Synthesis method of 2, 6-di-tert-butyl-4-methylphenol

Abstract

The invention discloses a synthesis method of 2, 6-di-tert-butyl-4-methylphenol, which comprises the following steps: filling a fixed bed reactor with an aluminum oxide or silicon dioxide supported metal oxide catalyst, introducing hydrogen and nitrogen mixed gas at 180-250 DEG C to activate the catalyst, cooling the fixed bed to a reaction temperature in a hydrogen atmosphere, and reacting for 2-4 hours at the temperature of 180-250 DEG C to obtain the 2, 6-di-tert-butyl-4-methylphenol. The invention discloses a method for preparing 2, 6-di-tert-butyl-4-methylphenol, which comprises the following steps of: pumping a 3, 5-di-tert-butyl-4-hydroxybenzyl methyl ether solution into a fixed bed at a fixed flow rate under the condition of keeping a certain hydrogen pressure, and cooling reaction liquid to obtain a 2, 6-di-tert-butyl-4-methylphenol solution, compared with the existing method, the method has the advantages of clean process, high efficiency and high reaction selectivity.

Description

Technical Field

[0001] The invention relates to 2,6-di-tert-butyl-4-methylphenol, in particular to a synthesis method of 2,6-di-tert-butyl-4-methylphenol, and belongs to the field of fine chemicals. Background Art

[0002] 2,6-di-tert-butyl-4-methylphenol (CAS No.: 128-37-0) is an important antioxidant, widely used in various oils and oil-containing foods, vitamins and health products, feed anti-rancidity, feed anti-mildew, feed mildew removal, and grain storage anti-oxidation.

[0003] At present, many domestic and foreign patents have reported the synthesis process of 2,6-di-tert-butyl-4-methylphenol. Relevant patents such as CN102311318, CN106317382, CN111099967, CN117886673, etc. have reported Figure 1 The p-cresol route shown in (a) uses p-cresol as a raw material and reacts it with isobutylene through an acid-catalyzed Friedel-Crafts reaction to produce 2,6-di-tert-butyl-4-methylphenol.

[0004] The paper Synthesis 2017, 49(04), 910-916 reported Figure 1 The 2,6-di-tert-butylphenol route shown in (b) uses 2,6-di-tert-butylphenol as a raw material and dichloro(pentamethylcyclopentadienyl)iridium(III) dimer as a catalyst. In the presence of excess potassium hydroxide, 2,6-di-tert-butylphenol and methanol are catalyzed to react to produce 2,6-di-tert-butyl-4-methylphenol.

[0005] Patent CN114395771 reported Figure 1 (c) shows the 3,5-di-tert-butyl-4-hydroxybenzaldehyde route, which uses 3,5-di-tert-butyl-4-hydroxybenzaldehyde as a raw material and generates 2,6-di-tert-butyl-4-methylphenol by reacting 3,5-di-tert-butyl-4-hydroxybenzaldehyde with formic acid.

[0006] The above-mentioned 2,6-di-tert-butyl-4-methylphenol has some shortcomings in the synthesis and preparation process: in the prior art p-cresol route, strong acids such as sulfuric acid are often used as catalysts, and alkali is required for neutralization after the reaction, which produces a large amount of sulfur-containing wastewater, causing environmental pollution. A large amount of heat energy is consumed in the neutralization process, and the treatment of wastewater also requires additional energy consumption. By-products may exist in the reaction process, affecting the purity and yield of the product, and the operation is complicated.

[0007] Based on this, a method for synthesizing 2,6-di-tert-butyl-4-methylphenol is proposed herein to solve the above problems. Summary of the invention

[0008] The purpose of the present invention is to provide a method for synthesizing 2,6-di-tert-butyl-4-methylphenol in order to solve the above problems. The method provided by the present invention has the advantages of clean process, high efficiency and high reaction selectivity.

