Method for preparing 1-cyclohexylbenzene hydrogen peroxide through solvent-free catalytic molecular oxygen selective oxidation of cyclohexylbenzene

Abstract

The invention relates to the field of thermocatalysis, and discloses a method for preparing 1-cyclohexylbenzene hydrogen peroxide through selective oxidation of cyclohexylbenzene by solvent-free thermocatalysis molecular oxygen. According to the method, metal bromide is used as a catalyst, azodiisobutyronitrile or tert-butyl hydroperoxide is used as an initiator, pure oxygen is used as an oxidizing agent, and cyclohexylbenzene (CHB) can be effectively and selectively oxidized into 1-cyclohexylbenzene hydroperoxide under normal pressure and no solvent at the temperature of 90 DEG C or above. The catalytic system disclosed by the invention has the outstanding advantages of low cost, simple and convenient operation process, high catalytic oxidation efficiency, excellent selectivity of target oxidation products and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing 1-cyclohexylbenzene hydroperoxide by selectively oxidizing cyclohexylbenzene with molecular oxygen without solvent thermal catalysis. Background Art

[0002] In industry, phenol is an important basic organic chemical raw material, widely used in the following aspects: ① Used to synthesize important chemicals such as phenolic resin, bisphenol A, phenolphthalein, salicylic acid and alkylphenol. ② As an important intermediate, it is used in the industrial production of medicines and pesticides. ③ In addition, phenol can also be used as a solvent or disinfectant in laboratories. At present, the world's annual demand for phenol has exceeded 10 million tons, of which the production of bisphenol A consumes about 45% of phenol each year, which is also the largest area of ​​phenol consumption. It is estimated that in the next few years, with the continued development of the electronic information industry and the automobile industry, the annual consumption of phenol in the world will continue to grow, with an increase of up to 5.5%.

[0003] Cyclohexanone is also an important organic chemical raw material. Its value is mainly reflected in the following aspects: ① It is an important raw material for the production of caprolactam, adipic acid, synthetic resins and synthetic fibers. ② In addition, cyclohexanone is also widely used in high-grade solvents, polishing agents and adhesives. Among many uses, caprolactam and adipic acid are the two major consumer areas of cyclohexanone. In the global annual production of 5 million tons of cyclohexanone, the consumption of cyclohexanone accounts for about 80% of the total production.

[0004] In recent years, with the gradual maturity of benzene partial hydrogenation and alkylation technology, the production cost of cyclohexylbenzene (CHB) has been greatly reduced, which has provided the possibility for the peroxidation-decomposition of CHB to co-produce phenol and cyclohexanone. Among them, the selective oxidation of CHB to produce 1-cyclohexylbenzene hydroperoxide (abbreviated as 1-CHBHP) as the key reaction for the co-production of phenol and cyclohexanone has attracted great attention and research from large foreign chemical companies and scholars at home and abroad. The French Societe Des Usines Chimiques Rhone-Poulenc Company first applied for a patent (US: 2680139, 1954-06-01) for synthesizing 1-CHBHP by self-oxidation of CHB using cumene hydroperoxide (CHP, the amount of which is 2.54wt.% of CHB) as an initiator and sodium hydroxide (the amount of which is 0.18wt.% of CHB) as an auxiliary agent. The content of CHBHP can reach 16.4wt.% by simply introducing air and stirring for 6h. Texaco of the United States also applied for a related self-oxidation patent (US: 3846499, 1974-11-05): oxygen and nitrogen are introduced into 400g cyclohexylbenzene at a rate of 0.5L / min in a ratio of 1:1, and the reaction is carried out at 130-150℃ for 1-3h, and then the temperature is lowered to 105-125℃ for 2-4h, and the final 1-CHBHP content can reach 25wt.%. Although the patents applied by the above two companies have promoted the development of CHB oxidation to a certain extent, their harsh reaction conditions and low conversion rate and selectivity cannot meet the requirements of industrial production. Therefore, subsequent research mainly focuses on the catalytic oxidation of CHB. In the 1980s, Standard Oil reported in its patent application (US:0296577A1, 2014-10-02) that polymaleimide was used as a catalyst and CHP was used as an initiator. 1g of the two was weighed and added to 45g of CHB in a ratio of 1:1. After reacting at 115°C for 4.5 hours, 5.7wt.% of 1-CHBHP was obtained. Texaco proposed a patent application for phenol and alkali metal or alkaline earth metal salts of substituted phenols as catalysts and CHP as an initiator (US:105829273B, 2014.11.14). The conversion of CHB was about 15%, and the selectivity of 1-CHBHP could reach 92.9%. In its invention patent (US: 4282383, 1981-08-04.), Upjohn Company selected 0.5wt.% NHPI as a catalyst and 2wt.% CHB peroxide as an initiator. Under solvent-free conditions, the reaction was carried out at 100°C for 8 hours, with a conversion rate of 32% and a 1-CHBHP selectivity of 97.6%. In addition to NHPI, some other catalysts have also been found to have good effects on the catalytic oxidation of CHB. Guo Xin compared the catalytic performance of some metal oxides in catalyzing the peroxidation of CHB and found that MnO2 Highest activity. 0.01gMnO 2 When added to 50g CHB, the reaction temperature was 120℃, and oxygen at a pressure of 1atm was continuously introduced for 10h, CHB conversion was 33.58%, and the selectivity of 1-CHBHP reached 80.09% (Fine Chemicals 2010, 27, 244-247). In the above catalytic oxidation CHB system, NHPI is the most effective catalyst, but its price is relatively expensive and its recycling efficiency is poor; MnO 2 It has the advantages of low cost and high catalytic oxidation activity, but it is easy to cause the decomposition of peroxy products and reduce the selectivity of 1-CHBHP. In view of such problems, it is imperative to develop an efficient and cheap catalytic system for the thermal catalytic oxidation of cyclohexylbenzene to synthesize 1-CHBHP in a solvent-free environment. Summary of the invention

