Preparation process of 2, 2-dinitrobibenzyl

Abstract

The invention relates to the technical field of organic synthesis, and particularly discloses a preparation process of 2, 2-dinitrobibenzyl. The hydrogen peroxide is added in the preparation process of the 2, 2-dinitrobibenzyl, the hydrogen peroxide is utilized to oxidize the nitroso intermediate generated in the reaction process, and accumulation of the nitroso intermediate is reduced. The accumulation of the nitroso intermediates is reduced, so that the total amount of by-products generated in the reaction is correspondingly reduced, the defects in related technologies are overcome, and the yield of the 2, 2-dinitrobibenzyl is improved.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and more specifically, to a preparation process of 2,2-dinitrobibenzyl. Background Art

[0002] 2,2-Dinitrobibenzyl can be used to produce drugs such as carbamazepine and imipramine. It is an important pharmaceutical intermediate and can be prepared from diphenylethane, o-nitrobenzaldehyde, 2-nitrobenzyl bromide and o-nitrotoluene as starting materials.

[0003] In the related art, there is a method for preparing 2,2-dinitrobibenzyl, comprising the following steps: adding a methanol solution of sodium methoxide and petroleum ether to a 250 mL three-necked flask, stirring evenly and cooling to below 7° C. Add a mixed solution of o-nitrotoluene and ethyl formate dropwise while stirring, reacting by stirring for 4 hours, adding water at below 10° C., acidifying with dilute hydrochloric acid to precipitate a crude dinitrobibenzyl, and recrystallizing the crude dinitrobibenzyl in ethanol to obtain 2,2-dinitrobibenzyl.

[0004] With respect to the above-mentioned related technologies, the inventors believe that although the methods in the related technologies can realize the preparation of 2,2-dinitrobibenzyl, the side reactions occurring during the reaction process will affect the yield of 2,2-dinitrobibenzyl, which is not conducive to fully improving the production efficiency of 2,2-dinitrobibenzyl. Summary of the invention

[0005] In the related art, the side reactions occurring during the reaction process will affect the yield of 2,2-dinitrobibenzyl, which is not conducive to fully improving the production efficiency of 2,2-dinitrobibenzyl. In order to improve this defect, the present application provides a preparation process of 2,2-dinitrobibenzyl.

[0006] The present application provides a preparation process of 2,2-dinitrobibenzyl, which adopts the following technical scheme: A preparation process of 2,2-dinitrobibenzyl comprises the following steps: (1) adding a nucleophilic reagent to a solvent and stirring to obtain a mixture, refrigerating the mixture, and then adding o-nitrotoluene and hydrogen peroxide to the mixture to obtain a reaction solution; (2) The reaction solution is stirred at a constant temperature, then cooled and diluted with water, an inorganic protonic acid is added for acidification, and then filtered to obtain a crude dinitrobibenzyl product, and the crude dinitrobibenzyl product is recrystallized in ethanol to obtain 2,2-dinitrobibenzyl.

[0007] By adopting the above technical scheme, when o-nitrotoluene is used as the starting material for producing 2,2-dinitrobenzyl, the reaction mechanism is that the nucleophilic reagent attacks o-nitrotoluene to generate an alkali metal salt, and the nitro group on the benzene ring loses an oxygen atom and forms a nitroso group, which reacts with the dissolved oxygen in the reaction system and is converted back into a nitro group. Due to the limited content of dissolved oxygen, the rate at which the nitro group is converted into a nitroso group is usually greater than the rate at which the nitroso group is converted back into a nitro group, so the nitroso intermediate will accumulate during the reaction and eventually produce azo compounds as a byproduct. In the present application, hydrogen peroxide is added in step (1), and hydrogen peroxide can oxidize the nitroso group, thereby reducing the accumulation of nitroso intermediates. Since the accumulation of nitroso intermediates is reduced, the total amount of by-products produced by the reaction is also reduced accordingly, thereby overcoming the defects in the related art and improving the yield of 2,2-dinitrobenzyl.

