CN108129251A - A kind of synthesis technology of 2- ethyl styrenes - Google Patents

Abstract

The invention discloses a synthesis process of 2-ethylstyrene; its specific steps are as follows: (1) 2-ethylbromobenzene is dissolved in a dry polar organic solvent, and under low temperature conditions, n-butyl Lithium, the dropwise addition time is 1‑4 hours, after the dropwise addition is completed, keep the reaction at low temperature for 1‑6 hours, then add anhydrous N,N‑dimethylformamide, keep the temperature for 1‑6 hours after the addition, and then add Quenching with a quenching solvent, washing with water, standing to separate layers, and concentrating the organic phase without further purification to obtain an intermediate with a yield of 95‑100%; (2) combining the intermediate, inorganic base, triphenylmethylphosphine and The dry solvents are mixed, and after mixing, under an inert atmosphere, under reflux conditions, the heat preservation reaction is carried out for 2-10 hours, and the target product is obtained after post-processing, with a yield of 80-90%. The product produced by the method of the invention has good quality, stable operation, high yield, less waste and low production cost.

Description

A kind of synthetic technique of 2-ethylstyrene

technical field

The invention relates to a method for preparing 2-ethylstyrene, which belongs to the field of organic synthesis technology.

Background technique

Olefin-containing compounds are important monomers of polymers, which are reactive and can undergo addition reactions such as hydrogenation, halogenation, hydration, hydrogenation, hypohalogenation, sulfation, epoxidation, polymerization, etc. Bonds are broken to generate aldehydes, carboxylic acids, etc. Compounds containing olefins are easy to carry out structural modification, and various functional groups can be easily introduced. 2-Ethylstyrene is a very widely used connecting block in chemistry, and no related synthesis method has been found in the literature; this patent design uses cheap and easy-to-obtain 2-ethylbromobenzene as raw material, after functional group conversion Obtain 2-ethylbenzaldehyde, and then react with triphenylmethylphosphine and alkali in reflux to obtain the target compound 2-ethylstyrene.

Contents of the invention

In view of the lack of literature on the synthesis of 2-ethylstyrene in the prior art, the invention provides a synthetic process route for the preparation of 2-ethylstyrene. The produced product has good quality, stable operation, high yield, and three wastes. Less, low production cost.

The technical solution of the present invention is specifically introduced as follows.

A kind of synthetic technique of 2-ethylstyrene, concrete steps are as follows,

(1) Dissolve 2-ethylbromobenzene in a dry polar organic solvent, add n-butyllithium dropwise under low temperature conditions, and the dropwise addition time is 0.5-4 hours. -6 hours, then add anhydrous N,N-dimethylformamide, keep warm for 1-6 hours after the addition, then add quenching solvent to quench, wash with water, stand to separate layers, and concentrate the organic phase without further purification. Obtain the intermediate 2-ethylbenzaldehyde, which is directly used in step (2) reaction, and the yield is 95-100%;

(2) Mix the intermediate 2-ethylbenzaldehyde, inorganic base, triphenylmethylphosphine and dry solvent, after mixing, under inert atmosphere, keep warm for 2-10 hours under reflux conditions, after the reaction is over, then The pure product of the target product is obtained by processing, and the yield is 80-90%.

In the present invention, in step (1), the low temperature is -60°C-78°C.

In the present invention, in step (1), the dry polar organic solvent is dichloromethane or tetrahydrofuran.

In the present invention, in step (1), the molar ratio of 2-ethylbromobenzene, n-butyllithium and N,N-dimethylformamide is 1:(1.1-2.0):(1.2-2.0), dry The volume-mass ratio of the polar organic solvent to 2-ethylbenzaldehyde is 10:1～20:1mL/g.

In the present invention, in step (1), the quenching reagent is a saturated ammonium chloride solution.

In the present invention, in step (1), the dropping time is 0.5 to 1 hour. After adding n-butyllithium dropwise, keep the temperature at low temperature for 1 to 2 hours. After adding N,N-dimethylformamide, keep the temperature for 1 to 2 hours. 2 hours.

In the present invention, in step (2), the inorganic base is any one of potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate or calcium hydroxide.

