JPH0245610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to 1,8-octanedial or 1,8-octanedial.
It relates to a method for producing 10-decane dial, and more specifically to a method for producing 1,8-decane dial, which comprises hydroformylating 1,5-hexadiene or 1,7-octadiene in a method suitable for industrial implementation.
This invention relates to a method for producing octanedial or 1,10-decanedial. 1,8-octanedial or 1,10-decanedial is an extremely useful compound as a protein and enzyme immobilizing agent, a bactericidal agent, a polymer crosslinking agent, and as a starting material for the corresponding dicarboxylic acids, diols, and diamines. This is well known, and an industrial method for producing it using a hydroformylation reaction of 1,5-hexadiene or 1,7-octadiene has already been proposed. However, the previously proposed method contains the following two technical problems, and perhaps because these problems have not been resolved, 1,8-octanedial or 1,10-decanedial is still not available on an industrial scale. It has not yet been produced, and has only been reagent-synthesized from the corresponding dicarboxylic acid ester by a partial reduction method using very expensive reagents. One of the problems with the previously proposed method is that in the hydroformylation reaction of 1,5-hexadiene or 1,7-octadiene, at least three isomers (n-type-n-type dialdehyde, n-type-i-type dialdehyde and i-type-i-type dialdehyde) is generated,
Since their boiling points are close to each other and they are not thermally stable enough, the n-type to n-type products 1,8-octanedial or 1,10-decanedial can be extracted from the mixture of these isomers. It is virtually impossible to separate and obtain the purity.
Another technical problem with the previously proposed method is the deterioration of the catalytic activity of the rhodium catalyst when the reaction product is separated and obtained from the hydroformylation reaction mixture.
In other words, in the conventionally proposed method, a distillation separation method is used to separate the rhodium catalyst and the reaction product, but the rhodium catalyst is thermally unstable in a solvent and easily degenerates into an inactive rhodium complex. In the distillation separation method, it is difficult to avoid the accumulation of high boiling point by-products in the reaction system. In this way, following the conventionally proposed method, high purity 1,8-octanedial or 1,
It is virtually impossible to produce 10-decandial industrially. Against this background, the present inventors aimed to complete an industrially viable method for producing highly pure 1,8-octanedial or 1,10-decanedial from 1,5-hexadiene or 1,7-octadiene. As a result of extensive research, we have arrived at the present invention.
That is, according to the present invention, () the weight ratio of sulfolane, 1,4-butanediol or 1,6-hexanediol to water is
(a) rhodium complex compound and (b) sodium salt of diphenylphosphinobenzene-m-monosulfonic acid in 15/85 to 75/25 sulfolane, 1,4-butanediol or 1,6-hexanediol aqueous solution , hydroformylating 1,5-hexadiene or 1,7-octadiene with a mixed gas of hydrogen and carbon monoxide in the presence of a potassium salt or a lithium salt, and () to the reaction mixture obtained in step (). An extraction operation using a saturated aliphatic primary alcohol having about 5 to 12 carbon atoms, or a mixture of the primary alcohol and a saturated aliphatic hydrocarbon or saturated alicyclic hydrocarbon having about 5 to 10 carbon atoms. 1,8-octanedial or 1,10-decanedial is extracted from the reaction mixture by subjecting it to step (), and the raffinate layer containing the catalyst component is recycled to the hydroformylation reaction step of step (). 1,8-octanedial or 1,10-decanedial is enriched by a method consisting of obtaining 1,8-octanedial or 1,10-decanedial from the extraction layer containing the produced dialdehyde obtained in step (). It can be produced with high yield. In addition, according to the present invention, the extraction operation in step () is performed using n-hexanol, n-heptanol, n-
A primary alcohol selected from the group consisting of octanol, n-nonanol and n-decanol, or a saturated aliphatic hydrocarbon selected from the group consisting of hexane, heptane, octane, decane, cyclohexane and methylcyclohexane, or 1,8-octanedial is extracted using a mixture of saturated alicyclic hydrocarbons at a temperature of 10 to 60°C, and the resulting extracted layer is washed with water and kept at a temperature of 0 to 50°C. Or 1,10-decandial is the general formula (A) (In the formula, n is 6 or 8, and R has 6 carbon atoms.
represents a straight-chain saturated aliphatic hydrocarbon group from By separating and obtaining the crystals, extremely high purity 1,8-octanedial or 1,10-decanedial can be obtained. As the rhodium complex compound used in the hydroformylation reaction of 1,5-hexadiene or 1,7-octadiene according to the method of the present invention, any rhodium complex compound having hydroformylation catalytic ability under the reaction conditions can be used.
