JPH11269118A - Production of dimer aldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the formation of the byproduct of a high-boiling compound in the production of a dimer aldehyde by subjecting a >=3C aldehyde having a hydrogen atom at the α-position to condensation and dehydration reactions in the presence of an aqueous solution containing a basic catalyst. SOLUTION: An organic solvent having a β-value, which is defined by the following formula, of 3 or more is placed in the reaction system, β=γAγC/γB<2> wherein, γA, γB and γB are infinite dilution activity coefficients calculated by a modified UNIFAC.Dortmund model for the raw material aldehyde, based on a forming dimer aldehyde and water in an organic solvent placed in the reaction system, respectively, The volume ratio of the organic solvent to the aldehyde supplied into the reaction system is 0.1 or more, and the volume ratio of the water phase to the organic phase supplied into the reaction system is 0.1 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a dimerized aldehyde by subjecting an aldehyde to a condensation reaction and a dehydration reaction in the presence of a basic catalyst. More specifically, the present invention relates to a method for suppressing the formation of undesired high-boiling compounds such as aldehyde trimers in the aldehyde condensation reaction and dehydration reaction, and for producing a dimerized aldehyde with high selectivity.

[0002]

2. Description of the Related Art It is known that an aldehyde is subjected to a condensation reaction and a dehydration reaction in the presence of an aqueous solution of caustic soda to produce a dimerized aldehyde. For example, when n-butyraldehyde is subjected to a condensation dehydration reaction, 2-ethylhexenal is obtained. One of the problems with this method is that the desired dimerized aldehyde further reacts to produce undesirable high-boiling compounds such as trimers and tetramers. Since the formation of these high-boiling compounds results in a decrease in the yield of dimerized aldehyde, various measures have been proposed to avoid this. For example, Japanese Patent Publication No. 39-24787 discloses that n-butyraldehyde and an aqueous alkali solution are brought into countercurrent contact with a packed tower or a perforated tower, and pulsation is applied to the tower to convert n-butyraldehyde into fine particles in the aqueous alkali solution. Dispersing is described. However, in this method, the yield of 2-ethylhexenal is at most 94%.

Further, Japanese Patent Publication No. 52-43810 discloses that n-butyraldehyde and an aqueous alkali solution are mixed in a two-stage reactor using a stirring mixer and a tubular reactor.
It is described that the reaction is performed at 130 ° C. and 4 to 5 kg / cm ² G. However, even in this method, a considerable amount of a high-boiling compound is produced, and unreacted n-butyraldehyde remains, so that the yield of dimerized aldehyde is not satisfactory. Further, French Patent No. 2,058,532 describes that acetaldehyde is condensed using an aqueous solution of caustic soda and the reaction is stopped by adding acetic acid to the reaction system before a dehydration reaction occurs. However, in this method, it is impossible to recycle the aqueous solution of caustic soda.

Further, Japanese Patent Publication No. 39-24952 and Japanese Patent Publication No. 39-17907 propose decomposition of a high-boiling compound produced as a by-product into an original aldehyde and an unsaturated aldehyde. However, these methods require a special device for decomposing high-boiling compounds, and are difficult to employ industrially.

[0005]

As described above, none of the conventionally proposed methods is satisfactory as a method for producing a dimerized aldehyde. Accordingly, an object of the present invention is to provide a method for producing a dimerized aldehyde which is easy to carry out on an industrial scale and in which by-products of a high boiling point compound are remarkably reduced.

[0006]

According to the present invention, an aldehyde having 3 or more carbon atoms and having a hydrogen atom at the α-position is subjected to a condensation reaction and a dehydration reaction in the presence of an aqueous solution containing a basic catalyst to thereby dimerize the aldehyde. When an aldehyde is produced, an organic solvent having a value of β defined by the following formula (1) of 3 or more is present in the reaction system, whereby by-products of high-boiling compounds are suppressed and the yield is high. A quantified aldehyde can be produced.

[0007]

## EQU2 ## β = γ _A γ _C / γ _B ² (1)

Wherein γ _A , γ _B and γ _C are respectively
4 shows the infinite dilution activity coefficient of an aldehyde to be reacted, dimerized aldevide and water produced in an organic solvent to be present in a reaction system, calculated by a modified UNIFAC Dortmund model. )

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an aldehyde having 3 or more carbon atoms and having a hydrogen atom at the α-position, such as n-butyraldehyde, isobutyraldehyde, valeraldehyde, 2-methyl Butyraldehyde and the like. The aldehyde can be used for the reaction alone or as a mixture. Preferably, a saturated aldehyde having two hydrogen atoms at the α-position, for example, n-butyraldehyde or valeraldehyde is used.

