阅读说明：本技术 一种在双催化剂及无溶剂条件下制备α,α-二甲基苄醇的方法 (Method for preparing alpha, alpha-dimethyl benzyl alcohol under double-catalyst and solvent-free conditions ) 是由 黄崇品 杨曼 李英霞 于 2019-09-25 设计创作，主要内容包括：本发明涉及一种在双催化剂及无溶剂条件下制备α,α-二甲基苄醇的方法,包括：1)制备离子液体催化剂；2)将异丙苯、所述离子液体催化剂以及无盐催化剂加入到带有回流装置的反应器中,向反应器内通入一定量的空气做为氧源,使异丙苯在无溶剂的条件下进行氧化反应；3)在反应结束后静置,待反应器内的物料分层后,上层物料即为反应产物α,α-二甲基苄醇,下层物料为所述离子液体催化剂与所述无机盐催化剂形成的混合催化体系；4)分离所述上层物料,得到反应产物α,α-二甲基苄醇。本发明是全新的合成机理,成本低,适合大规模工业生产。(The invention relates to a method for preparing alpha, alpha-dimethyl benzyl alcohol under the conditions of double catalysts and no solvent, which comprises the following steps: 1) preparing an ionic liquid catalyst; 2) adding the cumene, the ionic liquid catalyst and the salt-free catalyst into a reactor with a reflux device, and introducing a certain amount of air into the reactor to serve as an oxygen source so as to perform oxidation reaction on the cumene under the condition of no solvent; 3) standing after the reaction is finished, and after materials in the reactor are layered, obtaining a reaction product alpha, alpha-dimethyl benzyl alcohol as an upper layer material, and a mixed catalytic system formed by the ionic liquid catalyst and the inorganic salt catalyst as a lower layer material; 4) separating the upper material to obtain the reaction product alpha, alpha-dimethyl benzyl alcohol. The invention is a brand new synthesis mechanism, has low cost and is suitable for large-scale industrial production.)

1. A method for preparing α, α -dimethylbenzyl alcohol under dual-catalyst and solvent-free conditions, comprising:

1) preparing an ionic liquid catalyst;

2) adding the cumene, the ionic liquid catalyst and the salt-free catalyst into a reactor with a reflux device, and introducing a certain amount of air into the reactor to serve as an oxygen source so as to perform oxidation reaction on the cumene under the condition of no solvent;

3) standing after the reaction is finished, and after materials in the reactor are layered, obtaining a reaction product alpha, alpha-dimethyl benzyl alcohol as an upper layer material, and a mixed catalytic system formed by the ionic liquid catalyst and the inorganic salt catalyst as a lower layer material;

4) separating the upper material to obtain the reaction product alpha, alpha-dimethyl benzyl alcohol.

2. The process of claim 1, wherein the ionic liquid catalyst comprises [ Bmim ] Br, [ Bmim ] Cl, [ Bmim ] OH, [ Emim ] OH, [ Hmim ] OH and/or [ Omim ] OH.

3. The method of claim 1, wherein the reactor is provided with a paddle inlet, a reactant feed inlet and an air inlet.

4. The process according to claim 1, wherein the reaction in step 2) is carried out in a thermostated oil bath at a temperature of 60 ℃ to 120 ℃; preferably, the reaction temperature is 80 ℃ to 100 ℃; more preferably, the reaction temperature is 60 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃.

5. The method of claim 1, wherein in step 2), the mixture in the reactor is sampled at intervals by HPLC, and the progress of the reaction is monitored.

6. The method of claim 5, wherein the operation method of interval sampling is: taking 2 microlitres of the mixed material in the reactor at intervals of 2-4 hours, diluting the sampled mixed material to 10ml, measuring the content of the alpha, alpha-dimethylbenzyl alcohol by HPLC, and calculating the selectivity and the conversion rate of the alpha, alpha-dimethylbenzyl alcohol according to the following calculation formula:

cumene conversion rate ═ M (M)₀-M_x)/M₀×100％

CA Selectivity ═ M_CA/(M₀-M_x)×100％

Wherein M is₀Represents the molar concentration of cumene at the beginning of the reaction; m_xRepresents the molar concentration of cumene at the end of the reaction; m_CAIndicates the molar concentration of CA formed during the reaction.