Many such rhodium complex compounds are already known, and most of these conventionally known rhodium complex compounds can be used in the method of the present invention. Specifically, HRh (CO) (PA ₃ ) ₃ (A; aryl group), Rh ₄
(CO) ₁₂ and Rh ₆ (CO) ₁₆ . Also, RhCl(PA ₃ ) ₃ , Rh(acac) ₃ (acac;
acetylacetonate group), Rh(OAc) ₃ (OAc; acetoxyl group), [Rh(CO) ₂ (PA ₃ ) ₂ ] ₂ , RhCl ₃ .
It can also be used after activating rhodium (complex) compounds such as 3H ₂ O and Rh ₂ O ₃ in a separate catalyst preparation tank using a conventional method. The rhodium complex compound is usually used in a concentration range of 0.05 to 10 milligram atoms per hydroformylation reaction solution in terms of rhodium atoms. The sodium salt, potassium salt, and lithium salt of diphenylphosphinobenzene-m-monosulfonic acid used in the hydroformylation reaction of the present invention have the following general formula: (In the formula, M represents Na, K or Li.) It is a water-soluble trisubstituted phosphine represented by the following formula. These diphenylphosphinobenzene-m-monosulfonic acid salts are used in an amount of 10 equivalents or more, preferably 25 equivalents or more per gram atom of rhodium. In the hydroformylation reaction of 1,5-hexadiene or 1,7-octadiene according to the method of the present invention, the weight ratio of sulfolane, 1,4-butanediol or 1,6-hexanediol to water is 15/85.
~75/25 sulfolane, 1,4-butanediol or 1,6-hexanediol aqueous solution. Among these, it is more preferable to use a sulfolane aqueous solution in consideration of reaction results, subsequent product separation steps, chemical stability, and the like. If the concentration of sulfolane, 1,4-butanediol or 1,6-hexanediol in the aqueous solution is less than 15% by weight, the reaction rate will decrease and the layer separation properties in step (2) will deteriorate, which is not preferred. Furthermore, if the concentration of the aqueous solution exceeds 75% by weight, the rate of elution of the solvent and catalyst components into the extraction layer in step () increases, which is not preferable. A particularly desirable concentration of the aqueous solution of sulfolane, 1,4-butanediol or 1,6-hexanediol is the weight ratio of sulfolane, 1,4-butanediol or 1,6-hexanediol to water.
It is 25/75 to 60/40. This hydroformylation reaction is usually carried out at a temperature of 40 to 110°C, preferably 60 to 90°C. In the hydrogen/carbon monoxide mixed gas used in the reaction, the molar ratio of hydrogen to carbon monoxide is usually selected within the range of 0.5 to 5 as the input gas composition. The reaction pressure is generally selected from within the range of 1 to 30 atmospheres. The hydroformylation reaction can be carried out continuously or batchwise in a stirred reactor or bubble column reactor. Since the solubility of the raw material diene and the reaction intermediate monoaldehydes in the reaction mixture under the reaction conditions is relatively low, the feed rate of 1,5-hexadiene or 1,7-octadiene is adjusted depending on the reaction rate. It is desirable to control the reaction system, thereby preventing the reaction system from becoming heterogeneous. The concentration of 1,8-octanedial or 1,10-decanedial in the reaction mixture is preferably within the range of 0.5 to 3 mol/mole from the viewpoint of catalytic activity and product separation. According to detailed studies by the present inventors, for example, a mixed solution of sodium dihydrogen phosphate (NaH ₂ PO ₄ ) and sodium hydrogen phosphate (Na ₂ HPO ₄ ), potassium dihydrogen phosphate (KH The catalytic activity can be further increased by maintaining the pH of the reaction mixture in the range _of 5 to 7 by coexisting an appropriate amount of a buffer solution _, typically a mixed solution of potassium phosphate-hydrogen (K ₂ HPO ₄ ) and potassium hydrogen phosphate (K 2 HPO 4 ). Stabilization was observed. The reaction mixture obtained by hydroformylating 1,5-hexadiene or 1,7-octadiene is a saturated aliphatic primary alcohol having about 5 to 12 carbon atoms, or the primary alcohol and the carbon number. is subjected to an extraction operation with a mixture of about 5 to 10 saturated aliphatic or saturated alicyclic hydrocarbons. Saturated aliphatic primary alcohols having about 5 to 12 carbon atoms include n-pentanol, n-hexanol, 2-ethylhexanol, 3,5,5-
trimethylhexanol, n-heptanol, n
Examples include -octanol, n-nonanol, n-decanol, n-undecanol, and n-dodecanol. Also, the number of carbon atoms is about 5
