JPH0959201A - Production of enal using alkaline earth metal oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a straight-chain unsaturated aldehyde useful as a raw material for synthesizing medicines/agrochemicals, etc., in high selectivity with easy catalyst recovery under low wastewater treatment load by cross aldol condensation between acetaldehyde and a specific saturated aldehyde using each specific catalyst and solvent. SOLUTION: The objective compounds, crotonaldehyde of formula II and a compound of formula III, are obtained by cross aldol condensation between (C) acetaldehyde of the formula CH3 CHO and (D) a compound of formula I (R<1> is a 1-6C straight-chain alkyl) in the presence of (A) a catalyst containing a compound of the formula MO (M is Ca, Mg, Sr or Ba) and (B) a polar solvent such as water, N,N-dimethylformamide or dimethyl sulfoxide followed by a dehydration reaction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a linear unsaturated aldehyde such as crotonaldehyde which is synthesized from acetaldehyde and a saturated aldehyde. More specifically, it relates to a method for producing a linear unsaturated aldehyde with good selectivity by a dehydration reaction of a cross aldol condensation between acetaldehyde and a saturated aldehyde.

[0002]

2. Description of the Prior Art In the case of producing a linear unsaturated aldehyde, generally, acetaldehyde and a saturated aldehyde are subjected to so-called cross aldol condensation using a base catalyst such as an aqueous solution of sodium hydroxide to form aldol. Then, a dehydration reaction is subsequently performed, and the produced unsaturated aldehyde and the like are subjected to separation and purification operations such as distillation to obtain a product.

This cross aldol condensation and dehydration reaction are
For example, acetaldehyde and butyraldehyde are as follows using a base catalyst such as sodium hydroxide.

Embedded image

That is, in addition to linear unsaturated aldehydes such as crotonaldehyde and hexenal, 2-ethyl-2-butenal and 2-ethyl-2-hexenal which are branched unsaturated aldehydes are also produced. Increasing the molar ratio of acetaldehyde to butyraldehyde for the purpose of increasing the selectivity of linear unsaturated aldehydes improves the selectivity of crotonaldehyde but not the selectivity of hexenal, and the selectivity of linear unsaturated aldehydes is high. A manufacturing method is desired. Moreover, when the reaction is carried out using a base catalyst such as an aqueous solution of sodium hydroxide, when the aqueous solution of sodium hydroxide containing the remaining content after the completion of the reaction is disposed of as a waste liquid, not only the neutralization of sodium hydroxide etc. There is also a disadvantage that a costly operation such as the treatment of activated sludge is forced.

[0005]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, an object of the present invention is to provide a method for producing a linear unsaturated aldehyde from acetaldehyde and a saturated aldehyde with high selectivity.

[0006]

[Means for Solving the Problems] As a result of intensive studies, the inventors of the present invention focused on the fact that a solid base is effective as a catalyst for a cross aldol reaction, and as a result, obtained acetaldehyde and a specific saturated aldehyde as an alkaline earth metal. The present invention has been completed by finding a method for obtaining a linear unsaturated aldehyde such as crotonaldehyde with high selectivity by carrying out cross aldol condensation in the presence of a metal oxide, water or a polar solvent of dimethylsulfoxide.

The method for producing a linear unsaturated aldehyde according to the present invention comprises an alkaline earth metal represented by the formula (I) MO ... (I) (wherein M represents Ca, Mg, Sr or Ba). the catalyst comprises an oxide, and the presence of a polar solvent, represented by formula (II) CH ₃ CHO ...... acetaldehyde with the formula represented by ^{(II) (III) R 1} -CH 2 -CHO ...... (III) By a cross-aldol condensation reaction with a saturated aldehyde, and then a dehydration reaction, a crotonaldehyde represented by the formula (IV) CH ₃ —CH═CH—CHO (IV) and a formula (V) R ¹ —CH ₂ — CH = CH-CHO (V) [wherein R ¹ represents a linear alkyl group having 1 to 6 carbon atoms in the formulas (III) to (V)] with good selectivity. It is characterized by synthesizing.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of the present invention is represented by the following formula, and the branched-chain unsaturated aldehydes represented by formulas (VI) and (VII) are by-produced.

