A method for preparing 2-tert-butylphenol

Abstract

The invention discloses a method for preparing 2-tert-butylphenol, wherein phenol and isobutylene are subjected to an alkylation reaction under an acidic catalyst condition, and 2-isopropylphenol is added to the alkylation reaction. This method can significantly improve the selectivity of 2-tert-butylphenol, reduce the amount of tar generated, and thus reduce the process operation cost.

Description

Technical Field

[0001] The invention belongs to the field of phenol alkylation, and specifically relates to a method for preparing 2-tert-butylphenol by alkylation of phenol and isobutylene. Background Art

[0002] 2-tert-Butylphenol, also known as o-tert-butylphenol, is an organic compound with the chemical formula C 10 H 14 O. Mainly used as antioxidant, plant protection agent, synthetic resin, medicine, pesticide intermediate and raw material of flavors and fragrances.

[0003] The alkylation reaction mechanism follows the carbon cation reaction mechanism:

[0004] (1)Carbocation formation:

[0005]

[0006] (2) Formation of σ complex:

[0007]

[0008] (3) Proton departure:

[0009]

[0010] The alkylation reaction of phenol and isobutylene usually uses an acidic substance as a catalyst. Due to the catalytic properties of the acid catalyst, side reactions may occur during the alkylation reaction, resulting in a low yield of the alkylation reaction. In addition, the heavy components produced by the side reactions may have problems such as coking, which in turn leads to high investment and operating costs. How to create a method for preparing 2-tert-butylphenol with fewer side reactions and higher yields is of great significance.

[0011] Based on the above background, the present invention provides a method for preparing 2-tert-butylphenol. Summary of the invention

[0012] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a method for preparing 2-tert-butylphenol, by adding a side reaction inhibitor, the occurrence of side reactions is effectively inhibited, the reaction yield is high, and the reaction liquid does not have the problem of coking.

[0013] To solve the above problems, the present invention provides a method for preparing 2-tert-butylphenol, wherein phenol and isobutylene are subjected to an alkylation reaction under acidic conditions, and 2-isopropylphenol is added to the alkylation reaction. In the alkylation reaction of phenol, 2-isopropylphenol has an important promoting effect on the alkylation reaction, can significantly improve the selectivity of 2-tert-butylphenol, and inhibit the occurrence of the side reaction of generating tar.

[0014] The preferred molar ratio of phenol to isobutylene is 3-30:1-10, preferably 3-20:2-5, more preferably 4-6:2-3

[0015] Preferably, a diluent is also added to the alkylation reaction, and the diluent is an alkylated phenol with a boiling point of 250° C. to 350° C., which can significantly improve the thermal stability of the reaction solution.

[0016] Preferably, the alkylated phenol includes 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol and 3,5-di-tert-butylphenol, or a mixture of one or more phenols containing one or more long-chain alkanes on the benzene ring; preferably, the phenol containing one or more long-chain alkanes on the benzene ring is 2-tert-butyl-p-tert-octylphenol and / or p-tert-octylphenol. The addition of a diluent can improve the stability of the 2-tert-butyl reaction solution and reduce the amount of tar generated under a certain temperature and pressure.

[0017] Preferably, the acidic condition is achieved by adding an acid catalyst, and the acid catalyst is an inorganic acid, an organic acid or an acidic resin catalyst. Preferably, the acid catalyst is one or more of phosphoric acid, acetic acid, propionic acid, octanoic acid and maleic acid. The mass concentration of the catalyst in the alkylation reaction system is 50 to 1000 ppm, and the alkylation reaction system comprises phenol, isobutylene, a catalyst, a diluent and 2-isopropylphenol.

[0018] In the present invention, the inhibitor 2-isopropylphenol is added in an amount such that its mass concentration in the alkylation reaction system is 0.01wt% to 10wt%, preferably 1wt% to 5wt%, and more preferably 2.5wt% to 3.5wt%. There is no special description on the feeding method, and the alkylation reaction materials and catalysts can be mixed before entering the reactor, or they can be separately introduced into the reactor, or any two of them can be mixed before entering the reactor, and they can be evenly distributed in the reactor.

[0019] In the present invention, the amount of the diluent added is such that its mass concentration in the alkylation reaction system is 30 wt% to 80 wt%, preferably 40 wt% to 60 wt%.

[0020] In the present invention, the alkylation reactor may be an adiabatic kettle reactor, an isothermal kettle reactor, an adiabatic tower reactor, an isothermal tower reactor or other types of reactors.

[0021] In the present invention, the reactor for the alkylation reaction can adopt agitators such as paddle type, turbine type, propeller type, ribbon type, screw type and frame type, among which the paddle type can select straight blade and inclined blade paddle, the turbine type can select open turbine type and disc turbine type, among which each turbine type can select straight blade, inclined blade and curved blade paddle type respectively, and the four-inclined blade paddle type agitator is preferred.

[0022] In the present invention, the alkylation reaction process operating conditions are as follows:

[0023] The present invention needs to control the pressure of the alkylation reactor. Preferably, the pressure of the alkylation reactor is 100 to 300 kPaA, more preferably 200 to 300 kPaA.

