphthalene with propylene or by further transalkylating the obtained isopropylated product (Japanese Patent Application Laid-Open No. 17452/1983),
In this case, large amounts of diisopropylnaphthalene mixtures containing less than 2,6-diisopropylnaphthalene, monoisopropylnaphthalene, triisopropylnaphthalene, etc. are produced as by-products, and no effective method can be easily found to reduce these by-products. In particular, since it is difficult to isomerize a diisopropylnaphthalene mixture containing less than 2,6-diisopropylnaphthalene, which is an isomer of the target compound, to the target compound, this method is recommended as a high-yield production method for 2,6-diisopropylnaphthalene. was still unsatisfactory.

〔the purpose〕

An object of the present invention is to provide a method for producing 2,6-diisopropylnaphthalene in high yield using naphthalene and propylene as raw materials.

〔composition〕

According to the present invention, a mixture containing 2,7-isomer and naphthalene after separating the 2,6-isomer from a diisopropylnaphthalene isomer mixture fraction containing 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene Transalkylation treatment step (A) in which monoisopropylnaphthalene is produced by transalkylation reaction.
and an isopropylation treatment step (IP) in which monoisopropylnaphthalene or a mixture mainly consisting of monoisopropylnaphthalene and naphthalene is isopropylated with propylene.
, a transalkylation step (B) in which the isopropylated product is transalkylated, and a diisopropylnaphthalene fraction of at least the product of the transalkylation step (B) of each of the transalkylated products. Step 8 (I) of separating into a low boiling point fraction below diisopropylnaphthalene and a high boiling point fraction above triisopropylnaphthalene, and separating the 2,6-isomer contained therein from the separated diisopropylnaphthalene fraction. step (IT), in which the mixture containing the 2,7-isomer after separating the 2,6 monoisomer is recycled to the transalkylation treatment step (A) as a reaction raw material, and the separation step At least a portion of the high boiling point fraction of (1) is recycled to the transalkylation treatment step (B),
and at least a part of the product of the transalkylation treatment step (A) is subjected to the isopropylation treatment step (IP).
), a transalkylation process N (B), and at least one of the separation steps (1).

Next, each step of the present invention will be explained in detail.

[Isopropylation treatment step (IP) 3 In the present invention, when producing 2,6-diisopropylnaphthalene from naphthalene, naphthalene is not directly isopropylated, but is used as a raw material for isopropylation, for example, in 2 and 7 described below. - Monoisopropylnaphthalene or a mixture containing monoisopropylnaphthalene and naphthalene as main components, such as a product obtained by transalkylating a diisopropylnaphthalene mixture containing isomers, or a low-boiling fraction in the separation step (I) described below. isopropylated.

The transalkylated product can be taken directly to the isopropylation process (IP), or a part of it can be taken indirectly to the isopropylation process (IP) as a low-boiling fraction below dialkylnaphthalene through a separation process in advance. You can also send it to

This isopropylation reaction is a conventionally well-known reaction, and is carried out as a liquid phase or gas phase reaction according to a conventionally known method. As catalysts, solid acid catalysts such as silica/alumina, crystalline aluminosilicate, nickel oxide/silica, silver oxide/silica alumina, silica/magnesia, alumina/boria, solid phosphoric acid, aluminum phosphate, zirconium phosphate, etc. Free delta raft catalysts such as aluminum chloride, hydrogen cotton, and phosphoric acid are used. Through this isopropylation reaction, the isopropyl group attached to the naphthalene ring is easily rearranged to another naphthalene ring by a transalkylation reaction in the presence of the catalyst as described above. Therefore, this isopropylation reaction is considered to be a reversible reaction through a transalkylation reaction, and an equilibrium composition exists between naphthalene and isopropylnaphthalenes. The amount of diisopropylnaphthalene produced depends on the ratio of naphthalene nuclei to isopropyl groups in the reaction, temperature, type and amount of catalyst, etc.

