JPH05286887A - Production of methyl isopropyl ketone - Google Patents

Abstract

PURPOSE:To produce methyl isopropyl ketone in an excellent conversion ratio and in high selectivity almost free from deterioration of catalyst to be used. CONSTITUTION:In producing methyl isopropyl ketone by heating 2-methylbutanal in the presence of an oxy acid of boron and water in a liquid phase at >=220 deg.C, the ratio of the hydroxy acid of boron and water is >=25 pts.wt. hydroxy acid of boron calculated as orthoboric acid based on 75 pts.wt. water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing methyl isopropyl ketone by isomerizing 2-methylbutanal. The methyl isopropyl ketone produced by the present invention is useful as a solvent or an intermediate for dyes and pharmaceuticals.

[0002]

2. Description of the Related Art Conventionally, a method for producing a ketone by isomerizing an aldehyde is carried out in the gas phase in the presence of a mixed oxide containing tin, molybdenum and copper (see US Pat. No. 4,329,506). A method is known (see US Pat. No. 3,466,334) which is carried out in the gas phase in the presence of cerium oxide supported on aluminum oxide. There is known a method for producing methyl isopropyl ketone by isomerizing pivalaldehyde in a liquid phase or in a gas phase on various pentasil-type metal silicate zeolite catalysts (JP-A-62-22731). reference). Also, 2-
It has been reported that methyl isopropyl ketone is produced in the production of isoprene by dehydrating methylbutanal in the vapor phase in the presence of boron phosphate [CHEMTECH DECEMBER, 1986, 746- 7
See page 51].

[0003]

Problems to be Solved by the Invention US Pat. No. 4,329,506
The processes described in U.S. Pat. No. 3,466,334 and U.S. Pat. No. 3,466,334 do not allow the desired ketone to be obtained with a satisfactory selectivity when the conversion of aldehyde is increased. The catalyst used in the method described in JP-A-62-22731 is not easy to prepare. Generally, the deterioration of the catalyst used for the reaction in the gas phase is unavoidable,
Regeneration processing is required.

The object of the present invention is to provide an industrially advantageous process which can produce methyl isopropyl ketone with almost no deterioration of the catalyst used, with good conversion and good selectivity. is there.

[0005]

According to the present invention, the above object is achieved by heating 2-methylbutanal in the liquid phase at a temperature of 220 ° C. or higher in the presence of oxyacid of boron and water. A method for producing methyl isopropyl ketone, characterized in that, when producing isopropyl ketone, the ratio of the oxyacid of boron to water is 75 parts by weight of the latter and the former is 25 parts by weight or more in terms of orthoboric acid. Is achieved by

As the oxyacid of boron, for example, orthoboric acid, metaboric acid, tetraboric acid and other condensed boric acids are used, but it is industrially preferable to use orthoboric acid which is easily available. Further, a method of adding an oxygen-containing boron compound which changes into an oxyacid under the reaction conditions to the reaction system is also included in the embodiments of the present invention. Examples of the oxygen-containing boron compound include diboron trioxide and boric acid ester of aliphatic alcohol having 1 to 5 carbon atoms. An oxyacid of boron or an oxygen-containing boron compound that gives the oxyacid under reaction conditions is used as a mixture with water. The ratio of boron oxyacid to water is 75 parts by weight of the latter and 25 parts by weight or more of the former in terms of orthoboric acid.
If the amount of oxyacid of boron under the reaction conditions does not reach 25 parts by weight with respect to 75 parts by weight of water, a practical reaction rate cannot be obtained. When the oxyacid of boron is present in an amount of solubility or more under the reaction conditions, the undissolved component is naturally dispersed in the reaction system as fine-grained crystals. Not a hindrance. Therefore, it is not necessary to set the upper limit of the boron oxyacid to water under the reaction conditions, but the ratio of the boron oxyacid to water is 80 parts by weight in terms of the former 20 parts by weight in terms of orthoboric acid. It is preferable that the former is 3 to 30 parts by weight in terms of orthoboric acid in comparison with 65 to 30 parts by weight.
More preferably, it is in the range of 5-70 parts by weight. The oxyacid of boron is an extremely weak acid as compared with phosphoric acid, sulfuric acid and the like, and an apparatus made of a corrosion resistant and expensive material is not necessary for carrying out the present invention.