[0008] Preferably, in step (1) of the process, activated carbon is also added to the mixture, and the activated carbon is prepared according to the following method: the agricultural waste raw material is dried in an oven to constant weight, then crushed and sieved, the obtained dry powder is mixed with starch and wet granulated to obtain pellets; the pellets are dried to constant weight, and then pyrolyzed and carbonized under nitrogen protection to obtain activated carbon.

[0009] By adopting the above technical scheme, the present application uses agricultural waste raw materials and starch as raw materials to prepare activated carbon, and adds the activated carbon to the mixture of step (1). Activated carbon has a pore structure suitable for adsorbing gas, which can bring a certain amount of oxygen into the reaction system, and the pore structure of activated carbon also helps to increase the gas-liquid contact area. At the same time, activated carbon also has a certain catalytic effect on the decomposition of hydrogen peroxide, which can increase the total amount of oxygen in the reaction system. Therefore, the addition of activated carbon reduces the side reactions caused by uneven gas-liquid distribution in the reaction system, which helps to increase the yield of 2,2-dinitrobibenzyl.

[0010] Preferably, the agricultural waste raw material is selected from one of corn stalks, peanut shells and pine nut shells.

[0011] By adopting the above technical scheme, the present application optimizes the type of agricultural waste raw materials. Among them, when corn straw is selected as the agricultural waste raw material, activated carbon with a larger specific surface area can be obtained, which can more fully reduce the side reactions caused by uneven gas-liquid distribution in the reaction system, and help to increase the yield of 2,2-dinitrobibenzyl.

[0012] Preferably, in the method for preparing the activated carbon, the weight of starch accounts for 28-36% of the dry weight of the pellets.

[0013] By adopting the above technical solution, the present application optimizes the starch content range, increases the specific surface area of ​​activated carbon, helps to reduce side reactions caused by uneven gas-liquid distribution in the reaction system, and improves the yield of 2,2-dinitrobibenzyl.

[0014] Preferably, the activated carbon is pretreated before use as follows: the activated carbon is put into a nitric acid solution and allowed to stand overnight, then the activated carbon is taken out and dried to constant weight, then the activated carbon is immersed in a cobalt nitrate aqueous solution, after standing for a period of time, the activated carbon is taken out again and dried, and then calcined in an argon atmosphere to complete the pretreatment of the activated carbon.

[0015] By adopting the above technical solution, the present application first activates the activated carbon with nitric acid, then loads cobalt nitrate on the surface of the activated carbon, and then converts the cobalt nitrate into cobalt oxide by roasting. The formation of cobalt oxide can increase the specific surface area of ​​the activated carbon and enhance the catalytic effect of the activated carbon on the decomposition of hydrogen peroxide, which helps to reduce the side reactions in the reaction system and improve the yield of 2,2-dinitrobibenzyl.

[0016] Preferably, in step (1) of the process, activated carbon and manganese dioxide are added to the mixture together.

[0017] By adopting the above technical solution, the addition of manganese dioxide can produce a better catalytic effect on the decomposition of hydrogen peroxide, further increasing the total amount of oxygen in the reaction system. Because the pore structure of activated carbon can increase the gas-liquid contact area, the joint use of manganese dioxide and activated carbon can make the nitroso group more fully oxidized, thereby reducing the side reactions in the reaction system and increasing the yield of 2,2-dinitrobibenzyl.

[0018] Preferably, in step (1) of the process, a catalyst is also added to the mixture, and the catalyst is a transition metal salt.

[0019] By adopting the above technical solution, the metal ions in the transition metal salt are positively charged and have an electron-withdrawing effect. The addition of the transition metal salt can reduce the electron cloud density of the nitro group, thereby inhibiting the occurrence of side reactions. In addition, hydrogen peroxide can more fully oxidize the nitroso group, thereby effectively improving the yield of 2,2-dinitrobibenzyl.

[0020] Preferably, the catalyst is selected from one of ferrous sulfate, ferric chloride and cobalt chloride.

