A kind of preparation method of benzyl alcohol

Abstract

The present application relates to the field of benzyl alcohol preparation, and discloses a method for preparing benzyl alcohol, comprising the following steps: 1 part by weight of benzyl chloride, 0.055-0.065 parts by weight of sodium formate, 3-4 parts by weight of water, 0.01-0.02 parts by weight of activated carbon-supported quaternary ammonium salt catalyst, and 0.438-0.459 parts by weight of sodium carbonate are uniformly mixed, heated to reflux for 4-5 hours, separated, and the upper layer is vacuum distilled to obtain benzyl alcohol. According to the preparation method of the present application, benzyl alcohol can be prepared by hydrolyzing benzyl chloride at normal pressure and relatively low temperature, and its selectivity and conversion rate are both high, and by-products are few, and in particular, the generation of dibenzyl ether can be greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of benzyl alcohol preparation, and more specifically, to a method for preparing benzyl alcohol. Background Art

[0002] Benzyl alcohol, also known as benzyl alcohol, has a molecular formula of C 7 H 8 O, melting point is -15.3℃, boiling point is 205.7℃, relative density (water = 1) is 1.0419, it is slightly soluble in water, easily soluble in organic reagents such as alcohol, ether, aromatic hydrocarbons, and is a colorless liquid with aromatic odor at room temperature and pressure. Benzyl alcohol has a relatively active chemical property. It can react with hydrohalic acid and phosphorus halide to produce benzyl halide. Benzyl halide and benzyl alcohol are both benzylating agents. In addition, benzyl esters or ethers can be prepared, and it can react with benzene to produce diphenylmethane. In addition, benzyl alcohol is also easily oxidized to benzoic acid by a variety of oxidants. If oxidized with nitric acid, aldehydes or acids can be produced depending on the concentration and temperature.

[0003] Benzyl alcohol is the simplest and most important aromatic alcohol in industry. Most of it exists in the form of esters in essential oils. For example, jasmine oil, hyacinth oil, clove oil and Peru balsam all contain benzyl alcohol esters. Therefore, benzyl alcohol can be used to prepare perfumes and flavors, and is also a very useful fixative in cosmetics. In addition, benzyl alcohol is widely used in industrial fields such as coatings, prevention, medicine, and photosensitive materials. It can also be used as a preservative, solvent, viscosity reducer, degreasing agent, solder joint cleaning agent, viscosity stabilizer of silicone resin solution, paint stripping agent, etc.

[0004] At present, benzyl alcohol is mainly produced by chemical synthesis, such as benzyl chloride hydrolysis, toluene oxidation, benzaldehyde reduction, benzoic acid (ester) reduction, etc. Among them, benzyl chloride hydrolysis is the main industrial method at home and abroad. Its main process is to obtain benzyl alcohol by azeotropic hydrolysis of benzyl chloride and strong alkali aqueous solution. The benzyl chloride hydrolysis method is further divided into intermittent method and continuous method according to different operating conditions. The so-called intermittent method is to heat and reflux a mixture of water, soda ash and benzyl chloride until no carbon dioxide escapes, cool it, add salt to saturate and separate the upper layer carefully to obtain crude alcohol, and the crude alcohol is distilled under reduced pressure to obtain industrial-grade benzyl alcohol, with a yield of 70% to 72%. However, the intermittent method has poor reaction selectivity and will produce a large amount of by-product dibenzyl ether (up to 20% to 30%), which makes subsequent separation difficult and the yield is low. The so-called continuous method is to fully mix benzyl chloride and an aqueous solution of alkali at a high temperature of 180-275°C and a high pressure of 1-6.8 MPa for hydrolysis. The hydrolysis time only takes a few minutes. Its advantages are that there are very few by-products and it can be carried out in a tower reactor. Under appropriate conditions, benzyl alcohol with a purity of 99.8% can be obtained with a yield of 98%. However, the continuous method requires harsh conditions such as high temperature and high pressure, and has high requirements for reaction equipment.

[0005] Therefore, the art needs to develop a method for preparing benzyl alcohol by hydrolyzing benzyl chloride with mild reaction conditions, high selectivity and high conversion rate. Summary of the invention

[0006] [Technical issues]

[0007] In view of the shortcomings of the prior art, an object of the present application is to provide a method for preparing benzyl alcohol, which can prepare benzyl alcohol by hydrolyzing benzyl chloride at normal pressure and relatively low temperature, has high selectivity and conversion rate, and has few by-products, and can especially significantly reduce the generation of dibenzyl ether.