[0024] This method requires controlling the temperature of the alkylation reactor. Preferably, the temperature of the alkylation reaction is controlled at 100 to 250°C, more preferably 150 to 200°C.

[0025] The method needs to control the residence time of the alkylation reaction. Preferably, the residence time of the alkylation reaction is 20 to 40 minutes, more preferably 30 to 40 minutes.

[0026] The 2-tert-butylphenol reaction liquid of the present invention can be separated by conventional distillation to obtain a 2-tert-butylphenol product.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention can effectively inhibit the occurrence of side reactions by adding a side reaction inhibitor to the alkylation reaction of phenol and isobutylene, thereby not only improving the selectivity of 2-tert-butylphenol in the alkylation reaction, but also promoting the forward progress of the alkylation reaction and improving the conversion rate of phenol.

[0029] In a preferred embodiment, the present invention also improves the thermal stability of the reaction by adding a diluent, and the addition of an inhibitor can effectively reduce the generation of heavy components and improve economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a graph showing the change in 2-tert-butylphenol concentration over time in Comparative Example 1 and Example 3;

[0031] Figure 2 This is a graph showing the change in by-product concentration over time in Comparative Example 1 and Example 3. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with examples. It should be noted that the examples do not limit the scope of protection claimed for the present invention.

[0033] The main raw materials and specifications are as follows:

[0034] raw material Specification Source(Manufacturer) phenol >99％ Shanghai Aladdin Biochemical Technology Co., Ltd. Isobutylene >99％ Tianjin Saimet Special Gas Company Maleic acid >99％ Tianjin Xiensi Biochemical Technology Co., Ltd. 4-tert-octylphenol >99％ Jinan Element Chemical Co., Ltd. 2-tert-Butyl-4-octylphenol >99％ Jinan Element Chemical Co., Ltd. 2,6-Di-tert-butylphenol >99％ Shanghai Aladdin Biochemical Technology Co., Ltd. 2-Isopropylphenol >99％ Shanghai Aladdin Biochemical Technology Co., Ltd.

[0035] Chromatographic analysis conditions:

[0036] Instrument model: SHIMADZU 2010Plus

[0037] Chromatographic column: DB-5 (30m×0.32mm×0.25um)

[0038] Column temperature: programmed temperature rise (40°C for 4 min, heating rate of 15°C / min to 250°C, and hold for 12 min).

[0039] Inlet temperature: 200°C

[0040] FID temperature: 260℃

[0041] H2 flow rate: 40mL / min

[0042] Air flow rate: 350mL / min.

[0043] Septum purge (N2) flow rate: 3mL / min

[0044] Carrier gas (N2) flow rate: 1mL / min

[0045] Split injection, split ratio 45:1

[0046] Injection volume: 0.4 μL

[0047] Example 1

[0048] 300 g of phenol, 0.35 g of maleic acid, 45 g of isobutylene, 1 g of 2-isopropylphenol and 350 g of tert-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0049] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0050] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0051] Example 2

[0052] 300 g of phenol, 0.05 g of maleic acid, 45 g of isobutylene, 21 g of 2-isopropylphenol and 350 g of 2-tert-butyl-p-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0053] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0054] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0055] Example 3

[0056] 300 g of phenol, 0.35 g of maleic acid, 45 g of isobutylene, 25 g of 2-isopropylphenol and 350 g of tert-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0057] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0058] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0059] Example 4

[0060] 300 g of phenol, 0.35 g of maleic acid, 100 g of isobutylene, 30 g of 2-isopropylphenol and 400 g of 2,6-di-tert-butylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0061] The reactor pressure was controlled at 120 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0062] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0063] Example 5

[0064] 300 g of phenol, 0.35 g of maleic acid, 20 g of isobutylene, 40 g of 2-isopropylphenol and 450 g of tert-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0065] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 180°C. Stirring was started, and the reactor temperature was kept stable at 180°C by heat exchange.

[0066] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0067] Example 6

[0068] 300 g of phenol, 0.35 g of maleic acid, 10 g of isobutylene, 50 g of 2-isopropylphenol and 500 g of p-tert-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0069] The reactor pressure was controlled at 280 kPaA by nitrogen sealing, and the reactor temperature was controlled at 200°C. Stirring was started, and the reactor temperature was kept stable at 200°C by heat exchange.

[0070] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0071] Example 7

[0072] 300 g of phenol, 0.35 g of maleic acid, 7 g of isobutylene, 80 g of 2-isopropylphenol and 1000 g of tert-octylphenol were added to a 1.5-liter stainless steel container reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0073] The reactor pressure was controlled at 300 kPaA by nitrogen sealing, and the reactor temperature was controlled at 220° C. Stirring was started, and the reactor temperature was kept stable at 220° C. by heat exchange.

[0074] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0075] Example 8

[0076] 300 g of phenol, 0.35 g of maleic acid, 45 g of isobutylene and 25 g of 2-isopropylphenol were added to a 1.5-liter stainless steel reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0077] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0078] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0079] Comparative Example 1 (Compared with Example 3, without adding inhibitor)

[0080] 300 g of phenol, 0.35 g of maleic acid, 45 g of isobutylene and 350 g of p-tert-octylphenol were added to a 1.5-liter stainless steel reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to 30 min by controlling the isobutylene feed rate.