[0021] By adopting the above technical solution, the present application preferably selects specific types of transition metal salts, and the use of these transition metal salts can effectively improve the yield of 2,2-dinitrobibenzyl.

[0022] Preferably, the waste liquid obtained in step (2) of the process is treated as follows: The waste liquid remaining in step (2) is collected, subjected to reduced pressure distillation and pre-decolorization treatment, and then filtered. An adsorbent is added to the obtained filtrate, and the filtrate is filtered after stirring to complete the treatment of the waste liquid.

[0023] By adopting the above technical solution, the present application treats the waste liquid of step (2), which helps to reduce the total COD content of the waste liquid and reduces the pollution of the waste liquid to the environment.

[0024] Preferably, in the process of treating the waste liquid, the adsorbent used is modified attapulgite, and the modified attapulgite is prepared according to the following method: The attapulgite is dried to a constant weight, and then the attapulgite is mixed with a surfactant solution, and then filtered after heating and stirring. The obtained filter residue is dried and ground to obtain modified attapulgite.

[0025] By adopting the above technical solution, the present application uses surfactants to modify attapulgite, thereby enhancing the adsorption of organic pollutants by attapulgite and helping to reduce the impact of waste liquid on the environment.

[0026] In summary, this application has the following beneficial effects: 1. In the present application, hydrogen peroxide is added to the preparation process of 2,2-dinitrobibenzyl, and the nitroso intermediates produced during the reaction are oxidized by hydrogen peroxide, thereby reducing the accumulation of nitroso intermediates. Since the accumulation of nitroso intermediates is reduced, the total amount of by-products produced by the reaction is also reduced accordingly, thereby overcoming the defects in the related art and improving the yield of 2,2-dinitrobibenzyl.

[0027] 2. In addition to adding hydrogen peroxide, the present application also adds activated carbon to the reaction system and pre-treats the activated carbon. In the process of the present application, the activated carbon reduces the side reactions caused by the uneven distribution of gas and liquid in the reaction system on the one hand, and promotes the decomposition of hydrogen peroxide on the other hand, providing more oxygen to the reaction system, thus helping to improve the yield of 2,2-dinitrobibenzyl 3. The present application also purifies the waste liquid generated in step (2), thereby reducing the COD content of the waste liquid and helping to reduce the impact of the waste liquid on the environment. DETAILED DESCRIPTION

[0028] The present application is further described in detail below in conjunction with embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0029] Preparation example of activated carbon The following is an explanation using Preparation Example 1.

[0030] Preparation Example 1 In this preparation example, the agricultural waste raw material is peanut shells.

[0031] In this preparation example, activated carbon was prepared according to the following method: The agricultural waste raw material is dried in an oven at 75°C to constant weight, then crushed in a traditional Chinese medicine grinder at a rate of 25000r / min, and then sieved with a standard sieve of 80 meshes, and the obtained dry powder is mixed with starch in a weight ratio of 55%:45% and wet granulated to obtain a ball with an average diameter of 0.5cm; the ball is dried in an oven at 80°C to constant weight, and then heated to 500°C at a rate of 17°C / min in a muffle furnace with nitrogen protection, and then heated to 800°C at a rate of 20°C / min after keeping warm for 1h, nitrogen is introduced at a rate of 0.05L / min, water is added at a rate of 1.5mL / min, and the introduction of water and nitrogen is stopped after continued heat preservation and activation for 45min, and the furnace is cooled to 20°C to obtain activated carbon.

[0032] Preparation Example 2 The difference between this preparation example and preparation example 1 is that pine nut shells are selected as the agricultural waste raw material.

[0033] Preparation Example 3 The difference between this preparation example and preparation example 1 is that corn stalks are used as agricultural waste raw materials.

[0034] Preparation Example 4 The difference between this preparation example and preparation example 3 is that the dry powder and starch are mixed in a weight ratio of 60%:40%.

[0035] Preparation Example 5 The difference between this preparation example and preparation example 4 is that the dry powder and starch are mixed in a weight ratio of 64%:36%.

