CN110903162B - Production process of benzyl alcohol - Google Patents
Production process of benzyl alcohol Download PDFInfo
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- CN110903162B CN110903162B CN201811077309.5A CN201811077309A CN110903162B CN 110903162 B CN110903162 B CN 110903162B CN 201811077309 A CN201811077309 A CN 201811077309A CN 110903162 B CN110903162 B CN 110903162B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
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- C07—ORGANIC CHEMISTRY
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- C07C67/00—Preparation of carboxylic acid esters
- C07C67/10—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond
- C07C67/11—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond being mineral ester groups
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Abstract
The invention relates to the technical field of spice processing, in particular to a production process of benzyl alcohol; the method comprises the following operation steps of esterification: adding benzyl chloride and a phase transfer catalyst raw material solution into a sodium acetate solution, and carrying out an esterification reaction to obtain a first crude ester; primary water washing: washing the first crude ester with water to obtain a first brine and a second crude ester; and (3) secondary water washing: washing the second crude ester with water again to obtain second salt water and third crude ester; and (3) rectification under reduced pressure: carrying out reduced pressure distillation on the third crude ester, and condensing the distillate to obtain a finished product of benzyl acetate; and (3) hydrolysis reaction: hydrolyzing the benzyl acetate under alkaline conditions to obtain benzyl alcohol; the raw materials and the products are integrated into a circulating chain, and the method is suitable for industrial mass production.
Description
Technical Field
The invention relates to the technical field of spice processing, in particular to a production process of benzyl alcohol.
Background
Benzyl alcohol is a very useful fixative, is an essential spice for blending essence such as jasmine, evening primrose, ylang-ylang and the like, and is mainly used for preparing essence such as berries, nuts and the like. It can also be used for preparing soap and daily cosmetic essence. Benzyl alcohol also has wide application in the production of industrial chemicals, and can be used as coating solvent, photographic developer, polyvinyl chloride stabilizer, medicine, synthetic resin solvent, solvent for vitamin b injection, antiseptic for ointment or medicinal liquid, drying agent for nylon filament, fiber and plastic film, and solvent for dye, cellulose ester and casein. Meanwhile, the oil is widely used for manufacturing pens (ball-point pen oil), paint solvents and the like.
In the prior art, there are two main ways for industrially preparing benzyl alcohol: 1. the benzyl chloride hydrolysis method is characterized in that benzyl chloride is used as a raw material and is heated and hydrolyzed under the catalysis of alkali to obtain the benzyl chloride; however, the pressure, high temperature and increasing and decreasing concentration all favor the production of the benzyl ether as a byproduct, so that the purity and yield of the benzyl alcohol are affected. 2. The toluene oxidation method is to oxidize toluene to prepare benzyl alcohol under the action of an alkaline catalyst, but acetic acid and benzyl acetate are byproducts, so that high-purity benzyl alcohol cannot be easily obtained.
Currently, benzyl ester hydrolysis reaction can be adopted in a laboratory to prepare benzyl alcohol, and benzyl formate, benzyl propionate, benzyl acetate or benzyl benzoate and the like are used as raw materials to prepare benzyl alcohol through liquid phase hydrolysis; the reaction mixture is easy to separate after hydrolysis, and an organic phase is separated, so that the benzyl alcohol with the purity of more than 98 percent and the yield of more than 98 percent can be obtained. However, most of the methods are suitable for small-batch production or principle research operation in laboratories at present, because the raw material benzyl ester in the benzyl ester hydrolysis method is a component of perfume and has a large application value, if benzyl ester is used as a raw material for preparing benzyl alcohol, the obtained accessory products cannot be recycled in the production and processing of other products, and the raw materials, products or intermediate products cannot be synthesized into a circulating chain, so that the production cost is increased, and the method is not suitable for industrial large-batch production.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a production process of benzyl alcohol, which integrates raw materials and products into a circulating chain and is suitable for industrial mass production.
The purpose of the invention is realized by the following technical scheme:
a production process of benzyl alcohol sequentially comprises the following operation steps:
(1) esterification reaction: adding benzyl chloride and a phase transfer catalyst raw material solution into a sodium acetate solution, and carrying out an esterification reaction to obtain a first crude ester;
(2) primary water washing: washing the first crude ester with water to obtain a first brine and a second crude ester;
(3) and (3) secondary water washing: washing the second crude ester with water again to obtain second salt water and third crude ester;
(4) and (3) rectification under reduced pressure: carrying out reduced pressure distillation on the third crude ester, and condensing fractions to obtain a finished product of benzyl acetate;
(5) and (3) hydrolysis reaction: the benzyl acetate is hydrolyzed under alkaline conditions to obtain benzyl alcohol.
