CN102249860A - Method for preparing dichlorobenzalcohol diisopropyl benzene by diisopropyl benzene catalytic oxidation - Google Patents

Abstract

The invention discloses a method for preparing dichlorobenzalcohol diisopropyl benzene by diisopropyl benzene catalytic oxidation, belonging to the technical field of dichlorobenzalcohol preparation. The method comprises the following steps: taking a CoO-MgO compound catalyst as the catalyst and air as an oxygen source; oxidizing diisopropyl benzene into diisopropyl benzene dichlorobenzalcohol, wherein the molar weight of the catalyst is 0.001-1 times that of the diisopropyl benzene, the catalytic oxidation temperature is 60-150DEG C, the air flow is 50-200L/(h.mol diisopropyl benzene), and the reaction time is 6-72 hours. In the method disclosed by the invention, a cobalt salt serves as a main catalyst, and MgO serves as a carrier to synthesize the compound catalyst. The oxidization rate of DIPB (diisopropyl benzene) is improved, and isopropyl in the DIPB is oxidized. The method disclosed by the invention can keep the conversion rate of DIPB and the selectivity of DCL (dichlorobenzalcohol diisopropyl benzene) at the higher level.

Description

A kind of method that dicumyl alcohol dicumyl is prepared by catalytic oxidation of dicumyl

technical field

The invention belongs to the technical field of preparation of dibenzyl alcohol, and relates to a method for preparing dicumyl alcohol dicumyl by catalytic oxidation of dicumyl alcohol.

Background technique

Dicumyl dibenzyl alcohol (DCL) is an important organic intermediate for the production of dicumyl di-tert-butyl peroxide and the like. At present, its main production process is to use diisopropylbenzene (DIPB) as raw material to obtain diisopropylbenzene dihydroperoxide (DHP) through air oxidation, and then reduce DHP to generate DCL.

The preparation of DHP by DIPB peroxidation reaction is one of the key steps in the DCL synthesis process, and the peroxidation reaction has an important impact on the yield and purity of the final product DCL. This reaction follows the free radical reaction mechanism, the reaction induction period is long, and many side reactions occur, one of which is DCL. Therefore, choosing a catalyst with high selectivity to DCL can realize DIPB catalytic oxidation to generate DCL in one step, which is of great significance for shortening the production process of DCL and improving the process.

The oxidation of DIPB is a free radical chain reaction, and its oxidation products mainly include:

There have been a lot of research reports on the catalytic oxidation process of alkylbenzenes, especially DIPB. The conversion rate of DIPB and the selectivity of the target product are important indicators to measure its oxidation effect. At present, the most common one is to use alkaline substances as catalysts, such as inorganic bases, alkali metal oxides and alkaline earth metal oxides, etc., and more researches are based on this.

When an inorganic base such as NaOH solution is used as a catalyst for DIPB oxidation, DCL will inevitably be generated, which has been reported in patents EP0323743, EP0322246, US6350921, etc., but DCL appears as a by-product, and the yield does not exceed 4%.

Patents US4153635, US4935551, U4282384, US4282384, US2632774, and JP49025653 report using alkaline earth metal oxidation or hydroxide as a catalyst for DIPB peroxidation. BaO ₂ or alkaline earth metal hydroxide Ca(OH) ₂ is used as the catalyst for DIPB oxidation, but DCL is also a by-product, and the yield is about 3%.

Patent JP95-3011055 reports a method for producing DCL from HHP. The MIBK solution containing HHP, in the presence of hydrogen, uses palladium-alumina as a catalyst, and the reaction conditions are a pressure of 6atm and a temperature of 90°C to obtain DCL. However, this method is under high pressure and high temperature, and MIBK is volatile, so there are potential safety hazards . Patent US6350921 reports the continuous process of producing DHP and DCLD with DIPB as raw material. After DIPB is oxidized, DHP and HHP are generated respectively. The two are separated by a reciprocating plate extraction tower, and HHP is decomposed under alkaline conditions to obtain DCL. The final yield of DCL Above 90%. These two methods are actually two-step reactions to generate DCL, which do not play a role in shortening the reaction process.

Osamu Fukuda et al reported the role of N-hydroxyphthalimide (NHPI) in the catalytic oxidation of cumene in the literature (Adv.Synth.Catal.2001.343). Acetonitrile was used as a solvent and NHPI was used as a catalyst to add to the reaction system. After 75 hours of reaction, the oxidation solution was treated with excess triphenylphosphine to obtain dimethyl benzyl alcohol in a yield of 77%. Francesco Minisci et al reported in the literature (Organic Process Research & Development 2004, 8, 163-168) the role of NHPI and Co(OAc) 4H2O in the oxidation of 2,6 diisopropylnaphthalene. The yield of dibenzyl alcohol is 87% after using the two as catalysts.

