JP2000219645A - Method for producing alcohol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously produce plural kinds of alcohols industrially advantageously while inhibiting the formation of ester and/or ether as by-product by subjecting both an aldehyde and its polycondensation product simultaneously fed into a reaction system in a specific ratio to mixed hydrogenation reaction. SOLUTION: When feeding (A) a 2-5C aldehyde and (B) its polycondensation product in the weight ratio (the component A/the component B) of (95/5)-(5/95), preferably (10/1)-(1/10), into an identical reaction system and carrying out the mixed hydrogenation reaction in the presence of a catalyst, alcohols corresponding to respective aldehydes are produced simultaneously. When the above reaction is performed in a vapor phase and the component B is a dimer obtained by the aldol condensation, or more concretely when producing 2-ethylhexanol by the vapor phase hydrogenation reaction of (C) 2-ethyl-2-hexenal in the presence of a catalyst, it is preferable to simultaneously feed the component C and (D) butyraldehyde into the reaction system and to simultaneously produce 2-ethylhexanol and butyl alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for simultaneously producing an alcohol corresponding to each aldehyde by a mixed hydrogenation reaction of an aldehyde having 2 to 5 carbon atoms and a polycondensate of the aldehyde. Can suppress the production of by-product ester compounds and ether compounds by performing a mixed hydrogenation reaction of the two types of raw material aldehydes, and can simultaneously and efficiently produce alcohols corresponding to the respective aldehydes. And a method for producing alcohol.

[0002]

2. Description of the Related Art A method for producing an alcohol by subjecting an aldehyde to a hydrogenation reaction (hereinafter sometimes referred to as "hydrogenation") has been industrially used for a long time. For example, a method for producing n-butyl alcohol by hydrogenating n-butyraldehyde generated by a hydroformylation reaction of propylene, an aldol condensation reaction of the n-butyraldehyde, and then producing 2-ethyl-2-hexenal Is widely known to produce 2-ethylhexanol by hydrogenation of

[0003] Such an industrial hydrogenation reaction of an aldehyde is carried out in each of a liquid phase and a gaseous phase, but in any of the reaction systems, various side reactions occur to generate a large amount of by-products. , Reducing the selectivity of the reaction. One of the by-products generated in the gas phase hydrogenation reaction is an ester compound. For example, butyl butyrate is contained in the reaction solution obtained by the gas-phase hydrogenation reaction of n-butyraldehyde, and 2-ethylhexane is contained in the reaction solution obtained by the gas-phase hydrogenation reaction of 2-ethyl-2-hexenal. 2-Ethylhexyl acid is by-produced. As the formation mechanism of the ester compound, a mechanism in which hemiacetal is generated from aldehyde and alcohol and then generated by a dehydrogenation reaction of hemiacetal, or a mechanism in which the hemiacetal is generated from two aldehyde molecules by Tischenko reaction is known.

[0004] In order to suppress the by-products of these ester compounds, for example, a method of using a catalyst obtained by adding a selectivity enhancer to, for example, I) a reduced copper oxide-zinc oxide catalyst as a hydrogenation reaction catalyst (Japanese Patent No. 2655034) No.), II) Nickel,
Method of performing a hydrogenation reaction using a supported catalyst containing aluminum oxide and zirconium dioxide (Japanese Patent Publication No. 6-4551), III) Method of performing a hydrogenation reaction using a catalyst containing copper, zinc oxide, and aluminum oxide ( Tokuhei 8-2924
No. 9) or IV) a method of recovering the by-product ester by hydrogenolysis to convert it into an active ingredient (JP-A-58-4).
No. 3930).

[0005] However, the above methods I) to III) require a catalyst having a specific specification, which leads to an increase in the cost of producing the catalyst.
In addition to the aldehyde hydrogenation reactor, a reactor for ester decomposition is required, which increases construction costs, and none of them is industrially effective. In addition, Japanese Unexamined Patent Publication
JP-A-1733 discloses that when an aldehyde having 5 or less carbon atoms is subjected to a hydrogenation reaction to produce an alcohol, 1-octa-octanol, which is an unsaturated alcohol having 8 carbon atoms, is contained in a reaction system.
It is disclosed that 2,7-dienol coexists.