[0005] The purpose of the invention is to provide a highly efficient and inexpensive thermal catalytic system for selectively oxidizing cyclohexylbenzene to synthesize 1-CHBHP.

[0006] The present invention discloses a method for preparing 1-cyclohexylbenzene hydroperoxide by selectively oxidizing cyclohexylbenzene with molecular oxygen without solvent thermal catalysis, characterized in that the method comprises the following steps: (1) weighing a dry metal bromide catalyst, an initiator, and a substrate cyclohexylbenzene according to a set ratio, adding the three into a 50 mL three-necked flask, and stirring to form a uniform liquid-solid mixture; (2) The flask containing the mixture obtained in step (1) was moved to an oil bath pot with a magnetic stirrer, and an air condenser, a temperature measuring thermometer and a vent pipe were connected. The magnetic stirring was turned on, and after the oil bath pot was heated to a set temperature, pure oxygen was passed at a rate of 20 mL / min for a certain period of time.

[0007] The method according to claim 1, characterized in that the metal bromide catalyst in step (1) is LiBr, NaBr, KBr, MgBr 2 ,CoBr 2 , CuBr 2 、MnBr 2 , FeBr 2 One of the above, whose amount is 6.25-18.75 mol% of the amount of cyclohexylbenzene by mass;

[0008] The method according to claim 1, characterized in that the initiator in step (1) is azobisisobutyronitrile (AIBN), cumene hydroperoxide (CHP), hydrogen peroxide (H 2 O 2 ) in an amount of 0.125-1.25 mol% of the amount of cyclohexylbenzene.

[0009] The method according to claim 1, characterized in that the temperature of the oil bath in step (2) is 90-130°C.

[0010] The method according to claim 1, characterized in that the stirring time in step (2) is 8 to 16 hours.

[0011] The present invention has the following advantages: (1) The catalyst is cheap and easy to obtain, can be recycled and reused, the amount of initiator used is small, and the thermal catalytic reaction efficiency is high. (2) The catalytic reaction system is green, and the target product 1-cyclohexylbenzene hydroperoxide (1-CHBHP) has high yield and excellent selectivity. (3) Solvent-free conditions are conducive to the subsequent separation of products and are suitable for large-scale production.

[0012] The following examples are further illustrative of the present invention, but are not intended to limit the present invention to the embodiments described in the specific examples listed.

