JPS5885830A - Aluminum alkoxide-phenoxide and preparation of ester with the same as catalyst - Google Patents

Abstract

NEW MATERIAL:An aluminum alkoxide-phenoxide of formulaI[R<1> is 2-5C alkyl or cycloalkyl; (n) is an integer 1-40; X is formula II, etc. when (n) is 1, or formula III, etc. when (n) is >=2; R<2>-R<9> are H, 1-5C alkyl or cycloalkyl]. EXAMPLE:The compound of formula III. USE:Useful as a highly active effective catalyst in preparing esters from aldehydes, and capable of synthesizing the esters efficiently under mild conditions without causing side reactions, and further useful as a catalyst for the ortho-alkylation of the phenols and polymerization of aldehydes or alkylene oxides. PROCESS:A dihydric phenol is subjected to the exchange reaction of the alkoxyl group with an aluminum trialkoxide to give the compound of formulaI.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the following general formula CI) [wherein R1 is an alkyl group or a cycloalkyl group having 2 to 5 carbon atoms, n is 1 to about 40, X is nz 10 o'clock, and n-1 (where R2-R13 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a cycloalkyl group)] and aluminum alkoxides/phenoxites represented by the formula: The present invention relates to a method for producing esters characterized by trimerization. - Conventionally, the method for producing esters by trimerizing aldehydes as shown in the following reaction formula is
This reaction is known as =r (Ti5chtschenko) reaction.

(Here, R and R' may be the same or different and represent substituted or unsubstituted hydrogen, an alkyl group, an a6kenyl group, an aryl group, or a cycloalkyl group.) In this reaction, sodium A method in which reactions are carried out in a homogeneous phase using alkali metals such as alkaline earth metals such as magnesium, or alkoxides of aluminum as catalysts (Chemistry Region Vol. 18, p. 470 (1954), successor name: Organic Reaction Collection, p. 108 (1955), Breakfast A method of conducting a reaction in a heterogeneous phase (Nihon Kagaku Zasshi p. 1845 (1973)) is known as a catalyst for oxides of alkaline earth metals such as barium and strontium.

However, when the reaction is carried out in the above-mentioned homogeneous phase, in addition to the desired production of esters through trimerization, alcohol, hydroxyaldehyde, unsaturated aldehyde, glycol ester, polyol ester, etc. are produced as by-products. There is a problem with the selection rate.

In addition, - this type of conventional catalyst is sent to a reaction tank together with the raw material aldehyde, and after the reaction occurs there, the deactivated catalyst and the product are separated by distillation, etc., and are not reused, making it uneconomical. be.

On the other hand, the reaction carried out in the above-mentioned heterogeneous phase is limited to the production of esters by converting aromatic aldehydes, and also requires a high reaction temperature of 100C or higher.

The present inventors conducted various studies in order to solve the drawbacks of the method of manufacturing esters by converting aldehydes into the above-mentioned homogeneous phase or heterogeneous phase.

As a result, it has been found that the novel aluminum alkoxide/phenoxide compound represented by the general formula [■] is excellent as a catalyst that overcomes the above drawbacks. In other words, this catalyst is extremely highly active, causes almost no side reactions, and can produce esters more efficiently than aldehydes under mild conditions such as room temperature. I can do it.

Furthermore, among the compounds of the present invention, those having a polymer structure ([1
In formula 3, when carrying out the reaction using a compound (n is 2 or more) as a catalyst, the catalyst is packed in a packed column and the raw aldehye β is continuously passed through, thereby converting esters containing no catalyst component. Can be produced continuously. This has the advantage that the separation step between the catalyst and the product can be omitted in the process, and the cost of the catalyst can be reduced.

In addition, the aluminum alkoxide/phenoxy group of the present invention can be used as a catalyst for the synthesis of esters by the above-mentioned engineering reaction of aldehydes, as well as a catalyst for the orthoalkylation reaction of phenols and a catalyst for the polymerization of aldehydes and alkylene oxides. You can also take it.

