KR101051762B1 - Method for preparing high yield 5-ortho-tolinepentene - Google Patents

Abstract

The present invention relates to a method for producing 5-ortho-tolyl pentene by alkenylation of ortho-xylene with 1,3-butadiene, and to prevent organic fouling by 1,3-butadiene in order to prevent diethyl hydroxylamine. It is charged to this reactant and an alkali metal catalyst is used as a reaction catalyst.

When 5-ortho-tolylpentene is prepared according to the present invention, it is possible to prevent the formation of popcorn-type polymer by 1,3-butadiene polymerization to prevent clogging in the process reaction and to minimize the amount of alkali metal catalyst used in the process equipment. Can reduce the corrosion rate.

Alkenylation Reaction, Ortho-Xylene, 1,3-Butadiene, 5-Ortho-Tolyl-Pentene, Polymerization Agent, Alkali Metal

Description

Method for producing 5-ortho-tolylpentene {High yield}

In the present invention, 5-ortho-tolyl-pentene (hereinafter referred to as '5-OTP') is prepared by alkenylating 1,3-butadiene and ortho-xylene together with an alkali metal catalyst. It is about a method. More specifically, in order to suppress the polymerization of 1,3-butadiene during the reaction, a polymerization inhibitor is added to increase the efficiency of the alkenylation reaction, and the production of 5-OTP which can suppress the corrosion of the process equipment by using an acidic solution. It is about a method.

5-OTP is an intermediate raw material for the production of polyethylenenaphthalate, and 1,5-dimethyltetraline (hereinafter referred to as '1,5-DMT') through cyclization. It can be prepared as). Thus prepared 1,5-DMT can be converted to 1,5-dimethylnaphthalene (1,5-dimetylenaphthalene, hereinafter referred to as '1,5-DMN') through dehydrogenation, 1, 5-DMN is converted to 2,6-dimethylnaphthalene (2,6-DMN) through isomerization, and oxidized to 2,6-naphthalenedicarboxylic acid (2, 6-naphthalene dicarboxylic acid) is produced.

The process for preparing 5-OTP by alkenylating ortho-xylene and 1,3-butadiene, which is an early stage of the polyethylene naphthalate manufacturing process, is known (US Pat. No. 3,244,758). US Pat. No. 3,766,288, US Pat. No. 3,953,535, and US Pat. No. 3,904,702). The above technique suggests an alkali metal as an alkenylation catalyst, and mainly suggests sodium (Na), potassium (K), or sodium / potassium (NaK) mixture.

Prior art regarding the method of heat treating the catalyst (Japanese Patent Laid-Open Publication No. 1972-027929, Japanese Patent Laid-Open Publication No. 1972-031935), the degree of dispersion of the catalyst through the sonication of the catalyst in the alkylation reaction of alkyl aromatics, process reaction rate And techniques for increasing selectivity (US Pat. No. 5,198,594). There is also a prior document suggesting a technique that can increase the selectivity of the alkylation reaction by addition of amine without sonication (US Pat. No. 5,334,796).

However, the prior art documents do not disclose a technique for preventing the process reaction efficiency decrease due to fouling generated by the polymerization of 1,3-butadiene, and only high alkali 5-ortho-tolyl is presented due to the application conditions of the alkali metal catalyst. Insufficient contents in the production of pentene.

Since 1,3-butadiene, which is a raw material for various rubbers and synthetic resins in the mixed C4 fraction, is an unsaturated hydrocarbon, it can be easily polymerized and causes organic fouling in the process even during normal operation. The fouling caused by the polymerization of 1,3-butadiene is an organic fouling in which a popcorn polymer is produced by free radicals, and is promoted by oxygen in the process. The fouling produced by polymerization in the process is to block the process line (line) to reduce the reaction efficiency, and also affect the final high purity 2,6-dimethylnaphthalene production. In addition, organic fouling causes a decrease in the alkenylation reaction efficiency, which increases the amount of alkali metal catalyst used. Accordingly, the amount of acidic solution used to remove the metal catalyst at the end of the alkenylation reaction also increases, thereby reducing the corrosion rate of the process equipment. There is an increasing problem.

