A method for the preparation of α-hydroxyisobutyrylphenol by alkaline hydrolysis

Abstract

The application relates to an alkaline hydrolysis method for preparing alpha-hydroxyisobutyrylbenzene, which comprises the steps of alkaline hydrolysis, separation, washing with a baking soda solution and rectification; wherein the organic phase obtained through alkaline hydrolysis and separation is washed with a baking soda solution, and the pH is controlled to be less than or equal to 8, which can effectively avoid the influence of residual alkali in the alkaline hydrolysis reaction on the product quality in the rectification process, so as to improve the product quality obtained through rectification; compared with the traditional petroleum ether extraction method, the method can effectively neutralize the alkali in the reaction system, the water content in the obtained washed organic phase is small, organic solvent extraction is not needed, and the waste liquid generated in the washing process is less.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photoinitiator preparation, and relates to an alkali decomposition method for preparing alpha-hydroxyisobutyrylbenzene. BACKGROUND

[0002] Alpha-hydroxyisobutyrylbenzene, also known as photoinitiator 1173, is a free radical type I photoinitiator, which can be applied to an acrylic acid photocuring varnish system coated on paper, metal and plastic surfaces.

[0003] The preparation process of alpha-hydroxyisobutyrylbenzene generally takes isobutyrylbenzene as raw material, and the product is obtained through chlorination and alkali decomposition process; CN103613492A discloses a synthesis method of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propyl ketone, which comprises the following steps: 2-methyl-1-phenyl-1-propyl ketone is fed into a chlorination reaction kettle, chloroform is introduced at 35-40 DEG C, and 2-chloro-2-methyl-1-phenyl-1-propyl ketone is obtained after 1 hour of heat preservation at about 40 DEG C; a metered amount of liquid alkali is fed into an alkali decomposition reaction kettle, and a metered amount of 2-chloro-2-methyl-1-phenyl-1-propyl ketone is fed into the alkali decomposition reaction kettle, and the mixture is stirred for 0.5-1 hour, and the reaction is completed; petroleum ether is added, stirred, extracted, and the water phase is separated, and the petroleum ether is recovered by desolventizing, and 2-hydroxy-2-methyl-1-phenyl-1-propyl ketone is obtained; the crude 2-hydroxy-2-methyl-1-phenyl-1-propyl ketone is pumped into a distillation kettle, and the product fraction is collected by vacuum distillation, and 2-hydroxy-2-methyl-1-phenyl-1-propyl ketone is obtained; the above process uses petroleum ether extraction to collect the product after the alkali decomposition reaction is completed, which not only requires a large amount of organic solvent, but also has high energy consumption and high process cost in the subsequent desolventizing process.

[0004] Therefore, it is still of great significance to develop an alkali decomposition method which does not need organic solvent extraction, has good washing effect, and has less impurities in the product. SUMMARY

[0005] The alkali decomposition method for preparing alpha-hydroxyisobutyrylbenzene comprises the following steps: alkali decomposition, liquid separation, baking soda solution washing, and rectification.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] The alkali decomposition method for preparing alpha-hydroxyisobutyrylbenzene comprises the following steps:

[0008] (1) mixing the chloro compound shown in formula a, sodium hydroxide solution and phase transfer catalyst to perform alkaline hydrolysis reaction;

[0009]

[0010] (2) after the alkaline hydrolysis reaction in step (1) is completed, liquid separation is performed to obtain an organic phase;

[0011] (3) soda solution is added to the organic phase obtained in step (2) to perform washing until pH≤8, such as 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8 or 7.9, etc., and the front distillation water is removed by rectification to obtain α-hydroxyisobutyrylbenzene.

[0012] In the existing alkaline hydrolysis method, after the alkaline hydrolysis reaction is completed, the product is generally collected by petroleum ether extraction liquid separation or direct rectification without extraction. In the above traditional method, since the organic phase obtained by alkaline hydrolysis liquid separation still contains sodium hydroxide solution, direct rectification will greatly affect the product quality, resulting in high product impurity content. And using the petroleum ether extraction method, there are problems of large solvent consumption, high energy consumption, large solvent loss and affecting production capacity. Based on solving the above problems, the present application provides an alkaline hydrolysis method without organic solvent extraction, and the washing effect is good, and the product impurity content is small.