It can be seen from the analysis of the relevant technical reports before the present invention that the choice of catalyst has a great influence on the result of the peroxidation reaction and the feasibility of industrial application. For example, when inorganic bases, alkali metal oxides or alkaline earth metal oxides are used for the oxidation of DIPB, the oxidation depth of DIPB is not enough, the selectivity of DCL is not high, and it only appears as a by-product; NHPI and cobalt salts are used for the oxidation of DIPB , although the selectivity of DCL is high, but because the solubility of NHPI in DIPB is very low, generally need to use acetonitrile etc. as solvent, be unfavorable for the popularization of industrial application.

Contents of the invention

The object of the present invention is to provide a kind of method that catalytic oxidation DIPB prepares DCL, cobalt salt is loaded on solid alkali as the catalyzer of oxidation reaction, has improved the oxidation rate of DIPB, and isopropyl group wherein is all oxidized, and in the product DCL has high selectivity.

The invention provides a method for preparing dicumyl dibenzyl alcohol by catalytically oxidizing dicumene, the method comprising the following steps: loading cobalt salt on a solid base to prepare a CoO-MgO composite catalyst, and using it as a catalyst , air is the oxygen source, dicumyl benzene is oxidized to dicumyl dibenzyl alcohol. The molar weight of the catalyst is 0.001-1 times, preferably 0.002-0.2 times, the molar weight of dicumyl. The catalytic oxidation temperature is 60-150°C, preferably 90-130°C, the air flow rate is 50-200L/(h·mol dicumene), preferably 70-150L/(h·mol dicumene), The reaction time is 6-72 hours, preferably 12-36 hours.

The preparation of the catalyst adopts the co-precipitation method, using Na ₂ CO ₃ as the precipitating agent. Accurately weigh the cobalt salt and magnesium nitrate and dissolve them in deionized water, stir well and mix evenly. Cobalt salts include, but are not limited to, cobalt naphthenate, cobalt nitrate, cobalt chloride, and cobalt acetate. The amount ratio of cobalt salt and magnesium nitrate is 1:100-1:1. Prepare Na ₂ CO ₃ with a concentration of 1 mol/L as a precipitant. Under vigorous stirring, add the Na ₂ CO ₃ aqueous solution dropwise into the previously prepared nitrate aqueous solution with a constant pressure funnel until the pH value of the solution is 9.0, continue to stir for 1min-30min, then stand at room temperature for 1-12 Hours, after the aging is complete, suction filter, and wash with deionized water several times to remove Na ⁺ ions. The filter cake was dried overnight at 80-120°C. After the dried catalyst is calcined at 500°C-600°C for 6-12 hours, a CoO-MgO composite catalyst can be obtained.

The catalyst carrier used in the present invention is solid base MgO. MgO is a representative alkaline earth metal oxide and solid base. It is often used as a carrier to increase the specific surface area of the catalyst, and is also used as a catalyst in many reactions. On the other hand, MgO can increase the oxidation rate of DIPB, and its main product is DHP. The catalytic mechanism is that DIPB chemically adsorbs the alkali center on the surface of the alkaline earth metal catalyst through the hydrogen atom on the tertiary carbon of the isopropyl group, weakening the cumyl group. The C–H bond on the tertiary carbon is favorable for the isopropyl group to generate hydroperoxide, and the active center of the alkaline earth metal oxide may be the negatively charged lattice oxygen on the surface of the metal oxide.

Transition metal compounds, especially Co-based catalysts not only have good activity, but also have good DCL selectivity. Most metal ions have a decomposition effect on DIPB hydrogen peroxide, and the mechanism of Co ion catalytic decomposition of DHP is as follows

Co ⁺⁺ +ROOH→RO +Co ⁺⁺⁺ +OH ^-

Co ⁺⁺⁺ +ROOH →ROO +Co ⁺⁺ +H ⁺

The net reaction after adding the above two reactions is:

Co ⁺⁺⁺ +ROOH →ROO +Co ⁺⁺ +H ⁺

co ⁺⁺ +ROOH→RO·+Co ⁺⁺⁺ +OH ^-

2ROOH → RO·+ROO·+H ₂ O

This shows that Co ion is very obvious to the decomposition effect of alkylbenzene hydroperoxide. Therefore, with cobalt salt as the main catalyst and MgO as the carrier, the reaction route of DIPB is DIPB→DHP→DCL.

In addition, in the industrial process of DIPB oxidation, some alkaline solution (NaOH or Na ₂ CO ₃ aqueous solution, etc.) is often added to neutralize the acid generated during the oxidation process to prevent the generated peroxide from decomposing to produce by-products, such as ketones, monobenzyl Alcohol etc.

Effect of the invention: the method of the present invention adopts cobalt salt as the main catalyst, takes MgO as the carrier, synthesizes the composite catalyst, improves the oxidation rate of DIPB, and the isopropyl group in the DIPB is all oxidized (reflected in the raising of conversion rate) this The inventive method can keep the conversion rate of DIPB and the selectivity of DCL at a high level; implement the catalytic oxidation method of the present invention, the reaction system does not need to use additional organic solvents, realizes the one-step oxidation of DIPB to generate DCL, simplifies The process operation optimizes the implementation environment and improves the comprehensive cost effectiveness of the industrial application of the technology.