The reaction takes place in the liquid phase at temperatures above 220.degree. If the reaction temperature does not reach 220 ° C., not only a practical reaction rate cannot be obtained, but also the yield of the target methyl isopropyl ketone is significantly reduced. Reaction is 3
It is economical to carry out at temperatures up to 50 ° C. In order to carry out the reaction smoothly and efficiently, the reaction temperature is 250 to
A range of 300 ° C. is practical and preferable. The reaction is usually carried out under pressure, but a pressure at which the liquid phase boils under the reaction conditions is preferable. The reaction pressure is generally about the self-pressure of the reaction mixture under the reaction conditions. The reaction under pressure with an inert gas such as nitrogen can be carried out, but it does not bring any special benefit. Usually, the reaction is carried out in the absence of a solvent, but it can also be carried out in the presence of a solvent inert to the reaction. As such a solvent, for example, hydrocarbons such as hexane, octane, benzene, toluene and xylene, ethers such as diisopropyl ether, dioxane and tetrahydrofuran are used.

The reaction time is not particularly limited, but is usually 15
The range is from minutes to 6 hours, preferably from 30 minutes to 4 hours. The reaction can be carried out batchwise or continuously. Since the reaction system is a heterophasic system, it is possible to obtain good results by enhancing the contact between 2-methylbutanal and the catalyst aqueous solution by performing effective stirring or the like.

The concentration of 2-methylbutanal in the reaction system is preferably in the range of 5 to 50% by weight. 2-
If the concentration of methylbutanal exceeds 50% by weight, the amount of high-boiling by-products tends to increase. 2-
The concentration of methylbutanal is more preferably in the range of 10 to 30% by weight.

One of the preferred embodiments of the present invention will now be described. The boric acid aqueous solution is heated in the reactor, and 2-
Methylbutanal is supplied and, after a predetermined time of residence, the reaction is carried out while distilling the produced methyl isopropyl ketone. At this time, 2-methylbutanal is supplied at such a rate that the concentration in the aqueous boric acid solution is within the above range. When distilling methyl isopropyl ketone, water is also usually distilled at the same time, so the amount of water corresponding to this distilling amount is supplied to the reaction system to keep the concentration of the boric acid aqueous solution in the reactor almost constant. Preferably. As such makeup water,
The aqueous phase obtained when the distillate is condensed and liquefied can be separated from the organic phase and recycled.

When the reaction is carried out for a long time,
High boiling point by-products (particularly tar-like substances) slightly generated during the reaction accumulate in the reaction system, but since this product has a much smaller specific gravity than the aqueous oxyacid solution of boron, a part of the reaction mixture is By introducing it into a decanter, it is possible to easily separate and remove the boron from the aqueous oxyacid solution. The aqueous solution of boron oxyacid after removing the high-boiling by-products can be reused by circulating it in the reaction system after further washing it with a hydrocarbon such as hexane, if necessary.

2-Methylbutanal used as a raw material can be easily obtained by hydroformylation of 2-butene. N which is a by-product in the hydroformylation reaction
It is safe to use 2-methylbutanal mixed with pentanal and the like as a raw material in the present invention.

[0013]

EXAMPLES The present invention will now be described in detail with reference to Examples, but the present invention is not limited to these.

