JPS6212736A - Production of phenylacetaldehyde - Google Patents

Abstract

PURPOSE:To produce the titled compound useful as an intermediate for agricultural chemicals, pharmaceuticals, perfumes, artificial sweeteners, etc., in high purity, by isomerizing styrene oxide at a high temperature in a reactor filled with a catalyst suspended in an organic solvent having high boiling point, and distilling in a distillation column connected directly to the reactor. CONSTITUTION:Styrene oxide is supplied in vapor state or liquid state to the bottom of a reactor filled with an organic solvent having high boiling point (e.g. liquid paraffin) containing suspended catalyst such as synthetic silica-alumina and made to react at 160-220 deg.C under reduced pressure of 5-50mmHg at a temperature maintained above the temperature to evaporate the starting raw material and the reaction product until the conversion of the raw material reaches >=99.5%. A part of the organic solvent having high boiling point is extracted continuously or intermittently from the reactor and the reactor is replenished with the corresponding amount of regenerated or fresh solvent and catalyst. The objective compound can be obtained from the distillation column connected directly to the reactor. EFFECT:The polymerization loss of the objective compound having high reactivity can be suppressed and a colorless product having sufficiently high commercial value can be produced.

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention provides a method for filling a high-boiling organic solvent in which a catalyst is suspended.
A method for producing phenylacetaldehyde by isomerizing styrene oxide at high temperatures in a packed reactor.

Phenylacetaldehyde is used in agricultural medicines, fragrances, and □
It is an important compound as an intermediate for artificial sweeteners, and demand for it has been increasing in recent years.

(Prior Art and its Problems) Conventionally, the following various routes have been proposed for this manufacturing method.

Oxidation of styrene - isomerization of styrene oxide (C), dehydration of styrene glycol (d), oxidation of phenylethyl alcohol (e1), decomposition of phenyl glycide ester, etc. are known.

However, in the above conventional methods, there are many problems industrially because phenylacetaldehyde is highly reactive and easily changed by oxidation, polymerization, etc. A production method using isomerization of styrene oxide has been proposed which improves these problems.

For example, Tokuko Sho 52-3913. Japanese Patent Publication No. 59-1415
34. JP-A-59-144727, etc., discloses that it is produced by a gas phase fixed bed reaction using a special catalyst at high temperatures.

However, these methods produce highly reactive phenylacetaldehyde through a gas-solid catalytic reaction at high temperatures.
．． Since polymers and the like adhere to the surface of the catalyst and the catalyst activity deteriorates, complicated operations are required in which the reaction is interrupted and regeneration is necessary to burn off the polymers with air, etc. In addition, the reaction product may also contain polymers or be colored, requiring purification by distillation or the like, resulting in loss of 7-enyl acetaldehyde during purification.

In addition, special public interest rate 49-25932. According to , diphenylacetaldehyde is obtained by isomerizing styrene oxide by suspending activated clay as a catalyst in liquid paraffin. With this method, the distillate may be colored yellow-green or some of the polymer or heating medium may be distilled out, so it is necessary to take measures such as purifying the distillate, and during this process the reactivity may be reduced. It is not an industrially satisfactory method as it has the disadvantage of loss due to polymerization of phenylacetaldehyde.

(Means for Solving the Problem) The present inventors have conducted intensive studies on a method for producing highly pure phenylacetaldehyde without coloration by suppressing the polymerization loss of highly reactive phenyl acetaldehyde. The inventors have discovered that the problem can be solved and have arrived at the present invention. That is, the present invention provides the following steps: 1) styrene oxide is supplied in gaseous or liquid form from the bottom of the reactor to a reactor filled with a high-boiling organic solvent in which a catalyst is suspended; (B) under reduced pressure; In a reaction system maintained above the temperature at which the starting materials and reaction products vaporize, the reaction is carried out to a conversion rate of 99.5% or more. (C) The reaction products are then passed through a distillation tower directly connected to the reactor. A method for producing phenylacetaldehyde, the method comprising: extracting phenylacetaldehyde.

2) A claim characterized in that a part of the above-mentioned high-boiling organic solvent is continuously or intermittently extracted from the reaction system, and the corresponding regenerated or new solvent and catalyst are similarly replenished. , is the method described in Section 1.