[0081] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0082] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0083] Comparative Example 2 (Compared with Example 3, without adding inhibitor and high boiling point diluent)

[0084] 300 g of phenol, 0.35 g of maleic acid and 45 g of isobutylene were added to a 1.5-liter stainless steel reactor equipped with a four-paddle stirrer. The residence time of the reaction solution in the reactor was controlled to be 30 min by controlling the isobutylene feed rate.

[0085] The reactor pressure was controlled at 220 kPaA by nitrogen sealing, and the reactor temperature was controlled at 160° C., stirring was started, and the reactor temperature was kept stable at 160° C. by heat exchange.

[0086] Samples of the reaction mixture were taken out at different time points during the reaction, and the concentrations of the components of the reaction mixture were measured by chromatography (based on the total mass of the reaction mixture). The results are shown in Table 1.

[0087] The results show that in the experiment with a reaction temperature of 160°C and a reaction pressure of 220 kPaA, adding a small amount of 2-isopropylphenol can significantly increase the yield of 2-tert-butylphenol, inhibit the formation of by-products, and improve the atom economy of the alkylation reaction. The above experiments show that when the conversion rate is the same, adding 2-isopropylphenol to the reaction raw materials can shorten the reaction time and increase the reaction rate. This shortening of the reaction time (increasing the conversion rate) is very beneficial. Under the same production capacity, the equipment size can be reduced and the fixed investment cost can be reduced.

[0088] In addition, by adding a diluent to the alkylation reaction feed, the stability of 2-tert-butylphenol can be improved, resulting in further reducing the content of by-products, improving the yield of 2-tert-butylphenol and the atom economy of the entire reaction.

[0089] Table 1 Comparison of experimental results

[0090]

[0091]

[0092] The content of 2-tert-butylphenol in Table 1 is the concentration after removing excess phenol and the diluent added in the experiment.

Claims

1. A method for preparing 2-tert-butylphenol, characterized in that: Phenol and isobutylene are subjected to an alkylation reaction under an acidic catalyst condition, and 2-isopropylphenol is added into the alkylation reaction as a side reaction inhibitor.

2. The method according to claim 1, characterized in that A diluent is also added into the alkylation reaction, and the diluent is an alkylated phenol with a boiling point of 250°C to 350°C.

3. The method according to claim 2, characterized in that The alkylated phenol includes 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol and 3,5-di-tert-butylphenol, or a mixture of one or more phenols containing one or more long-chain alkanes on the benzene ring.

4. The method according to claim 3, characterized in that The phenol containing one or more long-chain alkanes on the benzene ring is 2-tert-butyl-p-tert-octylphenol and / or p-tert-octylphenol.

5. The method according to claim 1, characterized in that The molar ratio of phenol to isobutylene is 3-30:1-10.

6. The method according to claim 5, characterized in that The molar ratio of phenol to isobutylene is 3-20:2-5.

7. The method according to claim 6, characterized in that The molar ratio of phenol to isobutylene is 4-6:2-3.

8. The method according to claim 1, characterized in that The acid catalyst is an inorganic acid, an organic acid or an acid resin catalyst.

9. The method according to claim 8, characterized in that The acid catalyst is one or more of phosphoric acid, acetic acid, propionic acid, octanoic acid and maleic acid.

10. The method according to claim 8 or 9, characterized in that: The mass concentration of the acid catalyst in the alkylation reaction system is 50 to 1000 ppm.

11. The method according to claim 1, characterized in that: The inhibitor 2-isopropylphenol is added in an amount such that its mass concentration in the alkylation reaction system is 0.01 wt % to 10 wt %.

12. The method according to claim 11, characterized in that The inhibitor 2-isopropylphenol is added in an amount such that its mass concentration in the alkylation reaction system is 1 wt% to 5 wt%.

13. The method according to claim 12, characterized in that The inhibitor 2-isopropylphenol is added in an amount such that its mass concentration in the alkylation reaction system is 2.5 wt% to 3.5 wt%.

14. The method according to claim 2, characterized in that The amount of the diluent added is such that its mass concentration in the alkylation reaction system is 30 wt % to 80 wt %.

15. The method according to claim 14, characterized in that The amount of the diluent added is such that its mass concentration in the alkylation reaction system is 40 wt % to 60 wt %.

16. The method according to claim 1, characterized in that The pressure of the alkylation reaction is 100-300 kPaA.

17. The method according to claim 16, characterized in that The pressure of the alkylation reaction is 200-300 kPaA.

18. The method according to claim 1, characterized in that The temperature of the alkylation reaction is controlled at 100-250°C.

19. The method according to claim 18, characterized in that The temperature of the alkylation reaction is controlled at 150-200°C.

20. The method according to claim 1 or 16 or 18, characterized in that: The residence time of the alkylation reaction is 20 to 40 minutes.

21. The method according to claim 20, characterized in that The residence time of the alkylation reaction is 30 to 40 minutes.

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