-10 saturated aliphatic hydrocarbons or saturated alicyclic hydrocarbons include pentane, hexane, heptane, octane, nonane, decane, cyclohexane, and methylcyclohexane. By using a mixture of the primary alcohol and the saturated aliphatic hydrocarbon or saturated alicyclic hydrocarbon, the amount of the reaction solvent and catalyst component into the extraction layer can be increased compared to when the primary alcohol is used alone. The elution rate can be reduced. in this case,
The ratio of the saturated aliphatic primary alcohol having about 5 to 12 carbon atoms and the saturated aliphatic hydrocarbon or saturated alicyclic hydrocarbon having about 5 to 10 carbon atoms (primary alcohol/hydrocarbon) is determined by the volume. The ratio is preferably within the range of 1/5 to 5/1. Solubility of extractant in water, boiling point,
Physical properties such as melting point, extraction rate of 1,8-octanedial or 1,10-decanedial, elution rate of reaction solvent and catalyst components, and availability including price. Taking into consideration,
A primary alcohol selected from the group consisting of n-hexanol, n-heptanol, n-octanol and n-nonanol, and hexane, heptane,
Most preferably, mixtures with saturated aliphatic or saturated cycloaliphatic hydrocarbons selected from the group consisting of octane, decane and cyclohexane are used. The ratio of these primary alcohols or mixtures of primary alcohols and saturated aliphatic hydrocarbons or saturated alicyclic hydrocarbons to the reaction mixture is selected from a range of 1/5 to 5/1 by volume. is practical. In addition, since the phase separation property, extraction rate of reaction products, elution rate of reaction solvent and catalyst components, etc. are quite strongly controlled by extraction temperature, it is industrially recommended to select the extraction temperature within the range of 10 to 60℃. It's advantageous. As the extraction device, general-purpose stirring type extraction towers, RDC type extraction towers, perforated plate towers, etc. can be used. The extraction operation is usually carried out under an atmosphere of an inert gas such as nitrogen, helium, argon, or a hydrogen/carbon monoxide mixture. Through the extraction operation, the reaction product and unreacted 1,5-hexadiene or 1,7-octadiene are extracted as an extraction layer (upper layer).
The catalyst components are separated into a raffinate layer (lower layer). A part of the raffinate layer is subjected to a known catalyst activation treatment if necessary, and then subjected to the process ().
It is recycled and reused in the hydroformylation reaction step. 1,8-octanedial or 1,10-decanedial is separated and obtained from the extraction layer obtained in step () (step ()). The extraction layer contains a small amount of reaction solvent and catalyst components in addition to the reaction product and unreacted 1,5-hexadiene or 1,7-octadiene. Therefore, it is preferable to wash the extracted layer with water in a volume ratio of at least 0.25, and then remove the 1,8-
It is preferable to separate octanedial or 1,10-decanedial. Although there is no upper limit in a strict sense regarding the amount of water used, it is usually used at a volume ratio of 3 or less to the extraction layer. By washing the extraction layer with water, the reaction solvent and catalyst component contained in a small amount in the extraction layer can be transferred to the water layer side, making it easy to separate and recover the reaction solvent and catalyst component from the extraction layer. The aqueous solution containing the reaction solvent and catalyst component obtained by this operation can also be recycled to the hydroformylation reaction step of step () after water is distilled off from the aqueous solution. 1,8-octanedial or 1,10-decanedial can be obtained by subjecting the extracted layer to a conventional distillation operation. Further, according to detailed studies by the present inventors, the extraction operation in step () is
A primary alcohol selected from the group consisting of hexanol, n-heptanol, n-octanol, n-nonanol and n-decanol, or a group consisting of the primary alcohol and hexane, heptane, octane, decane, cyclohexane and methylcyclohexane. In the case of using a mixture of saturated aliphatic hydrocarbons or saturated alicyclic hydrocarbons selected from When maintained at an appropriate temperature, 1,
A dihemiacetal [see general formula (A) above] of 8-octanedial or 1,10-decanedial with the corresponding primary alcohol precipitates as a crystal, resulting in a branched dial that is a by-product of the hydroformylation reaction. It has been found that such crystals do not precipitate for monoaldehydes and monoaldehydes.