As the basic catalyst, any one commonly used in this reaction can be used. For example, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and calcium hydroxide and the like can be used. Various amines such as alkaline earth metal hydroxide, trimethylamine, triethylamine, tripropylamine, diethylamine, dipropylamine and dibutylamine, and hydroxylation such as trimethylbenzylammonium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide A quaternary ammonium compound or the like is used. Preferably, an inorganic basic compound is used because it is difficult to mix in the obtained dimerized aldehyde. Particularly preferred are sodium hydroxide, potassium hydroxide and lithium hydroxide.

The concentration of the basic catalyst in the aqueous solution is usually 0.1 to 50% by weight, preferably 0.5 to 10% by weight.
It is. The aqueous solution containing the basic catalyst is used in an amount of 0.1 or more, preferably 0.5 or more by volume, relative to the total amount of the organic phase supplied to the reaction system, ie, the aldehyde and the organic solvent described below. To supply. In particular, it is preferable to supply so as to be 0.7 to 10.

In the present invention, when the above-mentioned aldehyde is subjected to a condensation reaction and a dehydration reaction in the presence of the above-mentioned basic catalyst to produce a dimerized aldehyde, the value of β defined by the formula (1) is added to the reaction system. 3 or more organic solvents are present. According to the study of the present inventors, the high-boiling compound produced as a by-product is generated by further reaction of a dimerized aldehyde dissolved in water. Therefore, when a dimerized aldehyde is extracted from water into an organic solvent using an organic solvent, the by-product of a high-boiling compound should be able to be suppressed. For this purpose, an organic solvent having a large ratio (γ _C / γ _B ) of the infinite dilution activity coefficient (γ _C ) of water to the infinite dilution activity coefficient (γ _B ) of the dimerized aldehyde in the organic solvent is used. Good. In addition, in addition to the dimerized aldehyde in water, the raw material aldehyde is also dissolved, but if the organic solvent also extracts the raw material aldehyde, the condensation reaction is delayed and the reaction takes a long time, As a result, the production amount of the high boiling point compound increases. Therefore, the ratio of the infinite dilution activity coefficient (γ _A ) of the raw material aldehyde to the infinite dilution activity coefficient (γ _B ) of the dimerized aldehyde in the organic solvent used in the extraction is (γ _A / γ _B ). Must be big.

[0013] The present inventors have based on such a study,
As a result of examining the relationship between the β value defined by the above formula (1) and the by-product amount of the high-boiling compound, the use of an organic solvent having a β value of 3 or more indicates that the by-product amount of the high-boiling compound is significant. It was found that it could be reduced significantly. γ _A , γ _B and γ _C are calculated by the following equations.

[0014]

Equation 3] _{l n γ A = l n γ} A C + l n γ A R l n γ B = l n γ B C + l n γ B R l n γ C = l n γ C C + l n γ C R

[0015] ^{_{l n γ A C, l n}} γ B C and l _n gamma _C ^C is a contribution term due to a difference magnitude of the molecules constituting the mixture referred to as a combinatorial ^{_{term, l n γ A R, l}} n γ
_B ^R and l _n γ _C ^R are contribution terms due to intermolecular interaction called residual terms. Eng. Che
m. Res. It is calculated as follows from the modified UNIFAC Dortmund model described in 1993, 32, 178-193.

[0016]

(Equation 4)

[0017]

(Equation 5)

Any organic solvent may be used as long as it has a β value of 3 or more. Examples of the aldehyde used for the reaction include n-butyraldehyde, isobutyraldehyde, valeraldehyde, 2-methylbutyraldehyde and the like. When used, for example, benzene, toluene, xylene, ethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, octane, 2-ethylhexanol, cycloheptane, dichloroethane, cyclododecane, hexadecane, tetrahydronaphthalene,
Biphenyl, tetramethylbenzene, cyclohexylbenzene, diisopropylbenzene, diphenylmethane,
Terphenyl, cyclododecatriene, methylnaphthalene, bibenzyl, phenylheptane, allylphenylether, benzylphenylether, dioctylether, or the like may be used. Preferably, benzene, toluene, xylene, ethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, tetrahydronaphthalene, biphenyl, tetramethylbenzene, cyclohexylbenzene, diisopropylbenzene, diphenylmethane, terphenyl, methylnaphthalene, bibenzyl, phenylheptane, allylphenyl ether, Use benzyl phenyl ether or the like. Most preferred are benzene, toluene, xylene, ethylbenzene, tetrahydronaphthalene, biphenyl, diphenylmethane, bibenzyl and the like.