Examples of aldehydes that can be used in the present invention include formaldehyde, acetaldehyde, probionaldehyde, butyraldehyde, hexylaldehyde, aliphatic saturated aldehydes such as hexylaldehyde, octylaldehyde, and hexahydrobenzaldehyde, acrolein, crotonaldehyde, and tetrahydrobenzaldehyde. aliphatic unsaturated aldehydes and benzaldehyde,
Examples include aromatic aldehydes such as cinnamic aldehyde, which may be used alone or in combination of two or more.

[In the compound of formula 13, n is 1 (here, R1 represents an alkyl group or cycloalkyl group having 2 to 5 carbon atoms, and R2 to R, 13 are hydrogen atoms, and
represents an alkyl group or a cycloalkyl group, preferably hydrogen or a methyl group. ) is soluble in the solvent used, the raw material aldehydes and the produced esters, and can be used in the same manner as in the Teishchenko reaction, in which it is used as a catalyst in a homogeneous phase. 'on the other hand,
n is 2 or more; is preferably hydrogen or a methyl group, and n is from 2 to about 40.) is insoluble in the solvent used, the raw material aldehydes, and the produced esters, and can be used as a catalyst as it is, or if necessary, Alumina, silica, Sili J! ! By supporting or mixing with an inert carrier such as alumina, diatomaceous earth, activated clay, etc., and suspending them in the raw material aldehydes, or by filling them into a reaction tower and passing the raw material aldehydes. Esters can be produced batchwise or continuously.

In the above formula, those in which R1 is hydrogen or a methyl group have low catalytic activity and cannot be used as the catalyst of the present invention.

The aluminum alkoxide/phenoxites of the present invention are produced by the exchange reaction of alkoxyl groups between dihydric phenol and aluminum trialkoxide or by the reaction of dihydric phenol and trialkylaluminium, and converting the resulting alkyl aluminum diphenoxide into monovalent aliphatic It can be produced by reacting with alcohol to exchange the remaining alkyl groups with alkoxyl groups.

Typical examples of dihydric phenols as raw materials are shown below (where R2 to R13 represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a Schiff's alkyl group).

As mentioned above, in the dihydric phenols of the present invention, the carbon atoms to which the hydroxyl groups are bonded on the aromatic ring are not adjacent to each other. As shown in the comparative examples, aluminum alkoxide/phenoxites derived from aromatic rings with adjacent carbon atoms to which hydroxyl groups are bonded are undesirable because they have low catalytic activity and low selectivity.

The above-mentioned aluminum uramic alkoxide/phenoxite is used in an amount of 0.005 to 10 mol based on the raw material aldehyde. The reaction is carried out in the presence of an appropriate solvent as needed at -30
It is carried out at ~+100C for 15 minutes to 24 hours, preferably 1 hour to 10 hours. As the solvent, aliphatic hydrocarbons, aromatic hydrocarbons, etc. are used. The esters produced can be purified by conventional means such as distillation.

As mentioned above, the catalyst used in the method of the present invention, aluminum alkoxide/phenoxytochloride itself, is a new substance.

Next, the method of the present invention will be illustrated with specific examples. - Example 1 Triethylaluminum dissolved in benzene K (I Mot/p) in a nitrogen-substituted flask with an internal volume of 5'Oml
t.

ml! (corresponding to 10 mmol of ethylaluminum) and 1Qmg of 1,4-dioxane were added. A 1,4-dioxane solution IQme containing 10 mmol of hydroquinone was slowly added dropwise to this while stirring.

Thereafter, stirring was continued for 2 hours at room temperature and further for 1 hour at 95-98C. Then it was cooled to room temperature and heated under stirring for 10
Slowly add millimoles of inzolopanol to 95-98
After continuing stirring at C for 1 hour, the solvent and unreacted substances were removed by heating under vacuum, and the powdered compound was refluxed with 1 N hydrochloric acid for 10 hours to hydrolyze it, and then analyzed by gas chromatography. As a result, hydroquinone and impropatool were produced in a ratio of 1.03:1.00 (1 mole), respectively. 2 This value supports the following structural formula and also supports the following structural formula /c
This corresponds to n=32.