Therefore, if this property is used, particularly high purity 1,8-octanedial or 1,10-decanedial can be obtained from the extraction layer obtained in step (). That is, the extracted layer is washed with water and then kept at a temperature of 0 to 50°C to precipitate crystals, and the precipitated crystals are separated by an operation such as filtration or centrifugation. Add a small amount of water as needed to the crystals (process)
Very high purity 1,8-1,8- Octane dial or 1,10-decane dial can be obtained. If the extraction layer or a part of it is subjected to fractional distillation after crystal separation, unreacted raw materials,
Monoaldehydes and branched dials can be separated. Moreover, the extraction agent obtained at this time can be recycled to the step () and reused. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 0.25 mmol of Rh ₄ (CO) ₁₂ was added to a stainless steel autoclave with contents 1 equipped with a thermometer, a magnetic stirrer, a gas inlet and a gas outlet. After charging 75 mmol, 350 ml of water, and 150 ml of sulfolane, and thoroughly purging the inside of the autoclave with hydrogen/carbon monoxide mixed gas (molar ratio 3/1), the pressure inside the autoclave was brought to 10 atm with the mixed gas of this composition. While maintaining the temperature, the mixture was heated until the internal temperature became constant at 80°C, and stirring was continued for an additional 30 minutes. The autoclave was connected through a pressure control valve to a gas reservoir filled with a hydrogen/carbon monoxide mixed gas at a molar ratio of 3/1, so that a constant pressure was maintained at all times during the reaction. Then, with vigorous stirring, 40 g (488 mmol) of 1,5-hexadiene was continuously added into the autoclave using a metering pump over a period of 3 hours.
After the addition was complete, stirring was continued for an additional hour. After reacting for a total of 4 hours, a very small amount of the reaction mixture was taken out and analyzed by gas chromatography.The amount of unreacted 1,5-hexadiene remaining was 24.3 mmol (conversion rate 95.0%), and the amount of 1,8-octane remained. It was found that 352.1 mmol of dial was produced. Other products include 2-methyl-1,7-
heptane dial, 2,2-dimethyl-1,6-
83.5 mmol, 9.3 mmol and 6-heptene-1-al respectively.
8.9 mmol was produced. Next, the reaction mixture was previously mixed with hydrogen/carbon monoxide mixed gas (molar ratio 1/1).
Pour the n-hexanol into a three-necked flask without exposing it to air, and add n-hexanol.
150 ml and 350 ml of hexane were added, and the mixture was stirred for 20 minutes under a mixed gas atmosphere having the above composition while keeping the internal temperature at 30°C. As soon as stirring was stopped, two layers separated. After standing for 10 minutes, lower layer (yellow) and upper layer (colorless)
When analyzed by gas chromatography, 1,8-octanedial, 2-methyl-1,7-heptanedial,
2,5-dimethyl-1,6-hexane dial and 6-hepten-1-al each 89%,
It was found that 93%, 95% and 99% were extracted into the extraction layer. Next, the lower layer (raffinate layer) was transferred to an autoclave without being exposed to air again, and 5 ml of sulfolane was added. Under the same reaction conditions as the first time
40 g of 1,5-hexadiene was added continuously over 3 hours and stirring continued for an additional hour. Analysis of the reaction mixture revealed that 1,5 in the second reaction.