Embedded image (However, R ¹ is linear alkyl of ¹ to 6)

The aldol condensation reaction in the production method of the present invention is carried out by adding and mixing a polar solvent to a predetermined aldehyde and then adding a catalyst. The reaction temperature of this cross aldol condensation is not particularly limited, but is preferably -20 to 20.
The temperature is 100 ° C, more preferably 0 to 70 ° C.
The reaction temperature in the subsequent dehydration reaction is also not particularly limited, but is preferably 50 to 200 ° C, more preferably 80 to 150 ° C.

The saturated aldehyde represented by the formula (III) in the production method of the present invention includes propionaldehyde, n-butyraldehyde, n-valeraldehyde and n.
-Hexyl aldehyde, n-heptyl aldehyde, n-
Octyl aldehyde may be mentioned.

As the polar solvent used in the production method of the present invention, water, N, N-dimethylformamide, dimethylsulfoxide and the like are preferably used. 5 to 70 mole% based on the total amount of aldehyde as a raw material, preferably 10 to
It is 60 mole%. If necessary, alcohols such as methanol, ethanol and i-butanol, ethers such as diethyl ether and triethylene glycol, polar solvents such as acetonitrile and N-methylformamide can be used. In the dehydration reaction, no particular solvent or additive may be used, but the above polar solvent or other solvent that does not inhibit the dehydration reaction may be used.

Examples of the alkaline earth metal oxide of the catalyst used in the production method of the present invention include calcium oxide (CaO), magnesium oxide (MgO), strontium oxide (SrO) and barium oxide (BaO). However, calcium oxide or strontium oxide is particularly preferable. As a method for preparing the catalyst, the corresponding alkaline earth metal oxide, alkaline earth metal hydroxide, a method of treating the alkaline earth metal nitrate with an aqueous sodium hydroxide solution, preferably the alkaline earth metal carbonate, vacuum 400 to 10 in a stream of nitrogen or an inert gas
There is a method of firing at 00 ° C, preferably 500 to 900 ° C. The catalyst is used in an amount of 0.1 to 20% by weight, preferably 1.
It is 0 to 5.0% by weight.

The linear unsaturated aldehyde obtained by the production method of the present invention is used as it is, preferably as a raw material for synthetic chemicals such as pharmaceuticals, agricultural chemicals, fragrances, surfactants and dyes, after being subjected to purification operations such as rectification. Alternatively, it is used as a raw material for the corresponding saturated aldehyde, alcohol, carboxylic acid, amine and the like. In particular, crotonaldehyde is a raw material for food preservatives such as sorbic acid and potassium sorbate, and among the aldehydes represented by the formula (V), n-hexenal is an unsaturated compound produced by itself or as a raw material. Alcohol and its ester can be used as a fragrance.

[0014]

【Example】

Example 1 (1) Preparation of catalyst 1.20 g of commercially available calcium carbonate was charged into a 20 mmφ quartz glass reaction tube equipped with a breakable seal, and the reaction tube was evacuated to 2 ° C./in an electric furnace. The temperature was raised from 0 ° C to 600 ° C at a rate of min. Continue 600
Evacuation was carried out at 0 ° C. for 2 hours. After cooling, the breakable seal was broken while passing nitrogen through the reaction tube, and the produced calcium oxide catalyst was taken out.

(2) Cross aldol condensation reaction In a 100 ml four-necked flask fully replaced with nitrogen equipped with a stirrer, a thermometer, a cooling condenser and a nitrogen inlet tube, 13.70 g of n-butyraldehyde ( 0.1
9mole), 8.38g of acetaldehyde (0.19mo
le) and 1.80 g (0.10 mole) of water,
While keeping the temperature of the flask at 12 ° C. in an ice water tank and stirring, the total amount of the catalyst prepared in the above (1) was added and reacted for 3 hours. The reaction was stopped by continuing to stir 19.0 g of water,
It was carried out by adding 0.67 g of a 50% acetic acid aqueous solution and 0.67 g of a 25% sodium acetate aqueous solution.

(3) Dehydration reaction After the above reaction, the cooling condenser mounted on the flask was replaced with a column equipped with a Raschig ring and equipped with a distillation head (packing height of about 30 cm), and a ribbon heater was wound around the column to supply 105 to 115. Heat to about ℃. The water bath was replaced with a mantle heater, heating was started, and distillation was continued until no oil was distilled off. When the temperature in the flask had risen to about 105 ° C, heating was stopped, water in the fraction was separated, and gas chromatography analysis was performed. Table 1 shows the results of the analysis.