The catalyst used in the present invention is not particularly limited as long as it can generally convert an epoxy compound into an aldehyde. A commonly used catalyst is a solid acid catalyst, synthetic silica-alumina.

Examples include activated clay, alumina, silica-boria, silica-magnesia, sulfates such as cobalt sulfate and nickel sulfate, potassium aluminum sulfate, and acidic ion exchange resins.

The high boiling point organic solvent is one whose boiling point is at least higher than that of phenylacetaldehyde), preferably 250
Hydrocarbons with high boiling points above ℃ are preferable. For example, liquid paraffin, diethyl diphenyl (trade name: Therm-F 700 manufactured by Nippon Steel Chemical Co., Ltd., the same applies hereinafter), triethyl diphenyl (
These include (trade name: THERM-F 600) hydrogenated triphenyl (trade name: THERM-F 900).

As the reactor used in the present invention, a stirred tank type having a stirrer or an upright circular reaction tube without a stirrer can be used. Also, styrene glimpse
''''') ()/ tti K E m (D *“7
Sufficient transit time is guaranteed at ゛69ゞ80ゝ07゛1-. If this is charged in gaseous form, it is also possible to install a vaporizer to vaporize it outside the reactor. It is advantageous to use spargering or the like in order to improve the dispersibility of styrene oxide in the reactor. When applied in liquid form, it is also possible to entrain with an inert gas, such as nitrogen.

As the distillation column directly connected to the reactor, a bubble column, a perforated column, a packed column, etc. are used. The number of stages in the distillation column is aff.
1j6--,! :4J"z=,z7"t),hy
Although it varies depending on the boiling point difference between e and j, it is sufficient to use several stages. In addition, since this reaction is completed to #1 with a raw material conversion rate of 99.5% or more, there is no unused material in the reaction product gas.
□There is no reactive styrene oxide, and the fractional distillation of by-product high-boiling substances is promoted, resulting in improved product appearance (APHA).
゛garu.

When carrying out the present invention, the reaction consists of suspending the catalyst in a high-boiling organic solvent, charging styrene oxide at a rate corresponding to the reaction rate, and distilling the produced phenylacetaldehyde out of the reaction system.

Usually, the following operating conditions are adopted. The catalyst concentration in the organic solvent varies depending on the type of catalyst, but is 0.1 to 10%.
is appropriate. The reaction temperature is preferably 160 to 220°C. If the reaction temperature is high, polymers etc. will be produced and the catalyst life will be shortened, and if the reaction temperature is low, unreacted styrene oxide will be mixed in. The reaction pressure varies depending on the boiling point difference between the organic solvent and phenylacetaldehyde used, the reaction temperature, etc., but is generally preferably in the range of 5 to 50 Hg. °The feed rate of raw material styrene oxide is supplied according to the reaction rate so that the conversion rate is 99.5 cm or more, but the reaction temperature, pressure, type of catalyst, concentration, etc. It varies depending on the amount allowed in the product.
It should be determined appropriately through experiments.

The resulting phenylacetaldehyde does not require any further purification such as distillation, has no coloring, is highly pure, and has sufficient commercial value.

In addition, when renewing the organic solvent and catalyst in the present invention, the organic solvent is contaminated by polymers such as phenylacetaldehyde and the catalyst deteriorates, the reaction must be stopped, replaced, and restarted. In a discontinuous manner, and while the reaction continues, a portion of the internal medium and catalyst 1. is continuously extracted from the reaction system 1, and a new catalyst is added to the organic solvent K from which the deteriorated catalyst has been separated, or the separated organic solvent has been purified by distillation etc., and a new catalyst is added to the medium Q. It can be implemented. However, a continuous method of operation is advantageous.

(Example) Next, the present invention will be specifically explained with reference to Examples.