By adopting the technical scheme, benzyl acetate is obtained through esterification reaction, benzyl alcohol and sodium acetate are obtained through benzyl acetate hydrolysis reaction, sodium acetate is continuously recycled as a raw material for preparing benzyl acetate through esterification reaction, one part of ethyl acetate is output as a product, and the other part of ethyl acetate is continuously reacted as the raw material of benzyl alcohol; the auxiliary products are recycled in the production and processing of target products or products, and raw materials, products or intermediate products are synthesized into a circulating chain, so that the production cost is reduced, and the method is suitable for industrial mass production.
Preferably, the phase transfer catalyst raw material liquid of step (1) is prepared by: mixing a catalyst and benzyl chloride according to a mass ratio of (0.5-1.0): (5-10), and reacting at 40-80 ℃ for 20-50min to obtain a phase transfer catalyst raw material solution.
By adopting the technical scheme, a large number of tests prove that the improved phase transfer catalyst raw material liquid has higher catalytic activity and stability, and still has better phase transfer catalytic effect after being repeatedly used for many times, and at least in the production of benzyl acetate in the same batch, the phase transfer catalyst raw material liquid always keeps higher catalytic activity, so that acetate ions can be continuously and flexibly transferred and transferred between an organic phase and a water phase under the carrying condition of the phase transfer catalyst, and the phase transfer catalyst, the acetate ions and halide ions are continuously and repeatedly combined and dissociated, so that the esterification reaction can be continuously and efficiently reacted, and the yield of the benzyl acetate is improved.
Preferably, the catalyst is a mixture of benzyltriethylammonium chloride and hexadecyltrimethylammonium bromide, and the mass ratio of the benzyltriethylammonium chloride to the hexadecyltrimethylammonium bromide is (0.8-1.3): (0.2-0.5).
By adopting the technical scheme, in the traditional quaternary ammonium salt catalyst catalysis process, if water exists, the self-recovery of the catalyst in the catalysis process can be influenced, namely the catalyst can not be perfectly converted into the original catalyst, so that the catalysis effect is influenced. The catalyst is a mixture of benzyltriethylammonium chloride and hexadecyltrimethylammonium bromide with a specific ratio, and is prepared by compounding and mixing two catalysts in advance and then heating the mixture and benzyl chloride, so that part of the catalysts are reacted with the benzyl chloride firstly, and then sodium acetate is added, so that the catalysts can be continuously compounded with acetate ions, chloride ions and the like and dissociated in the catalysis process, and a high-activity catalysis effect is achieved. A large number of experiments prove that the phase transfer catalyst raw material solution is pretreated with benzyl chloride according to the specific proportion, so that the yield and the purity of benzyl acetate can be effectively improved.
Preferably, the weight ratio of the sodium acetate solution, the benzyl chloride and the phase transfer catalyst raw material solution in the step (1) is (4-7): (9-15): (1-2).
By adopting the technical scheme, in the production process, the yield and the purity of the target product of each raw material in the proportioning range are better.
Preferably, the alkali liquor of the hydrolysis reaction in the step (5) is sodium hydroxide solution, and is added in a one-time adding manner, and the pH value of the hydrolysis solution is controlled to be 12-13.
Preferably, in the hydrolysis reaction of the step (1), the reaction temperature is controlled to be 180-250 ℃; and cooling the reaction mixture to 80-150 ℃ after hydrolysis, layering, and separating out an organic phase to obtain the benzyl alcohol.
By adopting the technical scheme, in the invention, the unreacted benzyl chloride is recovered and treated in the benzyl acetate production process, and the condition that the unreacted benzyl chloride is condensed to generate dibenzyl ether under an alkaline condition can not occur, so that the alkali liquor is added in a one-time adding manner in the hydrolysis reaction, and the energy consumption of continuous addition is saved. In experiments, the alkali concentration is too low, the hydrolysis rate is slow, and the alkali concentration is too high, so that the emulsification of the reaction liquid can be caused, and the quality of the product can not be ensured. The two factors of hydrolysis rate and benzyl alcohol quality are comprehensively considered, and the pH value of the hydrolysate is preferably controlled to be 12-13. The hydrolysis reaction temperature and the cooling temperature of the reaction mixture are controlled to ensure that the aqueous phase and the organic phase can be better separated, thereby improving the yield of the benzyl alcohol.