[0009] The present invention achieves the above-mentioned purpose through the following technical scheme. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol comprises the following steps: loading an aluminum oxide or silicon dioxide-supported metal oxide catalyst in a fixed bed reactor, activating the catalyst by passing a hydrogen and nitrogen mixed gas at 180-250° C., cooling the fixed bed to a reaction temperature under a hydrogen atmosphere, pumping a 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether solution into the fixed bed at a fixed flow rate while maintaining a certain hydrogen pressure, and obtaining a 2,6-di-tert-butyl-4-methylphenol solution after the reaction liquid is cooled.

[0010] As a further feasible solution, the aluminum oxide includes: aluminum oxide loaded with copper oxide and aluminum oxide loaded with nickel oxide.

[0011] As a further feasible solution, the silica-supported metal oxide includes silica-supported copper oxide and silica-supported nickel oxide.

[0012] As a further feasible scheme, the reaction temperature is 100-180°C.

[0013] As a further feasible solution, the reaction pressure is 0.2-5 MPa.

[0014] As a further feasible scheme, the 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether forms a mixed solution with one of benzene, toluene, hexane, methanol, ethanol, and propanol.

[0015] As a further feasible solution, the reaction space velocity is 0.05-5h -1 .

[0016] The invention has the beneficial effects that: a fixed bed reactor is loaded with an aluminum oxide or silicon dioxide-supported metal oxide catalyst, a hydrogen-nitrogen mixed gas is passed at 180-250° C. to activate the catalyst, the fixed bed is cooled to a reaction temperature under a hydrogen atmosphere, a 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether solution is pumped into the fixed bed at a fixed flow rate under the condition of maintaining a certain hydrogen pressure, and a 2,6-di-tert-butyl-4-methylphenol solution is obtained after the reaction liquid is cooled. The method provided by the invention has the advantages of clean process, high efficiency and high reaction selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1The invention is a prior art synthesis route of 2,6-di-tert-butyl-4-methylphenol.

[0018] Figure 2 This is the synthesis route of 2,6-di-tert-butyl-4-methylphenol of the present invention;

[0019] Figure 3 This is a schematic diagram of the mass spectrometry signal of the reactant 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether of the present invention;

[0020] Figure 4 Schematic diagram of mass spectrometry signal of the product 2,6-di-tert-butyl-4-methylphenol of the present invention;

[0021] Figure 5 The present invention adopts different reaction temperatures to carry out the reaction results;

[0022] Figure 6 The reaction results of the present invention using different hydrogen pressures;

[0023] Figure 7 The reaction results of the present invention using different solvents;

[0024] Figure 8 The present invention adopts different space velocity reaction results. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] 10.0 g of aluminum oxide loaded copper oxide was loaded into a fixed bed reactor, and a hydrogen-nitrogen mixed gas was passed at 240° C. to activate the catalyst for 6 hours. The fixed bed was cooled to 160° C. under a hydrogen atmosphere, and the hydrogen pressure of the fixed bed was set to 3 MPa. 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether benzene solution (3,5-di-tert-butyl-4-hydroxybenzyl methyl ether mass content 10%) was pumped into the fixed bed at a flow rate of 1 g / min (corresponding to a space velocity of 0.6 h -1 ), after the reaction solution was cooled, mass spectrometry analysis of the reaction solution showed that the product was the target compound 2,6-di-tert-butyl-4-methylphenol ( Figure 3 and Figure 4 ), gas phase analysis showed that the conversion rate of 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether was 92.6%, and the selectivity of 2,6-di-tert-butyl-4-methylphenol was 99.1%.