7. The method of claim 5, wherein the Cumene Hydroperoxide (CHP) content in the monitored result is monitored during the intermittent sampling operation, and the reaction conditions are adjusted to maintain the cumene hydroperoxide molar concentration in the reaction mass below 30% during the reaction.

8. The method according to claim 1, wherein in the step 3), after the reaction is completed, the reaction product is cooled and left to stand.

9. The method as claimed in claim 1, wherein in the step 3), the separated lower material layer is washed by ethyl acetate to remove other components, and then the washed material is dried in vacuum to obtain the recycled mixed catalyst system for recycling.

10. The method of claim 1, wherein the inorganic salt catalyst comprises sodium chloride and/or sodium bromide.

Technical Field

The invention relates to the technical field of catalytic reaction, in particular to a method for preparing alpha, alpha-dimethyl benzyl alcohol under the conditions of double catalysts and no solvent.

Background

Alpha, alpha-dimethylbenzyl alcohol (CA) is an important organic intermediate for preparing dicumyl peroxide (DCP) and the like. DCP can be used as vulcanizing agent for rubber material, initiator for polymerization reaction, cross-linking agent for resin material, foaming agent for copolymer, etc. Currently, the main production process of CA is to use cumene (IPB) as a raw material, oxidize the raw material with air to obtain Cumene Hydroperoxide (CHP), and reduce the CHP to obtain CA.

The preparation of CHP by cumene peroxidation is one of the key steps in the CA synthesis process, and the peroxidation has a great influence on the yield and purity of the final product CA. The current commercial CA is in Na₂SO₃Or Na₂Aqueous solution of S is prepared by reducing CHP as a reducing agent. The process generates a large amount of waste water, generates toxic gas hydrogen sulfide in the post-treatment process, and does not meet the requirement of green chemistry. Therefore, it is of great significance to select a catalyst with high selectivity to CA and to find other reaction paths from the reaction process.

Under the condition of an Ionic Liquid (ILs) + alkali mixed catalyst, cumene is catalytically oxidized to generate CA, and the reaction follows a free radical reaction mechanism.

The oxidation of IPB belongs to a free radical chain reaction, and its oxidation products mainly include:

there have been numerous reports of catalytic oxidation of alkylbenzenes, particularly cumene, and these studies have focused primarily on the field of cumene oxidation to produce phenol with the aim of increasing cumene conversion and cumene hydroperoxide selectivity. In the cumene oxidation process, the conversion rate and the selectivity of a target product are important indexes for measuring the oxidation effect of the cumene. At present, the research on the catalytic oxidation of the cumene is mostly carried out by utilizing catalysts of alkali metal or alkaline earth metal, transition metal, molecular sieve and the like.

CN102295533A discloses the preparation of α, α -dimethylbenzyl alcohol from olefin and Cumene Hydroperoxide (CHP) as raw materials, and a nonpolar organic compound inert to the reaction system as a solvent, which mainly solves the problems of large amount of sulfur-containing wastewater, high energy consumption, serious pollution and low productivity in the prior art.

CN1248579A discloses a technology for preparing propylene oxide by catalytic oxidation of propylene with ethylbenzene hydroperoxide (EBHP) as an oxidant and a titanium-containing silicon oxide catalyst as a catalyst. However, the preparation of the catalyst is extremely complex and not beneficial to industrialization, and the process does not relate to the preparation process of the alpha, alpha-dimethyl benzyl alcohol.

US4367342 discloses that ethylbenzene hydroperoxide (EBHP) can oxidize propylene to propylene oxide with a titanium-containing amorphous silica catalyst with a by-product of α, α -dimethylbenzyl alcohol, and does not relate to the reaction of cumene hydroperoxide with propylene and other olefins.