However, as in the method of the present invention, 2
There is no description or suggestion that two types of aldehydes, namely, aldehydes having 2 to 5 carbon atoms and a corresponding polycondensate of the aldehyde are simultaneously produced industrially to produce two corresponding alcohols simultaneously. In the present invention, "two types of aldehydes, that is, the corresponding two types of alcohols are simultaneously industrially produced by a mixed hydrogenation reaction of an aldehyde having 2 to 5 carbon atoms and a polycondensate of the aldehyde" is defined as having 2 carbon atoms. Aldehyde and a polycondensate of the aldehyde are mixed at a specific ratio and subjected to a hydrogenation reaction. In the aldehyde condensation step, a composition containing unreacted raw material aldehyde, for example, As disclosed in JP-A-8-29249, a hydrogenation reaction is carried out using a feed solution having a composition in which the reaction raw materials are about 91.0% of 2-ethyl-2-hexenal and about 1.6% of n-butyraldehyde. It does not mean.

[0007] Conventionally, the method of simultaneously obtaining two kinds of alcohols by the mixed hydrogenation reaction in the method of the present invention has not been carried out because of the hydrogenation reaction in the presence of two or more aldehydes. In such a case, by-products which cannot be produced when each aldehyde is subjected to a hydrogenation reaction alone are usually produced, and a great deal of labor is required to separate the by-products in the purification system.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the production of by-product esters and / or ethers in producing two kinds of alcohols, and to industrially advantageously produce the two kinds of alcohols. And a method for simultaneously producing the same alcohol.

[0009]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have simultaneously supplied an aldehyde having 2 to 5 carbon atoms and a polycondensate of the aldehyde to a reaction system at a specific mixing ratio. Surprisingly, by performing the mixed hydrogenation reaction, it is possible to suppress the formation of an undesired by-product, the ester compound, and also to considerably reduce the amount of the by-produced ether compound. For example, it has been found that two types of alcohols can be produced at the same time industrially advantageously, and the present invention has been achieved. In addition, by using the method of the present invention, conventionally, when two types of aldehydes are hydrogenated to produce the corresponding alcohol, two hydrogenation reaction sequences were required, but can be integrated into one sequence. As a result, industrial implementation is advantageous by reducing the number of reaction series.

That is, the gist of the present invention is that the carbon number is 2 to 5;
Of the aldehyde and the polycondensate of the aldehyde from 95: 5
Fed into the same reaction system at a weight ratio in the range of 5:95,
An alcohol production method characterized by simultaneously producing alcohols corresponding to respective aldehydes by performing a mixed hydrogenation reaction in the presence of a catalyst.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the raw material aldehyde compound used in the mixed hydrogenation reaction of the present invention, those having 2 to 5 carbon atoms and their polycondensates are used. Specifically, for example, propionaldehyde and its condensation dimer, butyraldehyde and its dimer, valeraldehyde and its condensation dimer, and the like are preferable, and butyraldehyde and its condensation dimer are preferable. These aldehyde compounds are usually obtained by hydroformylation of an olefinic compound having 4 or less carbon atoms, and an aldol condensate of the aldehyde compound is used as a polycondensate thereof. Specifically, for example,
Butyraldehyde and 2-ethyl-2-hexenal made from propylene. In this case, butyraldehyde substantially means n-butyraldehyde, but may contain a small amount of i-butyraldehyde.

The starting olefinic compound used in the hydroformylation reaction may be used without any special pretreatment or the like. However, sulfur-containing compounds and halogen-containing compounds known as poisoning substances for the hydroformylation catalyst, dienes, Trienes, further peroxides and the like, known,
What has been removed by a method such as adsorption, extraction, distillation, heat treatment and membrane separation which are usually used can also be used. As the catalyst, usually, VIII having an organic phosphorus compound as a ligand
A transition metal complex catalyst is used. The Group VIII transition metal usually includes rhodium, cobalt, iridium and the like, preferably rhodium. Rhodium sources include:
Hydride carbonyl tris (triphenylphosphine)
Rhodium, acetoxybis (triphenylphosphine)
In addition to rhodium complexes such as rhodium, oxides such as rhodium acetylacetonate and rhodium acetate are also used.