- the remaining amount of hexadiene is 25.8 mmol,
1,8-octanedial, 2-methyl-1,7
-heptane dial, 2,5-dimethyl-1,6
- 351.3 mmol and 81.4 mmol of hexane dial and 6-heptene-1-al, respectively;
It was found that 9.0 mmol and 11.3 mmol were produced. After performing an extraction operation using the same operating method and conditions as the first extraction, the raffinate layer was placed in an autoclave, and 5 ml of sulfolane was added again. A third hydroformylation reaction was carried out under the same reaction conditions and reaction operations as the first. After the reaction was stopped, the reaction mixture was analyzed and found that 1,5-
The remaining amount of hexadiene and the amount of each product produced were almost the same as in the second time. After washing the extract obtained from the three reactions and extraction operations described above with the same volume of water, the organic layer was left at a temperature of about 5° C. to precipitate crystals. The crystals were separated, washed with hexane, and dried under vacuum at room temperature to obtain about 330 g of crystals. When a part of this crystal was dissolved in tetrahydrofuran and analyzed by gas chromatography, it was found that it contained 1,8-octanedial and 2 times the mole of n-hexanol relative to 1,8-octanedial. I found out that When we measured the infrared absorption spectrum of this crystal using the KBr tablet method, no absorption indicating the presence of aldehyde groups was observed, and the absorption indicating the presence of hydroxyl groups and acetal bonds was at 3400 cm ^-1 and 1000 to 1200 cm ^-1 , respectively. Observed. Also, this crystal
¹ H-NMR spectrum measurement of CDCl ₃ solution The crystals were also dihemiacetal (1,8-diheptyloxy- octane-1,8-diol). After melting these crystals, a fraction of 1,8
- Approximately 118 g of octanedial was obtained. This one is 98.6 from analysis by gas chromatography.
It was confirmed that the purity was over %. Example 2 0.15 mmol of Rh ₆ (CO) ₁₆ was added to the reactor used in Example 1. 60 mmol, 300 ml of water, and 200 ml of 1,4-butanediol were charged, and the inside of the autoclave was heated with hydrogen/
After sufficient replacement with carbon monoxide mixed gas (molar ratio 3/1), the internal temperature under stirring was raised to 80°C while maintaining the pressure inside the autoclave at 8 atm and the gas flow rate at 10/hour using this mixed gas composition. The mixture was heated to a constant temperature and stirring was continued for an additional 30 minutes. Then, with vigorous stirring, 50 g (455 mmol) of 1,7-octadiene was continuously added into the autoclave using a metering pump over 3 hours, and stirring was continued for an additional hour after the addition was completed. After reacting for a total of 4 hours, the reaction mixture was analyzed by gas chromatography, and the remaining amount of unreacted 1,7-octadiene was 18.2 mmol, and 1,10-decane dial and 2-
Methyl-1,9-nonanedial is each
336.4 mmol and 74.2 mmol were produced,
It was found that 2,7-dimethyl-1,8-octanedial and 8-nonen-1-al were also produced in small amounts. Next, in the same manner as in Example 1, the reaction mixture was transferred to a flask with content 2, and 160 ml of n-octanol was added under a nitrogen gas atmosphere.
Extraction was performed at 30°C using a mixture of 250 ml of octane and 250 ml of octane. After separation, the raffinate layer was analyzed by gas chromatography, then transferred to the autoclave again, 10 ml of 1,4-butanediol was added, and the first
The hydroformylation of 1,7-octadiene was repeated under the same reaction conditions as the first time. After the reaction, the reaction mixture was analyzed and found that 1,
The remaining amount of 7-octadiene is 20.1 mmol, 1,10-decandial and 2-methyl-
The amount of 1,9-nonanedial produced is
It was found to be 332.8 mmol and 73.6 mmol. Next, an extraction operation was performed using the same operating method and conditions as the first time. The extract obtained from the above two reactions and operations was washed with the same volume of water and then left to stand at a temperature of about 10°C to precipitate crystals. The crystals were separated, washed with Gactan, and then distilled under reduced pressure to obtain about 84 g of 1,10-decane dial as a fraction with a boiling point of 89-90°C/0.5 mmHg. This was analyzed by gas chromatography.
It was found that the purity was over 98.9%. Example 3 HRh(CO) as a catalyst in Example 2
(PPh ₃ ) ₃ 1 mmol and The hydroformylation reaction of 1,7-octadiene was carried out for 4 hours in the same manner as in Example 2, except that 75 mmol was used and 300 ml of water and 200 ml of sulfolane were used as solvents. After the reaction was completed, the reaction mixture was analyzed by gas chromatography, and it was found that the remaining amount of 1,7-octadiene was 25.4 mmol, and 1,10-decandial, 2-methyl-1,9-nonanedial, and 2,5-octadiene remained. -dimethyl-1,8-octanedial respectively
It was found that 328.5 mmol, 68.3 mmol and 8.5 mmol were produced. Then, in the same manner as in Example 2, using 300 ml of 2-ethylhexanol.
