JPH03123748A - Preparation of allyl vinyl ether - Google Patents

Abstract

PURPOSE:To probitably prepare the subject compound by reacting acetaldehyde with allyl alcohol in the presence of an acidic catalyst, separating the non- reacted raw material together with the resultant water from the tower tip of a reactor and subsequently pyrolyzing the tower bottom solution in the presence of a phosphoric acid catalyst. CONSTITUTION:i) A compound of formula I is reacted with a compound of formula II in the presence of an acidic catalyst to prepare the solution of a compound of formula III. ii) The reaction solution is subjected to a distillation treatment to evaporate off the non-reacted compound of formula I and the resultant water as an azeotropic mixture with the non-reacted compound of formula II from the tower tip of the reactor and also separate the mixture solution of the resultant compound of formula III and to remained portion of the non-reacted compound of formula II from the tower bottom. iii) The tower bottom solution is pyrolyzed in the presence of a phosphoric acid by a reaction distillation method to probitably provide the objective compound useful as a raw material for various functional polymers without any complicated process for separating and purifying the acetal.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing allyl vinyl ether, which is useful as a raw material for various functional polymers.

<Prior Art> It is well known to obtain allyl vinyl ether from acetaldehyde and allyl alcohol via acetaldehyde diallyl acetal.

The reaction formula for synthesizing allyl vinyl ether from acetaldehyde and allyl alcohol via acetaldehyde diallyl acetal is as follows.

CH3CHO+ 2 CH2-CHCH20H; CH3CH(OCH2CH4CH2)2+ H20 CHCH(OCH2CH-CH2)2 CH2-CHCH20CH-CH2 + CH2-CHCH20H The above reaction is an equilibrium reaction and the conversion rate does not exceed the equilibrium composition.

Therefore, - For boat fishing, when producing the corresponding acetal from acetaldehyde and alcohol, in order to increase the conversion rate, dehydrating agents such as calcium chloride or inert solvents are used to separate the produced water. Measures may be taken to advance the reaction.

<Problems to be solved by the invention> However, when calcium chloride is used, a large amount of calcium chloride is required, causing pollution problems such as water contamination, and equipment is severely corroded by calcium chloride, causing problems such as glass lining etc. This method requires a reactor made of a special material and accompanying equipment, and is by no means a satisfactory method for industrially producing allyl vinyl ether via acetaldehyde diallyl acetal.

These methods focus on increasing the conversion rate due to the difficulty of separating and purifying the produced acetal, and implement the complicated process.

As a result of intensive research into a method that does not require the complicated process of separating and purifying acetal, the present inventors have found that allyl vinyl ether can be industrially advantageously produced from acetaldehyde and allyl alcohol via acetaldehyde diallyl acetal. I found a possible way.

Means for Solving the Problems〉 That is, the present invention provides ``In the production of allyl vinyl ether from acetaldehyde and allyl alcohol, (a) a synthetic solution of acetaldehyde diallyl acetal is obtained from acetaldehyde and allyl alcohol in the presence of an acidic catalyst. First step (b) The synthesis liquid is distilled to distill unreacted acetaldehyde and water, which is a reaction product, from the top of the tower by azeotroping with unreacted allyl alcohol, and from the bottom of the tower, the reaction product is distilled. A second step of obtaining a mixed solution of acetaldehyde diallyl acetal and unreacted allyl alcohol that has not been distilled from the top of the column (C) A second step of thermally decomposing the acetaldehyde diallyl acetal by a reactive distillation method using the bottom liquid in the presence of a phosphoric acid catalyst. ``A method for producing allyl vinyl ether, which is characterized by comprising three steps.''

The present invention will be explained in detail below.

When carrying out the present invention, the mixing ratio of acetaldehyde and allyl alcohol in the first step is not particularly limited.

The charging ratio (molar ratio) of acetaldehyde and allyl alcohol is theoretically 1/2 according to the reaction formula, but considering the equilibrium reaction, any ratio may be used.

However, in order to obtain an appropriate space-time yield and take into account the entire process, in order to reduce the amount of recycled raw material recycled, it is recommended to use allyl alcohol in an amount of 1 to 3 times the mole of acetaldehyde for boat fishing. is preferred.

There is no particular restriction on the reaction temperature, but a range of 0 to 80°C is preferred.

If the temperature exceeds 80°C, the boiling point of the raw material mixture will be exceeded or the by-product of high-boiling compounds will increase, which is disadvantageous.

If the temperature is below 0°C, the reaction rate becomes slow, which is not preferable.