Preferably, the first brine obtained in the step (2) is subjected to oil separation treatment to obtain a first oil layer and a first water layer; adding the first oil layer into the esterification reaction raw material in the step (1) for re-reaction; evaporating and crystallizing the first water layer to obtain a solid, namely crude sodium chloride; the liquid is distilled water and is used for primary washing or secondary washing.
Preferably, the second brine in the step (3) is subjected to oil separation treatment to obtain a second oil layer and a second water layer; the second water layer is directly used for primary washing of the next batch of materials; adding the second oil layer into the esterification reaction raw material in the step (1) for re-reaction.
By adopting the technical scheme, the oil layer washed twice by water is added into the reaction raw materials for continuous reaction, so that the reaction raw materials can be fully reacted, and the yield of benzyl acetate is improved. The first water layer contains more sodium chloride, and crude sodium chloride is obtained by evaporation crystallization and recovery, is used for selling industrial salt and is environment-friendly. The distilled water obtained by evaporation is used for primary or secondary washing, the washing effect cannot be influenced, namely, impurity ions cannot be introduced, the distilled water is recycled, and the production cost is reduced.
Preferably, the temperature of the esterification reaction is 100-125 ℃, and the esterification is continuously stirred for 20-25 h.
By adopting the technical scheme, the raw materials in the esterification reaction reach the maximum conversion rate, and the yield of the benzyl acetate is improved.
Preferably, the vacuum distillation in step (4) is specifically performed as follows: and after primary rectification separation, collecting the fraction at 118 ℃, continuously performing secondary rectification on the fraction, and collecting the fraction at 115 ℃ to obtain a pure benzyl acetate product.
By adopting the technical scheme, the fraction collection temperature is strictly controlled in batches, and the purity of the target product benzyl acetate is improved, so that the quality of the benzyl alcohol raw material is ensured.
In conclusion, the invention has the following beneficial effects:
(1) obtaining benzyl acetate through esterification reaction, obtaining benzyl alcohol and sodium acetate through benzyl acetate hydrolysis reaction, continuously and circularly using the sodium acetate as a raw material for preparing benzyl acetate through esterification reaction, outputting one part of ethyl acetate as a product, and continuously reacting the other part of ethyl acetate as the raw material of the benzyl alcohol; the raw materials, the products or the intermediate products are synthesized into a circulating chain, so that the production cost is reduced, and the method is suitable for industrial mass production;
(2) the phase transfer catalyst raw material solution has high catalytic activity and stability, and still has good phase transfer catalytic effect after being repeatedly used for many times, so that the esterification reaction can be continuously and efficiently reacted, and the conversion rate of the raw material and the yield of benzyl acetate are improved, thereby improving the raw material utilization rate of benzyl acetate, increasing the raw material self-supply amount of benzyl alcohol, and reducing the production cost;
(3) the phase transfer catalyst raw material liquid obtained by pre-treating the compounded catalyst plays a role in catalyzing high activity, and the yield and the purity of the benzyl acetate are effectively improved.
Detailed Description
The invention will be further explained and illustrated with reference to specific examples.
Preparing phase transfer catalyst raw material liquid, wherein the parts are parts by weight, and 1 part represents 10 kg; the method comprises the following specific steps:
and (2) fully mixing 8 parts of benzyltriethylammonium chloride and 5 parts of hexadecyltrimethylammonium bromide, adding 260 parts of benzyl chloride, and reacting at 40 ℃ for 20min to obtain a phase transfer catalyst raw material solution I.
And fully mixing 13 parts of benzyltriethylammonium chloride and 2 parts of hexadecyltrimethylammonium bromide, adding 75 parts of benzyl chloride, and reacting at 50 ℃ for 30min to obtain a phase transfer catalyst raw material liquid II.
And (2) fully mixing 12 parts of benzyltriethylammonium chloride and 3 parts of hexadecyltrimethylammonium bromide, adding the mixture into 150 parts of benzyl chloride, and reacting at 80 ℃ for 50min to obtain a phase transfer catalyst raw material liquid III.
And (2) fully mixing 13 parts of benzyltriethylammonium chloride and 5 parts of hexadecyltrimethylammonium bromide, adding into 120 parts of benzyl chloride, and reacting at 60 ℃ for 35min to obtain a phase transfer catalyst raw material solution IV.