IR Spectrum - IR and spectra were measured using the so-called Nujol method, in which the powdered compound of the present invention is mixed with liquid paraffin and measured. Its spectrum contains the following 865.940.1, which is different from those of the raw materials isozolopanol and no-hydroquinone.
Absorption bands at 000 and 1290 tM were detected.

The 11'L spectrum is shown in FIG.

Q -i C3H7 In Example 1, instead of using 10 mmol of 4.hydroquinone, 10 mmol of 4.hydroquinone was used. Chidihydro The above compound was refluxed for 10 hours with 1N hydrochloric acid to hydrolyze it,
When the product was analyzed by gas chromatography, it was found that 4
．． 4'-dihydroxydiphenyl and inzolopanol were produced in a ratio of 1.05:1.00 (1 mole), respectively. This value supports the above structural formula, and the IR spectrum of the present compound was measured using the 2-sho method. Its spectrum includes the raw materials Improper Tool and 4
, different from those of 4'-dihydroxydiphenyl
865.935. ! 095.1255 and 15
A new absorption band of ``Q5crn-'' appeared. These pastes Example 3 Instead of using 10 mmol of no-hydroquinone and 10 mmol of isozolopanol in Example 1, 10 mmol of resorcinol and 10 mmol of isozolopanol were used. When the above compound was hydrolyzed by refluxing with 1N hydrochloric acid for 10 hours and analyzed by gas chromatography, the ratio of resorcinol and ethanol was 1.09:1.00, respectively.
(1 mole).

This value supports the above structural formula, and in the following structural formula n″
= corresponds to ilO.

IR Spectrum The IR spectrum of this compound was measured by the Nujol method. Its spectrum contains 620.685°890, 1095 which is different from those of raw material ethanol and resorcinol.
．． New absorption bands at 1170.1255 and 1590 crn-1 appeared. Among these, l Q95 cm
-' IR spectrum is shown in Figure 3. "Example 4 Synthetic NMR spectrum (as a deuterium chloroform solution) was obtained under the same conditions as in Example 1, except that 10 mmol of 1,1'-bi-2-naphthol was used instead of 10 mmol of hydroquinone. Measurement) Hl ((a) 8-7δ (, a) equivalent to 3.6δ (b) 1.2δ (C) Area ratio (a) : (b) : (c) = 12.
6: 6: 1.2 This value is a theoretical value 12: 6
: Close to 1.

The NMR spectrum is shown in FIG.

Using a solution cell with an IR spectrum thickness of 0.1 rate, the IR spectrum was measured as a carbon disulfide solution. Its spectrum differs from those of inzolobil alcohol and 1,1'-bi-2-naphthol, including 395°, 460°,
520.550.585.615.690.840.8
70°995, 1030.1070 and 1210Cr
A new absorption band of 1030 crn-1 was found among these absorptions.Example 5 260 mmol of propionaldehyde was added to an Erlenmeyer flask with an internal volume of 50 mm, which was purged with nitrogen, and cooled to 0°C.
e) Add 0.5 ml (0.5 mmol) and add 2
The temperature was raised to 5C, and the reaction was continued at that temperature for 4 hours with stirring.

After the reaction was completed, the contents were analyzed by gas chromatography, and 1.5 mmol of unreacted aldehyde and 98.6 mmol of -0-propyl zolopionate were detected.

These results indicate that the conversion rate of blown aldehyde is 99.
3% and selectivity of converted aldehydes to esters 9
This corresponds to 9.4%, respectively.

Example 6 When the reaction was carried out under the same conditions except that Q-iC3H7 0-iC3H7 o, 5 mmol was used and the reaction was carried out for 5 hours, unreacted aldehyde was 16.9 mmol, zolopionic acid -〇- Zorogil is 88
．． 1 mmol each was detected.