The organic phosphorus compound is not particularly limited, but for example, cyclic and / or tributylphosphine, trioctylphosphine, tricyclohexylphosphine, butyldicyclohexylphosphine and the like.
Or acyclic trialkyl phosphine; cyclic and / or acyclic alkyl aryl phosphine such as monobutyl diphenyl phosphine, dipropyl phenyl phosphine, cyclohexyl phenyl phosphine; triphenyl phosphine, tolyl phosphine, and hydrogen of phenyl Triarylphosphines such as triphenylphosphine substituted with halogen; cyclic and / or noncyclic trialkylphosphites such as trioctyl phosphite and tricyclohexyl phosphite; triphenylphospho which may have a substituent And triaryl phosphites such as phytate and trinaphthyl phosphite, and alkylaryl phosphites. U.S. Patent Nos. 3,415,906, 4,599,206, and 43,
No. 51759, No. 4748261, No. 4567306
And the compounds disclosed in JP-A-5,235,113 and JP-A-5,522,532 may be used.

[0014] Two or more of the organic phosphorus compounds may be used as a mixed ligand. Further, the above organic phosphorus compound and a pentavalent organic phosphorus compound such as triphenylphosphine oxide can be used as a mixture.

As a catalyst preparation method, a rhodium source and an organophosphorus compound ligand may be independently supplied to a hydroformylation reactor to form a catalyst in the reaction system. Treated with carbon monoxide and hydrogen under high temperature and pressure in a solvent together with a phosphorus compound ligand,
A catalyst solution can be prepared in advance. The solvent for preparing the catalyst is usually selected from the reaction solvents described below, but may not be the same as the reaction solvent. The rhodium concentration in the catalyst preparation solution is usually from 1 to 100,000 ppm, and the amount of the organophosphorus compound ligand is from 1 to 10,000 mol times in terms of the atomic ratio of phosphorus to rhodium. Processing temperature is 60 ~
The treatment is carried out at a temperature of 200 ° C., a normal pressure to 200 kg / cm ² , and a treatment time of 0.01 to 20 hours. The container used for the above treatment may be a batch type or a continuous type.

As the reaction solvent for the hydroformylation, the olefin itself may be used as the solvent, or a aldehyde formed or a high-boiling compound produced as a by-product in the reaction may be used.
In addition, aliphatic hydrocarbons such as hexane and octane; aromatic hydrocarbons such as toluene and xylene; butanol;
Various solvents that dissolve the catalyst and do not adversely affect the reaction, such as alcohols such as ethylhexanol, ethylene glycol and propylene glycol, ethers such as triglyme, esters such as dioctyl phthalate, and water can be used.

The pressure of the mixed gas of hydrogen and carbon monoxide in the hydroformylation reaction is usually 0.1 to 3
00 kg / cm ² , the ratio of the hydrogen partial pressure to the carbon monoxide partial pressure is 0.1 to 10, the temperature is 60 to 200 ° C., the rhodium concentration in the reaction solution is 1 to 100,000 ppm, and the addition amount of the organophosphorus compound ligand is , The atomic ratio of phosphorus to rhodium,
The reaction is performed in a range of 1 to 10000 mol times and a reaction time of 0.01 to 20 hours.

The method for obtaining the product aldehyde from the hydroformylation reaction zone carried out as described above is not particularly limited.
A method by gas stripping as described in JP-A No. 03, and a method by distillation as described in JP-A-54-89974. Whichever means is taken, as a result, most of the unreacted olefin, solvent and catalyst solution containing high-boiling by-products are removed, so that the components contained in the aldehyde obtained by the above-described method and the like are used. In addition to aldehyde as the main component, a very small amount of dissolved gas (hydrogen, carbon monoxide, methane, carbon dioxide, etc.), a small amount of unreacted olefins and paraffins that are lighter than aldehyde, water, It is a fraction lighter than the main aldehyde, such as an aldehyde having one carbon number less than the aldehyde component, a small amount of a solvent, and a high-boiling by-product.

The aldehyde obtained from the hydroformylation reaction zone contains a linear group and a branched group.
The linear product may be separated and purified and used in a subsequent step, that is, a hydrogenation reaction or a condensation step. When the content of the branched product is extremely small, or when the branched product or impurities derived from the branched product can be sufficiently separated and removed in the separation step after the hydrogenation reaction, the post-process is performed without separating the linear and branched products of the aldehyde. In some cases, they may be brought to When a linear product is separated and purified, the separation method is not limited as long as the linear product and the branched product can be directly separated. For example, when separation is performed by distillation, the pressure at the top of the distillation column is not particularly limited, but if the pressure is reduced, aldehyde loss due to non-condensation occurs in the top condenser. The temperature in the distillation column varies depending on the number of carbon atoms of the aliphatic aldehyde, the pressure at the top, and the bottom pressure determined by the type of the distillation column, but is 60 to 120 ° C. at the top and 70 to 150 ° C. at the bottom.
It is preferred that

The aldol condensation of the aldehyde formed in the hydroformylation reaction can be carried out in a liquid phase or a gas phase. When the reaction is carried out in a liquid phase, it is usually carried out in an alkaline aqueous solution such as an aqueous sodium hydroxide solution. Temperature is 8
The pressure may be 0 to 120 ° C. and the pressure may be equal to or higher than the saturation pressure of the liquid at the set temperature, and for example, is preferably in the range of normal pressure to 10 kg / cm ² .