Fully mixing 10 parts of benzyltriethylammonium chloride and 2 parts of hexadecyltrimethylammonium bromide, adding into 136 parts of benzyl chloride, and reacting at 65 ℃ for 45min to obtain a phase transfer catalyst raw material solution V.
The sodium acetate solution used in the present invention is prepared by the following operations: putting solid sodium carbonate into a reaction kettle, adding water to dissolve the solid sodium carbonate, and dropwise adding an acetic acid solution to sequentially prepare a 52% sodium acetate solution I, a 55% sodium acetate solution II, a 58% sodium acetate solution III, a 65% sodium acetate solution IV and a 60% sodium acetate solution V in percentage by mass. CO production during the reaction 2 Gas, the exhaust gas in the reactor is sent to WGL-3 type active carbon organic phase through a pipeline through a gas outlet of the reaction kettleThe waste gas is purified by the waste gas purifier and then discharged through a 15m high exhaust funnel.
The liquid materials in the invention are all added through the elevated tank, and the vacuum pump is used for pumping negative pressure in the production process, and transferring the materials through the pipeline. The parts in the following examples are all parts by weight, and 1 part represents 40 kg.
Example 1
A production process of benzyl acetate specifically comprises the following operation steps:
(1) esterification reaction: adding 40 parts of sodium acetate solution I (52%) into a reaction kettle, pumping 90 parts of benzyl chloride into a metering tank through vacuum, then putting the metering tank into the reaction kettle, simultaneously adding 10 parts of phase transfer catalyst raw material solution I, continuously stirring, opening a steam valve, heating to 120 ℃, enabling the temperature of reaction liquid in the kettle to be 100 ℃, and carrying out esterification reaction for 15 hours to obtain first crude ester.
(2) Primary water washing: putting the first crude ester into a washing kettle, adding washing water (distilled water, a first water layer and a second water layer) to wash the first crude ester, and washing out salts generated in the reaction process to obtain first brine and second crude ester; at the moment, the temperature of the first brine is 80-90 ℃, and the water temperature is reduced to 50-60 ℃ after cooling heat exchange. And then discharging the oil-separated oil into an oil separation tank for oil separation treatment, wherein organic waste gas is generated in the oil separation process, and the separated first oil layer is added into the esterification reaction raw material in the step (1) to continue esterification reaction for 3 hours. And evaporating and crystallizing the separated first water layer, continuously recycling the obtained distilled water (used for primary washing or secondary washing), and selling the crystals as sodium chloride as industrial salt. The oil separation tank is arranged in a closed space, an indoor air draft system is installed for 6 times/h air change to form micro negative pressure for the indoor space, and the indoor air change is sent to a WGL-3 type active carbon organic waste gas purifier for purification treatment and then is discharged through a 15m high-exhaust cylinder.
(3) And (3) secondary water washing: washing the second crude ester with water again to obtain second salt water and third crude ester; performing oil separation treatment on the second brine to obtain a second oil layer and a second water layer; the second water layer is directly used for primary washing of the next batch of materials; and (2) adding the second oil layer into the esterification reaction raw material in the step (1), and continuing the esterification reaction for 2 hours.
(4) And (3) rectification under reduced pressure: sucking the third crude ester into a reduced pressure rectifying tower for reduced pressure distillation twice, collecting the fraction at 118 ℃ after primary rectification separation, continuing secondary rectification of the fraction, and collecting the fraction at 115 ℃; condensing the distillate at 115 ℃ by a coil condenser to obtain a pure benzyl acetate product. The benzyl acetate enters a full-sealed filling chamber for split charging, and the exhaust gas of a vacuum pump is purified by a low-temperature cooling device and then is discharged by an exhaust funnel of 22 m; the low polymer of benzyl chloride remained in the kettle and is sold as a byproduct plastic plasticizer. The purity of benzyl acetate in the product is 99.92%, and the yield is 97.2%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysate to 12, feeding all the produced benzyl acetate into the hydrolysis kettle for hydrolysis, and controlling the temperature of the hydrolysis reaction to be 180 ℃; because the benzyl alcohol is slightly soluble in water, after hydrolysis, the reaction mixture is cooled to 80 ℃, and the benzyl alcohol is layered with the sodium acetate solution, and the layering is obvious; separating out an organic phase to obtain benzyl alcohol; the water phase, namely the sodium acetate solution, is recovered and recycled for the esterification reaction of benzyl acetate. The final hydrolysis reaction gave benzyl alcohol in a yield of 98.0%.
