JPH07291960A - Method for producing 1,4-butanedialmonoacetal - Google Patents

Abstract

PURPOSE:To enable to perform a selective hydroformylation reaction at the terminal of 2-propenalacetal in a lower catalyst concentration and in a higher selectivity than those of conventional methods, and industrially and advantageously produce 1,4-butanedialmonoacetal. CONSTITUTION:A method for producing 1,4-butanedialmonoacetal comprises reacting an acetal with carbon monoxide and hydrogen in the presence of rhodium catalyst and tris(3,5-dichlorophenyl)phosphine catalyst, the acetal being obtained by reacting 2-propenal with 2,2,4-trimethyl-1,3-propanediol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 1,4-butanediol monoacetal. 1,4-butanedial monoacetal can be converted to 1,4-butanediol by hydrolysis and reduction reaction. 1,4-butanediol is a compound useful as a raw material for resins such as polyester and polyurethane.

[0002]

2. Description of the Related Art A method for producing 1,4-butanediol has been known for a long time, which is composed of the following three steps (a) to (c). (A) A cyclic acetal (2-vinyl-1,3-dioxane derivative) is produced by an acetalization reaction of propenal and 1,3-diol using an acid as a catalyst; (b) Rhodium and organic phosphorus are used as the cyclic acetal. After reacting with carbon monoxide and hydrogen in the presence of a compound catalyst to form a cyclic monoacetal of 1,4-butanedial (hydroformylation); (c) Reacting with water and hydrogen in the presence of an acid and a hydrogenation catalyst To give 1,4-butanediol.

In the case of producing 1,4-butanediol by the above-mentioned method, it is necessary to solve the following three problems in the second step (b). (1) In the hydroformylation reaction of 2-propenal acetal, generally, a monoacetal of 2-methyl-1,3-propanedial (branched aldehyde) and a monoacetal of 1,4-butanedial which is a desired compound (direct It is important to increase the regioselectivity of the hydroformylation reaction, since two isomers of (chain aldehyde) are obtained. (2) The hydroformylation reaction of 2-propenal acetal has a remarkably low reaction rate as compared with the usual reaction of 1-alkene. Catalyst concentrations of are required. The original purpose was achieved, for example, a method of increasing the reaction temperature to increase the rate produces a high boiling point mixture with a complicated composition by a side reaction, and a method of increasing the reaction pressure significantly reduces the yield of linear aldehyde. Not done. (3) Since the catalyst uses an expensive metal, it must be stable under the reaction conditions and the product separation conditions.

Regarding the solution of the above problem (1), a rhodium compound and P (O) are used as a catalyst in the step (b).
Method using a tertiary phosphite compound having a structure of R ¹ ) (OR ² ) (OR ³ ) (R ^{1 to} R ³ are alkyl or aryl substituents) (JP-A-51-36406 and 51-39612) Japanese Patent Application Laid-Open Publication No. 1989-242, which describes in its examples, 2-methyl-2,4-pentanediol as a diol,
1,3-butanediol, 2-methyl-by-product
The results of the hydroformylation reaction using an acetal as a raw material using 1,3-propanediol are shown.
The selectivity of the target 1,4-butanedial monoacetal was the same for all diols. Further, when trimethylphosphite is used as a reaction accelerator, it is said that regioselectivity of 80% or more can be achieved when the molar ratio of the starting acetal to the rhodium catalyst is about 1000 (JP-A-51-36406). Issue). However, trimethylphosphite is generally unstable under hydroformylation reaction conditions (eg, US Pat.
No. 17,775), and it is impossible from an economical point of view to industrially carry out this method from the point of (3).

On the other hand, rhodium / triarylphosphine is a very stable catalyst system, and satisfies the requirement (3) in that it is widely used as an industrial catalyst, for example, in the production of butanol by hydroformylation of propene. There is. U.S. Pat. Nos. 4,003,918 and 4,05
No. 2,401, in the above step (b), a cyclic acetal of propenal is used as a raw material, and a rhodium compound and a tertiary phosphine compound such as triphenylphosphine, alkyl group-substituted triphenylphosphine, or trialkylphosphine are used. 1,4-in the presence of a catalyst
A method of making butanedial monoacetal is disclosed. In the specification, a catalyst in which a rhodium compound and a triarylphosphine are combined is used, and the molar ratio of rhodium to 2-propenal acetal is 1.25 × 1.
0-5 to 6.2 x 10-2, preferably 1.24 x 10-4
It is described that 3-formylpropanal acetal can be obtained in a yield of about 85% by carrying out the hydroformylation reaction under the condition of 1.24 × 10 −2, but the corresponding example describes the yield. Therefore, in our study, it was impossible to obtain regioselectivity commensurate with the described yield (see Comparative Example of the present application).

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention carries out the terminal hydroformylation reaction of an aimed olefin with high regioselectivity even at a lower catalyst concentration than that of known reaction systems. It is intended to propose a reaction system that can be used.