An aldehyde obtained by the hydroformylation reaction and a polycondensation aldehyde obtained by subjecting the aldehyde to aldol condensation;
For example, 2-butyraldehyde obtained by hydroformylation of propylene and its aldol condensate
In carrying out the mixed hydrogenation reaction with ethyl-2-hexenal, the hydrogenation catalyst and the reaction conditions can be arbitrarily selected from methods known per se and commonly used. The hydrogenation catalyst is not particularly limited as long as it promotes the hydrogenation reaction of the aldehyde.For example, a catalyst containing a Group VIII metal such as nickel, palladium or platinum, or a solid catalyst containing a copper oxide and zinc oxide reduction mixture , A copper-chromium catalyst or a copper-chromium-manganese-barium catalyst.
Further, for example, an improved copper oxide-zinc oxide mixed catalyst described in Japanese Patent No. 2655034 may be used.

In the present invention, the mixing ratio of the raw material aldehyde simultaneously supplied to the hydrogenation reaction system is 2 to 5 carbon atoms.
Aldehyde: The polycondensate of the aldehyde has a weight ratio of 9
The range is 5: 5 to 5:95, preferably 10: 1 to 1:10, and more preferably 10: 3 to 3:10. When the mixing ratio of the aldehyde having 2 to 5 carbon atoms is less than the lower limit, the effect of suppressing the formation of the ester and ether to which the polycondensate of two or more aldehydes is bonded becomes extremely small. If the percentage is below the lower limit,
This is not preferable because the effect of suppressing the formation of esters and ethers having two or more aldehydes having 2 to 5 carbon atoms bonded thereto is significantly reduced.

The mixed hydrogenation reaction of the starting aldehyde can be carried out in a liquid phase or a gaseous phase. However, the gaseous phase is more effective than the mixed hydrogenation in the liquid phase because the formation of ether by-products is suppressed. ,preferable. The hydrogenation reaction conditions are not particularly limited, but usually the reaction temperature is 50 to 300.
° C, preferably 100 to 250 ° C, more preferably 15 ° C.
0-200 ° C, hydrogen pressure is normal pressure-200 kg / cm ² ,
Preferably, it is carried out within the range of normal pressure to 100 kg / cm ² , more preferably normal pressure to 10 kg / cm ² . Any of a batch system and a continuous system may be used as the reaction system.

The reaction product liquid produced by the above mixed hydrogenation reaction can be separated and purified into individual alcohols by a method known per se, such as distillation. The product alcohol has a large difference in boiling point because one is a monomer and the other is a polycondensate, and thus can be easily separated. For example, n-butyl alcohol has a boiling point of 117.7.
° C, whereas 2-ethylhexanol is 18
3.5 ° C.

The alcohol obtained by the method of the present invention can be esterified with a carboxylic acid or a carboxylic anhydride to produce an ester compound, and the ester compound can be used as a plasticizer for resins. As the carboxylic acid or carboxylic anhydride used in the esterification reaction, for example, phthalic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid or pyromellitic acid Menlitic anhydride and the like can be mentioned, and among these, phthalic acid or phthalic anhydride is preferable. The esterification reaction is
Any known method known per se may be used. For example, an alcohol and a carboxylic acid may be reacted in the presence of a catalyst ("Plasticizer-Its Theory and Application-", edited by Koichi Murai, Koshobo, 415-426, March 1, 1973
Date). The ester compound thus obtained can be used as a plasticizer by adding it to a resin such as polyvinyl chloride ("Plasticizer-Theory and Application-", edited by Koichi Murai,
Koshobo, pages 481-536, issued March 1, 1973).