Example 2
Example 2 differs from example 1 in that:
(1) in the esterification reaction, 70 parts of sodium acetate solution II (55%), 150 parts of benzyl chloride and 20 parts of phase transfer catalyst raw material solution II are used as raw materials, and the temperature of reaction liquid in the kettle is 125 ℃, so that the esterification reaction is carried out for 18 hours; adding the first oil layer into the raw materials for esterification reaction, and continuing the esterification reaction for 4 hours; and adding the second oil layer into the esterification reaction raw materials, and continuing to perform esterification reaction for 3 hours. The purity of benzyl acetate in the final product was 99.94% with a yield of 98.1%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysis solution to 13, and controlling the hydrolysis reaction temperature to 200 ℃; after hydrolysis, the reaction mixture is cooled to 100 ℃, and an organic phase is separated out, so that the benzyl alcohol is obtained. The final hydrolysis reaction gave benzyl alcohol in a yield of 98.5%.
Example 3
Example 3 differs from example 1 in that:
(1) in the esterification reaction, 40 parts of sodium acetate solution III (58%), 90 parts of benzyl chloride and 20 parts of phase transfer catalyst raw material solution III are used as raw materials, and the temperature of reaction liquid in the kettle is 110 ℃ to carry out esterification reaction for 20 hours; adding the first oil layer into the raw materials for esterification reaction, and continuing the esterification reaction for 3 hours; and adding the second oil layer into the esterification reaction raw materials, and continuing to perform esterification reaction for 2 hours. The purity of benzyl acetate in the final product was 99.95% and the yield was 97.8%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysis solution to 13, and controlling the hydrolysis reaction temperature to 242 ℃; after hydrolysis, the reaction mixture is cooled to 150 ℃, and the organic phase is separated out, thus obtaining the benzyl alcohol. The final hydrolysis reaction gave benzyl alcohol in a yield of 99.2%.
Example 4
Example 4 differs from example 1 in that:
(1) in the esterification reaction, 40 parts of sodium acetate solution IV (65%), 150 parts of benzyl chloride and 20 parts of phase transfer catalyst solution IV are used as raw materials, the temperature of reaction liquid in the kettle is 120 ℃, and the esterification reaction is carried out for 16 hours; adding the first oil layer into the raw materials for esterification reaction, and continuing the esterification reaction for 5 hours; and adding the second oil layer into the esterification reaction raw materials, and continuing to perform esterification reaction for 2 hours. The purity of benzyl acetate in the final product was 99.92% with a yield of 96.7%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysis solution to 13, and controlling the hydrolysis reaction temperature to 230 ℃; after hydrolysis, the reaction mixture is cooled to 135 ℃, and the organic phase is separated out, thus obtaining the benzyl alcohol. The final hydrolysis gave benzyl alcohol in 98.7% yield.
Example 5
Example 5 differs from example 1 in that:
(1) in the esterification reaction, 50 parts of sodium acetate solution V (60%), 120 parts of benzyl chloride and 15 parts of phase transfer catalyst raw material solution V are used as raw materials, the temperature of reaction liquid in a kettle is 120 ℃, and the esterification reaction is carried out for 22 hours; adding the first oil layer into the esterification reaction raw materials, and continuing carrying out esterification reaction for 1 h; and adding the second oil layer into the esterification reaction raw materials, and continuing to perform esterification reaction for 1 h. The purity of benzyl acetate in the final product was 99.92% with a yield of 99.2%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysis solution to 13, and controlling the hydrolysis reaction temperature to 235 ℃; after hydrolysis, the reaction mixture is cooled to 130 ℃, and an organic phase is separated out, so that the benzyl alcohol is obtained. The final hydrolysis reaction gave benzyl alcohol in a yield of 99.1%.
Example 6
Example 6 differs from example 1 in that:
(1) in the esterification reaction, 63 parts of sodium acetate solution V (60%), 138 parts of benzyl chloride and 13 parts of phase transfer catalyst raw material solution V are used as raw materials, the temperature of reaction liquid in a kettle is 123 ℃, and the esterification reaction is carried out for 22 hours; adding the first oil layer into the esterification reaction raw materials, and continuing carrying out esterification reaction for 1 h; and adding the second oil layer into the esterification reaction raw materials, and continuing to perform esterification reaction for 1 h. The purity of benzyl acetate in the final product was 99.94% and the yield was 99.5%.