Example 2 (1) Preparation of catalyst A catalyst was prepared by the same method as in (1) of Example 1. (2) Cross aldol condensation reaction 14.42 g (0.20 mol) of n-butyraldehyde
e), 8.82 g (0.20 mole) of acetaldehyde
And (2) of Example 1 except that the amount of water was 2.70 g (0.15 mole). (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 1 are shown.
Shown in

Comparative Example 1 (1) Cross-Aldol Condensation Reaction In a 200 ml four-necked flask sufficiently replaced with nitrogen equipped with a stirrer, a thermometer, a cooling condenser and a nitrogen inlet tube, 45 parts of n-butyraldehyde was placed. 0.4 g (0.63
mole), and 27.8 g of acetaldehyde (0.6
3mole) and add 12 to the inside of the flask with a water bath.
2% of 2% sodium hydroxide solution while stirring at 2 ℃
4.4g was added and it was made to react for 1.5 hours. To stop the reaction,
While continuing stirring, 63.0 g of water, 2.2 g of a 50% aqueous solution of acetic acid, and 2.2 g of a 25% aqueous solution of sodium acetate were added. (2) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1
Shown in

Comparative Example 2 (1) Preparation of catalyst A catalyst was prepared by the same method as in Example 1 (1). (2) Cross aldol condensation reaction It carried out according to (2) of Example 2 except not using 2.70 g (0.15 mole) of water. (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 1 are shown.
Shown in

Example 3 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction Example 2 except that the amount of water was 1.44 g (0.08 mole).
It was performed according to (2). (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 2 are shown.
Shown in

Example 4 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction 15.14 g (0.21 mol) of n-butyraldehyde
e), 9.26 g (0.21 mole) of acetaldehyde
And (2) of Example 1 except that the amount of water was 0.90 g (0.05 mole). (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 2 are shown.
Shown in

Example 5 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction Example 4 except that the amount of water was 3.60 g (0.20 mole).
It was performed according to (2). (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 2 are shown.
Shown in

Comparative Example 3 (1) Preparation of catalyst A catalyst was prepared by the same method as in Example 1 (1). (2) Cross aldol condensation reaction Example 1 except that the amount of water used was 54.7 g (3.04 mole).
It was performed according to (2). (3) Dehydration reaction The results of the analysis were conducted in the same manner as in (3) of Example 1 and the results of Table 2 are shown.
Shown in

Example 6 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction Using a 200 ml four-necked flask, 58.4 g (0.80) of N, N-dimethylformamide was used instead of water.
The same procedure as in (2) of Example 2 was carried out except that the mole) was used. (3) Dehydration reaction The result of the analysis was carried out in the same manner as in (3) of Example 1 and the results of the analysis are shown in Table 3.
Shown in

Example 7 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction 56.0 g of dimethyl sulfoxide (0.
The procedure was carried out according to (2) of Example 1 except that 70 mole) was used. (3) Dehydration reaction The result of the analysis was carried out in the same manner as in (3) of Example 1 and the results of the analysis are shown in Table 3.
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Example 8 (1) Preparation of catalyst A 20 mmφ quartz glass reaction tube equipped with a breakable seal was charged with 1.20 g of commercially available strontium carbonate, and the reaction tube was evacuated in an electric furnace. 2 ℃ / min.
The temperature was raised from 0 ° C to 900 ° C at the rate of. Continue to 90
Evacuation was performed at 0 ° C. for 2 hours. After cooling, the breakable seal was broken while passing nitrogen through the reaction tube, and the produced strontium oxide catalyst was taken out. (2) Cross aldol condensation reaction It was carried out according to (2) of Example 1 except that the whole amount of the catalyst prepared in (1) above was used. (3) Dehydration reaction The result of the analysis was carried out in the same manner as in (3) of Example 1 and the results of the analysis are shown in Table 3.
Shown in

Comparative Example 4 (1) Preparation of Catalyst A catalyst was prepared in the same manner as in Example 8 (1). (2) Cross aldol condensation reaction It carried out according to (2) of Example 8 except not using water. (3) Dehydration reaction The result of the analysis was carried out in the same manner as in (3) of Example 1 and the results of the analysis are shown in Table 3.
Shown in