[0028] Example 2

[0029] 10.0 g of aluminum oxide loaded nickel oxide was loaded into a fixed bed reactor, and a hydrogen-nitrogen mixed gas was passed at 200° C. to activate the catalyst for 6 hours. The fixed bed was cooled to 160° C. under a hydrogen atmosphere, and the hydrogen pressure of the fixed bed was set to 3 MPa. 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether benzene solution (3,5-di-tert-butyl-4-hydroxybenzyl methyl ether mass content 10%) was pumped into the fixed bed at a flow rate of 1 g / min (corresponding to a space velocity of 0.6 h / min). -1 ), after the reaction solution was cooled, gas phase analysis showed that the conversion rate of 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether was 90.7%, and the selectivity of 2,6-di-tert-butyl-4-methylphenol was 99.3%.

[0030] Example 3

[0031] 10.0 g of silica-supported copper oxide was loaded into a fixed bed reactor, and a hydrogen-nitrogen mixed gas was passed at 250° C. to activate the catalyst for 6 hours. The fixed bed was cooled to 160° C. under a hydrogen atmosphere, and the hydrogen pressure of the fixed bed was set to 3 MPa. A 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether benzene solution (3,5-di-tert-butyl-4-hydroxybenzyl methyl ether mass content 10%) was pumped into the fixed bed at a flow rate of 1 g / min (corresponding to a space velocity of 0.6 h / min). -1 ), after the reaction solution was cooled, gas phase analysis showed that the conversion rate of 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether was 93.9%, and the selectivity of 2,6-di-tert-butyl-4-methylphenol was 99.2%.

[0032] Example 4

[0033] 10.0 g of silica-supported nickel oxide was loaded into a fixed bed reactor, and a hydrogen-nitrogen mixed gas was passed at 220° C. to activate the catalyst for 6 hours. The fixed bed was cooled to 160° C. under a hydrogen atmosphere, and the hydrogen pressure of the fixed bed was set to 3 MPa. A 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether benzene solution (3,5-di-tert-butyl-4-hydroxybenzyl methyl ether mass content 10%) was pumped into the fixed bed at a flow rate of 1 g / min (corresponding to a space velocity of 0.6 h / min). -1 ), after the reaction solution was cooled, gas phase analysis showed that the conversion rate of 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether was 93.1%, and the selectivity of 2,6-di-tert-butyl-4-methylphenol was 99.4%.

[0034] Embodiment 5-8

[0035] Similar to Example 1, the reaction was carried out at different reaction temperatures, and the results were as follows: Figure 5 shown.

[0036] Examples 9-14

[0037] Similar to Example 1, the reaction was carried out using different hydrogen pressures, and the results were as follows: Figure 6 shown.

[0038] Examples 15-19

[0039] Similar to Example 1, different solvents were used to carry out the reaction, and the results were as follows: Figure 7 shown.

[0040] Examples 20-23

[0041] Similar to Example 1, the reaction was carried out at different space velocities, and the results were as follows: Figure 8 shown.

[0042] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol, characterized in that: The method comprises the following steps: loading an aluminum oxide or silicon dioxide-supported metal oxide catalyst in a fixed bed reactor, passing a hydrogen-nitrogen mixed gas at 180-250° C. to activate the catalyst, cooling the fixed bed to a reaction temperature in a hydrogen atmosphere, pumping a 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether solution into the fixed bed at a fixed flow rate while maintaining a certain hydrogen pressure, and obtaining a 2,6-di-tert-butyl-4-methylphenol solution after the reaction liquid is cooled.

2. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 1, characterized in that: The aluminum oxide includes: aluminum oxide loaded with copper oxide and aluminum oxide loaded with nickel oxide.

3. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 2, characterized in that: The silica-supported metal oxides include silica-supported copper oxide and silica-supported nickel oxide.

4. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 2, characterized in that: The reaction temperature is 100-180°C.

5. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 2, characterized in that: The reaction pressure is 0.2-5Mpa.

6. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 1, characterized in that: The 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether forms a mixed solution with one of benzene, toluene, hexane, methanol, ethanol and propanol.

7. A method for synthesizing 2,6-di-tert-butyl-4-methylphenol according to claim 1, characterized in that: The reaction space velocity is 0.05-5h -1 .

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