[0007]

That is, the present invention provides an acetal obtained by the reaction of 2-propenal and 2,2,4-trimethyl-1,3-propanediol with rhodium and tris (3,5-dichlorophenyl). 1, 4-, which is characterized by reacting with carbon monoxide and hydrogen in the presence of a phosphine catalyst, under mild reaction conditions, and which achieves a high reaction rate and regioselectivity even at a catalyst concentration sufficiently lower than before. The present invention provides a method for producing butanedial monoacetal.

(Raw materials) In the present invention, the raw materials used for the hydroformylation reaction are 2-propenal and 2,
It is a cyclic acetal obtained by an acetalization reaction with 2,4-trimethyl-1,3-propanediol, that is, 4,4,6-trimethyl-2-vinyl-1,3-dioxane. This compound can be obtained by a known method using an acid catalyst (for example, JP-A-51-59614 or JP-A-51-1).
No. 25005, etc.) can be produced in good yield.

(Rhodium Catalyst) The rhodium catalyst used in the present invention is a carbonyl complex having one or more molecules of carbon monoxide bonded as a ligand. Examples of these rhodium compounds include hydrido tetracarbonyl rhodium, octacarbonyl dirhodium, dicarbonyl acetylacetonato rhodium, dodecacarbonyl tetrarhodium,
Hexadecacarbonyl hexarhodium and the like can be mentioned.
Further, compounds which are converted into these carbonyl complexes under hydroformylation reaction conditions, for example, organic acid salts such as rhodium acetate, rhodium oxalate, rhodium formate, and rhodium stearate; rhodium chloride, rhodium bromide, rhodium iodide, etc. In addition to inorganic acid salts such as rhodium sulfate and rhodium nitrate, metal rhodium can also be used. The amount of rhodium catalyst used relative to the raw material acetal is
In general, the molar ratio is from 1 to 0.0000001, preferably 0.1.
It is in the range of 1 to 0.000001 molar ratio.

(Phosphine Compound) The phosphine compound used in the present invention is tris (3,5-dichlorophenyl) phosphine. This cocatalyst is 1-bromo-3,
It is produced by the reaction of a Grignard reagent of 5-dichlorobenzene with phosphorus trichloride. The optimum amount of phosphine varies depending on the catalyst concentration and reaction conditions, but generally, the molar ratio to the rhodium catalyst is 0.1 to 1000.
It is 0, preferably in the range of 0.5 to 1000.

(Solvent) This reaction can be carried out without using a solvent, but if necessary, a solvent which does not react with the acetal as a raw material can be used. Examples of these solvents are hydrocarbons such as hexane, benzene and toluene; alcohols such as methanol, ethanol, propanol and butanol; diols such as ethylene glycol, propylene glycol, butanediol and hexylene glycol; diethyl ether. , Ethers such as tetrahydrofuran, dioxane; esters such as methyl acetate, ethyl acetate, butyrolactone, tricaprylin; amides such as dimethylformamide, dimethylacetamide, methylpyrrolidinone; ureas such as dimethylimidazolidinone and tetramethylurea Is mentioned.
The amount of these solvents used is not particularly limited and is arbitrary.

(Reaction Conditions) This reaction is carried out in the presence of a mixed gas of carbon monoxide and hydrogen. The carbon monoxide / hydrogen molar ratio is in the range 0.1 to 10, preferably 0.5 to 8. The reaction proceeds sufficiently even if the partial pressure of the mixed gas is 1 atm or less, but in order to obtain a higher reaction rate, it may be carried out under a higher pressure than usual. In addition, it is not preferable to use too high pressure in order to make the regioselectivity of the olefin terminal sufficient. Therefore, the partial pressure of the gas mixture usually carried out is in the range of 0.5 to 150 bar, preferably 1 to 100 bar. It should be noted that the mixed gas does not necessarily have to be high in purity, but if necessary, an inert gas that does not interfere with the target reaction, such as nitrogen, carbon dioxide, or argon, can be mixed in any ratio.

Although the progress of the reaction can be observed at room temperature, it is usually carried out under heating in order to obtain a higher reaction rate. The reaction temperature is generally 10 to 200 ° C., preferably 20 to 1
It is in the range of 50 ° C. Since the reaction time varies depending on the reaction conditions, the time when the gas absorption is no longer recognized is generally regarded as the end point of the reaction. Generally, 0.1-5
It is in the range of 0 hours, preferably 0.2 to 30 hours.

(Reaction product) 1,4-as the reaction product
In addition to butanedial monoacetal compound (4,4,6-trimethyl-2- (3-oxopropyl) -1,3-dioxane), compounds usually found are mainly 2
A monoacetalized product of methyl-1,3-propanedial and an acetalized product of propanal. In addition to this, a small amount of high boiling point compounds may be generated. For separation of these reaction products and catalysts, known methods such as distillation, extraction and adsorption can be used.