(5) Adding 35wt% sodium hydroxide solution into a closed hydrolysis kettle at one time, adjusting the pH of the hydrolysis solution to 13, and controlling the hydrolysis reaction temperature to be 250 ℃; after hydrolysis, the reaction mixture is cooled to 125 ℃, and an organic phase is separated out, so that the benzyl alcohol is obtained. The final hydrolysis reaction gave benzyl alcohol in a yield of 99.4%.
Example 7
Example 7 is different from example 6 in that only one water washing is performed, the first oil layer is added to the esterification reaction raw material, and the esterification reaction is continued for 2 hours; the rest corresponds to example 6. The purity of benzyl acetate in the finally obtained product is 99.35 percent, and the yield is 98.8 percent; the yield of benzyl alcohol was 98.0%.
Example 8
Example 8 differs from example 6 in that the esterification reaction time was 24 h; the oil layer obtained by the two water washes was not added to the raw material reaction solution, and the rest was the same as in example 6. The purity of benzyl acetate in the finally obtained product is 99.62%, and the yield is 98.4%; the yield of benzyl alcohol was 97.6%.
Different comparative examples are listed below, and it should be noted that the comparative examples are intended to prove and find the optimum conditions for the reaction, and are not put into mass production, so the parts referred to in the comparative examples are parts by weight and 1 part is 100g, although different from the weight in the examples, the ratio of the component distribution is kept as a single variable in the examples, and thus, the practical reference value is still obtained.
Comparative example 1
Comparative example 1 differs from example 6 in that: in the esterification reaction, 23 parts of phase transfer catalyst raw material liquid is replaced by 23 parts of benzyltriethylammonium chloride; the hydrolysis reaction was carried out at a pH of 10 for the hydrolysate, which was otherwise identical to that of example 6. The purity of the final benzyl acetate was 99.24% with a yield of 92.0%; the yield of benzyl alcohol was 95.1%.
Comparative example 2
Comparative example 2 differs from example 6 in that: in the esterification reaction, replacing 23 parts of phase transfer catalyst raw material liquid five by 23 parts of hexadecyl trimethyl ammonium bromide; the hydrolysis reaction was carried out at a pH of 14 for the hydrolysate, which was otherwise identical to that of example 6. The purity of benzyl acetate in the finally obtained product is 98.62 percent, and the yield is 87.2 percent; after the hydrolysis reaction, the mixture was emulsified and hardly separated into layers, so that benzyl alcohol was hardly obtained.
Comparative example 3
Comparative example 3 differs from example 6 in that in the esterification reaction, phase transfer catalyst raw material liquid five is replaced with: 4 parts of benzyltriethylammonium chloride and 8 parts of hexadecyltrimethylammonium bromide are fully mixed, added into 136 parts of benzyl chloride solution and reacted for 45min at 65 ℃ to obtain a phase transfer catalyst raw material solution of a comparative example 3; the hydrolysis temperature in the hydrolysis was 170 ℃ and the rest was the same as in example 6. The purity of benzyl acetate in the finally obtained product is 95.00 percent, and the yield is 82.3 percent; the yield of benzyl alcohol was 91.5%.
Comparative example 4
Comparative example 4 differs from example 6 in that in the esterification reaction, phase transfer catalyst raw material liquid five is replaced with: fully mixing 15 parts of benzyltriethylammonium chloride and 1.5 parts of hexadecyltrimethylammonium bromide, adding the mixture into 136 parts of benzyl chloride solution, and reacting at 65 ℃ for 45min to obtain a phase transfer catalyst raw material solution of a comparative example 4; the hydrolysis temperature in the hydrolysis was 260 ℃ and the rest was the same as in example 6. The purity of benzyl acetate in the finally obtained product is 92.23%, and the yield is 82.5%; the yield of benzyl alcohol was 99.0%.
Comparative example 5
Comparative example 5 is different from example 6 in that, in the esterification reaction, 10 parts of benzyltriethylammonium chloride and 2 parts of hexadecyltrimethylammonium bromide are fully mixed, added into 50 parts of benzyl chloride, and reacted for 45min at 65 ℃ to obtain a phase transfer catalyst raw material liquid of comparative example 5; in the hydrolysis reaction, the reaction mixture was cooled to 70 ℃ after hydrolysis, and the rest was identical to example 6. The purity of benzyl acetate in the finally obtained product is 93.64 percent, and the yield is 82.7 percent; the yield of benzyl alcohol was 96.1%.