[0013] The present application found that the residual sodium hydroxide and water in the alkaline hydrolysis reaction will greatly affect the product quality. The alkaline hydrolysis method described in the present application uses soda solution to wash the organic phase obtained by alkaline hydrolysis liquid separation, and adjusts the pH to ≤8. The residual alkali in the soda solution is neutralized, and the water content in the obtained washed organic phase is low. Direct rectification operation is performed, and the water in the front distillation is removed. The normal distillation part can obtain α-hydroxyisobutyrylbenzene. The purity of the obtained product can reach 99% to 99.5%.

[0014] The present application compares the water washing method. Compared with the soda solution washing method described in the present application, it has the problems of large water consumption, large amount of wastewater, and the residual liquid alkali in the rectification process will react with the product, resulting in high product impurity content. And using acid washing method, there is a problem of product decomposition caused by pH fluctuation.

[0015] Preferably, after washing with soda solution in step (3), saturated brine is not added for dehydration treatment.

[0016] The application verifies through experiments that after washing with baking soda solution, not only the residual alkali can be effectively removed, but also the moisture content in the obtained washed organic phase is not high, so that it is not necessary to use saturated brine for dehydration treatment. On the contrary, using saturated brine for dehydration treatment not only increases the process operation steps, but also produces a large amount of wastewater, increasing the wastewater treatment cost.

[0017] Preferably, in step (3), the washing with the baking soda solution is carried out until the pH is 7-8, for example 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8 or 7.9, etc.

[0018] Preferably, in step (3), the concentration of the baking soda solution is 7wt%-9wt%, for example 7.2wt%, 7.5wt%, 7.8wt%, 8wt%, 8.2wt%, 8.5wt% or 8.5wt%, etc.

[0019] The application uses the above-mentioned concentration of baking soda solution for washing, which can effectively neutralize the residual alkali in the organic phase, and the moisture content in the washed organic phase obtained by washing is small; compared with the water washing method, the obtained product has less impurities and higher product purity.

[0020] Preferably, in step (1), the concentration of the sodium hydroxide solution is 15wt%-25wt%, for example 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt% or 24wt%, etc.

[0021] Preferably, in step (1), the phase transfer catalyst is selected from tetrabutylammonium bromide.

[0022] Preferably, in step (1), the molar ratio of the chlorinated compound represented by formula a to sodium hydroxide is 1:1.1-1.3, for example 1:1.15, 1:1.2 or 1:1.25, etc.

[0023] Preferably, in step (1), the mass ratio of the chlorinated compound represented by formula a to the phase transfer catalyst is 1:0.0002-0.001, for example 1:0.0003, 1:0.0005, 1:0.0007 or 1:0.0009, etc.

[0024] In the alkali decomposition method of the application, the material ratio uses the above-mentioned ratio, which facilitates the full performance of the alkali decomposition reaction.

[0025] Preferably, in step (1), the temperature of the alkali decomposition reaction is 75°C-85°C, for example 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C or 84°C, etc.

[0026] Preferably, in step (1), the chlorinated compound represented by formula a is prepared by a method comprising the following steps:

[0027] (a) introducing chlorine into the compound of formula b to perform a chlorination reaction;

[0028]

[0029] (b) after the reaction in step (a) is completed, introducing an inert atmosphere gas into the reaction solution to perform a chlorine removal to obtain the chlorinated compound shown in formula a;

[0030] Preferably, the temperature is controlled at 55-65℃, such as 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃ or 64℃, etc. during the process of introducing the inert atmosphere gas in step (b).

[0031] Preferably, the reaction device is vacuumized during the process of introducing the inert atmosphere gas in step (b).