In the present invention, in step (2), the molar ratio of 2-ethylbenzaldehyde, inorganic base and triphenylmethylphosphine is 1:(1.1-2.0):(1.1-2.5).

Among the present invention, in step (2), the dry solvent is selected from cyclohexane or any one in 1,4-dioxane; The volume ratio of intermediate 2-ethylbenzaldehyde and the dry solvent is 1: 8～1:15.

In the present invention, in step (2), the post-treatment method is specifically as follows: firstly filter the reacted solution, wash the obtained filtrate successively, extract with ethyl acetate, dry, concentrate ethyl acetate, add petroleum Ether, triphenylphosphine oxide was fully analyzed, and then filtered and concentrated to obtain 2-ethylstyrene.

In the present invention, in step (2), the temperature is kept for 7-8 hours under reflux conditions.

Compared with the prior art, the beneficial effects of the present invention are:

The present invention designs a reasonable and simple process synthesis route of 2-ethylstyrene. The present invention uses cheap and easy-to-obtain 2-ethylbromobenzene as a raw material, and directly reacts with DMF in a dry solvent in the presence of low temperature to obtain 2-ethylbenzaldehyde, and then reacts with triphenylmethylphosphine under an alkali environment Reflux reaction to prepare 2-ethylstyrene, the obtained crude product is purified by water washing, petroleum ether washing and filtration, and the high-purity target product can be obtained without using more expensive reagents and complicated purification methods. This process route synthesizes o-ethyl styrene The styrene process has low cost, simple operation, high purity and high yield, which is above 80%.

Detailed ways

Now, the present invention will be further described in conjunction with the embodiments, but the implementation of the present invention is not limited thereto.

With the polar organic solvent in the step (1) being DMF, the inorganic base in the step (2) is potassium carbonate as an example, the chemical reaction equation of the synthesis technique of the present invention is as follows:

The synthesis technique of embodiment 1 2-ethylstyrene, its steps are as follows:

One, the synthesis of 2-ethylbenzaldehyde

2-Ethylbromobenzene (6g, 32.4mmol) was dissolved in 100ml of dry THF, then cooled to -78°C, 2.5mol/L (14.4ml) of tert-butyl lithium cyclohexane solution was added dropwise, and The adding time is 0.5 hours, and the temperature is controlled not to exceed -65°C during the dropping process. After the dropping is completed, react at -75°C for 1 hour, then add 3ml DMF solution and keep it warm for 1 hour, spot plate detection, saturated ammonium chloride solution Quenched, washed with water, dried, and concentrated under reduced pressure to obtain a colorless solution (4.3 g, yield 98.8%).

Two, the synthesis of 2-ethylstyrene

Put 2-ethylbenzaldehyde (4.35g) in a single-necked flask, add 6.7g of potassium carbonate and 18g of triphenylmethylphosphine bromide, add 40ml of dry 1,4-dioxane, and Warm to 110°C for reflux reaction, react for 6 hours for TLC plate detection, then cool to room temperature, perform suction filtration, wash with petroleum ether and then wash with water, concentrate under reduced pressure, add petroleum ether, and then filter again to collect the liquid phase Concentrate under reduced pressure to obtain 2-ethylstyrene (3.64 g, yield 85%) as a colorless liquid product. ¹ H NMR (501MHz, CDCl ₃ ) δ7.49 (dd, J=13.8, 12.7Hz, 1H), 7.25–7.16 (m, 3H), 7.02 (dd, J=17.4, 11.0Hz, 1H), 5.67( dd,J=17.4,1.1Hz,1H),5.31(dd,J=11.0,1.1Hz,1H),2.73(q,J=7.6Hz,2H),1.22(t,J=7.6Hz,3H).

The synthesis technique of embodiment 2 2-ethylstyrene, its steps are as follows:

One, the synthesis of 2-ethylbenzaldehyde

2-Ethylbromobenzene (6g, 32.4mmol) was dissolved in 100ml of dry dichloromethane, then cooled to -75°C, and 2.5mol/L (18ml) of tert-butyllithium cyclohexane solution was added dropwise, The dropping time is 0.5 hours, and the temperature is controlled not to exceed -65°C during the dropping process. After the dropping is completed, react at -75°C for 1 hour, then add 3.7ml of DMF solution and keep it warm for 1 hour, spot plate detection, saturated chlorination Quenched with ammonium solution, washed with water, dried, and concentrated under reduced pressure to obtain a colorless solution (4.27g, yield 99%).