Reference Example (Catalyst Preparation) Aerosil 380 (silica gel manufactured by Nippon Aerosil Co., Ltd.) 1.20.9 is suspended in water 1.21. another
To □, Cataloid AP (manufactured by Catalysts & Chemicals Co., Ltd., alumina content 67%) 809 is added to 4.00 ml of water and suspended to obtain an alumina sol. After adding the obtained alumina sol to the silica gel suspension solution with stirring, a slurry was obtained by adding 14 thiammonia aqueous solution until 1) H7.2 was obtained. After drying this slurry at 150°C, it was heated at 500°C.
The mixture was calcined for 2 hours and pulverized to obtain a catalyst. (Composition, 31%
(Al2O, -69%5iO2) Example 1 (see Figure 1) Liquid paraffin 300II and the catalysts 10 and 9 obtained above were placed in advance in a cylindrical reactor (4) with a length of 500 and an inner diameter of 45 mm. The mixture was charged and heated to 180° C. under a vacuum of 10+ mHg while being forcefully stirred via a circulation pump (8). Next, styrene oxide was vaporized in the vaporizer (3) and continuously supplied from the raw material container (1) via the charging pump (2) at a rate of 30 g/By. The generated phenylacetaldehyde passes through a perforated distillation column (5) with 5 stages and an inner diameter of 35 mm installed at the top of the reactor, and is then sent to a product container [7] via a condenser (6) at a reflux ratio of 0.5. It was dispensed continuously. [Reaction time was 58 Hr] During this period, the total amount of raw materials charged was 1.785 g, and the amount of residual product dripped out was 1.6509 g.

As a result, the concentration of 7-ethyl acetaldehyde in the dripping liquid was 98
．． 6%, unreacted styrene oxide was not detected.

The hue of the drop rate was colorless and ApHA 10. (Styrene oxide conversion rate 99.8%, phenylacetaldehyde yield 92.5%) Comparative Example A reaction was carried out for 54 hours using the same catalyst and the same reaction conditions as in Example 1, except that only the distillation column section was removed. During this period, the total amount of raw materials charged was 1,616 g, and the residual amount of product dripped out was 1,52 g.
It was 1.9.

As a result, the concentration of 7-ethyl acetaldehyde in the dripping liquid was 98
．． 5%, unreacted styrene oxide was not detected.

The hue of the droplet liquid was yellow-green and ApHA50.

Example 2 (see Figure 1) Length 2 + 000: Jx Hs Inner diameter 1,500gm
Utilizing a φ reactor and a 450 mφ packed column in Nagatoro Y-H1, 700 kg of liquid paraffin and catalyst 5 were used.
The reaction was carried out under the same reaction conditions as in Example 1 for 75 Hr, except that the raw material feeding rate was changed to 0.0 kg/Hr and the raw material charging rate was 100 kg/Hr.

Then, the organic solvent containing the catalyst was added at a rate of 16.5 per hour.
The catalyst and by-product high-boiling substances were separated from liquid paraffin using a separator (9).

Then, 3.5 kg of recovered liquid paraffin, 3.5 kg of new liquid paraffin corresponding to the separated amount, and 0.5 kg of new catalyst were replenished to the reactor every hour. (Reaction time: 25 Hr) As a result, the composition of the droplet solution was 98% of phenylacetaldehyde.
51 unreacted styrene 7 oxyl' 0.2%.

The rest? 1.3%, and the color of the droplet liquid is colorless and ApHA.
It was lo.

[Brief explanation of drawings]

FIG. 1 is a system diagram schematically showing an example of an apparatus for carrying out the method of the present invention. In the diagram, 1: Raw material container 2: Preparation pump 3: Vaporizer
4: Reactor 5: Distillation column 6: Condenser 7: Product container 8: Circulation pump 9: Separator

Claims (1)

[Claims] 1) (A) Styrene oxide is supplied in gas or liquid form from the bottom of the reactor to a reactor filled with a high-boiling organic solvent in which a catalyst is suspended; (B) under reduced pressure; In a reaction system maintained at a temperature higher than the temperature at which the starting materials and reaction products vaporize, the reaction is carried out to a conversion rate of 99.5% or higher, and (C) the reaction products are passed through a distillation column directly connected to the reactor. A method for producing phenylacetaldehyde, which comprises taking out phenylacetaldehyde. 2) Claims characterized in that a portion of the high-boiling organic solvent is continuously or intermittently withdrawn from the reaction system, and the corresponding regenerated or new solvent and catalyst are similarly replenished; The method described in Section 1.