[0032] In the preparation method of the chlorinated compound shown in formula a, after the chlorination reaction is completed, the residual unreacted chlorine and the generated HCl in the reaction system, if not treated, directly perform the alkaline hydrolysis reaction, which will cause the increase of alkali consumption and instability, and the generated sodium hypochlorite will also have an adverse effect on the alkaline hydrolysis reaction; the traditional method adopts alkali washing to neutralization, and then performs the alkaline hydrolysis reaction, which not only has a complicated operation, but also generates a large amount of wastewater by alkali washing; based on this, the method disclosed in the present application introduces the inert atmosphere gas to remove the chlorine and HCl in the chlorinated product after the chlorination reaction is completed, and the temperature is controlled in the temperature range of 55-65℃ during the operation process, which can effectively remove the inorganic chlorine in the system, the inorganic chlorine content in the obtained organic phase is small and stable, and the influence on the subsequent alkaline hydrolysis section is reduced; and compared with the traditional alkali washing method, the operation is simpler, and the generation of high-salinity wastewater is reduced.

[0033] Preferably, after the chlorine removal in step (b), the method further comprises adding a reducing agent into the reaction solution.

[0034] Preferably, the reducing agent is selected from sodium sulfite.

[0035] Preferably, the ratio of the molar amount of the compound of formula b to the molar amount of the reducing agent is 1:0.001-0.01, such as 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007, 1:0.008 or 1:0.009, etc., preferably 1:0.001-0.005.

[0036] In the preparation method disclosed in the present application, after the chlorine removal by introducing the inert atmosphere gas, part of the inorganic chlorine still remains in the reaction solution, thereby affecting the subsequent treatment; the present application adds a small amount of reducing agent after the chlorine removal by introducing the gas, which can reduce the influence on the subsequent process.

[0037] Preferably, the inert atmosphere gas in step (b) is selected from nitrogen.

[0038] Preferably, the temperature of the chlorination reaction in step (a) is 45-55°C, such as 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C or 54°C, etc.

[0039] Preferably, the end point of chlorine removal in step (b) is that the concentration of HCl in the chlorinated compound of formula a is ≤0.5g / kg, such as 0.1g / kg, 0.2g / kg, 0.3g / kg or 0.4g / kg, etc.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] (1) The alkali decomposition method of the present application uses baking soda solution to wash the organic phase obtained by alkali decomposition and fractionation, and adjusts the pH to ≤8. The baking soda solution neutralizes the residual alkali in the organic phase, and the obtained washed organic phase has low water content. Direct rectification operation is performed, and water in the pre-distillation fraction is removed. The normal distillation fraction can obtain α-hydroxyisobutyrylbenzene. The obtained product has low impurity content, and the purity can reach 99-99.5%;

[0042] (2) The method of the present application does not need to extract with petroleum ether organic solvent, and has simple process operation, low energy consumption, and less water consumption, and produces less waste water. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application, and should not be regarded as specific limitations on the present application.

[0044] Example 1

[0045] The present embodiment provides an alkali decomposition method for preparing α-hydroxyisobutyrylbenzene, which specifically comprises the following steps:

[0046] (1) 1000 kg of compound of formula b is added to a reaction kettle, the temperature is controlled to 50°C, chlorine is introduced, and chlorination reaction is carried out;

[0047]

[0048] (2) After the reaction in step (1) is completed, the temperature is controlled to 60°C, nitrogen is introduced to remove chlorine, and the concentration of HCl in the chlorinated compound is controlled to be <0.5g / kg;

[0049] (3) After the chlorine removal in step (2) is completed, 1800 kg of 18% NaOH solution and 0.6 kg of tetrabutylammonium bromide (TBAB) are added, the temperature is raised to 80°C, and the alkali decomposition reaction is carried out for 2h;

[0050] (4) After the base hydrolysis reaction in step (3) is completed, the organic phase is obtained by liquid separation;

[0051] (5) The organic phase obtained in step (4) is washed with a baking soda solution with a concentration of 8 wt% until the pH is 7-8, and the front fraction is removed by rectification, and the alpha-hydroxyisobutyrylbenzene is obtained by normal distillation.

[0052] The purity of the alpha-hydroxyisobutyrylbenzene product obtained in this example is 99.0%, and the yield is 98.1%.