[0008] [Technical solution]

[0009] In order to achieve the above object, according to one embodiment of the present application, a method for preparing benzyl alcohol is provided, which comprises the following steps:

[0010] 1 part by weight of benzyl chloride, 0.055-0.065 parts by weight of sodium formate, 3-4 parts by weight of water, 0.01-0.02 parts by weight of activated carbon-supported quaternary ammonium salt catalyst and 0.438-0.459 parts by weight of sodium carbonate are uniformly mixed, heated under reflux for reaction for 4-5 hours, separated, and the upper layer is vacuum distilled to obtain benzyl alcohol.

[0011] In the present application, benzyl chloride will first react with sodium formate to generate benzyl formate, and then hydrolysis reaction will occur by heating reflux under the catalytic action of the alkalinity of sodium carbonate and the activated carbon-supported quaternary ammonium salt catalyst, and then benzyl alcohol and sodium formate will be generated, and sodium formate can be circulated in the system to participate in the reaction, and has played a catalytic effect, and has promoted the progress of the reaction, and has effectively improved the conversion rate of benzyl chloride and the yield of benzyl alcohol. The alkalinity of the sodium carbonate and the intermolecular force of the sodium ion on the product benzyl alcohol greatly hinder the formation of the by-product dibenzyl ether, thereby effectively improving the conversion rate of benzyl chloride and the selectivity and yield of benzyl alcohol, and the reaction conditions are mild, without high temperature and high pressure. However, there is a problem of slow reaction rate in sodium carbonate, so the present application adopts the catalytic system of sodium formate and supported quaternary ammonium salt to improve the reaction rate.

[0012] Preferably, in the present application, 1 part by weight of benzyl chloride, 0.06 parts by weight of sodium formate, 3.65 parts by weight of water, 0.015 parts by weight of activated carbon-supported quaternary ammonium salt catalyst and 0.4485 parts by weight of calcium carbonate are used for the reaction. Under this material ratio, the best conversion rate of benzyl chloride and the selectivity and yield of benzyl alcohol can be obtained.

[0013] Preferably, in the present application, the activated carbon-supported quaternary ammonium salt catalyst is prepared by the following method:

[0014] S1. Immerse the activated carbon in a nitric acid solution with a mass fraction of 20-24%, reflux at a temperature of 85-90°C for 4-5 hours, and then dry to obtain oxidized activated carbon; wherein the weight ratio of the activated carbon to the nitric acid solution is 1:(10-15);

[0015] S2. The oxidized activated carbon is mixed with diethylenetriaminopropyltrimethoxysilane to obtain an intermediate, and then the intermediate, 1-bromobutane and toluene are mixed, refluxed for 12-14 hours, filtered and dried to obtain an activated carbon-supported quaternary ammonium salt catalyst; wherein the weight ratio of the oxidized activated carbon to diethylenetriaminopropyltrimethoxysilane is 1:(8-10); the weight ratio of the intermediate, 1-bromobutane and toluene is 1:(0.45-0.5):(10-15).

[0016] The supported quaternary ammonium salt catalyst prepared by the above method has high catalytic activity, high thermal stability, strong selectivity, and is easy to separate from the reaction system. After the reaction stops, it can be recovered by simple filtration. The recovered catalyst can be reused, which meets the requirements of large-scale continuous production.

[0017] Preferably, in the present application, the temperature of heating and reflux is 105-110° C. At this temperature, sufficient reflux can be achieved to achieve hydrolysis of benzyl chloride.

[0018] Preferably, in the present application, the heating rate of reflux is 5-7°C / min. At this heating rate, the hydrolysis reaction can be smoothly started and carried out, and the time loss caused by too low heating rate and the side reaction caused by too fast heating rate can be avoided.

[0019] Preferably, in the present application, 0.03-0.06 parts by weight of dimethyl dibutyl ammonium chloride is further added to the reaction system before the reaction. Dimethyl dibutyl ammonium chloride is a quaternary ammonium salt, which can play a catalytic role, further promote the formation of benzyl formate, and further promote the directional hydrolysis of benzyl formate into benzyl alcohol, reducing the formation of by-product dibenzyl ether.

