CN1660743A - Method for synthesizing 4-methoxy styrene - Google Patents

Abstract

A process for synthesizing 4-methoxy styrene includes reductive reaction of 4-methoxy acetophenone to obtain 4-(4'-methoxyphenyl) ethanol, esterifying reaction to obtain 1-(4'-methoxyphenyl) ethyl sulfonate, abate reaction to obtain 4-methoxy styrene, and vacuum rectifying.

Description

The synthetic method of 4-methoxy styrene

Technical field

The present invention relates to a kind of synthetic method of 4-methoxy styrene.

Background technology:

Substituted phenylethylene is the very important industrial chemicals of a class, is widely used in material, medicine intermediate, tackiness agent, coating, fields such as sun-screening agent.This compounds is easy to polymerization, but both homopolymerizations, but also copolymerization adopts different polymerization methodses can obtain the macromolecular material of various different molecular weights, and these macromolecular materials often show than polystyrene better properties.As: the coating that substituted polystyrene is made has the expelling water and the displacement of reservoir oil (EP 541395) preferably than ordinary polystyrene.In addition, the polymkeric substance of substituted phenylethylene can also be made liquid crystal material (JP 08271739).In these substituted phenylethylene compounds, a very important compound is the 4-methoxy styrene.Development along with information industry; system integration degree is more and more higher, and semiconductor device is more and more littler, and this has just proposed very high requirement to the erosion resistant at lithography; this erosion resistant requires that a protecting group of seeing the easy acidolysis of light is arranged, and before and after the acidolysis different solvabilities will be arranged.The polymkeric substance of 4-methoxy styrene is exactly a kind of erosion resistant (US 4603101) that can satisfy above-mentioned requirements.The method for preparing substituted phenylethylene of report has much at present, roughly can be divided into following three classes:

One is raw material with aromatic hydrocarbon

(1) with the ethylbenzene be raw material, catalytic dehydrogenation gets vinylbenzene, and (DE 2317525; EP 128984).

This method feed stock conversion is low, and by product is many, separation difficulty, and when preparation had substituent vinylbenzene, by product was more, sometimes even can not get required product.

(2) replace toluene and monochloro methane and also can prepare substituted phenylethylene (US3636182) 700 ℃ of following reactions.

This method needs special reaction unit, to adapt to the reaction conditions of High Temperature High Pressure.And conversion of raw material is low, and by product is many, and the substituted phenylethylene of generation is easily polymerization at high temperature.

Two is raw material with the aromatic aldehyde

(1) substituted benzaldehyde and Grignard reagent reaction, (US 2404319 for dehydration preparation substituted phenylethylene again; J.Am.Chem.Soc., 1985,80,3645), used Grignard reagent in the reaction process.Grignard reagent requires the reaction system strictness anhydrous in preparation and use, and the raw material that this method is used costs an arm and a leg as substituted benzaldehyde and methyl Grignard reagent, is not suitable for suitability for industrialized production.

(2) substituted benzaldehyde and Witting reagent prepared in reaction substituted phenylethylene (Polymer, 1983,24,995), though this method has been lacked a step than use Grignard reagent method on synthesis step, the method for shortcoming and use Grignard reagent is similar.And the preparation Witting reagent is more loaded down with trivial details than Grignard reagent, need use gasiform one monobromethane, reagent such as highly basic, and these all need special conversion unit.Desired raw material substituted benzaldehyde, the price of triphenyl phosphorus are also all expensive.

(3) with the activated zinc powder be catalyzer, substituted benzaldehyde and methylene bromide react substituted phenylethylene (US5763560), zinc powder will activate with Acetyl Chloride 98Min. under the condition of anhydrous and oxygen-free before use in this method.And react and also will under the condition of anhydrous and oxygen-free, carry out, prevent that zinc powder is oxidized.Severe reaction conditions is not suitable for mass production.

Three β-elimination prepared in reaction substituted phenylethylene

(1) with the substituted acetophenone be raw material, through the reduction, dewater substituted phenylethylene (J.Org.Chem., 1958,23,544), this method raw material is easy to get, and is simple to operate.Key is a dehydrating step, generates by product ether easily.

(2) Aslam etc. makes ether to the alcohol that the substituted acetophenone reduction obtains earlier by the intermolecular condensation reaction, then, ether dewaters and also makes substituted phenylethylene (US 5194672), this method generates alkene to dehydration of alcohols and finishes in two steps, overcome the direct many disadvantages of olefin by-products, the good method of can yet be regarded as of generating of a step.

(3) acid amides is eliminated reaction and also can be obtained substituted phenylethylene (US 4650910), and this reaction is rarely found, needs to use highly basic in the reaction, and as potassium tert.-butoxide, not only price is expensive, and equipment is also had special requirement.The preparation of raw material acid amides is also more loaded down with trivial details.