[0013] Example 1: A method for preparing 1-cyclohexylbenzene hydroperoxide by selective oxidation of cyclohexylbenzene with molecular oxygen without solvent thermal catalysis according to the present invention comprises the following steps: (1) Accurately weigh 1 mmol of NaBr, 0.05 mmol of AIBN, and 8 mmol of cyclohexylbenzene (CHB), add the three into a 50 mL three-necked flask, and stir to form a uniform liquid-solid mixture; (2) The flask containing the mixture obtained in step (1) was moved to an oil bath pot with a magnetic stirrer, and an air condenser, a temperature measuring thermometer and a vent tube were connected. The magnetic stirring was turned on, and the oil bath pot was heated to 110° C., and pure oxygen was passed at a rate of 20 mL / min for 12 h; (3) After the reaction, the peroxidation product was reduced to alcohol using triphenylphosphine. The conversion rate of CHB was 18.5 mol % and the selectivity of the target product 1-CHBHP was 92.1 % by quantitative analysis using gas chromatography internal standard method.

[0014] Comparative Example 1: The method described in Example 1 was used, except that NaBr and AIBN were not added to the CHB oxidation reaction. The gas phase spectrum analysis results showed that the conversion rate of CHB was 2.1 mol%, and the selectivity of the target product 1-CHBHP was 93.2%.

[0015] Comparative Example 2: The method described in Example 1 was used, except that AIBN was not added to the CHB oxidation reaction. The gas phase spectrum analysis results showed that the conversion rate of CHB was 13.1 mol% and the selectivity of the target product 1-CHBHP was 86.9%.

[0016] Comparative Example 3: The method described in Example 1 was used, except that no NaBr was added to the CHB oxidation reaction. The gas spectrum analysis results showed that the conversion rate of CHB was 3.2 mol%, and the selectivity of the target product 1-CHBHP was 80.6%.

[0017] Example 2 (2-1 to 2-7): The method described in Example 1 is the same, except that LiBr, KBr, MgBr 2 ,CoBr 2 , CuBr 2 、MnBr 2 , FeBr 2 Instead of NaBr as catalyst, the reaction results are shown in Table 1. Table 1 It can be seen from Table 1 that among the metal bromide catalysts tested, NaBr has the highest selectivity for 1-CHBHP.

[0018] Example 3 (3-1 to 3-2): The method described in Example 1 is used, except that cumene hydroperoxide (CHP) and hydrogen peroxide (H 2 O 2 ) was used as the initiator instead of AIBN, and the reaction results are shown in Table 2. Table 2 Serial number Initiator CHB conversion (mol%) 1-CHBHP selectivity (%) Example 1 AIBN 18.5 92.1 Example 3-1 CHP 17.6 78.9 Example 3-2 <![CDATA[H 2 THE 2 ]]> 10.1 84.6 It can be seen from Table 2 that among the three initiators tested, AIBN has the best promoting effect on the NaBr-catalyzed molecular oxygen oxidation of CHB to 1-CHBHP.

[0019] Example 4 (4-1 to 4-4): The method described in Example 1 was followed, except that the amount of cyclohexylbenzene (CHB) used was changed to 4 mmol, 6 mmol, 10 mmol, and 12 mmol, respectively. The reaction results are shown in Table 3. Table 3 As shown in Table 3, within the range of CHB dosage tested (4-12 mmol), as the CHB dosage increases, the CHB conversion rate shows a downward trend, accompanied by a significant increase in the 1-CHBHP selectivity, followed by a slight decrease and stabilization. The 1-CHBHP yield is also slightly affected by the substrate dosage, reaching a maximum of 1.434 mmol at a CHB dosage of 10 mmol.

[0020] Example 5 (5-1 to 5-4): The method described in Example 1 was followed, except that the amount of sodium bromide used was changed to 0.5 mmol, 0.75 mmol, 1.25 mmol and 1.5 mmol, respectively. The reaction results are shown in Table 4. Table 4 Serial number Sodium bromide dosage (mmol) CHB conversion (mol%) 1-CHBHP selectivity (%) Example 5-1 0.5 13.5 93.6 Example 5-2 0.75 18.7 92.7 Example 1 1.0 18.5 92.1 Example 5-3 1.25 14.5 90.2 Example 5-4 1.5 13.2 89.4 As shown in Table 4, the CHB conversion first increases with the increase of NaBr dosage, and reaches the maximum when the NaBr dosage is 0.75mmol. After that, the CHB conversion rate decreases with the further increase of NaBr dosage. The selectivity of 1-CHBHP is less affected by the NaBr dosage, and the optimal value can be obtained at the dosage of 0.75-1mmol NaBr.