[0020] Preferably, the amount of dimethyldibutylammonium chloride used is 0.05 parts by weight. At this amount, the sufficiency of the esterification reaction, the selectivity and conversion rate of the hydrolysis reaction can be further improved.

[0021] Preferably, in the present application, sodium chloride is added to saturation to promote liquid separation. By adding sodium chloride, on the one hand, the ionic strength of the aqueous phase is further increased to fully reduce the solubility of benzyl alcohol in the aqueous phase. On the other hand, since the relative density of benzyl alcohol (1.04) is close to that of water, the addition of sodium chloride can further increase the density of the aqueous phase, thereby promoting separation from the product benzyl alcohol phase and making it float on the upper layer of the aqueous phase.

[0022] Preferably, in the present application, the reaction is naturally cooled to room temperature after completion before liquid separation. When the temperature is high, the solubility of benzyl alcohol in water is relatively high, which is not conducive to liquid separation and extraction of the product benzyl alcohol.

[0023] Preferably, in the present application, the vacuum distillation condition is to collect the fraction at 118-122° C. under a pressure of 5.4-6.0 kPa. Under this vacuum distillation condition, benzyl alcohol with higher purity can be obtained.

[0024] [Beneficial Effects]

[0025] In summary, this application has the following beneficial effects:

[0026] According to the preparation method of the present application, benzyl alcohol can be prepared by hydrolyzing benzyl chloride at normal pressure and relatively low temperature, and the reaction conditions are mild, the selectivity and conversion rate are high, and the by-products are small, especially the generation of dibenzyl ether can be greatly reduced. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to understand the present application more clearly, the present application is further described in detail below in conjunction with the examples. However, it should be understood that the following examples are only preferred implementation modes of the present application, and the scope of protection claimed in the present application is not limited thereto.

[0028] Material Source

[0029] Benzyl chloride was purchased from Shandong Liaocheng Luxi Chemical Group Co., Ltd.;

[0030] Sodium formate, purchased from Shandong Liang New Materials Technology Co., Ltd.;

[0031] Sodium carbonate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0032] Dimethyldibutylammonium chloride was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0033] Diethylenetriaminopropyltrimethoxysilane was purchased from Suzhou Qihang Biotechnology Co., Ltd.;

[0034] Hexadecyltrimethylammonium bromide was purchased from Shanghai Shengwei Chemical Raw Materials Co., Ltd.

[0035] <Preparation Example>

[0036] Preparation Example 1

[0037] The activated carbon-supported quaternary ammonium salt catalyst is prepared by the following method:

[0038] S1. 10 kg of activated carbon was immersed in 125 kg of 22% nitric acid solution, refluxed at 87.5 ° C for 4.5 h, and then dried to obtain oxidized activated carbon;

[0039] S2. 8 kg of oxidized activated carbon was mixed with 72 kg of diethylenetriaminopropyltrimethoxysilane to obtain an intermediate, and then 5 kg of the intermediate, 13.625 kg of 1-bromobutane and 62.5 kg of toluene were mixed, refluxed for 13 h, filtered, and dried to obtain an activated carbon-supported quaternary ammonium salt catalyst.

[0040] Preparation Example 2

[0041] The activated carbon-supported quaternary ammonium salt catalyst is prepared by the following method:

[0042] S1. 10 kg of activated carbon was immersed in 100 kg of 20% nitric acid solution, refluxed at 85 ° C for 4 hours, and then dried to obtain oxidized activated carbon;

[0043] S2. 8 kg of oxidized activated carbon was mixed with 64 kg of diethylenetriaminopropyltrimethoxysilane to obtain an intermediate, and then 5 kg of the intermediate, 2.25 kg of 1-bromobutane and 50 kg of toluene were mixed, refluxed for 12 hours, filtered, and dried to obtain an activated carbon-supported quaternary ammonium salt catalyst.