[0036] Preparation Example 6 The difference between this preparation example and preparation example 4 is that the dry powder and starch are mixed in a weight ratio of 68%:32%.

[0037] Preparation Example 7 The difference between this preparation example and preparation example 4 is that the dry powder and starch are mixed in a weight ratio of 72%:28%.

[0038] Preparation example of modified attapulgite The following is an explanation using Preparation Example 8 as an example.

[0039] Preparation Example 8 In this preparation example, modified attapulgite was prepared according to the following method: The attapulgite with a specific surface area of ​​130 m2 / g was dried at 110°C to constant weight, and then the attapulgite was mixed with a HDTMA surfactant solution, and the mixture was heated and stirred before filtering. The filter residue was dried and ground to obtain modified attapulgite.

[0040] In the above method, the amount of HDTMA surfactant used is determined by the cation exchange capacity (CEC) of attapulgite, that is, 20 mmol of HDTMA surfactant is mixed with every 100 g of attapulgite. Example

[0041] Examples 1-5 The following description is given by taking Example 1 as an example.

[0042] Example 1 In this embodiment, the nucleophilic reagent used is sodium methoxide.

[0043] This embodiment provides a preparation process of 2,2-dinitrobibenzyl, comprising the following steps: (1) In a 250 mL three-necked flask, 24 g of a nucleophilic reagent was added to 95 mL of methanol, and then mixed with 20 g of petroleum ether and stirred to obtain a mixture, the mixture was refrigerated at 5° C. for 4 h, and then 54.8 g of o-nitrotoluene and 5 g of hydrogen peroxide were added to the mixture to obtain a reaction solution; (2) The reaction solution is stirred at a constant temperature of 15° C. for 4 hours, then cooled to 10° C. and diluted with 200 mL of water, followed by adding hydrochloric acid to adjust the pH to 5.8 and filtering to obtain a crude dinitrobibenzyl product, which is recrystallized in ethanol to obtain 2,2-dinitrobibenzyl.

[0044] Example 2 The difference between this embodiment and embodiment 1 is that in step (1), activated carbon is further added to the mixture, the amount of activated carbon used is 5% of the total weight of the mixture, and the activated carbon is prepared according to the method of preparation example 1.

[0045] As shown in Table 1, the difference between Examples 2-8 is that the activated carbon is prepared according to different preparation examples.

[0046] Table 1 Example 9 The difference between this embodiment and embodiment 8 is that the activated carbon is pretreated according to the following method before use: The activated carbon is put into a 1wt% nitric acid solution so that the nitric acid just covers the top of the activated carbon. After standing for 12 hours, the activated carbon is taken out and dried at 110°C to constant weight. The activated carbon is then immersed in an aqueous solution of cobalt nitrate. After standing for a period of time, the activated carbon is taken out again and dried, and then calcined in an argon atmosphere at 400°C for 3 hours to obtain activated carbon with cobalt oxide loaded on the surface, thus completing the pretreatment of the activated carbon. After the above pretreatment, the weight of cobalt oxide (in terms of CoO) loaded on the surface of the activated carbon is equivalent to 10% of the weight of the activated carbon before pretreatment.

[0047] Example 10 The difference between this embodiment and embodiment 9 is that in step (1), activated carbon and manganese dioxide are added to the mixture together, and the amount of manganese dioxide used is 1% of the weight of hydrogen peroxide.

[0048] Embodiment 11 The difference between this embodiment and embodiment 10 is that in step (1), a catalyst is further added to the mixture, the catalyst is a transition metal salt, and the transition metal salt is ferrous sulfate. In this embodiment, the amount of the transition metal salt corresponding to each gram of o-nitrotoluene is 0.3 mmol.

[0049] Example 12 The difference between this embodiment and embodiment 11 is that the transition metal salt is ferric chloride. Example 13 The difference between this embodiment and embodiment 11 is that cobalt chloride is used as the transition metal salt.