The acid catalyst is not particularly limited, and examples include acidic ion exchange resins, sulfuric acid, hydrochloric acid, phosphoric acid, toluenesulfonic acid, etc.; however, when considering catalyst separation, reactor material, etc., acidic It is preferred to use a type ion exchange resin.

As acidic type ion exchange resins, - boat fishing gel type, MR
Any type can be used, but due to catalyst life and strength, MR
It is preferable to use an acidic type ion exchange resin.

The amount of catalyst used should be determined depending on the strength of the acid used, the reaction temperature, etc.;
It may be set to about 0%.

The reaction residence time is determined by the molar ratio, reaction temperature, amount of catalyst, etc., but is generally about 0.5 to 10 hours.

The reaction can usually be carried out under normal pressure, but it may be carried out under increased pressure depending on the composition of the raw materials and the reaction temperature.

Further, as the reaction type, either continuous or batch type can be employed.

In the second step, after separating the catalyst, the reaction solution is introduced into a continuous distillation column and distilled, and unreacted acetaldehyde and water, which is a reaction product, are distilled out from the top of the column by azeotroping with unreacted allyl alcohol. A mixed solution of acetaldehyde diallyl acetal, which is a reaction product, and unreacted allyl alcohol that was not distilled out from the top of the column is obtained from the bottom of the column.

As the distillation column, a general packed column or tray column can be used.

There is no particular restriction on the column length, but in general, if the column length is short, it is necessary to increase the reflux ratio, and if the column length is long, the reflux ratio can be decreased. It is preferable to select a reflux ratio according to the length of the column to be used, distill the distillate with an azeotropic composition of allyl alcohol and water, and operate the column under conditions that completely remove water from the bottom liquid.

Distillation can be carried out at normal pressure, increased pressure, or reduced pressure, but it is generally desirable to carry out the distillation at normal pressure.

In the third step, allyl vinyl ether is obtained by thermally decomposing acetaldehyde diallyl acetal using the bottom liquid obtained in the second step.

Reactive distillation can be carried out either batchwise or continuously.

In the case of batch reaction distillation, allyl vinyl ether and allyl alcohol are obtained from the top of the column by charging the bottom liquid obtained in the second step into a catalyst and a distillation column pot and carrying out normal distillation.

In the case of continuous distillation, the bottom liquid obtained in the second step is charged with a catalyst and into the vessel of the distillation column, and normal distillation is carried out.

When allyl vinyl ether and allyl alcohol start to be distilled from the top of the column, allyl vinyl ether and allyl alcohol are continuously obtained from the top of the column by continuously charging the column bottom liquid obtained in the second step into the column or kettle.

The concentration of phosphoric acid used as a catalyst is 0.0 in the still liquor.
A range of 1 to 1% is preferred.

If the phosphoric acid concentration is less than 0.01%, the catalytic effect is too small to be practical.

If it is more than 1%, the reaction amount of acetaldehyde diallyl acetal will increase, but the production of high-boiling compounds in the still liquor will increase, so the selectivity to allyl vinyl ether will decrease, which is not preferable.

The bottom liquid obtained in the second step can be supplied to the rectification column or the distillation pot, and the supply location is not particularly limited.

When implementing this patent, it is more advantageous to feed triethylamine to the distillation column.

In this case, triethylamine may be fed into the distillation column in addition to the bottom liquid obtained in the second step, or triethylamine alone may be fed into the distillation column.

Triethylamine is supplied to the distillation pot or rectification column section of the distillation column.

In the case of a still, it is desirable to supply the gas to the gas phase.

In the case of a rectification column, it is desirable to supply triethylamine from the lower part of the column so that triethylamine is present throughout the rectification column.

If triethylamine is supplied to the upper part of the rectification column, the effect of adding triethylamine will be small, which is not preferable.

When implementing this patent, the distillation column is not limited in any way, and general packed columns, tray columns, etc. can be used.

When the column length is short, unreacted acetaldehyde diallyl acetal is easily distilled from the top of the column, so it is necessary to increase the reflux ratio.

However, when implementing this patent, the column length, reflux ratio, and concentration of unreacted acetaldehyde diallylacetal in the distillate are not important issues, and the most economical method may be used when implementing this patent.

The present invention can be carried out under reduced pressure, normal pressure, or increased pressure, but it is generally preferable to carry out the process under normal pressure.