The present invention improves the reaction efficiency by suppressing fouling caused by 1,3-butadiene used in the alkenylation reaction, and minimizes the amount of alkali metal catalyst, thereby reducing the amount of acidic solution used to remove the metal catalyst. The purpose is to prevent corrosion by

According to a preferred embodiment of the present invention, the method for preparing 5-OTP is made by reacting ortho-xylene with 1,3-butadiene, wherein diethyl hydroxyl is used to prevent organic fouling by 1,3-butadiene. An amine is added to the reactant, and an alkali metal catalyst is used as the reaction catalyst.

According to another suitable embodiment of the present invention, the method for preparing 5-OTP is wherein diethyl hydroxylamine is introduced at 50 to 80 ppm relative to the total weight of ortho-xylene and 1,3-butadiene, and Li, Na, K At least one alkali metal catalyst selected from the group consisting of Rb, and Sc may be used at 50 to 100 ppm relative to the total weight of ortho-xylene and 1,3-butadiene.

According to another suitable embodiment of the present invention, the method for preparing 5-OTP may be recovered after completion of the reaction and reused in the reactant.

When 5-OTP is prepared according to the present invention, the formation of popcorn polymer due to the polymerization of 1,3-butadiene is suppressed, so that clogging in the process reaction occurs less. In addition, the 5-OTP manufacturing method of the present invention can reduce the amount of acidic solution to remove the metal catalyst by minimizing the amount of alkali metal catalyst, thereby reducing the corrosion rate by acid in the process equipment to improve the alkenylation reaction efficiency of the first half. Has an advantageous effect.

5-OTP production method of the present invention is made by reacting ortho-xylene with 1,3-butadiene. At this time, the polymerization inhibitor is added to the reactants to suppress fouling of the organic material by 1,3-butadiene, thereby increasing the efficiency of the alkenylation reaction and minimizing the amount of the alkali metal catalyst to suppress corrosion of the process equipment.

The reaction of ortho-xylene with 1,3-butadiene is a commonly known electrophilic substitution reaction between benzene substituents and dienes. However, under normal process conditions, the polymer can be polymerized with 1,3-butadiene itself, which may cause organic fouling problems. In the present invention, diethyl hydroxylamine is added to the reactant as a polymerization inhibitor to inhibit polymerization between 1,3-butadiene. Diethyl hydroxylamine is a compound of molecular formula (C ₂ H ₅ ) ₂ NOH which is widely used as a deoxidizer in boiler water and petrochemical processes in the chemical industry, and is liquid at room temperature. Fouling by 1,3-butadiene is mainly promoted by oxygen in the reactor, and diethyl hydroxylamine can remove the oxygen in the reactor during the process, thus exhibiting anti-polymerization effect in the gaseous process part. . The polymerization inhibitor only serves to prevent the self polymerization of 1,3-butadiene and does not affect the process or the product.

Hereinafter, the present invention will be described in more detail.

In the present invention, the supply amount of ortho-xylene and 1,3-butadiene, which is an alkenylation reactant, has a molar ratio of ortho-xylene. 3 to 20 times, preferably 5 to 15 times, relative to the number of moles of 1,3-butadiene. The molar ratio of ortho-xylene is for maximizing polymerization of 1,3-butadiene, suppressing generation of impurities due to overreaction, and increasing selectivity of 5-OTP. The 1,3-butadiene supplied to the reactor is preheated to 125 ° C to 130 ° C together with the polymerization inhibitor through a heater of the front end, converted into the gaseous state from the liquid state, and the polymerization inhibitor is introduced into the lower portion of each alkenylation reactor in the liquid phase.

Dimethyl hydroxylamine as the polymerization inhibitor of the present invention is preferably added at 50 to 80 ppm of the ortho-xylene and 1,3-butadiene reaction mixture. The amount of 1,3-butadiene introduced into the alkenylation reaction is 4 to 5 L / hr, and the amount of the reaction mixture of ortho-xylene and 1,3-butadiene is 40 to 60 L / hr. Diethyl hydroxylamine is introduced into the reactor with 1,3-butadiene at the end of the water purification column and at the front of the 1,3-butadiene phase transition heater.

The alkali metal catalyst used in the present invention is a mixture of Na and K, and optionally at least one of Li, Na, K, and Rb may be used. The alkali metal catalyst is introduced into the alkenylation reactor through the first and second ultrasonicators. In this case, the first sonicator reaction time is 0.5 to 12 hours per 50 to 200 g of the alkali metal catalyst and 45 L of the ortho-xylene dehydrated. Since the thick oxide film and impurities of the alkali metal catalyst have to be removed by sonication for a long time, the range of the reaction time is preferable in a general process, but the reaction time outside the above range can be applied by adjusting the manufacturing process. The second sonicator reaction time is 10 minutes to 6 hours per 10 to 500 ppm of the alkali metal catalyst ratio to the ortho-xylene content. The reaction time range is preferable in a general process, but a reaction time outside the range may be applied by adjusting the manufacturing process.