[0050] Embodiment 14 The difference between this embodiment and embodiment 1 is that the waste liquid obtained in step (2) is treated according to the following method: the waste liquid remaining in step (2) is collected, the waste liquid is subjected to reduced pressure distillation to remove methanol, and then activated carbon (prepared according to the method of Preparation Example 7) is added in an amount equivalent to 3% of the weight of the remaining waste liquid, and the pre-decolorization treatment is completed after being kept at 65°C for 30 hours, and then filtered, and an adsorbent is added to the obtained filtrate in an amount of 0.02 g / mL, and the filtrate is filtered after stirring for 30 minutes to complete the treatment of the waste liquid; in the method of this embodiment, the adsorbent used is a 130 m 2 / g of attapulgite.

[0051] Embodiment 15 The difference between this embodiment and Example 14 is that the adsorbent is the modified attapulgite of Preparation Example 8.

[0052] Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is that no hydrogen peroxide is added in step (1).

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that the hydrogen peroxide added in step (1) is replaced by the same weight of deionized water.

[0054] Performance testing methods 1. Yield The theoretical output of 2,2-dinitrobibenzyl was calculated based on the feeding amount of o-nitrotoluene, and then the yield was calculated based on the theoretical output and actual output of 2,2-dinitrobibenzyl. The results are shown in Table 2.

[0055] 2. Wastewater treatment effect Example 14 and Example 15 were evaluated, and the absorbance of the wastewater was measured at a wavelength of 254 nm using a Shimadzu UV-visible spectrophotometer (UV-2450). The COD removal effect of the wastewater was monitored by the change in absorbance, and the results are shown in Table 3. The COD removal rate was calculated according to the following formula: E = (A0-A1) / A0×100%; where: A0 is the difference between the absorbance of the wastewater before treatment and the absorbance of the blank test; A1 is the difference between the absorbance of the wastewater after treatment and the absorbance of the blank test.

[0056] Table 2 Reaction yield Table 3 sample COD removal rate / % Embodiment 14 17.1 Embodiment 15 38.6 Combining Example 1 and Comparative Examples 1-2 and Table 2, it can be seen that the yield of Example 1 is significantly higher than that of Comparative Examples 1 and 2, indicating that in Example 1, the addition of hydrogen peroxide allows the nitroso group to be more fully oxidized, while in Comparative Examples 1 and 2, due to insufficient oxidation of the nitroso group, more by-products are produced, affecting the yield of the target product 2,2-dinitrobibenzyl.

[0057] Combining Example 1 and Example 2-8 and Table 2, it can be seen that the yields measured in Example 2-8 are all higher than those in Example 1, indicating that the addition of activated carbon increases the yield of the target product 2,2-dinitrobibenzyl. In particular, when the agricultural waste raw material is corn stalks and the weight of starch accounts for 28-36% of the dry weight of the pellets, the yield of 2,2-dinitrobibenzyl can be significantly improved.

[0058] Combining Example 8 and Example 9 with Table 2, it can be seen that the yield measured in Example 9 is higher than that in Example 8. This is because cobalt nitrate is converted into cobalt oxide during the calcination process and loaded onto the surface of the activated carbon. The formation of cobalt oxide can increase the specific surface area of ​​the activated carbon and enhance the catalytic effect of the activated carbon on the decomposition of hydrogen peroxide, which helps to reduce side reactions in the reaction system, thereby increasing the yield of 2,2-dinitrobibenzyl.

[0059] Combining Example 9, Example 10 and Table 2, it can be seen that the yield measured in Example 10 is higher than that in Example 9. This is because the addition of manganese dioxide can produce a better catalytic effect on the decomposition of hydrogen peroxide, further increasing the total amount of oxygen in the reaction system. The pore structure of activated carbon can increase the gas-liquid contact area, so the joint use of manganese dioxide and activated carbon can make the nitroso group more fully oxidized, thereby reducing the side reactions in the reaction system and improving the yield of 2,2-dinitrobibenzyl.