However, in the above prior art, all the reaction processes require the use of organic solvents, which results in high production process cost, difficult pollution treatment of subsequent solvents, and poor selectivity of α, α -dimethylbenzyl alcohol in the product. Therefore, it is an urgent need to provide a synthesis method that does not require a solvent and allows the product α, α -dimethylbenzyl alcohol to have a higher selectivity.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for preparing alpha, alpha-dimethyl benzyl alcohol under the conditions of double catalysts and no solvent.

The invention relates to a method for preparing alpha, alpha-dimethyl benzyl alcohol under the conditions of double catalysts and no solvent, which comprises the following steps:

1) preparing an ionic liquid catalyst;

2) adding the cumene, the ionic liquid catalyst and the salt-free catalyst into a reactor with a reflux device, and introducing a certain amount of air into the reactor to serve as an oxygen source so as to perform oxidation reaction on the cumene under the condition of no solvent;

3) standing after the reaction is finished, and after materials in the reactor are layered, obtaining a reaction product alpha, alpha-dimethyl benzyl alcohol as an upper layer material, and a mixed catalytic system formed by the ionic liquid catalyst and the inorganic salt catalyst as a lower layer material;

4) separating the upper material to obtain the reaction product alpha, alpha-dimethyl benzyl alcohol.

Further, the ionic liquid catalyst comprises [ Bmim ] Br, [ Bmim ] Cl, [ Bmim ] OH, [ Emim ] OH, [ Hmim ] OH, [ Omim ] OH

Furthermore, the reactor is provided with a stirring paddle access port, a reactant feeding port and an air inlet.

Further, the reaction in the step 2) is carried out in a constant-temperature oil bath, and the reaction temperature is 60-120 ℃; preferably, the reaction temperature is 80 ℃ to 100 ℃; more preferably, the reaction temperature is 60 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃.

Further, in step 2), the mixture in the reactor is sampled at intervals by HPLC, and the progress of the reaction is monitored.

Further, the operation method of the interval sampling is as follows: taking 2 microlitres of the mixed material in the reactor at intervals of 2-4 hours, diluting the sampled mixed material to 10ml, measuring the content of the alpha, alpha-dimethylbenzyl alcohol by HPLC, and calculating the selectivity and the conversion rate of the alpha, alpha-dimethylbenzyl alcohol according to the following calculation formula:

cumene conversion rate ═ M (M)₀-M_x)/M₀×100％

CA Selectivity ═ M_CA/(M₀-M_x)×100％

Wherein M is₀Represents the molar concentration of cumene at the beginning of the reaction; m_xRepresents the molar concentration of cumene at the end of the reaction; m_CAIndicates the molar concentration of CA formed during the reaction.

Further, the Cumene Hydroperoxide (CHP) content in the obtained monitoring result is monitored during the intermittent sampling operation, and the molar concentration of the cumene hydroperoxide in the reaction material is controlled to be 30% or less by adjusting the reaction conditions during the reaction. Due to unstable and explosive properties of Cumene Hydroperoxide (CHP), the invention finally determines that the conversion rate of the cumene and the selectivity of CA can be considered on the basis of ensuring the reaction safety by a great deal of research work when the CHP molar concentration is controlled below 30 percent, thereby realizing the optimal reaction condition.

In the process of the invention, the conversion rate of the isopropylbenzene or the selectivity of the CHP is controlled, wherein the conversion rate is controlled below 40 percent, and the selectivity of the CHP is controlled below 30 percent, which is considered to be an industrial safety problem. The industrial production is the first safety issue while paying attention to the benefits. The oxidation products of cumene are mainly CHP and CA, CHP has certain danger, and the content of CHP is controlled. The control of the conversion rate of the isopropylbenzene is also used for controlling the concentration of CHP, when the isopropylbenzene reaches the required conversion rate in the industrial production, the isopropylbenzene is separated from the product through the separation tower, the unreacted isopropylbenzene flows back to the reaction tower to continue the reaction, and the product enters the next operation. By doing so, the concentration of CHP can be controlled, and the operation process can reach the safety requirement.