Extraction operation was performed at 40°C. After separation, the upper layer was washed with an equal volume of water and then subjected to vacuum distillation. Approximately 59 g of 1,10-decandial and
-methyl-1,9-nonanedial and 2,5
A mixture of -dimethyl-1,8-octanedial was obtained. The content of 1,10-decandial in this mixture was 86.1%. Furthermore, when the hydroformylation reaction of 1,7-octadiene was repeated using the above raffinate layer, almost the same reaction results as the first reaction were obtained. Example 4 The hydroformylation reaction of 1,5-hexadiene was carried out in the same manner as in Example 1 except that a mixed solution of 250 ml of water and 250 ml of 1,6-hexanediol was used as the hydroformylation solvent in Example 1. . After the reaction was stopped, the mixture was analyzed by gas chromatography, and then extracted twice at 30° C. under a nitrogen gas atmosphere using an extractant consisting of 150 ml of n-hexanol and 250 ml of cyclohexane. The extracted layer obtained from the two extractions was washed with 300 ml of water and left at a temperature of about 5°C, and the obtained crystals were dried in vacuum to obtain about 100 g of crystals, which were distilled under reduced pressure. Approximately 36 g of 1,8-octanedial was obtained. Comparative Examples 1 to 4 In Example 1, 350 ml of water and 150 ml of monohydric alcohol listed in Table 1 were used as the hydroformylation solvent.
The hydroformylation reaction of 1,5-hexadiene was carried out in the same manner as in Example 1, except that ml of the mixed solution was used. After the reaction was stopped, the mixture was analyzed by gas chromatography, and then extracted twice at 30° C. under a nitrogen gas atmosphere using an extractant consisting of 150 ml of n-hexanol and 350 ml of hexane. The extracted layer obtained by the two extractions was washed with 300 ml of water and then left at a temperature of about 5°C, and the obtained crystals were dried in vacuum. 1,8-octanedial was obtained by distilling this product under reduced pressure. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1 () Sulfolane, 1,4-butanediol or 1,6-hexanediol and water in a weight ratio of 15/85 to 75/25. - 1,5-hexadiene or 1,7
- Hydroformylating octadiene with a mixed gas of hydrogen and carbon monoxide, and adding a saturated aliphatic primary alcohol having about 5 to 12 carbon atoms, or 1,8-octanedial or 1,10-decane dial is extracted, and the raffinate layer containing the catalyst component is recycled to the hydroformylation reaction step of step () to produce 1,8-octanedial or 1,10-decane dial obtained in step (). 1. A method for producing 1,8-octanedial or 1,10-decanedial, characterized in that 1,8-octanedial or 1,10-decanedial is obtained from an extraction layer containing. 2. The hydroformylation reaction of 1,5-hexadiene or 1,7-octadiene in step () is carried out at a weight ratio of sulfolane and water of 25/75 to 60/40.
The method according to claim 1, which is carried out in an aqueous solution of sulfolane. 3. In step (), a rhodium complex compound is used at a concentration of 0.05 to 10 milligram atoms per reaction mixture in terms of rhodium atoms, and the sodium salt, potassium salt or lithium salt of diphenylphosphinobenzene-m-monosulfonic acid is added to rhodium. The method according to claim 1, wherein the amount is 10 equivalents or more per gram atom. 4 In step (), the extraction operation is performed using n-hexanol, n-heptanol, n-octanol, n-
- a mixture of a primary alcohol selected from the group consisting of nonanol and n-decanol and a saturated aliphatic hydrocarbon or saturated alicyclic hydrocarbon selected from the group consisting of hexane, heptane, octane, decane, cyclohexane and methylcyclohexane; The method according to claim 1, wherein the method is carried out at a temperature of 10 to 60°C. 5. In step (), after washing the extracted layer obtained in step () with water, 1,8-octanedial or 1,10-decanedial is obtained from the extracted layer by distillation. the method of. 6 In step (), the extraction operation is performed using n-hexanol, n-heptanol, n-octanol, n-
- a primary alcohol selected from the group consisting of nonanol and n-decanol, or a saturated aliphatic hydrocarbon or saturated fat selected from the group consisting of hexane, heptane, octane, decane, cyclohexane and methylcyclohexane; 10-60 using a mixture of cyclic hydrocarbons
1,8-octanedial or 1,10-decanedial and the primary alcohol by washing the resulting extracted layer with water and keeping it at a temperature of 0 to 50°C. After precipitating crystals of dihemiacetal and separating the precipitated crystals from the extraction layer, 1,8-
A method according to claim 1 for obtaining octanedial or 1,10-decanedial.