Two, the synthesis of 2-ethylstyrene

Put 2-ethylbenzaldehyde (4.35g) in a single-necked flask, add 7.8g of sodium carbonate and 13.5g of triphenylmethylphosphine, add 40ml of dry 1,4-dioxane, and under nitrogen protection , warmed to 110°C for reflux reaction, reacted for 8 hours for TLC plate detection, then cooled to room temperature, carried out suction filtration, washed with petroleum ether and then washed with water, concentrated under reduced pressure, added petroleum ether, solid precipitated and filtered again, collected liquid phase and concentrated , the colorless liquid product 2-ethylstyrene (3.5g, yield 81.7%) can be obtained.

The synthesis technique of embodiment 3 2-ethylstyrene, its steps are as follows:

One, the synthesis of 2-ethylbenzaldehyde

Dissolve 2-ethylbromobenzene (6g, 32.4mmol) in 100ml of dry tetrahydrofuran, then cool to -78°C, add dropwise 2.5mol/L (25ml) of tert-butyllithium cyclohexane solution, and dropwise The time is 0.5 hours. During the dropping process, the temperature is controlled not to exceed -65°C. After the dropwise addition is completed, react at -78°C for 1 hour, then add 3.7ml of DMF solution and keep it warm for 1 hour. Spot detection, saturated ammonium chloride solution Quenched, washed with water, dried and concentrated to obtain a colorless solution (4.2g, yield 96.5%).

Two, the synthesis of 2-ethylstyrene

Put 2-ethylbenzaldehyde (4.35g) in a single-necked flask, add 1.95g of sodium hydroxide and 15.7g of triphenylmethylphosphine, add 40ml of dry 1,4-dioxane, and , heated to reflux reaction, and reacted for 7 hours for TLC plate detection. After cooling to room temperature, suction filtration was performed, washed with petroleum ether and then washed with water. After concentration under reduced pressure, petroleum ether was added and solids were precipitated and filtered again. The liquid phase was collected and concentrated. The colorless liquid product 2-ethylstyrene (3.55g, yield 82.9%) could be obtained.

The synthesis technique of embodiment 4 2-ethylstyrene, its steps are as follows:

One, the synthesis of 2-ethylbenzaldehyde

2-Ethylbromobenzene (6g, 32.4mmol) was dissolved in 100ml of dry dichloromethane, then cooled to -70°C, and 2.5mol/L (22.7ml) of tert-butyllithium cyclohexane solution was added dropwise , the dropping time is 0.5 hours, and the temperature is controlled not to exceed -65°C during the dropping process. Quenched with ammonium chloride solution, washed with water, dried and concentrated to obtain a colorless solution (4.21g, yield 96.8%).

Two, the synthesis of 2-ethylstyrene

Put 2-ethylbenzaldehyde (4.35g) in a single-necked flask, add 1.95g of potassium hydroxide and 15.7g of triphenylmethylphosphine, add 40ml of dry cyclohexane, and heat to reflux under nitrogen protection Reaction, reacted for 6 hours for TLC plate detection, then decompressed to spin out cyclohexane, after decompression, suction filtration, petroleum ether washing and then water washing, decompression concentration, adding petroleum ether, solid precipitation and filtration again, The liquid phase was collected and concentrated to obtain the colorless liquid product 2-ethylstyrene (3.4 g, yield 85.1%).

The synthesis technique of embodiment 5 2-ethylstyrene, its steps are as follows:

One, the synthesis of 2-ethylbenzaldehyde

2-Ethylbromobenzene (6g, 32.4mmol) was dissolved in 100ml of dry tetrahydrofuran, then cooled to -75°C, 2.5mol/L (25.8ml) of tert-butyl lithium cyclohexane solution was added dropwise, The addition time is 0.5 hours, and the temperature is controlled not to exceed -65°C during the dropwise addition process. After the dropwise addition is completed, react at -75°C for 1 hour, then add 3.7ml DMF solution and keep it warm for 1 hour, spot plate detection, saturated ammonium chloride The solution was quenched, washed with water, dried, and concentrated under reduced pressure to obtain a colorless solution (4.25 g, yield 97.7%).