When performing the isopropylation reaction using a Friedel-Crafts catalyst, the reaction is carried out at room temperature to 150°C, preferably at 50°C to
Temperature of 100°C, pressure of normal pressure to 10 atmospheres, catalyst to raw material ratio of 0.001 to 0.3, preferably 0.02 to 0.
．． This is done under the following conditions. When using a solid acid catalyst, the reaction temperature is 150 to 500°C, the pressure is O to 501Cg/cXI
G, contact time 0.02-6. Ohr range, preferably temperature 200~350℃, pressure 0~35kg/al
G, contact time ranges from 0.4 to 2.5 hr. When the temperature is high or the contact time is long, a decomposition reaction occurs and by-products are produced. Furthermore, if the temperature is low or the contact time is short, the yield of diisopropylnaphthalene decreases.

This isopropylation process (IP) yields an isopropylation product containing unreacted naphthalene, monoisopropylnaphthalene, diisopropylnaphthalene, triisopropylnaphthalene and higher polyisopropylnaphthalene.

In the present invention, this isopropyl treatment process 8 (I
For P), a low boiling point fraction below monoisopropylnaphthalene obtained in the subsequent separation step of the transalkylation reaction product can be recycled to this isopropylation reaction step and reacted with propylene. When conducting an isopropylation reaction by circulating such a fraction, an isopropylation reaction occurs by the reaction of unreacted naphthalene and monoisopropylnaphthalene constituting the recycled low-boiling fraction with propylene, resulting in diisopropyl Naphthalene is produced.

The molar ratio of isopropyl groups to naphthalene nuclei in the isopropylated product obtained in this isopropylation treatment step (IP) is usually 0.5 to 1.9, preferably 0.7 to 1.
．． The range is 8. This molar ratio can be adjusted by adjusting the reaction time, the rate of introduction of propylene into the isopropylation treatment step (IP), and the like.

[Transalkylation treatment step (B) of isopropylated product]

This transalkylation treatment step (B) is a step in which the isopropylated product obtained above is brought into contact with a transalkylation catalyst and the isopropyl group bonded to a naphthalene nucleus is transferred to another naphthalene nucleus. For example, the reaction between naphthalene or monoisopropylnaphthalene and triisopropylnaphthalene produces diisopropylnaphthalene. Further, in this transalkylation treatment, in addition to the transalkylation reaction, an isomerization reaction of diisopropylnaphthalene also occurs, and the ratio of isomers in diisopropylnaphthalene is maintained at approximately an equilibrium composition.

In the present invention, this transalkylation treatment step (
B) circulates at least a portion of the substance with a higher boiling point than triisopropylnaphthalene obtained in the subsequent separation step (I) to this transalkylation treatment step (B) to transfer isopropyl groups to other naphthalene nuclei. cause a reaction to occur.

The catalyst and reaction conditions used in this transalkylation treatment step (B) are the same as those used in the isopropylation treatment step (I).
Catalysts and reaction conditions similar to those shown in P) are used, but the reaction conditions are generally more severe than the isopropylation reaction treatment conditions.

Moderate reaction temperatures are preferably employed. It is also preferable that the amount of catalyst is greater than that in the isopropylation treatment step (IP). This transalkylation treatment can be carried out in the same reactor as the isopropylation treatment or in a separate reactor. The reaction time is 5 to 300 minutes, preferably 15 to 120 minutes.

In this transalkylation treatment step (B), a part of the low boiling point fraction below diisopropylnaphthalene and/or a part of the high boiling point fraction above triisopropylnaphthalene separated in the separation step (1) described later is recycled. However, in this transalkylation step, if a large amount of polyisopropylnaphthalene (triisopropylnaphthalene or higher) is present in the reaction system, by-products such as isopropyltetralin having structural units other than the isopropyl group and naphthalene nucleus may be produced. generate. Therefore, to suppress these by-products, the molar ratio of isopropyl groups to naphthalene nuclei in the total feed (including the recycled fraction) fed to this transalkylation process step (B) should be 1.9. below,
Preferably, it is defined in the range of 1.0 to 1.8.