Comparative example 6
Comparative example 6 is different from example 6 in that, in the esterification reaction, 10 parts of benzyltriethylammonium chloride and 2 parts of hexadecyltrimethylammonium bromide are fully mixed, added into 84 parts of benzyl chloride, and reacted for 45min at 65 ℃ to obtain a phase transfer catalyst raw material liquid of comparative example 6; in the hydrolysis reaction, the reaction mixture was cooled to 160 ℃ after hydrolysis, and the rest was identical to example 6. The purity of benzyl acetate in the finally obtained product is 95.18%, and the yield is 83.5%; the yield of benzyl alcohol was 96.5%.
Comparative example 7
Comparative example 7 differs from example 6 in that in the esterification reaction, 75 parts of sodium acetate solution five (60%), 152 parts of benzyl chloride, 7 parts of phase transfer catalyst raw material solution five were used, the temperature of the reaction solution in the kettle was 123 ℃, and the esterification reaction was carried out for 22 hours, and the rest was the same as example 6. The purity of benzyl acetate in the finally obtained product is 92.70%, and the yield is 90.3%; the yield of benzyl alcohol was 95.3%.
Comparative example 8
Comparative example 8 is different from example 6 in that in the esterification reaction, 35 parts of sodium acetate solution five (60%), 85 parts of benzyl chloride, 23 parts of phase transfer catalyst material solution five were used as raw materials, the temperature of the reaction solution in the kettle was 123 ℃, and the esterification reaction was carried out for 22 hours, and the rest was the same as example 6. The purity of benzyl acetate in the finally obtained product is 91.73 percent, and the yield is 92.8 percent; the yield of benzyl alcohol was 94.9%.
As can be seen from examples 1-6, the benzyl acetate prepared by the benzyl acetate production process has high purity and good yield; the benzyl acetate prepared by the method is continuously hydrolyzed, and benzyl alcohol obtained under the hydrolysis condition of the method has high yield, so that raw material resources are utilized to the maximum extent, the raw material (benzyl acetate) of the hydrolysis reaction is from a self-produced product, the product is used for continuously producing the raw material (benzyl acetate), and the benzyl acetate is output as the product, so that a comprehensive circulation chain of the raw material, the product and an intermediate product is formed, and the method is suitable for mass production. From the examples 6 to 8, it can be known that the water washing after the esterification reaction has a certain influence on the purity of the target product, namely benzyl acetate, and after the water washing is carried out for the second time, the purity and the yield of the purity benzyl acetate are both increased; the oil layer after washing with water is returned to be used, so that the yield of benzyl acetate is further improved.
As can be seen from comparative examples 1 and 2, the pH of the hydrolysis reaction has a great influence on the yield of final benzyl alcohol, and too low pH results in incomplete hydrolysis reaction and reduced yield of benzyl alcohol; the pH value is too high, so that the mixture after hydrolysis is emulsified, the quality of the product cannot be ensured, and the benzyl alcohol cannot be separated out, thereby causing failure and wasting resources. As can be seen from examples 1 to 6 and comparative examples 3 to 4, the temperature of the hydrolysis reaction has a large influence on the reaction, and within the scope of the present invention, the higher the temperature, the higher the yield of benzyl alcohol; however, after the temperature range of the invention is exceeded, the yield of the benzyl alcohol begins to decrease, which proves that the temperature of 250 ℃ is the best point of the hydrolysis reaction of the invention, and the temperature interval higher than 250 ℃ is abandoned in consideration of factors such as production cost, influence on equipment and the like. From comparative examples 5 and 6, it can be seen that the cooling temperature of the mixture after hydrolysis also has an effect on the yield of benzyl alcohol; beyond the cooling temperature range of the present invention, the yield of benzyl alcohol decreases. In addition, as is clear from comparative examples 1 to 6, the phase transfer catalyst raw material liquid in the present invention has an important effect and influence on the yield of the objective product, and the yield of the objective product is greatly reduced by changing the component ratios or changing the composition thereof. As can be seen from comparative examples 7 and 8, the ratio of the raw materials for the esterification reaction also plays an important role in the present invention, and if the ratio is not within the range of the ratio of the present invention, the yield and purity will be reduced.