Two, the synthesis of 2-ethylstyrene

Put 2-ethylbenzaldehyde (4.35g) in a single-necked flask, add 3.6g of potassium hydroxide and 22.5g of triphenylmethylphosphine, add 40ml of dry cyclohexane, and heat to reflux under nitrogen protection Reaction, reacted for 6 hours for TLC plate detection, and then decompressed to spin out cyclohexane. After decompression, after distillation, cool to room temperature, perform suction filtration, wash with petroleum ether, then wash with water, add petroleum after concentrating under reduced pressure After the ether, the solid precipitated and was filtered again, and the liquid phase was collected and concentrated to obtain the colorless liquid product 2-ethylstyrene (3.9 g, yield 91.1%).

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and that described in the above-mentioned embodiments and the description only illustrates the principles of the present invention, and the present invention also has various aspects without departing from the spirit and scope of the present invention. Variations and improvements all fall within the scope of the claimed invention.

Claims (10)

1. a synthetic technique of 2-ethylstyrene, is characterized in that, concrete steps are as follows, (1) Dissolve 2-ethylbromobenzene in a dry polar organic solvent, add n-butyllithium dropwise under low temperature conditions, and the dropwise addition time is 0.5-4 hours. -6 hours, then add anhydrous N,N-dimethylformamide, keep warm for 1-6 hours after the addition, then add quenching reagent to quench, wash with water, stand to separate and separate, the organic phase is concentrated without further purification, Obtain the intermediate 2-ethylbenzaldehyde, which is directly used in step (2) reaction, and the yield is 95-100%; (2) Mix the intermediate 2-ethylbenzaldehyde, inorganic base, triphenylmethylphosphine and dry solvent, after mixing, under inert atmosphere, keep warm for 2-10 hours under reflux conditions, after the reaction is over, then The pure product of the target product is obtained by processing, and the yield is 80-90%. 2. The synthesis process according to claim 1, characterized in that: in step (1), the low temperature is -60°C-78°C. 3. The synthesis technique according to claim 1, characterized in that: in step (1), the dry polar organic solvent is methylene chloride or tetrahydrofuran. 4. synthetic technique according to claim 1, is characterized in that: in step (1), the mol ratio of 2-ethylbromobenzene, n-butyllithium and N,N-dimethylformamide is 1:( 1.1-2.0): (1.2-2.0), the volume-mass ratio of dry polar organic solvent to 2-ethylbenzaldehyde is 10:1～20:1mL/g. 5. synthetic technique according to claim 1, is characterized in that, in step (1), quenching reagent is saturated ammonium chloride solution. 6. The synthetic process according to claim 1, characterized in that, in step (1), the dropping time is 0.5 to 1 hour, and after adding n-butyllithium dropwise, it is kept at a low temperature for 1 to 2 hours, and after adding N, After N-dimethylformamide, keep warm for 1-2 hours. 7. synthetic technique according to claim 1, is characterized in that: in step (2), inorganic base is any in potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate or calcium hydroxide ; In step (2), the molar ratio of 2-ethylbenzaldehyde, inorganic base and triphenylmethylphosphine is 1:(1.1-2.0):(1.1-2.5). 8. The synthetic technique according to claim 1, characterized in that: in step (2), the dry solvent is selected from any one of cyclohexane or 1,4-dioxane; intermediate 2-ethyl The volume ratio of benzaldehyde and dry solvent is 1:8～1:15. 9. synthetic technique according to claim 1, is characterized in that: in step (2), the method for aftertreatment is specifically as follows: first the solution after reaction is filtered, and the filtrate that obtains is washed successively, ethyl acetate extracts , dry, concentrate ethyl acetate, add petroleum ether after concentration, fully analyze triphenylphosphine oxide, filter and concentrate again to obtain 2-ethylstyrene. 10. The synthesis process according to claim 1, characterized in that, in step (2), the temperature was incubated under reflux conditions for 7-8 hours.