Summary of the invention:

The objective of the invention is to overcome problems of the prior art, a kind of mass production that is suitable for is provided, simple to operate, with low cost, highly selective, the method for preparing the 4-methoxy styrene of high yield.

The reaction mechanism of the inventive method is as follows:

For achieving the above object, the present invention adopts following technical scheme:

A kind of synthetic method of 4-methoxy styrene is characterized in that, the concrete steps of present method are as follows:

A. adopt reduction method, the 4-methoxyacetophenone is reduced to 1-(4 '-p-methoxy-phenyl) ethanol: in reaction flask, add the 4-methoxyacetophenone, with ethanol is solvent, stir, after waiting to dissolve, add the borane reducing agent potassium hydride KH in batches, keep temperature of reaction between 20 ℃-40 ℃, reacted 4-12 hour; After reaction finishes, add and the isopyknic water of reaction solution, fully stir, with hydrolysis excessive POTASSIUM BOROHYDRIDE and boronate complex; Use ethyl acetate extraction then, separatory gets organic layer; Water layer is used ethyl acetate extraction twice again, merges organic layer, uses anhydrous magnesium sulfate drying, is spin-dried for solvent with Rotary Evaporators, gets product 1-(4 '-p-methoxy-phenyl) ethanol.The mol ratio of raw material 4-methoxyacetophenone and borane reducing agent potassium hydride KH is 1: 0.1-0.5;

B. esterification: the product of step a gained being added in the reaction flask, add sal enixum again, is solvent with the hexanaphthene; Under agitation be heated to backflow, reacted 6-12 hour; After reaction finished, solids removed by filtration got filtrate, uses anhydrous magnesium sulfate drying, and Rotary Evaporators is spin-dried for solvent, got product sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl ester.The mol ratio of reactant 1-(4 '-p-methoxy-phenyl) ethanol and sal enixum is 1: 0.5-1.5:

C. eliminate reaction: with the product of step b gained, 80-100 ℃ cut is collected in rectification under vacuum under 5-8 mmhg condition, and in receiving bottle, add stopper, avoid product polymerization in long-time collection process, promptly get product 4-methoxy styrene, place refrigerator to preserve.

Described reductive agent can also adopt Lithium Aluminium Hydride, sodium borohydride, but is advisable with POTASSIUM BOROHYDRIDE, and required equipment is simple, reaction temperature and, the reaction times is short.

The present invention divides dehydration of alcohols two steps of work to finish, and at first generates sulphonate, eliminates then.The alcohol directly reaction of dehydration generation alkene not only easily generates by products such as ether, and the temperature of reaction height, the easy polymerization of product 4-methoxy styrene.Just do not have above problem when two steps of minute work when finishing, the temperature of reaction in two steps do not have by product to generate all below 100 ℃.

In eliminating reaction process, the present invention adopts under the condition of decompression, the limit reaction, and the method for limit rectifying breaks away from the 4-methoxy styrene of generation rapidly from reaction system.Can impel chemical equilibrium to move to the direction that helps generating product so on the one hand, avoid the accumulation of 4-methoxy styrene in the reaction system on the other hand, it is big that concentration becomes, polymerization reaction take place under hot conditions.Sulfuric acid under reaction is eliminated simultaneously makes reaction system be acid, also can prevent the 4-methoxy styrene polymerization in reaction system that generates.

The present invention experienced for three steps and has finished the synthetic of 4-methoxy styrene, and the overall yield in three steps is about 85%, and the reaction required equipment is simple, raw material is cheap and easy to get, per step reaction conditions gentleness, productive rate height, do not have by product, target product only need just can obtain through simple the processing.

Specific implementation method:

Embodiment one: existing concrete processing step with the inventive method is described below:

A. reduction reaction: in 5 liters round-bottomed flask, add 1 kilogram of methoxyacetophenone of 4-(6.659 moles), 2 liters of industrial spirit, stir, after waiting to dissolve, add POTASSIUM BOROHYDRIDE 120 grams (2.224 moles) in batches, keep temperature of reaction to be advisable simultaneously at 20 ℃-40 ℃, reacted 6 hours, reaction adds isopyknic water after finishing, fully stir, with hydrolysis excessive POTASSIUM BOROHYDRIDE and boronate complex.The ethyl acetate extraction that adds 2 liters then, separatory gets organic layer.Water layer is used a spot of ethyl acetate extraction twice again, merges organic layer.Use anhydrous magnesium sulfate drying, be spin-dried for solvent with Rotary Evaporators again, get 0.993 kilogram of product 1-(4 '-p-methoxy-phenyl) ethanol, productive rate 98% (productive rate is as the criterion with raw material 4-methoxyacetophenone, down together);