If this amount increases, the formation of the above-mentioned by-products becomes significant.

Further, the production of this by-product becomes significant if the reaction time of the transalkylation treatment step (B) becomes longer than necessary.

Therefore, the preferable reaction time is within the range described above. This reaction time, even if it is short, becomes substantially longer due to the circulation of the low boiling point fraction and/or the high boiling point fraction in the separation step (1) of the present invention, so that the formation of by-products is avoided. For the purpose of suppression, it is preferable to limit the circulating fraction to a fraction consisting of an isopropyl group and naphthalene nucleus structure as much as possible. For that purpose, it is effective to further separate the low boiling point fraction and/or the high boiling point fraction in the separation step (1) into a heavy fraction and a heavy fraction, respectively, and to circulate only the heavy fraction.

[2,7-diisopropylnaphthalene and naphthalene 1
- Lance alkylation treatment step (A)] In the present invention, the isomer mixture containing 2,7-diisopropylnaphthalene after separating 2,6-diisopropylnaphthalene from the subsequent diisopropylnaphthalene isomer fraction is separated from naphthalene. to perform a transalkylation reaction. In this case, the naphthalene may be any type of naphthalene produced from petroleum-based or coal-based oil. It can be carried out in the same manner as shown. However, this transalkylation treatment step (A)
Supplying polyisopropylnaphthalene in excess of triisopropylnaphthalene has great disadvantages and should be avoided. This is because diisopropylnaphthalenes such as 2,7-diisopropylnaphthalene undergo transalkylation with polyisopropylnaphthalene when it exists, and the progress of efficient transalkylation with naphthalene is inhibited. In the transalkylation reaction involving polyisopropylene naphthalene, the heavy fraction of the low boiling point fraction and the heavy fraction of the high boiling point fraction to be intensively separated in the latter separation step (1) and extracted from the system. By-products that appear as In this transalkylation treatment step (A), a transalkylation reaction occurs between a diisopropylnaphthalene isomer containing 2,7-diisopropylnaphthalene and naphthalene to produce monoisopropylnaphthalene.

In this transalkylation treatment step (A), at least a portion of diisopropylnaphthalene separated in the subsequent distillation separation step (I) may be recycled and reacted, but the product may be used in the subsequent isopropylation treatment. Process (IP
) to 1 to lance It is necessary to select the raw material so that it becomes a preferable raw material for the alkylation treatment step (B) or the separation step (I). The molar ratio of isopropyl groups to naphthalene nuclei in the total feed for this transalkylation step (A) ranges from 1 (usually from 0.5 to 6), preferably from 0.8 to 1.4.

[Transalkylated product separation step (■)] This step involves the trans-alkylation of the isopropylated product obtained above and/or the mixture containing 2.7-diisopropylnaphthalene and naphthalene. Distilling the alkylated product to obtain a diisopropylnaphthalene fraction and a low boiling fraction below diisopropylnaphthalene;
This is a step of separating the high boiling point fraction from triisopropylnaphthalene or higher. The dipropylnaphthalene fraction separated in this distillation separation step is supplied to the subsequent 2,6-diisopropylnaphthalene separation step (II), and at least a part of the low boiling point fraction is transferred to the transalkylation step. (^) to/and (B) to/and can be recycled to the isopropylation treatment step (IP), preferably to the isopropylation treatment step (IP).

Further, at least a portion of the high boiling point fraction is recycled to the transalkylation treatment step (B). It is also possible to recover a portion of the low boiling point fraction and/or the high boiling point fraction. It is also a preferred embodiment to separate the low boiling point fraction and/or the high boiling point fraction into a heavy fraction and a heavy fraction, and to circulate only each heavy fraction. Furthermore, it is a more preferred embodiment that the heavy fraction of the high boiling point fraction is recycled to the transalkylation treatment step (B), and the heavy fraction of the low boiling fraction is recycled to the isopropylation treatment step (IP).