The above-mentioned embodiments are merely illustrative and not restrictive, and those skilled in the art can modify the embodiments without inventive contribution as required after reading this specification, but only fall within the scope of the claims of the present invention.
Claims (8)
1. The production process of benzyl alcohol is characterized by sequentially comprising the following operation steps of:
(1) esterification reaction: adding benzyl chloride and a phase transfer catalyst raw material solution into a sodium acetate solution, and carrying out an esterification reaction to obtain a first crude ester;
(2) primary water washing: washing the first crude ester with water to obtain a first brine and a second crude ester;
(3) and (3) secondary water washing: washing the second crude ester with water again to obtain second salt water and third crude ester;
(4) and (3) rectification under reduced pressure: distilling the third crude ester under reduced pressure to obtain a finished product of benzyl acetate;
(5) and (3) hydrolysis reaction: hydrolyzing the benzyl acetate under alkaline conditions to obtain benzyl alcohol;
the phase transfer catalyst raw material liquid in the step (1) is prepared by the following operations: mixing a catalyst and benzyl chloride according to a mass ratio of (0.5-1.0): (5-10) reacting for 20-50min at 40-80 ℃ after proportioning to obtain a phase transfer catalyst raw material liquid; the catalyst is a mixture of benzyltriethylammonium chloride and hexadecyltrimethylammonium bromide, and the mass ratio of the benzyltriethylammonium chloride to the hexadecyltrimethylammonium bromide is (0.8-1.3): (0.2-0.5).
2. The process for producing benzyl alcohol according to claim 1, wherein: the weight ratio of the sodium acetate solution in the step (1) to the benzyl chloride and the phase transfer catalyst raw material liquid is (4-7): (9-15): (1-2).
3. The process for producing benzyl alcohol according to claim 1, wherein: and (3) adding the alkali liquor obtained in the hydrolysis reaction in the step (5) into sodium hydroxide solution in a one-time adding manner, and controlling the pH value of the hydrolysate to be 12-13.
4. The process for producing benzyl alcohol according to claim 1, wherein: in the hydrolysis reaction in the step (1), the reaction temperature is controlled to be 180-250 ℃; and cooling the reaction mixture to 80-150 ℃ after hydrolysis, layering, and separating out an organic phase to obtain the benzyl alcohol.
5. The process for producing benzyl alcohol according to claim 1, wherein: carrying out oil separation treatment on the first brine obtained in the step (2) to obtain a first oil layer and a first water layer; adding the first oil layer into the esterification reaction raw material in the step (1) for re-reaction; evaporating and crystallizing the first water layer to obtain a solid, namely crude sodium chloride; the liquid is distilled water and is used for primary washing or secondary washing.
6. The process for producing benzyl alcohol according to claim 1, wherein: performing oil separation treatment on the second brine obtained in the step (3) to obtain a second oil layer and a second water layer; the second water layer is directly used for primary washing of the next batch of materials; adding the second oil layer into the esterification reaction raw material in the step (1) for re-reaction.
7. The process for producing benzyl alcohol according to claim 1, wherein: the temperature of the esterification reaction is 100 ℃ and 125 ℃, and the esterification is continuously stirred for 20-25 h.
8. The process for producing benzyl alcohol according to claim 1, wherein the vacuum distillation in step (4) is specifically performed as follows: and after primary rectification separation, collecting the fraction at 118 ℃, continuously carrying out secondary rectification on the fraction, and collecting the fraction at 115 ℃ to obtain the pure benzyl acetate.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1227213A (en) * | 1997-12-18 | 1999-09-01 | Dsm有限公司 | Process for preparation of benzyl alcohol |
| CN104368385A (en) * | 2014-10-11 | 2015-02-25 | 江苏常州酞青新材料科技有限公司 | Preparation method of catalyst for hydrolysis of benzyl acetate |
| CN104402719A (en) * | 2014-12-01 | 2015-03-11 | 福州福大辉翔化工科技有限公司 | Preparation method of benzyl acetate |
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| CN1227213A (en) * | 1997-12-18 | 1999-09-01 | Dsm有限公司 | Process for preparation of benzyl alcohol |
| CN104368385A (en) * | 2014-10-11 | 2015-02-25 | 江苏常州酞青新材料科技有限公司 | Preparation method of catalyst for hydrolysis of benzyl acetate |
| CN104402719A (en) * | 2014-12-01 | 2015-03-11 | 福州福大辉翔化工科技有限公司 | Preparation method of benzyl acetate |
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