EXAMPLE 1 30 g of orthoboric acid and 20 parts of water were placed in a magnetic stirring type 100 ml Hastelloy autoclave equipped with a distillate receiver connected to a raw material introducing pipe, a thermometer and a cooler.
g was charged, and the mixture was heated and dissolved under stirring to maintain the temperature at 275 ° C. To the reaction system kept in this state, 11.4 ml of 2-methylbutanal (corresponding to 16% by weight of the total reaction solution) was introduced from a raw material introduction tube using a pressure-resistant constant-volume feed pump to start the reaction. After 1 hour, the introduction valve from the cooler to the receiver was opened to start distilling the product, and at the same time, water was introduced from the raw material introduction pipe using the pressure resistant constant-volume feed pump to increase or decrease the amount of liquid in the reaction system. Adjusted so that there is no After 30 minutes, distillation and addition of water were stopped, and the reaction was stopped. The distillate collected in the receiver was separated into an organic phase and an aqueous phase, and when analyzed by gas chromatography and high performance liquid chromatography, the conversion rate of 2-methylbutanal was 88.1%. , Methyl isopropyl ketone selectivity is 72.2%
Met.

Subsequently, 11.4 ml of 2-methylbutanal was charged again into the above autoclave, and the reaction and the product distillation operation were carried out in exactly the same manner. When the collected distillate was analyzed, the conversion rate of 2-methylbutanal was 8
It was 3.5% and the selectivity of methyl isopropyl ketone was 74.5%. This series of operations was repeated 6 times. The results are shown in Table 1. In the table, 2-MBL means 2-methylbutanal and MIPK means methyl isopropyl ketone.

[0016]

[Table 1]

After the completion of the reaction, the aqueous solution in which boric acid was deposited inside the autoclave was washed with hexane and the organic phase was distilled off. As a result, the high boiling product was 3% by weight based on the total amount of 2-methylbutanal charged. It was below.

Example 2 The same autoclave as used in Example 1 was charged with 20 g of orthoboric acid and 30 g of water, heated and dissolved under stirring and kept at a temperature of 275 ° C. 11.4 ml of 2-methylbutanal (16% of the total reaction solution) was added to the reaction system kept in this state.
(Corresponding to wt%) was introduced from the raw material introduction pipe using a pressure resistant constant quantity liquid feed pump to start the reaction. After 1 hour, the introduction valve from the cooler to the receiver was opened to start distilling the product, and at the same time, water was introduced from the raw material introduction pipe using the pressure resistant constant-volume feed pump to increase or decrease the amount of liquid in the reaction system. Adjusted so that there is no
After 30 minutes, distillation and addition of water were stopped, and the reaction was stopped. The distillate collected in the receiver was separated into an organic phase and an aqueous phase. When analyzed by gas chromatography and high performance liquid chromatography, the conversion rate of 2-methylbutanal was 60.1%. The selectivity of methyl isopropyl ketone was 81.4%.

Examples 3 to 6 and Comparative Examples 1 to 2 The reaction was carried out in the same manner as in Example 2 except that the concentration of orthoboric acid, the charged amount of 2-methylbutanal, the reaction temperature and the reaction time were changed. It was The results are shown in Table 2. In the table, 2-MBL means 2-methylbutanal and MIPK means methyl isopropyl ketone.

[0020]

[Table 2]

Example 7 In Example 2, 20 g of orthoboric acid and 30 g of water
Instead of charging, 16.9 g of diboron trioxide and 3 parts of water
The reaction was performed in the same manner except that 3.1 g was charged. Two
-The conversion of methylbutanal was 75.3% and the selectivity of methylisopropylketone was 74.7%.

[0022]

Industrial Applicability According to the present invention, there is provided an industrially advantageous method capable of producing methyl isopropyl ketone with almost no deterioration of the catalyst used and with good selectivity.

Claims (1)

[Claims] 1. To produce methyl isopropyl ketone by heating 2-methylbutanal in the liquid phase in the presence of oxyacid of boron and water to a temperature of 220 ° C. or higher,
A method for producing methyl isopropyl ketone, characterized in that the ratio of the oxyacid of boron to water is 75 parts by weight of the latter and the former is 25 parts by weight or more in terms of orthoboric acid.