[0021] Example 6 (6-1 to 6-4): The method described in Example 1 was followed, except that the amount of AIBN was changed to 0.01 mmol, 0.025 mmol, 0.075 mmol and 0.1 mmol respectively. The reaction results are shown in Table 5. Table 5 Serial number AIBN dosage (mmol) CHB conversion (mol%) 1-CHBHP selectivity (%) Example 6-1 0.01 13.5 93.6 Example 6-2 0.025 18.7 92.7 Example 1 0.05 18.5 92.1 Example 6-3 0.075 14.5 90.2 Example 6-4 0.1 13.2 89.4 As shown in Table 6, the CHB conversion first increases with the increase of AIBN dosage, and reaches the maximum when the AIBN dosage is 0.025 mmol. After that, the CHB conversion rate gradually decreases with the further increase of AIBN dosage. The 1-CHBHP selectivity is less affected by the AIBN dosage, and the optimal value can be obtained at the AIBN dosage of 0.025-0.05 mmol.

[0022] Example 7 (7-1 to 7-4): The method described in Example 1 was followed, except that the reaction temperature was changed to 90°C, 100°C, 120°C and 130°C respectively. The reaction results are shown in Table 6. Table 6 Serial number Reaction temperature (℃) CHB conversion (mol%) 1-CHBHP selectivity (%) Example 7-1 90 10.2 93.6 Example 7-2 100 13.5 92.7 Example 1 110 18.5 92.1 Example 7-3 120 20.5 88.5 Example 7-4 130 24.2 70.4 It can be seen from Table 6 that the CHB conversion first increases continuously with the increase of reaction temperature, but the 1-CHBHP selectivity gradually decreases. Based on the conversion rate and selectivity, 110-120°C is the optimal reaction temperature.

[0023] Example 8 (8-1 to 8-4): The method described in Example 1 was followed, except that the reaction time was changed to 8 h, 10 h, 14 h and 16 h respectively. The results are shown in Table 7. Table 7 Serial number Reaction time (h) CHB conversion (mol%) 1-CHBHP selectivity (%) Example 8-1 8 11.8 87.8 Example 8-2 10 14.2 90.2 Example 1 12 18.5 92.1 Example 8-3 14 22.1 91.2 Example 8-4 16 22.4 88.6 As shown in Table 7, CHB conversion first increases with the increase of reaction time, while 1-CHBHP selectivity first increases with the extension of reaction time, reaches a maximum at 12h, and then gradually decreases. Considering conversion rate and selectivity, 14h is the optimal reaction time.

[0024] Example 9 (9-1 to 9-29): Based on the above single factor experiment, the substrate amount was fixed at 8 mmol, and the temperature, time, NaBr and AIBN dosage were selected as four variables to further explore the optimal reaction conditions using the response surface method (RSM), so as to comprehensively obtain a higher CHB conversion rate and 1-CHBHP selectivity. For this purpose, 29 groups of experiments were designed using the Box-Behnken experimental method, with CHB conversion rate and 1-CHBHP selectivity as response values, and the designed variable levels and experimental results are listed in Tables 8 and 9, respectively. Table 8 Table 9 The CHB conversion and 1-CHBHP selectivity in Table 9 were subjected to analysis of variance (ANOVA), and the results of the response surface quadratic model of CHB conversion and 1-CHBHP selectivity ANVOA analysis are listed in Tables 10 and 11, respectively. The response variables of CHB conversion and 1-CHBHP selectivity can be expressed by equations (1) and (2), respectively: where A, B, C and D represent the four response variables of reaction time, reaction temperature, NaBr and AIBN dosage, respectively. CHB conversion rate = 33.94 + 5.44A + 9.88B - 0.17C - 0.43D + 0.96AB + 0.28AC + 1.35AD + 0.97BC + 0.13BD - 0.68CD - 1.43A 2 -11.35B 2 -4.02C 2 -4.67D 2 (Formula 1) 1-CHBHP selectivity = 72.63-10.67A-15.15B-0.19C-1.09D-4.95AB+0.4AC-5.98AD-2.7BC-1.08BD+3.42CD-4.91A 2 -4.97B 2 +5.02C 2 +2.7D 2 (Formula 2) Table 10 R in Table 10 2 and Adj-R 2 The coefficient of variation (CV) of this model is 8.52%, which is within the acceptable accuracy range (10%). The “Pred-R 2 ” and “Adj-R” of 0.7891 2 " is reasonably consistent. "Adeq Precision" is used to represent the signal-to-noise ratio. It is generally believed that a ratio greater than 4 is within the desirable range. The ratio of this fitting model is 10.5409, indicating that the signal strength meets the requirements. In summary, this model can be used to represent the relationship between CHB conversion rate and various variables. Table 11 R in Table 11 2 and Adj-R 2 The coefficient of variation (CV) of this model is 4.1%, which is within the acceptable accuracy range (10%). The “Pred-R 2 ” and “Adj-R” of 0.9113 2 " is reasonable and consistent. The "Adeq Precision" of this fitting model is 19.861, indicating that the signal intensity meets the requirements. The above results show that the model can be used to represent the relationship between the selectivity of 1-CHBHP and various variables. The P value of the fitting model is significantly 0.0001, while the lack of fit term is not significant, indicating that the degree of fit of the simulation prediction value is consistent with the test value. According to the above analysis results, the optimal conditions are predicted to be a reaction time of 9h, a reaction temperature of 121.76℃, a NaBr dosage of 0.77mmol, and an AIBN dosage of 56mmmol. Under this condition, the predicted conversion rate of CHB is 31.0%, and the selectivity of 1-CHBHP is 82.6%.