[0060] It can be seen from Example 10, Example 11-13 and Table 2 that the yields measured in Example 11-13 are all higher than those in Example 10. This is because the metal ions in the transition metal salt are positively charged and have an electron-withdrawing effect. The addition of the transition metal salt can reduce the electron cloud density of the nitro group, thereby inhibiting the occurrence of side reactions. In addition, hydrogen peroxide can more fully oxidize the nitroso group, thereby effectively improving the yield of 2,2-dinitrobibenzyl. Among the three transition metal salts, cobalt chloride has a better improvement effect on the yield of 2,2-dinitrobibenzyl.

[0061] It can be seen from Examples 14-15 and Table 2 that the total COD content of the waste liquid can be reduced by treating the waste liquid in step (2), and the modified attapulgite has a better removal effect on the COD in the waste liquid.

[0062] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application without any creative contribution as needed. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for preparing 2,2-dinitrobibenzyl, characterized in that: The following steps are involved: (1) adding a nucleophilic reagent to a solvent and stirring to obtain a mixture, refrigerating the mixture, and then adding o-nitrotoluene and hydrogen peroxide to the mixture to obtain a reaction solution; (2) The reaction solution is stirred at a constant temperature, then cooled and diluted with water, an inorganic proton acid is added for acidification, and then filtered to obtain a crude dinitrobibenzyl product. The crude dinitrobibenzyl product is recrystallized in ethanol to obtain 2,2-dinitrobibenzyl.

2. The process for preparing 2,2-dinitrobibenzyl according to claim 1, characterized in that: In step (1) of the process, activated carbon is also added to the mixture, and the activated carbon is prepared according to the following method: the agricultural waste raw material is dried in an oven to constant weight, then crushed and sieved, the obtained dry powder is mixed with starch and wet granulated to obtain pellets; the pellets are dried to constant weight, and then pyrolyzed and carbonized under nitrogen protection to obtain activated carbon.

3. The preparation process of 2,2-dinitrobibenzyl according to claim 2, characterized in that: The agricultural waste raw material is selected from one of corn stalks, peanut shells and pine nut shells.

4. The process for preparing 2,2-dinitrobibenzyl according to claim 3, characterized in that: In the method for preparing the activated carbon, the weight of starch accounts for 28-36% of the dry weight of the pellets.

5. The process for preparing 2,2-dinitrobibenzyl according to claim 2, characterized in that: The activated carbon is pretreated before use as follows: the activated carbon is placed in a nitric acid solution and allowed to stand overnight, then the activated carbon is taken out and dried to constant weight, then the activated carbon is immersed in a cobalt nitrate aqueous solution, after standing for a period of time, the activated carbon is taken out again and dried, and then calcined in an argon atmosphere to complete the pretreatment of the activated carbon.

6. The process for preparing 2,2-dinitrobibenzyl according to claim 2, characterized in that: In step (1) of the process, activated carbon and manganese dioxide are added together into a mixture.

7. The process for preparing 2,2-dinitrobibenzyl according to claim 1, characterized in that: In step (1) of the process, a catalyst is also added to the mixture, and the catalyst is a transition metal salt.

8. The process for preparing 2,2-dinitrobibenzyl according to claim 7, characterized in that: The catalyst is selected from one of ferrous sulfate, ferric chloride and cobalt chloride.

9. The process for preparing 2,2-dinitrobibenzyl according to claim 1, characterized in that: The waste liquid obtained in step (2) of the process is treated as follows: The waste liquid remaining in step (2) is collected, and the waste liquid is subjected to reduced pressure distillation and pre-decolorization treatment, and then filtered. An adsorbent is added to the obtained filtrate, and the filtrate is filtered after stirring to complete the treatment of the waste liquid.

10. The process for preparing 2,2-dinitrobibenzyl according to claim 9, characterized in that: In the process of treating the waste liquid, the adsorbent used is modified attapulgite, and the modified attapulgite is prepared according to the following method: The attapulgite is dried to a constant weight, and then the attapulgite is mixed with a surfactant solution, and then filtered after heating and stirring. The obtained filter residue is dried and ground to obtain modified attapulgite.

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