B. esterification: 1-(4 '-p-methoxy-phenyl) ethanol 0.993 kilogram (6.524 moles) added in 5 liters the three-necked flask, add 1 kilogram of sal enixum (7.344 moles) more successively, 1 liter of hexanaphthene.Thermometer is installed, agitator, reflux condensing tube on the three-necked flask.Heating in water bath to hexanaphthene refluxes, and reacts 6 hours.After reaction finished, solids removed by filtration got filtrate, and anhydrous magnesium sulfate drying is spin-dried for solvent, got 1.455 kilograms of product sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl esters.Productive rate 96%;

C. eliminate reaction: in the round-bottomed flask with 1 liter of 1.455 kilograms of (6.265 moles) adding of sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl ester, rectifying column is installed, still head, straight cold finger carries out rectification under vacuum, adds a small amount of tert-butyl catechol 1 gram (0.006 mole) in the receiving bottle, the about 5-8 mmhg of control pressure, collect 80-100 ℃ cut, promptly get 0.765 kilogram of product 4-methoxy styrene (5.701 moles), productive rate is 91%, three step overall yield 85.6%.Place refrigerator to preserve product.

Embodiment two: present embodiment and embodiment one are basic identical, and different is, in step a, the amount of used POTASSIUM BOROHYDRIDE is 72 grams (1.332 moles), then the reaction times of step a extends to 12 hours, gets 0.801 kilogram of product 1-(4 '-p-methoxy-phenyl) ethanol, productive rate 79%.0.617 kilogram of the product 4-methoxy styrene that obtains at last, overall yield is 69.0%.

Embodiment three: present embodiment and embodiment one are basic identical, and different is, in step a, the amount of used POTASSIUM BOROHYDRIDE is 180 grams (3.329 moles), then the reaction times of step a foreshortens to 4 hours, gets 0.989 kilogram of product 1-(4 '-p-methoxy-phenyl) ethanol, productive rate 98%.0.758 kilogram of the product 4-methoxy styrene that obtains at last, overall yield is 84.8%.

Embodiment four: present embodiment and embodiment one are basic identical, and different is that in step b, 0.725 kilogram of the amount of used sal enixum (5.327 moles) gets 1.182 kilograms of product sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl esters, productive rate 78%.0.621 kilogram of the product 4-methoxy styrene that obtains at last, overall yield is 69.5%.

Embodiment five: present embodiment and embodiment one are basic identical, and different is that in step b, 1.360 kilograms of the amounts of used sal enixum (9.988 moles) get 1.485 kilograms of product sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl esters, productive rate 98%.0.781 kilogram of the product 4-methoxy styrene that obtains at last, overall yield is 87.4%.

Claims (1)

1. the synthetic method of a 4-methoxy styrene is characterized in that, the concrete steps of present method are as follows:

A. adopt reduction method, the 4-methoxyacetophenone is reduced to 1-(4 '-p-methoxy-phenyl) ethanol: in reaction flask, add the 4-methoxyacetophenone, with ethanol is solvent, stir, after waiting to dissolve, add the borane reducing agent potassium hydride KH in batches, keep temperature of reaction between 20 ℃-40 ℃, reacted 4-12 hour; After reaction finishes, add and the isopyknic water of reaction solution, fully stir, with hydrolysis excessive POTASSIUM BOROHYDRIDE and boronate complex; Use ethyl acetate extraction then, separatory gets organic layer; Water layer is used ethyl acetate extraction twice again, merges organic layer, uses anhydrous magnesium sulfate drying, is spin-dried for solvent with Rotary Evaporators, gets product 1-(4 '-p-methoxy-phenyl) ethanol; The mol ratio of raw material 4-methoxyacetophenone and borane reducing agent potassium hydride KH is 1: 0.1-0.5;

B. esterification: the product of step a gained being added in the reaction flask, add sal enixum again, is solvent with the hexanaphthene; Under agitation be heated to backflow, reacted 6-12 hour; After reaction finished, solids removed by filtration got filtrate, uses anhydrous magnesium sulfate drying, and Rotary Evaporators is spin-dried for solvent, got product sulfonic acid-1-(4 '-p-methoxy-phenyl) ethyl ester.The mol ratio of reactant 1-(4 '-p-methoxy-phenyl) ethanol and sal enixum is 1: 0.5-1.5;

C. eliminate reaction: with the product of step b gained, 80-100 ℃ cut is collected in rectification under vacuum under 5-8 mmhg condition, and in receiving bottle, add stopper, avoid product polymerization in long-time collection process, promptly get product 4-methoxy styrene, place refrigerator to preserve.