The reaction temperature of the reactor was kept uniform at a minimum of 130 ° C. As a result, the polymerization inhibitor was vaporized to recover the polymerization inhibitor to the upper part of the reactor, and then condensed and reused as a 1,3-butadiene phase change shear heater. The 1,3-butadiene and ortho-xylene were subjected to alkenylation. Prepared with ortho-tolylpentene. By adhering to the reaction temperature, the production of the polymer material due to the reaction temperature too high was suppressed as much as possible. The shear heater temperature of 1,3-butadiene was 125-130 ° C, the minimum temperature of the polymerization inhibitor, and the phase change of 1,3-butadiene from the liquid phase to the gaseous phase was carried out by the alkenylation reaction in the liquid phase. .

The reaction pressure of the reactor was maintained in the range of 0.01 to 10 atm, preferably 0.1 to 5 atm, which is a condition under which the reactants ortho-xylene and 1,3-butadiene can be maintained in the liquid phase. The reaction time of the alkenylation reaction was maintained at 0.01 to 50 hours, preferably 0.1 to 5 hours as the residence time in the reactor.

The percent conversion of ortho-xylene, the alkenylation reactant, is from 5 to 50%, preferably from 10 to 25%, and the selectivity (%) of the resulting 5-OTP is from 50 to 100%, preferably 90 To 100%.

Unreacted ortho-xylene is recovered through the purification column, and the purification process reaction is carried out at a reaction pressure of 130 to 200 torr, preferably 145 to 150 torr, and the lower temperature of the purified column is 145 to 200 ° C. It carried out at 150 to 160 ℃, the upper temperature was carried out at 80 to 120 ℃, preferably 90 to 97 ℃.

Hereinafter, the embodiments of the present invention and the comparative examples will be described in more detail and clarity. However, the present invention is not limited by these examples.

Example 1

1,3-butadiene input at 4L / hr, 2.5L / hr (50ppm) of diethyl hydroxylamine (polymerization inhibitor), and 5 alkenylated at the front end of a 1,3-butadiene heater with a preheating temperature of 120 ° C. The reactors were evenly fed to the bottom of the reactor. The ortho-xylene input was 45 L / hr, and the alkenyl reactor was added to the alkenyl reactor with the amount of 100 ppm relative to the NaK alkali catalyst ortho-xylene content subjected to the second sonication in the alkenylation reactor to react at 130 ° C. with 5-ortho-tolylpentene. 100 ml of an acid solution (HCl) was added to remove an alkali metal catalyst at the rear of the reactor. The results are shown in Table 1.

Example 2

5-Ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 1 except that the diethyl hydroxylamine (polymerization inhibitor) was added in an amount of 4.0 L / hr (80 ppm). The results are shown in Table 1.

Example 3

5-Ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 1, except that the diethyl hydroxylamine (polymerization inhibitor) was 5.0 L / hr (100 ppm). The results are shown in Table 1.

Comparative Example 1

5-Ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 1 except that the diethyl hydroxylamine (polymerization inhibitor) was 1.5 L / hr (30 ppm). The results are shown in Table 1.

Comparative Example 2

Except not adding diethyl hydroxylamine (antipolymerization agent), the alkenylation reaction was implemented by the method similar to Example 1, and 5-ortho- tolylpentene was manufactured. The results are shown in Table 1.

Example 1 to Example 3 and Comparative Examples 1 to 2 of Table 1, the conversion rate (%), selectivity of 5-ortho-tolylpentene according to the charge and input amount of diethyl hydroxyamine (polymerization inhibitor) (%), The amount of acidic solution (HCl) to remove the alkali metal catalyst and the number of times the process line is clogged with the popcorn type polymer produced by the polymerization of 1,3-butadiene. When the dose of the polymerization inhibitor is 50 to 80 ppm of the mixed amount of 1,3-butadiene and ortho-xylene, the reaction efficiency and the number of process line clogging are once / monthly / than when the polymerization inhibitor is not used. 6 months to 1 times / 6.5 months or so was about 6 times longer. However, when the input amount of the polymerization inhibitor is less than 50ppm did not have a significant effect to the same level as when not used, and when the input amount of the polymerization inhibitor is more than 80ppm the alkenylation reaction efficiency does not increase any more.