[0026]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 A 1-inch φ × 60 cm SUS single-tube reactor filled with 10 cc of a 5 mmφ × 5 mm cylindrical Cu—Cr-based hydrogenation catalyst (manufactured by Nikki Chemical Co., trade name: N202E) was vaporized into 2-ethyl- 2-hexenal (hereinafter referred to as “EP
A) 68.35 mmol / H
r, n-butyraldehyde (hereinafter sometimes referred to as “NBD”) 45.74 mmol / Hr and hydrogen 240
0 mmol / Hr, and the reaction pressure was 4.6 kg / c.
A gas-phase hydrogenation reaction is carried out at a reaction temperature of 180 ° C. and a reaction liquid (condensate from the reactor outlet) at m ² G (indicated pressure of a pressure gauge).
Was analyzed by gas chromatography. The weight ratio of EPA: NBD at the time of charging the raw materials was 72:28. The results are shown in Table 1. The catalyst in the reactor was previously heated at a temperature of 200 ° C. with a dilute hydrogen stream containing nitrogen as a diluent.
Was reduced by

Comparative Example 1 In Example 1, EPA 10 was used as the starting aldehyde.
The same operation as in Example 1 was performed except that only 3.8 mmol / Hr was supplied. The results are shown in Table 1. Comparative Example 2 In Example 1, NBD10 was used as the raw material aldehyde.
The same operation as in Example 1 was performed except that only 7.6 mmol / Hr was supplied. The results are shown in Table 1.

[0028]

Table 1 Example 1 Comparative Example 1 Comparative Example 2 NBD: EPA EPA 72 100 0 weight ratio NBD 28 0 100 Conversion [%] EPA 100 100- NBD 99.90-99.95 Production rate [%] 2EH 99.83 99.40- NBA 99.90 - 97.05 Ester1 0.212 0.384 - Ester2 0.0219 - 0.525 byproducts 0.0 0.22 2.42

Terms in Table 2EH: 2-ethylhexanol EPA: 2-ethyl-2-hexenal Ester 1: 2-ethylhexanoic acid-2-ethylhexyl Ester 2: butyl butyrate NBA: n-butyl alcohol NBD: n-butyraldehyde Organisms: Other by-products

Example 2 A 5 mmφ × 5 mm cylindrical Cu—Cr-based hydrogenation catalyst (manufactured by JGC Corporation, trade name: N202E) was pulverized to 16 to 24 mesh. 8mmφ filled with 7.4cc of the catalyst
Evaporated EPA into × 60cm SUS single tube reactor
90 mmol / Hr, 105 mmol / Hr of NBD and 13300 mmol / Hr of hydrogen were added at a reaction temperature of 180 ° C.
The reaction was supplied at a reaction pressure of 4 kg / cm ² G (indicated pressure of a pressure gauge). The weight ratio of EPA: NBD at the time of raw material preparation is 60:
It was 40. The catalyst in the reactor was previously reduced at a temperature of about 200 ° C. with a dilute hydrogen stream containing nitrogen as a diluent. The condensate from the reactor outlet was analyzed by gas chromatography. The results are shown in Table 2.

Example 3 In Example 2, the supply amount of the starting aldehyde was changed to EPA7.
The same operation as in Example 2 was performed except that 4 mmol / Hr and 130 mmol / Hr of NBD were used. E during raw material preparation
The weight ratio of PA: NBD was 50:50. The results are shown in Table 2. Example 4 In Example 2, the supply amount of the raw material aldehyde was changed to EPA1.
The same operation as in Example 2 was carried out except that 75 mmol / Hr and NBD were 34 mmol / Hr. E during raw material preparation
The weight ratio of PA: NBD was 90:10. The results are shown in Table 2.

COMPARATIVE EXAMPLE 3 A 5 mmφ × 5 mm cylindrical Cu—Cr-based hydrogenation catalyst (manufactured by JGC Chemicals, trade name: N202E) was pulverized to 16 to 24 mesh. 8mmφ × 6 filled with 7cc of the catalyst
Evaporated NBD23 into a 0 cm SUS single tube reactor
3 mmol / Hr and hydrogen 13000 mmol / Hr
Was supplied at a reaction temperature of 170 ° C. and a reaction pressure of 4 kg / cm ² G (indicated pressure of a pressure gauge). The catalyst in the reactor is preliminarily heated to a dilute hydrogen stream containing nitrogen as a diluent at a temperature of 2.
It was reduced at about 00 ° C. The condensate from the reactor outlet was analyzed by gas chromatography. The results are shown in Table 2.