[0044] Preparation Example 3

[0045] The activated carbon-supported quaternary ammonium salt catalyst is prepared by the following method:

[0046] S1. 10 kg of activated carbon was immersed in 150 kg of 24% nitric acid solution, refluxed at 90 ° C for 5 h, and then dried to obtain oxidized activated carbon;

[0047] S2. 8 kg of oxidized activated carbon was mixed with 80 kg of diethylenetriaminopropyltrimethoxysilane to obtain an intermediate, and then 5 kg of the intermediate, 2.5 kg of 1-bromobutane and 75 kg of toluene were mixed, refluxed for 14 hours, filtered, and dried to obtain an activated carbon-supported quaternary ammonium salt catalyst.

[0048] <Example>

[0049] Example 1

[0050] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0051] 200 g of benzyl chloride, 12 g of sodium formate, 730 g of water, 3 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 1 and 89.7 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 6 ° C / min at a temperature of 110 ° C for 4.5 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 167.12 g of benzyl alcohol (purity 99.90%, yield 97.73%).

[0052] Example 2

[0053] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0054] 200 g of benzyl chloride, 11 g of sodium formate, 670 g of water, 2 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 2 and 87.6 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 5 ° C / min at a temperature of 110 ° C for 4 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 161.28 g of benzyl alcohol (purity 99.91%, yield 94.32%).

[0055] Example 3

[0056] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0057] 200 g of benzyl chloride, 13 g of sodium formate, 760 g of water, 4 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 3 and 91.8 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 7 ° C / min at a temperature of 107 ° C for 5 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 163.70 g of benzyl alcohol (purity 99.86%, yield 95.69%).

[0058] Example 4

[0059] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0060] 200 g of benzyl chloride, 11.6 g of sodium formate, 800 g of water, 2.4 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 1 and 86 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 7 ° C / min at a temperature of 110 ° C for 4 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 166.03 g of benzyl alcohol (purity 99.89%, yield 97.08%).

[0061] Example 5

[0062] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0063] 200 g of benzyl chloride, 12.4 g of sodium formate, 600 g of water, 2.8 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 2 and 88 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 5 ° C / min at a temperature of 105 ° C for 4.5 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 160.65 g of benzyl alcohol (purity 99.92%, yield 93.96%).

[0064] Example 6

[0065] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0066] 200 g of benzyl chloride, 11.4 g of sodium formate, 700 g of water, 3.4 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 3 and 90 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 6 ° C / min at a temperature of 110 ° C for 4 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 164.87 g of benzyl alcohol (purity 99.90%, yield 96.41%).

[0067] Example 7

[0068] The following preparation method according to the present application is used to prepare benzyl alcohol:

[0069] 200 g of benzyl chloride, 12.8 g of sodium formate, 660 g of water, 3.8 g of the activated carbon-supported quaternary ammonium salt catalyst prepared in Preparation Example 2 and 91 g of sodium carbonate were mixed uniformly, heated under reflux at a heating rate of 5 ° C / min at a temperature of 108 ° C for 4.5 hours, and naturally cooled to room temperature after the reaction was completed. Sodium chloride was added to saturation, and the liquid was separated. The upper layer was vacuum distilled, and the fraction of 118-122 ° C was collected at a pressure of 5.4-6.0 kPa to obtain 163.05 g of benzyl alcohol (purity 99.88%, yield 95.33%).

[0070] Example 8

[0071] 169.12 g of benzyl alcohol (purity 99.89%, yield 98.89%) was obtained in the same manner as in Example 1, except that 10 g of dimethyldibutylammonium chloride was further added to the reaction system before the reaction.

[0072] Example 9

[0073] 167.93 g of benzyl alcohol (purity 99.91%, yield 98.21%) was obtained in the same manner as in Example 1, except that 6 g of dimethyldibutylammonium chloride was further added to the reaction system before the reaction.

[0074] Example 10

[0075] 168.29 g of benzyl alcohol (purity 99.87%, yield 98.38%) was obtained in the same manner as in Example 1, except that 12 g of dimethyldibutylammonium chloride was further added to the reaction system before the reaction.

[0076] Comparative Example 1

[0077] 148.21 g of benzyl alcohol (purity 99.88%, yield 86.65%) was prepared in the same manner as in Example 1, except that 200 g of benzyl chloride, 15 g of sodium formate, 540 g of water, 6 g of activated carbon-supported quaternary ammonium salt catalyst and 100 g of sodium carbonate were used for the hydrolysis reaction.