Example 4

A 5-ortho-tolylpentene was prepared by performing an alkenylation reaction in the same manner as in Example 1, except that the NaK alkali catalyst subjected to the second sonication was introduced into the alkenyl reactor at a ratio of 60 ppm to the ortho-xylene content. It was. The results are shown in Table 2.

Comparative Example 3

A 5-ortho-tolylpentene was prepared by performing an alkenylation reaction in the same manner as in Example 1, except that the NaK alkali catalyst subjected to the second sonication was introduced into the alkenyl reactor at a ratio of 10 ppm to the ortho-xylene content. It was. The results are shown in Table 2.

Comparative Example 4

A 5-ortho-tolylpentene was prepared by performing an alkenylation reaction in the same manner as in Example 1 except that the NaK alkali catalyst subjected to the second sonication was introduced into the alkenyl reactor at a rate of 200 ppm relative to the ortho-xylene content. It was. The results are shown in Table 2.

Comparative Example 5

A 5-ortho-tolylpentene was prepared by performing an alkenylation reaction in the same manner as in Example 1 except that the NaK alkali catalyst subjected to the second sonication was introduced into the alkenyl reactor at a rate of 250 ppm relative to the ortho-xylene content. It was. The results are shown in Table 2.

In Example 1, Example 4, and Comparative Examples 3 to 5 of Table 2, the reaction efficiency and the process according to the amount of the alkali metal catalyst while the diethyl hydroxylamine (polymerization inhibitor) in a uniform amount, The number of line clogs is shown. Alkali metal catalyst introduced for the reaction activity by using the polymerization inhibitor as in Examples 1 and 4 to improve the reaction efficiency degradation due to blocking of the process line due to fouling of 1,3-butadiene The amount also decreased from 100ppm to 50ppm, showing the same level of reactivity. However, when the alkali metal catalyst is less than 10ppm or more than 200ppm as in Comparative Examples 3 to 5, the reaction effect is not affected by a small amount, and the dispersibility of the alkali catalyst is lowered by a large amount, resulting in an alkenylation reaction. It showed a falling result.

Example 5

A 5-ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 1 except that 50 ml of an acid solution (HCl) was added to remove the alkali metal catalyst at the rear of the alkenylation reactor. The results are shown in Table 3.

Example 6

A 5-ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 4 except that 50 ml of an acid solution (HCl) was added to remove the alkali metal catalyst at the rear of the alkenylation reactor. The results are shown in Table 3.

Comparative Example 6

A 5-ortho-tolylpentene was prepared by performing the alkenylation reaction in the same manner as in Example 4, except that 100 ml of an acid solution (HCl) was added to the alkenylation reactor to remove the alkali metal catalyst. The results are shown in Table 3.

Example 1, Example 5, Example 6 and Comparative Example 6 of the Table 3 is an acid solution for the removal of the alkali metal catalyst of the alkenylation reaction, with a uniform amount of diethyl hydroxylamine (antipolymerization agent) The influence of the process on the (HCl) input amount is shown. This is due to fouling due to the polymerization of 1,3-butadiene by the use of the polymerization inhibitor, and the alkali metal to be removed because the amount of alkali metal catalyst used is reduced than the condition without using the polymerization inhibitor. As the amount of catalyst decreases, the amount of acidic solution (HCl) to be used is reduced, which lowers the corrosion rate of acid by the process equipment. Even a small amount of acid solution can be used to remove the catalyst in the alkenylation process, which can be economically effective due to the increased replacement cycle of the process equipment.

Claims (3)

In the method for preparing 5-ortho-tolylpentene by reacting ortho-xylene with 1,3-butadiene, the molar ratio of ortho-xylene is 3 to 20 times the number of moles of 1,3-butadiene, and 1,3-butadiene In order to prevent organic fouling by diethyl hydroxylamine is added 50 to 80ppm relative to the total weight of ortho-xylene and 1,3-butadiene, at least selected from the group consisting of Li, Na, K and Rb as a reaction catalyst A method for producing 5-ortho-tolylpentene, wherein one alkali metal catalyst is used in an amount of 50 to 100 ppm relative to the total weight of ortho-xylene and 1,3-butadiene. delete delete