[0015]

According to the present invention, 2-propenal acetal obtained from 2,2,4-trimethyl-1,3-propanediol is used, and the cocatalyst is tris (3,3).
Since 5-dichlorophenyl) phosphine is used, 2
-The terminal regioselective hydroformylation reaction of propenal acetal can be carried out at a lower catalyst concentration and higher selectivity than ever before, and 1,4-butanedial monoacetal can be industrially advantageously produced.

[0016]

EXAMPLES The present invention will be described in more detail with reference to experimental examples. In the examples below, conversion, selectivity and linearity are defined as percentages as follows:

[0017]

[Equation 1]

<Example 1> In a stainless steel autoclave (internal volume: 30 ml), 4,266,6-trimethyl-2-vinyl-1,3-dioxane (0.1266 g, 64.8) was added.
1 mmol), 0.8 mg (0.0033 mmol) of acetylacetonato dicarbonyl rhodium, and 150 mg of tris (3,5-dichlorophenyl) phosphine.
After charging (0.3199 mmol) and sealing, the gas phase in the system was replaced with a mixed gas of carbon monoxide and hydrogen (1: 1 molar ratio), and then this gas was injected under pressure to 10 bar. While stirring, the reaction was performed at a predetermined temperature for 3 hours. During this time,
The absorbed gas was replenished from the outside, and the pressure of the reactor was kept at a predetermined pressure.

The reactor was cooled to room temperature and opened to obtain a uniform solution. As a result of quantitative analysis of the product by gas chromatography, unreacted 4,4,6-trimethyl-2-
Vinyl-1,3-dioxane 0.14 mmol, 4,
4,6-Trimethyl-2- (3-oxopropyl)-
54.32 mmol of 1,3-dioxane, 4,4,6-
Trimethyl-2- (1-oxo-2-propyl) -1,
3-dioxane 6.98 mmol, and 2-ethyl-
4,4,6-trimethyl-1,3-dioxane 1.02
mmol had been produced. 4,4,6-trimethyl-2
The conversion of vinyl-1,3-dioxane is 99.8%,
The hydroformylation selectivity was 94.8% and the linearity was 88.6%.

<Examples 2 and 3> In Example 1,
Examples except that the amounts of 4,4,6-trimethyl-2-vinyl-1,3-dioxane, acetylacetonato dicarbonyl rhodium, and tris (3,5-dichlorophenyl) phosphine used were as shown in Table 1. The same operation as in 1 was repeated. The results are shown in Table 1 together with the results of Example 1.
Shown in.

[0021]

[Table 1]

<Embodiment 4> In Embodiment 1, 4, 4,
6-trimethyl-2-vinyl-1,3-dioxane 1
0.4211 g (66.7 mmol), acetylacetonato dicarbonyl rhodium 0.2 mg (0.0007)
mmol), and 173.3 mg (0.3696 mmo) of tris (3,5-dichlorophenyl) phosphine.
The same operation as in Example 1 was repeated, except that 1) was used, the reaction time was 5 hours, and the reaction pressure was 13 bar.

As a result, unreacted 4,4,6-trimethyl-2-vinyl-1,3-dioxane was not detected,
4,4,6-Trimethyl-2- (3-oxopropyl)
-1,3-dioxane 57.07 mmol, 4,4,6
-Trimethyl-2- (1-oxo-2-propyl)-
1,3-dioxane 7.39 mmol and 2-ethyl-4,4,6-trimethyl-1,3-dioxane 1.
16 mmol had formed. The conversion was 100%, the selectivity was 96.7%, and the linearity was 88.6%.

<Comparative Example> In the autoclave used in Example 1, 3.3256 g (25.94 mmol) of 5-methyl-2-vinyl-1,3-dioxane, 0.3 mg of acetylacetonate dicarbonyl rhodium (0. 001
3 mmol), triphenylphosphine 65.6 mg
(0.25 mmol) was used, and the same operation as in Example 1 was repeated except that the reaction time was 2 hours.

As a result, unreacted 5-methyl-2-vinyl-1,3-dioxane 6.82 mmol, 5-methyl-2- (3-oxopropyl) -1,3-dioxane 1
0.61 mmol, 5-methyl-2- (1-oxo-2
-Propyl) -1,3-dioxane 7.43 mmol,
And 2-ethyl-5-methyl-1,3-dioxane (6.82 mmol) had been produced. The conversion of 5-methyl-2-vinyl-1,3-dioxane was 73.7%, the selectivity was 94.4%, and the linearity was 58.8%.

Claims (1)

[Claims] 1. An acetal obtained by reacting 2-propenal with 2,2,4-trimethyl-1,3-propanediol is treated with carbon monoxide in the presence of a rhodium and tris (3,5-dichlorophenyl) phosphine catalyst. And a method for producing 1,4-butanedial monoacetal, which comprises reacting with hydrogen.