Further, in the step 3), after the reaction is finished, the material obtained by the reaction is cooled and kept stand.

Further, in the step 3), washing the separated lower-layer material with ethyl acetate to remove other components, and then performing vacuum drying on the washed material to obtain a recycled mixed catalytic system for recycling.

Further, the inorganic salt catalyst comprises sodium chloride and/or sodium bromide.

Further, the mass ratio of the ionic liquid catalyst to the inorganic salt catalyst is (1-100): 1.

further, in the step 2), the molar ratio of the ionic liquid to the cumene is (0.0001-1): 1.

further, in the step 2), the temperature of the reaction is 60-120 ℃.

Further, in the step 2), the reaction time is 2-36 hours.

Further, in the step 2), the flow rate of the air is 50-300 ml/min.

Due to the existence of the double-catalyst system, a large number of free radicals are formed in the reaction system due to molecular polarization, so that the conversion rate of isopropyl benzene and the conversion rate of alpha, alpha-dimethyl benzyl alcohol in the reaction process are greatly improved. Specifically, after NaCl and/or NaBr are added into the ionic liquid, the integral material environment can induce cumene to generate alpha, alpha-dimethyl benzyl alcohol free radicals, the free radicals and OH < - > form polar molecules, the polar molecules can induce NaCl and/or NaBr molecules to generate polarization reaction, an intermediate complex is formed between two different polar molecules due to electrostatic interaction, finally, a large number of free radicals (including cumene free radicals, cumene hydroperoxide free radicals and/or alpha, alpha-dimethyl benzyl alcohol free radicals) are generated due to thermal decomposition, and the oxidation rate is accelerated due to the increase of the number of the free radicals.

The invention has the following effective effects:

1. the reaction process of the invention does not need to add solvent, meets the requirement of green environmental protection and can greatly save the synthesis cost;

2. in the reaction process, the mixed catalyst system is used, and after the reaction, the mixed catalyst system can be recycled, so that the synthesis cost is greatly saved;

3. according to the invention, a large number of researches show that the existence of bromide ions and/or chloride ions can greatly improve the conversion rate and selectivity of alpha, alpha-dimethyl benzyl alcohol in the product;

4. the invention uses ionic liquid and inorganic salt to form a mixed catalytic system, improves the oxidation speed of the cumin, improves the selectivity and the conversion rate of alpha, alpha-dimethyl benzyl alcohol, reduces the link of oxidizing the cumin into dicumyl peroxide in the reaction process, leads the cumin to be directly oxidized into the alpha, alpha-dimethyl benzyl alcohol, and takes NaCl as an example to analyze the reaction mechanism of the system as follows:

chain initiation:

RH+·OH→R·+H₂O (1)

R·+O₂→ROO· (2)

chain transmission:

ROO·+RH→ROOH+R· (3)

ROOH+NaCl(NaBr)→ROOH·NaCl(NaBr) (4)

ROOH·NaCl→RO·+NaOH+Cl· (5)

RH+·Cl→R·+HCl (6)

HCl+NaOH→H₂O+NaCl (7)

ROOH→RO·+·OH (3)

RO·+RH→ROH+R· (9)

ROOH+ROH→RO·+R·+H₂O (10)

2ROOH→R·+ROO·+H₂O (11)

chain termination:

ROO·+ROO→ROOR+O₂ (12)

the mechanism of chain type free radical reaction shows that under the double catalytic system of the present invention, the number of the free radicals of the alpha, alpha-dimethyl benzyl alcohol generated in the reaction process is more, so that the selectivity of the alpha, alpha-dimethyl benzyl alcohol in the product is increased.

5. The invention adopts a catalytic oxidation reaction system, does not need to add an organic solvent additionally, simplifies the synthesis process, optimizes the environment for implementing the synthesis reaction, is easy to separate the product after the reaction, can recycle the mixed catalyst system, can greatly save the production cost while reducing the environmental pollution of the acid catalyst, and is beneficial to large-scale industrial production and implementation.

Detailed Description