Detailed ways

The implementation process and effects of the present invention will be described in detail below through specific examples, but the scope of protection is not limited by the examples.

The catalytic oxidation reaction system is a two-port glass reactor with stirring and condensation. Mechanical stirring is used to disperse the entire reaction system evenly, and air enters the reaction system through a gas disperser.

The conversion rate of DIPB and the yield of product DCL were analyzed by high performance liquid chromatography (HPLC).

Example 1

Using Na ₂ CO ₃ as the precipitating agent, accurately weigh 0.5 g of cobalt nitrate and 4.4 g of magnesium nitrate and dissolve them in 100 ml of deionized water, stir and mix well. Prepare Na ₂ CO ₃ with a concentration of 1 mol/L as a precipitant. Under vigorous stirring, the _Na2CO3 aqueous solution was added dropwise to the previously prepared nitrate aqueous solution with a constant pressure funnel until the pH value of the _solution was 9.0. After continuing to stir for 5 minutes, let it stand at room temperature for 3 hours, and the aging was complete. Afterwards, filter with suction and wash with deionized water several times to remove Na+ ions and the like. The filter cake was dried overnight at 100°C. The dried catalyst was calcined at 530° C. for 8 hours, and placed in a desiccator for use.

Get 40g DIPB and put it in the reactor, add 0.4g catalyst, add 3g2% _Na2CO3 aqueous solution, reaction temperature 100 ℃, feed air 160ml/min, after _reacting for 45 hours, the conversion rate of DIPB is 78%, the conversion rate of DCL The selectivity is 65%.

Example 2

Get 40gDIPB and put it in the reactor, add 0.8g catalyst of embodiment 1, add 3g2% _Na2CO3 aqueous solution, _reaction temperature 120 ℃, pass into air 200ml/min, after reacting for 36 hours, the conversion of diisopropylbenzene The rate is 75%, and the selectivity of DCL is 70%.

Example 3

Get 40gDIPB and put in the reactor, add 0.4g catalyst of embodiment 1, add 3g2% _Na2CO3 aqueous solution, _reaction temperature 140 ℃, pass into air 200ml/min, after reacting for 30 hours, the conversion of diisopropylbenzene The rate is 80%, and the selectivity of DCL is 75%.

Claims (5)

1. the preparation method of a CoO-MgO composite catalyst is characterized in that, may further comprise the steps: adopt coprecipitation method, with Na ₂CO ₃Be precipitation agent, take by weighing cobalt salt and magnesium nitrate respectively and be dissolved in the deionized water, fully mix, the material of cobalt salt and magnesium nitrate the amount ratio be 1: 100-1: 1; The Na of preparation 1mol/L concentration ₂CO ₃As precipitation agent, under vigorous stirring, with Na ₂CO ₃The aqueous solution is added drop-wise in the above-mentioned nitrate aqueous solution, is 9.0 up to the pH of solution value, continue to stir 1min-30min after, at room temperature left standstill aging complete back suction filtration, and remove Na 1-12 hour with deionized water wash ⁺Ion; Filter cake is dried under 80-120 ℃ of condition and is spent the night, and dried catalyzer can obtain the CoO-MgO composite catalyst after 500 ℃ of-600 ℃ of following roasting 6-12 hours.

2. according to the method for claim 1, it is characterized in that described cobalt salt comprises cobalt naphthenate, Xiao Suangu, cobalt chloride, Cobaltous diacetate.

3. a catalyst oxidation diisopropylbenzene(DIPB) that adopts claim 1 preparation prepares the method for diisopropylbenzene(DIPB) two benzylalcohols, it is characterized in that may further comprise the steps: air is an oxygen source, and diisopropylbenzene(DIPB) is oxidized to diisopropylbenzene(DIPB) two benzylalcohols; The molar weight of catalyzer is 0.001-1 a times of diisopropylbenzene(DIPB) molar weight, and the temperature of catalyzed oxidation is 60-150 ℃, and air flow quantity is 50-200L/ (a hmol diisopropylbenzene(DIPB)), and the reaction times is 6-72 hour.

4. according to the method for claim 3, it is characterized in that the molar weight of catalyzer is 0.002-0.2 a times of diisopropylbenzene(DIPB) molar weight, the temperature of catalyzed oxidation is 90-130 ℃, and air flow quantity is 70-150L/ (a hmol diisopropylbenzene(DIPB)), and the reaction times is 12-36 hour.

5. according to the method for claim 3, it is characterized in that, also add NaOH or Na ₂CO ₃The acid that produces produces by product with the peroxide breakdown that prevents to generate in the aqueous solution and in the oxidising process.