The organic solvent is supplied to the reaction system so that the volume ratio with respect to the aldehyde to be reacted is 0.01 or more, preferably 0.1 or more. When the supply amount is too small, the effect of suppressing the by-product of the high boiling point compound is not sufficiently exhibited. Conversely, if the supply amount is too large, it is disadvantageous because the size of the reaction apparatus and the subsequent separation / purification apparatus is increased. Usually, it is preferable to supply the aldehyde to be supplied in a volume ratio of 0.1 to 5.0 times the aldehyde to be subjected to the reaction.

The reaction is usually carried out at atmospheric pressure to 10 kg / cm ² . Although it is not impossible to perform the reaction under reduced pressure, a device that condenses the vapor generated from the raw material aldehyde or organic solvent and returns it to the reaction system is required. The reaction temperature may be appropriately selected depending on the aldehyde to be subjected to the reaction,
For example, in the case of n-butyraldehyde, usually 30 ° C.
100 ° C. Of course, the reaction can be carried out at higher temperatures. The reaction is usually performed in a continuous mode, but can be performed in a batch mode if desired. The dimerized aldehyde can be recovered from the reaction product by a conventional method. Usually, the reaction product is allowed to stand and separated into an oil phase and an aqueous phase. Since the aqueous phase contains a basic catalyst, it is circulated to the reaction system as it is, and the oil phase is distilled to separate the desired dimerized aldehyde from high-boiling compounds. The recovered dimerized aldehyde is further purified by distillation if necessary, and then catalytically hydrogenated to obtain a corresponding alcohol.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Examples 1 to 24 and Comparative Examples 1 to 3 n- obtained by hydroformylation of propylene
Butyl aldehyde was condensed and dehydrated to produce 2-ethylhexenal. 50 ml of a 5% by weight aqueous solution of caustic soda was placed in a 200 ml round bottom flask, and the temperature was raised to 80 ° C. while stirring under a nitrogen stream. An organic solvent was added to 25 ml of n-butyraldehyde to make a total volume of 50 ml, and the solution was added dropwise over about 15 minutes. Subsequently, the mixture was further stirred at 80 ° C. for 30 minutes. The reaction solution was collected, allowed to stand, separated into an aqueous phase and an oil phase, and the oil phase was analyzed by gas chromatography. The results are shown in Table 1. In the table, NBD is n
-Butylaldehyde, EPA stands for 2-ethylhexenal.

COMPARATIVE EXAMPLE 4 Except that 50 ml of n-butyraldehyde was used instead of 50 ml of a mixture of n-butyraldehyde and an organic solvent,
The reaction was carried out as described above. The results are shown in Table 1.

[0023]

[Table 1]

[0024]

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroki Emoto 3-10 Ushidori, Kurashiki-shi, Okayama Prefecture Mitsubishi Chemical Mizushima Office (72) Inventor Akio Tsuboi 3--10, Utsudori, Kurashiki-shi, Okayama Mitsubishi Chemical Mizushima Office Co., Ltd.

Claims (8)

[Claims] 1. A method for producing a dimerized aldehyde by subjecting an aldehyde having 3 or more carbon atoms and a hydrogen atom at the α-position to a condensation reaction and a dehydration reaction in the presence of an aqueous solution containing a basic catalyst, A method characterized in that an organic solvent having a value of β defined by the following formula of 3 or more is present. Wherein β = γ _A γ _C / γ _B ² (where γ _A , γ _B and γ _C are each an aldehyde to be subjected to the reaction in an organic solvent to be present in the reaction system,
Modified UNIFAC of dimerized aldehyde and water formed
-Indicates the infinite dilution activity coefficient calculated by the Dortmund model. ) 2. The volume ratio of the organic solvent to the aldehyde supplied to the reaction system is 0.1 or more, and the volume ratio of the aqueous phase to the organic phase supplied to the reaction system is 0.1 or more. The method according to claim 1, wherein 3. The method according to claim 1, wherein the organic solvent to be present in the reaction system has an optionally substituted aromatic ring. 4. The organic solvent to be present in the reaction system is benzene, toluene, xylene, ethylbenzene, chlorobenzene, tetrahydronaphthalene, biphenyl, tetramethylbenzene, cyclohexylbenzene, diisopropylbenzene, diphenylmethane, terphenyl, methylnaphthalene, bibenzyl, phenyl 3. The method according to claim 1, wherein at least one selected from the group consisting of heptane, allyl phenyl ether and benzyl phenyl ether. 5. The method according to claim 1, wherein the aldehyde used for the reaction is n-butyraldehyde and / or isobutyraldehyde. 6. The method according to claim 1, wherein the aldehyde used for the reaction is valeraldehyde and / or 2-methylbutyraldehyde. 7. The method according to claim 1, wherein the basic catalyst is an inorganic basic compound. 8. The method according to claim 7, wherein the inorganic basic compound is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.
The described method.