[0053] In step (2) of this example, the temperature is controlled and nitrogen is introduced to remove chlorine, which can effectively remove inorganic chlorine in the chlorinated product, and the content of inorganic chlorine in the obtained chlorinated product is small and stable, which is beneficial to the subsequent base hydrolysis reaction. Compared with the traditional alkali washing method for removing chlorine, the operation is simple, and the generation of high-salinity wastewater is reduced.

[0054] In step (5) of this example, the baking soda solution is used for washing, which can effectively neutralize the residual alkali in the organic phase, and the water content in the obtained washed organic phase is small, so that high-purity alpha-hydroxyisobutyrylbenzene product can be obtained by direct rectification and removal of the front fraction.

[0055] Example 2

[0056] The difference between this example and Example 1 is that the temperature is controlled to 25°C in step (2), and the other parameters and conditions are exactly the same as in Example 1.

[0057] In the process of introducing nitrogen to remove chlorine in this example, the temperature is too low, and the chlorine removal time is long.

[0058] Example 3

[0059] The difference between this example and Example 1 is that the temperature is controlled to 80°C in step (2), and the other parameters and conditions are exactly the same as in Example 1.

[0060] The purity of the alpha-hydroxyisobutyrylbenzene product obtained in this example is 98.2%, and the yield is 97.1%.

[0061] In the process of introducing nitrogen to remove chlorine in this example, the temperature is too high, and there is a problem of over-chlorination.

[0062] Example 4

[0063] The difference between this example and Example 1 is that after the chlorine removal in step (2) is completed, 1.5 kg of sodium sulfite is added to the reaction solution, and the other parameters and conditions are exactly the same as in Example 1.

[0064] The purity of the alpha-hydroxyisobutyrylbenzene product obtained in this example is 99.5%, and the yield is 98.7%.

[0065] After the chlorine is removed under an inert atmosphere, a small amount of chlorine and hydrogen chloride will remain in the reaction solution, which will affect the subsequent reaction, thereby affecting the purity and yield of the product. By adding an appropriate amount of sodium sulfite after the chlorine is removed, the purity and yield of the product are improved to a certain extent.

[0066] Example 5

[0067] The difference between this example and Example 4 is only that the amount of sodium sulfite added is replaced by 1 kg, and the other parameters and conditions are exactly the same as in Example 1.

[0068] The purity of the α-hydroxyisobutyrylbenzene product obtained in this example is 99.3%, and the yield is 98.5%.

[0069] Example 6

[0070] The difference between this example and Example 1 is only that in step (2), instead of passing nitrogen gas, 60 L of saturated baking soda solution is added to adjust the pH to 7-8, and then the organic phase is separated. Then, steps (3) and (4) are performed, and in step (5), the organic phase is washed with the baking soda solution until the pH is 7-8, and then saturated brine is added for washing. Finally, α-hydroxyisobutyrylbenzene is obtained by distillation.

[0071] The purity of the α-hydroxyisobutyrylbenzene product obtained in this example is 99.2%, and the yield is 97.8%.

[0072] In step (2) of this example, saturated baking soda solution is used to remove inorganic chlorine from the chlorinated compound. The above process is complex and generates a large amount of high-salinity wastewater, which is costly to treat.

[0073] In step (5) of this example, saturated brine is added for washing after washing with the baking soda solution. Since the water content in the organic phase is not high after washing with the baking soda solution, the dehydration effect of the saturated brine is not obvious, and the treatment cost of the wastewater is increased.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is only that in step (5), the organic phase obtained in step (4) is directly distilled without washing with the baking soda solution, and the other parameters and conditions are exactly the same as in Example 1.

[0076] The purity of the α-hydroxyisobutyrylbenzene product obtained in this comparative example is 96.2%, and the yield is 97.5%.

[0077] In this comparative example, the alkaline hydrolysis reaction is not washed after completion, and the organic phase contains residual alkali. The residual alkali can cause side reactions of the product, resulting in a decrease in product quality and yield.

[0078] Comparative Example 2

[0079] The difference between the present comparative example and Example 1 is that the baking soda solution is replaced by water in step (5), and other parameters and conditions are exactly the same as in Example 1.