[0025] Example 10 (10-1 to 10-3): The method described in Example 1 was followed, except that the above-predicted optimal conditions were adopted, i.e., CHB dosage was 8 mmol, reaction time was 9 h, reaction temperature was 121.76°C, NaBr dosage was 0.77 mmol, AIBN dosage was 56 μmmol, and three parallel experiments were performed. The results are shown in Table 12. Table 12 Serial number Parallel experiments (number of times) CHB conversion (mol%) 1-CHBHP selectivity (%) Example 10-1 1 33.8 87.1 Example 10-2 2 32.6 85.9 Example 10-3 3 34.1 86.5 It can be seen from Table 12 that the CHB conversion rate and 1-CHBHP selectivity obtained by the three parallel experiments are slightly better than the results of response surface simulation. The deviation between the three parallel experiments is less than 2%. The average CHB conversion rate and the average 1-CHBHP selectivity are 33.33 mol% and 86.47%, respectively, and the average production amount of 1-CHBHP is 2.31 mmol.

[0026] The above is only a preferred embodiment of the present invention. Several optimizations may be made without departing from the principle of the present invention, and these optimizations should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing 1-cyclohexylbenzene hydroperoxide by selective oxidation of cyclohexylbenzene with molecular oxygen without solvent thermal catalysis, characterized in that: The method comprises the following steps: (1) Weigh the dry metal bromide catalyst, initiator and substrate cyclohexylbenzene in a predetermined ratio, add them into a 50 mL three-necked flask, and stir to form a uniform liquid-solid mixture; (2) Move the flask containing the mixture obtained in step (1) into an oil bath pot with a magnetic stirrer, connect an air condenser, a temperature measuring thermometer and a ventilation tube, turn on the magnetic stirring, heat the oil bath pot to the set temperature, and then pass pure oxygen at a rate of 20 mL / min for a certain period of time; (3) After the reaction is completed, the peroxidation product is reduced to alcohol using triphenylphosphine, and the conversion rate of cyclohexylbenzene and the yield and selectivity of the target product 1-cyclohexylbenzene hydroperoxide are quantitatively analyzed using a gas chromatography internal standard method.

2. The method according to claim 1, characterized in that The metal bromide catalyst in step (1) is one of LiBr, NaBr, KBr, MgBr2, CoBr2, CuBr2, MnBr2, and FeBr2, and its amount is 6.25-18.75 mol% of the amount of cyclohexylbenzene in terms of mass.

3. The method according to claim 1, characterized in that The initiator in step (1) is one of azobisisobutyronitrile, cumene hydroperoxide and hydrogen peroxide, and its amount is 0.125-1.25 mol% of the amount of cyclohexylbenzene in terms of mass.

4. The method according to claim 1, characterized in that The temperature of the oil bath in step (2) is 90-130°C.

5. The method according to claim 1, characterized in that The stirring reaction time in step (2) is 8 to 16 hours.

Images