[0033]

[Table 2] Example 2 Example 3 Example 4 Comparative Example 3 EPA: NBD EPA 60 50 90 0 Weight ratio NBD 40 50 10 100 Conversion [%] EPA 99.99 100.00 99.98 NBD 99.92 99.90 99.95 99.88 Production rate [%] Ester1 0.01 0.01 0.03 Ester2 0.01 0.02 0.01 0.48 By -product 0.0 0.0 0.0 0.11

Terms in Table EPA: 2-ethyl-2-hexenal Ester 1: 2-ethylhexanoic acid-2-ethylhexyl Ester 2: butyl butyrate NBD: n-butyraldehyde By-product: Other by-products

[0035]

According to the method of the present invention, an aldehyde having 2 to 5 carbon atoms and a polycondensate of the aldehyde are fed into the same reaction system at a specific mixing ratio to cause a mixed hydrogenation reaction. Can suppress the formation of ester and / or ether by-products as compared to a single hydrogenation reaction of
In addition, the production rate of alcohol corresponding to the raw aldehyde can be improved. Further, since the number of reactors conventionally required in total of two for each aldehyde can be reduced to one, the industrial utility value of the present invention is extremely large.

Continued on the front page (72) Inventor Hiroki Emoto 3-10 Ushidori, Kurashiki-shi, Okayama Pref.Mitsubishi Chemical Co., Ltd. In business office

Claims (17)

[Claims] 1. An aldehyde having 2 to 5 carbon atoms and a polycondensate of the aldehyde are fed into the same reaction system at a weight ratio of 95: 5 to 5:95, and mixed hydrogen is added in the presence of a catalyst. A method for producing an alcohol, wherein an addition reaction is carried out to simultaneously produce alcohols corresponding to the respective aldehydes. 2. The method according to claim 1, wherein the weight ratio of the aldehyde having 2 to 5 carbon atoms to the polycondensate of the aldehyde is in the range of 10: 1 to 1:10. 3. The method according to claim 1, wherein the weight ratio of the aldehyde having 2 to 5 carbon atoms to the polycondensate of the aldehyde is in the range of 10: 3 to 3:10. 4. The method according to claim 1, wherein the mixed hydrogenation reaction is carried out in the gas phase. 5. The method according to claim 1, wherein the polycondensate of the aldehyde is a dimer obtained by aldol condensation. 6. The method according to claim 1, wherein the aldehyde has 4 carbon atoms. 7. The process according to claim 1, wherein the aldehyde is produced by hydroformylation of an olefin. 8. When producing 2-ethylhexanol by subjecting 2-ethyl-2-hexenal to gas-phase hydrogenation reaction in the presence of a catalyst, 95: 5 to 5: 5 : A method for producing alcohol, characterized in that 2-ethylhexanol and butyl alcohol are produced at the same time by simultaneously supplying them to the reaction system at a weight ratio in the range of 95 to cause a mixed gas-phase hydrogenation reaction. 9. The method according to claim 8, wherein the weight ratio of 2-ethyl-2-hexenal to butyraldehyde is in the range of 10: 1 to 1:10. 10. The method according to claim 8, wherein the weight ratio of 2-ethyl-2-hexenal to butyraldehyde is in the range of 10: 3 to 3:10. 11. The process according to claim 8, wherein the butyraldehyde is produced by hydroformylation of propylene. 12. An aldehyde having 4 or less carbon atoms is hydroformylated with hydrogen and carbon monoxide in the presence of a catalyst to obtain an aldehyde, and a part of the aldehyde is converted into a dimer by aldol condensation, and the aldehyde and aldol condensation are obtained. The dimers are fed into the same reaction system at a weight ratio of 95: 5 to 5:95, and mixed gas-phase hydrogenation reaction is performed in the presence of a catalyst to simultaneously produce alcohols corresponding to the respective aldehydes. And isolating each alcohol with a separation device. 13. The method according to claim 12, wherein the weight ratio of the aldehyde to the aldol condensation dimer is in the range of 10: 1 to 1:10. 14. The method according to claim 12, wherein the weight ratio of the aldehyde to the aldol condensation dimer is in the range of 10: 3 to 3:10. 15. The process according to claim 12, wherein the olefin is propylene and the aldol condensation dimer is 2-ethyl-2-hexenal. 16. A method for producing a phthalic acid ester, comprising reacting an alcohol produced by the method according to claim 12 with phthalic acid or phthalic anhydride. 17. A plasticizer comprising a phthalate obtained by the method according to claim 16.