[0080] The purity of the α-hydroxyisobutyrylbenzene product obtained in the present comparative example is 97.6%, and the yield is 97.8%.

[0081] In the present comparative example, water is used instead of the baking soda solution for washing, which can reduce the amount of residual alkali, but since the product still dissolves part of the residual alkali, it will still cause the product quality and yield to decrease.

[0082] Comparative Example 3

[0083] The difference between the present comparative example and Example 1 is that the baking soda solution is replaced by a dilute hydrochloric acid solution in step (5), and other parameters and conditions are exactly the same as in Example 1.

[0084] The purity of the α-hydroxyisobutyrylbenzene product obtained in the present comparative example is 97.2%, and the yield is 95.7%.

[0085] In the present comparative example, a dilute hydrochloric acid is used instead of the baking soda solution for washing, which can reduce the amount of residual alkali, but since the acid can be excessive, it can cause the product to decompose.

[0086] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing α-hydroxyisobutyrylbenzene by alkaline hydrolysis, characterized in that, The alkaline hydrolysis method includes the following steps: (1) Mix the chlorinated product shown in formula a, sodium hydroxide solution and phase transfer catalyst to carry out alkaline hydrolysis reaction; (2) After the alkaline hydrolysis reaction in step (1) is completed, separate the liquid and obtain the organic phase; (3) Add baking soda solution to the organic phase obtained in step (2) and wash until pH ≤ 8. Remove the foredistilled water by distillation to obtain α-hydroxyisobutyrylbenzene; In step (1), the molar ratio of the chlorinated compound shown in formula a to sodium hydroxide is 1:1.1 to 1.

3.

2. The alkaline hydrolysis method according to claim 1, characterized in that, In step (3), the concentration of the baking soda solution is 7 wt% to 9 wt%.

3. The alkaline hydrolysis method according to claim 1, characterized in that, The concentration of the sodium hydroxide solution in step (1) is 15wt% to 25wt%.

4. The alkaline hydrolysis method according to claim 1, characterized in that, The phase transfer catalyst in step (1) is selected from tetrabutylammonium bromide.

5. The alkaline hydrolysis method according to claim 1, characterized in that, In step (1), the mass ratio of the chlorinated compound shown in formula a to the phase transfer catalyst is 1:0.0002 to 0.

001.

6. The alkaline hydrolysis method according to claim 1, characterized in that, The alkaline hydrolysis reaction in step (1) is carried out at a temperature of 75℃~85℃.

7. The alkaline hydrolysis method according to claim 1, characterized in that, The chlorinated compound shown in formula a in step (1) is prepared by the following method, which includes the following steps: (a) Chlorine gas is introduced into compound b to carry out a chlorination reaction; (b) After the reaction in step (a) is completed, an inert atmosphere gas is introduced into the reaction solution to remove chlorine, and the chlorinated product shown in formula a is obtained.

8. The alkaline hydrolysis method according to claim 7, characterized in that, Step (b) after removing chlorine also includes adding a reducing agent to the reaction solution.

9. The alkaline hydrolysis method according to claim 8, characterized in that, The reducing agent is selected from sodium sulfite.

10. The alkaline hydrolysis method according to claim 8, characterized in that, The molar ratio of compound b to reducing agent is 1:0.001 to 0.

01.

11. The alkaline hydrolysis method according to claim 10, characterized in that, The molar ratio of compound b to reducing agent is 1:0.001 to 0.

005.

12. The alkaline hydrolysis method according to claim 7, characterized in that, The inert atmosphere gas in step (b) is selected from nitrogen.

13. The alkaline hydrolysis method according to claim 7, characterized in that, During the introduction of the inert atmosphere gas in step (b), the temperature is controlled at 55℃~65℃.

14. The alkaline hydrolysis method according to claim 7, characterized in that, The chlorination reaction in step (a) is carried out at a temperature of 45°C to 55°C.

15. The alkaline hydrolysis method according to claim 7, characterized in that, In step (b), the endpoint of chlorination is reached when the concentration of HCl in the chlorinated product shown in formula a is ≤0.5 g / kg.

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