[0078] Comparative Example 2

[0079] 143.42 g of benzyl alcohol (purity 99.90%, yield 83.87%) was prepared in the same manner as Example 1, except that 200 g of benzyl chloride, 9.6 g of sodium formate, 860 g of water, 1 g of activated carbon-supported quaternary ammonium salt catalyst and 200 g of sodium carbonate were used for the hydrolysis reaction.

[0080] Comparative Example 3

[0081] 154.31 g of benzyl alcohol (purity 99.89%, yield 90.23%) was prepared in the same manner as Example 1, except that the hydrolysis reaction was carried out at a heating rate of 10° C. / min under reflux.

[0082] Comparative Example 4

[0083] 144.05 g of benzyl alcohol (purity 99.88%, yield 84.22%) was prepared in the same manner as Example 1, except that the activated carbon-supported quaternary ammonium salt catalyst was replaced with hexadecyltrimethylammonium bromide.

[0084] It can be seen from the above-mentioned Examples 1 to 10 and Comparative Examples 1 to 4 that the preparation methods within the scope of the present application all obtain benzyl alcohol with very high purity and yield, and the reaction conditions are mild, so it can be seen that the method achieves higher benzyl alcohol selectivity and conversion rate, and there are few by-products, so the amount of benzyl ether generated is also extremely low. In addition, compared to Examples 1 to 7, Examples 8 to 10 further add dimethyl dibutyl ammonium chloride in the reaction system, thereby further improving the benzyl alcohol yield, and it can be seen that it can promote the directional hydrolysis of benzyl chloride into benzyl alcohol, reducing the formation of by-product benzyl ether. In contrast, Comparative Examples 1 and 2 use a material ratio outside the scope of the present application, and the yield of benzyl alcohol has a significant decline, Comparative Example 3 uses a higher heating rate to heat, and the yield of benzyl alcohol is also significantly affected, and Comparative Example 4 uses a common quaternary ammonium salt catalyst to replace the supported quaternary ammonium salt catalyst, which also has a significant impact on the yield of benzyl alcohol.

[0085] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing benzyl alcohol, characterized in that: The following steps are involved: 1 part by weight of benzyl chloride, 0.055-0.065 parts by weight of sodium formate, 3-4 parts by weight of water, 0.01-0.02 parts by weight of activated carbon-supported quaternary ammonium salt catalyst, 0.05 parts by weight of dimethyldibutylammonium chloride and 0.438-0.459 parts by weight of sodium carbonate are uniformly mixed, heated under reflux for reaction for 4-5 hours, separated, and the upper layer is vacuum distilled to obtain benzyl alcohol; The heating reflux temperature is 105~110℃, and the heating reflux rate is 5~7℃ / min; The activated carbon-supported quaternary ammonium salt catalyst is prepared by the following method: S1. Immerse the activated carbon in a nitric acid solution with a mass fraction of 20-24%, reflux at a temperature of 85-90°C for 4-5 hours, and then dry to obtain oxidized activated carbon; wherein the weight ratio of the activated carbon to the nitric acid solution is 1:(10-15); S2. The oxidized activated carbon is mixed with diethylenetriaminopropyltrimethoxysilane to obtain an intermediate, and then the intermediate, 1-bromobutane and toluene are mixed, refluxed for 12-14 hours, filtered and dried to obtain an activated carbon-supported quaternary ammonium salt catalyst; wherein the weight ratio of the oxidized activated carbon to diethylenetriaminopropyltrimethoxysilane is 1:(8-10); the weight ratio of the intermediate, 1-bromobutane and toluene is 1:(0.45-0.5):(10-15).

2. The method for preparing benzyl alcohol according to claim 1, characterized in that The reaction was carried out using 1 part by weight of benzyl chloride, 0.06 parts by weight of sodium formate, 3.65 parts by weight of water, 0.015 parts by weight of activated carbon-supported quaternary ammonium salt catalyst, and 0.4485 parts by weight of sodium carbonate.

3. The method for preparing benzyl alcohol according to claim 1, characterized in that: Sodium chloride was added to saturation to facilitate separation.

4. The method for preparing benzyl alcohol according to claim 1, characterized in that: After the reaction was completed, the mixture was naturally cooled to room temperature and then separated.

5. The method for preparing benzyl alcohol according to claim 1, characterized in that: The vacuum distillation conditions are to collect the fraction at 118~122°C at a pressure of 5.4~6.0 kPa.