The diisopropylnaphthalene fraction separated above contains 1,6-isomer, 1.7-isomer, 1.4-isomer, 2,6-isomer, 2,7-isomer, and 1-isomer of diisopropylnaphthalene. , 5-isomer, ■, 3-isomer, 2,3-isomer, especially 2,6-isomer and 2,7-isomer are contained as main components.

[Separation process of 2,6-diisopropylnaphthalene (■)
] This step is a step of separating and recovering the 2,6-isomer from the diisopropylnaphthalene fraction separated in the distillation separation step (1). In this separation process 8 (■), any separation method can be adopted as long as it is a method that can separate the 2,6-isomer from the diisopropylnaphthalene fraction, but - quantitatively, crystallization separation method, Chromatography separation methods etc. are employed. For example, a liquid phase simulated moving bed fractionation method can be used in a chromatographic separation method.

After 2,6-diisopropylnaphthalene has been separated in this separation step (■), the diisopropylnaphthalene isomer mixture containing the 2,7-isomer as a main component is subjected to the transalkylation treatment step (A) using naphthalene. It is recycled and undergoes a transalkylation reaction with naphthalene.

Next, the present invention will be explained in more detail with reference to the drawings. 1st
The figure shows an example of a flow sheet for the method of the present invention.

In FIG. 1, raw naphthalene is fed through line 1 to the transalkylation process (A). Also,
This transalkylation treatment step (A) includes 2, which is separated in the separation step (II) and recycled through line 6;
A mixture containing 7-diisopropylnaphthalene is provided. In this transalkylation step (A), the feeds are transalkylated and the resulting product is sent through line 8 to the isopropylation step (IP).

In this isopropylation treatment step (IP), propylene is supplied through line 2, and is separated in the separation step (1), and light fractions of low-boiling fractions below monoisopropyl naphthalene are passed through line 4. Supplied. In this isopropylation treatment step (IP).

The heavy fraction of the low boiling point fraction and the product of the transalkylation treatment step (A) are isopropylated with propylene, and the obtained isopropylation product is supplied to the transalkylation treatment step (B), where The isopropylated product is separated in the separation step (1) and is subjected to a transalkylation treatment together with the heavy fraction of the high-boiling fraction above triisopropylnaphthalene which is recycled through line 5. The resulting transalkylated product is subjected to a separation step (I
) will be sent to.

In the separation step (1), a transalkylation treatment step (B
) is subjected to distillation treatment and separated into a diisopropylnaphthalene fraction, a low-boiling fraction below the diisopropylnaphthalene fraction, and a high-boiling fraction above triisopropylnaphthalene. The diisopropylnaphthalene fraction is then sent to the separation step (II) through line 3, and the low-boiling point fraction is further separated into a heavy fraction below the mononaphthalene fraction and a heavy fraction in the separation step (I). , the heavy part is line 4
is recycled to the isopropylation treatment step (IP) through
The heavy components are extracted out of the system through line 9.

The high boiling point fraction is further separated into a heavy fraction below the triisopropylnaphthalene fraction and a heavy fraction in the separation step (1), and the heavy fraction passes through line 5 to the transalkylation treatment step (B). It is circulated, and its heavy components are extracted out of the system through line 10.

The diisopropylnaphthalene fraction sent to the separation step (If) is separated into 2,6-isomers and is recovered through line 7. On the other hand, after the 2,6-isomer has been separated, the mixture mainly composed of the 2,7-isomer is in line 6.
and is recycled to the transalkylation treatment step (A).

Note that the flow sheet shown in FIG. 1 can be modified in various ways. For example, the product of the transalkylation treatment step (A) can be supplied to the separation step (1), it can also be supplied to the transalkylation treatment step (B), or the product of the three It is also possible to use a plurality of supply lines at the same time. Also,
A part of the naphthalene supplied from line 1 can be supplied to the isopropylation process (IP) or/and the transalkylation process (B), or it can be separated in one separation process (1). It is possible to feed a portion of the low-boiling fraction to the transalkylation step (A) or/and (B). Furthermore, among the low-boiling fractions separated in the separation step (1), the naphthalene fraction can be sent to the transalkylation treatment step (A), and the monoisopropyl fraction can be sent to the isopropylation treatment step (IP). .