<Effects of the Invention> According to the present invention, it is possible to industrially produce allyl vinyl ether very advantageously without the complicated operations required in the past.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 First step: In a reactor equipped with a stirrer and a condenser, 3718 g of allyl alcohol and an ion exchange resin (Amparite 15:
Pour 77g of Organo ■'s product) and add 1 part of acetaldehyde.
410 g was added over 60 minutes.

After the addition was completed, the reaction was allowed to proceed for 5 hours to complete the reaction.

During this time, the reaction temperature was maintained at 20°C.

The composition of the obtained crude reaction liquid was 13.9% acetaldehyde.
, allyl alcohol 36.7%, acetaldehyde diallyl acetal 43.7%, and water 5.6%.

The reaction result obtained was a change rate of acetaldehyde of 49.4.
%, and the selectivity of acetaldehyde diallyl acetal to reacted acetaldehyde was 99.7%.

Second step: After separating the catalyst from the reaction crude liquid obtained in the first step, it was charged at a rate of 615 g/hour from the bottom of a 40-plate distillation column with an inner diameter of 30 mraΦ to the 20th plate.

By performing continuous distillation at normal pressure with a reflux ratio of 1, a composition of 39.4% acetaldehyde, 42.2% allyl alcohol, 2.7% acetaldehyde diallyl acetal, and 15.7% water was obtained from the top of the column (temperature 74°C). 219 g of a liquid was obtained per hour.

From the bottom of the column (temperature 112°C) allyl alcohol 33.7%, acetaldehyde diallyl acetal 66.3%.
396 g of liquid was obtained per hour.

Anhydrous allyl alcohol was recovered from the top liquid by simple azeotropic distillation using benzene and recycled for use in the first step.

Third step: 700 g of the bottom liquid obtained in the second step was charged with 0.3'zr of 85% phosphoric acid into the distillation column of a 30-stage sieve tray distillation column having a 1 g distillation vessel, and the mixture was heated under total reflux. Start heating.

When the top temperature reaches 85°C, start reporting at a reflux ratio of 2. The tower is heated at a temperature of 110 to 130℃ at the 10th stage from the pot.
Adjust so that

From the time when notification starts from the top of the column, the bottom liquid obtained in the second step containing 0.1% triethylamine is fed from the fifth stage from the pot.

The feed rate should be the same as the reported rate from the top of the tower.

As a result of carrying out the reaction for 83 hours, allyl vinyl ether of 2031+r was obtained with an acetaldehyde diallyl acetal conversion rate of 99.7% and an allyl vinyl ether selectivity of 92.6%.

Note that the yield of allyl vinyl ether based on the acetaldehyde standard changed from the first step was 90.2%.

Example 2 793.1 g of the bottom liquid from the second step obtained in Example was charged together with 0.71 g of 85% phosphoric acid into the distillation pot of a 30-stage sieve tray distillation column having a 1 g distillation pot, and heating was started. The mixture was distilled at a reflux ratio of 2 for 6 hours.

During this time, 15 g of the bottom liquid obtained in the second step containing 20% triethylamine was fed from the fifth stage of the pot.

85.09% of the acetaldehyde diallyl acetal charged to the bottom of the column was converted, and 84.7% of the changed acetaldehyde diallyl acetal became allyl vinyl ether.

Note that the yield of allyl vinyl ether based on the acetaldehyde standard changed from the first step was 82.5%.

Comparative Example 2 The same operation as in Example 1 was carried out, except that the triethylamine in Example 1 was changed to monoethylamine and mono-n-butylamine, and the concentration was further changed to 1%.

The results after 6 hours of reaction are shown in Table 1.

The abbreviations and units in Table 1 above are as follows.

A: Type of amine V: Production rate of allyl vinyl ether (g/hr) S: Selectivity of allyl vinyl ether (%) MEA: Monoethylamine MNBA: Mononormal butylamine

Claims (1)

[Scope of Claims] In producing allyl vinyl ether from acetaldehyde and allyl alcohol, (a) the first step of obtaining a synthetic solution of acetaldehyde diallyl acetal from acetaldehyde and allyl alcohol in the presence of an acidic catalyst (b) distilling the synthetic solution As a result, unreacted acetaldehyde and water, which is a reaction product, are distilled out from the top of the column by azeotroping with unreacted allyl alcohol, and acetaldehyde diallyl acetal, which is a reaction product, is distilled out from the bottom of the column, and water is not distilled out from the top of the column. A second step (c) of obtaining a mixed solution of unreacted allyl alcohol; and a third step of thermally decomposing the acetaldehyde diallyl acetal using a reactive distillation method in the presence of a phosphoric acid catalyst. How to make ether.