Example 9 (1) Preparation of catalyst 1.20 g of commercially available magnesium carbonate was charged into a 20 mmφ quartz glass reaction tube equipped with a breakable seal, and the reaction tube was evacuated in an electric furnace. The temperature was raised from 0 ° C to 400 ° C at a rate of 2 ° C / min. Continue 400
Evacuation was carried out at 0 ° C. for 2 hours. After cooling, the breakable seal was broken while passing nitrogen through the reaction tube, and the produced magnesium oxide catalyst was taken out. (2) Cross aldol condensation reaction It was carried out according to (2) of Example 8 except that the catalyst prepared in (1) above was used. (3) Dehydration reaction The dehydration reaction was performed in the same manner as in (3) of Example 1, and the results of the analysis are shown in Table 4.

Comparative Example 5 (1) Preparation of catalyst A catalyst was prepared in the same manner as in Example 9 (1). (2) Cross aldol condensation reaction It carried out according to (2) of Example 9 except not using water. (3) Dehydration reaction The result of the analysis was carried out in the same manner as in (3) of Example 1 and the results of the analysis are shown in Table 4.
Shown in

Example 10 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction 11.62 g (0.20 mol of propionaldehyde
e), 8.82 g (0.20 mole) of acetaldehyde
And (2) of Example 1 except that the amount of water was 1.80 g (0.10 mole). (3) Dehydration reaction After the above reaction, the cooling condenser attached to the flask was replaced with a column equipped with a Raschig ring and equipped with a distillation head (packing height of about 30 cm), and a ribbon heater was wound around the column to 100 to 110 ° C. Heat to about 30 minutes. Replace the water bath with a mantle heater,
Heating was started and distillation was continued until no oil was distilled off.
When the temperature inside the flask had risen to about 101 ° C., heating was stopped, water in the fraction was separated, and gas chromatographic analysis was performed. The results of the analysis are shown in Table 4.

Example 11 (1) Preparation of catalyst A catalyst was prepared in the same manner as in (1) of Example 1. (2) Cross aldol condensation reaction Propionaldehyde 11.62 g (0.20 mole) was converted into n-hexyl aldehyde 20.02 g (0.20 mol).
The same procedure as (2) of Example 10 was carried out except that e) was replaced. (3) Dehydration reaction After the above reaction, the cooling condenser attached to the flask was replaced with a column with a distillation head filled with a Raschig ring (filling height of about 30 cm), and a ribbon heater was wound around the column, and the column was heated at 115 to 125 ° C. Heat to about 30 minutes. Replace the water bath with a mantle heater,
Heating was started and distillation was continued until no oil was distilled off.
When the temperature of the flask had risen to about 115 ° C., the heating was stopped, the water of the fraction was separated and the gas chromatographic analysis was carried out. The results of the analysis are shown in Table 4.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

INDUSTRIAL APPLICABILITY According to the production method of the present invention, a linear unsaturated aldehyde can be obtained with good selectivity. Further, in the production method of the present invention, after the completion of the reaction, the activated sludge treatment load of wastewater does not become large unlike the conventional technique, and the used catalyst can be recovered, and the recovered catalyst is recycled many times. Can be used.

Claims (3)

[Claims] 1. A catalyst containing an alkaline earth metal oxide represented by the formula (I) MO ... (I) (wherein M represents Ca, Mg, Sr, and Ba), and the presence of a polar solvent. The cross aldol condensation reaction between the acetaldehyde represented by the formula (II) CH ₃ CHO (II) and the saturated aldehyde represented by the formula (III) R ¹ —CH ₂ —CHO (III), Then, by a dehydration reaction, crotonaldehyde represented by the formula (IV) CH ₃ —CH═CH—CHO (IV) and the formula (V) R ¹ —CH ₂ —CH═CH—CHO (V) [V] In formulas (III) to (V), R ¹ represents a straight chain alkyl group having 1 to 6 carbon atoms], and a straight chain unsaturated aldehyde represented by the following formula: Method for producing aldehyde. 2. The straight chain catalyst according to claim 1, wherein the catalyst is an alkaline earth metal oxide formed by calcining a carbonate compound of Ca or Sr in the range of 400 to 1000 ° C. in a vacuum or an inert gas. Method for producing saturated aldehyde. 3. The method for producing a linear unsaturated aldehyde according to claim 1, wherein the polar solvent is 5 to 70 mole% with respect to the total amount of aldehyde.