〔effect〕

In the present invention, naphthalene and propylene are used as raw materials, and 2
, 6-line probylnaphthalene can be efficiently produced.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 [Transalkylation step (A)] A mixture having the following component composition was trans-transformed for 1 hour at a reaction temperature of 85° C. and normal pressure in the presence of 0.11 mol of aluminum chloride catalyst per 1 mol of naphthalene nuclei. Alkylation treatment was performed.

Table 1 As a result of the above transalkylation treatment, a reaction product having the following component composition was obtained.

Table 2 [Isopropylation treatment step (IP)] Table 3 For the mixture shown in Table 3, 0.1 per mole of naphthalene nucleus
In the presence of 1 mol of aluminum chloride catalyst, reaction temperature 85
The reaction was carried out at normal pressure by blowing 0.35 mol of propylene per mol of naphthalene nucleus. As a result of this isopropylation treatment, a reaction product having the following component composition was obtained.

Table 4 [Transalkylation step (B)] Table 5 Triisopropylnaphthalene fraction was added to the reaction product obtained in the isopropylation step (IP) to obtain the mixture shown in Table 5. 1 in the presence of 0.11 mol of aluminum chloride catalyst per 1 mol of naphthalene nucleus.
The transalkylation treatment was carried out at a reaction temperature of 85° C. and a normal pressure of 1.0 hours.

As a result of this transalkylation treatment, a reaction product having the following component composition was obtained.

Table 6

[Brief explanation of the drawing]

FIG. 1 shows an example of a flow sheet for carrying out the method of the present invention. IP... Isopropylation treatment step A, B... Transalkylation treatment step 1, n...
Separation process. Applicant's agent Patent attorney Toshiaki Ikeura (and 1 other person)

Claims (3)

[Claims] (1) 2,6-diisopropylnaphthalene and 2,7-
A transalkylation treatment in which a 2,6-isomer is separated from a diisopropylnaphthalene isomer mixture fraction containing diisopropylnaphthalene, and a mixture containing a 2,7-isomer is subjected to a transalkylation reaction with naphthalene to produce monoisopropylnaphthalene. Step (A), an isopropylation treatment step (IP) in which monoisopropylnaphthalene or a mixture mainly consisting of monoisopropylnaphthalene and naphthalene is isopropylated with propylene, and a transalkylation treatment in which the isopropylation product is transalkylated. Step (B), and at least the product of the transalkylation treatment step (B) of each of the above-mentioned transalkylation products is divided into a diisopropylnaphthalene fraction, a low boiling point fraction below diisopropylnaphthalene, and a high boiling point fraction above triisopropylnaphthalene. The process of separating into distillate (
I) and step (II) of separating the 2,6-isomer contained therein from the separated diisopropylnaphthalene fraction.
After separating the 2,6-isomer, the mixture containing the 2,7-isomer is subjected to the transalkylation step (
At least a part of the high boiling point fraction of the separation step (I) is recycled to the transalkylation step (B) as a raw material for the reaction; 2,6- characterized in that at least a part of the product of ) is recycled to at least one of the isopropylation treatment step (IP), the transalkylation treatment step (B) and the separation step (I).
Method for producing diisopropylnaphthalene. (2) At least a portion of the low boiling point fraction separated in the separation step (I) is transferred to at least one of the transalkylation treatment step (A), the transalkylation treatment step (B), and the isopropylation treatment step (IP). 2. A method according to claim 1, characterized in that the process is repeated in two steps. (3) The low-boiling fraction and the high-boiling fraction separated in the separation step (I) are further separated into a light fraction and a heavy fraction, respectively, and the light fraction of the high-boiling fraction is subjected to the transalkylation. The process according to claim 1, characterized in that the light fraction of the low-boiling fraction is recycled to the isopropylation treatment step (IP).