These results show that the conversion rate of probionaldehy, P is 91
．． 6% and a selectivity of converted aldehydes to esters of 96.2%, respectively.

Example 7 100 mmol of zolopionaldehyde and 100 mmol of acetaldehyde were added to an Erlenmeyer flask (having an internal volume of 50 ml) which was purged with nitrogen and cooled to OC.

1+++l (1 mmol 5) of 0- i C3T-It Mot74) was added, and the reaction was continued under stirring under OC for 5.5 hours.

After the reaction was completed, the contents were analyzed by gas chromatography, and it was found that 0.5 mmol of unreacted acetaldehyde,
Unreacted zolopionaldehyde 0.5 mmol, ethyl acetate 23.8 mlJ mol, ethyl zolopionate 17.8
27.5 mmol of m-n-zorogyl acid and 24.0 mmol of zorobio/acid-1-zorogyl were detected.

These results indicate a conversion rate of total aldehydes of 99.5% and a selectivity of total converted aldehydes to total esters of 93.6%.
% respectively.

When the reaction was carried out under the same conditions except that 1 mmol was used and the reaction was carried out for 5.5 hours instead of 5.5 hours, 3.3 mmol of unreacted acetaldehyde, 3.9 mmol of unreacted zolopionaldehyde, and acetic acid were obtained. 21.7 mmol of ethyl, 15.9 mmol of ethyl zoropionate, 27.2 mmol of n-zorobi-acetate, and 23.6 mmol of 0-propyl propionate were detected.

These results indicate a conversion rate of total aldehydes of 96.4% and a selectivity of total converted aldehydes to total esters of 91.7%.
% respectively.

The catalyst was prepared under the same conditions as in Example 1 except that 10 mmol of resorcinol was used instead of 10 mmol of hydroquinone.

Instead of using IJ moles, reaction was carried out under the same conditions except for the one synthesized in Example 4, and the results were as follows: 22.8 mmol of unreacted acetaldehyde, 10.8 mmol of unreacted zolopionaldehyde, and acetic acid. 16.7 mmol of ethyl, 12.0 mmol of ethyl zorooate, 24.8 mmol of propyl acetate, and 24.8 mmol of broonic acid.
20.6 mmol of zologil was detected in each case.

These results indicate a conversion rate of total aldehydes of 83.2% and a selectivity of total converted aldehydes to total esters of 89.1%.
% respectively.

Example 10 100 mmol of propionaldehyde and 100 mmol of inbutyraldehyde were added to an Erlenmeyer flask with an internal volume of 50 ml and purged with nitrogen, and the flask was cooled to OC. In addition, under stirring, (I MatA) 0 synthesized in Example 1
．． Add 5 ml (0.5 mmol) and, under stirring, OC
The reaction was continued for 5.5 hours. After the reaction was completed, the contents were analyzed by gas chromatography and found to be 1.3 mmol of unreacted propionaldehyde, 0.8 mmol of unreacted inbutyraldehyde, 28.0 mmol of n-propyl zoropionic acid, and isobutyl aldehyde. flll-n-progil 14
．． 5 mmol, 29.7 mmol of isodityl zolopionate and 18.4 mmol of isobutyl isobutyrate were detected.

These results indicate a conversion rate of total aldehydes of 99.0% and a selectivity of total converted aldehydes to total esters of 91.6%.
% respectively.

Example 11 Into a 50 ml Erlenmeyer flask purged with nitrogen, 200 mIJ mol of benzaldehyde was charged, and 0.5 rnl (0.5 mmol) of the chilled suspension (I Mot/A) was added to the OC under stirring. The reaction was continued for 0.5 hour.

After the reaction was completed, the contents were analyzed by gas chromatography, and 126 mmol of unreacted benzaldehyde and 34.2 mmol of benzyl benzoate were detected.

These results correspond to an aldehyde conversion of 37.0% and a selectivity of converted aldehyde to ester of 92.4%, respectively.

Example 12 An Erlenmeyer flask with an internal volume of 50 ml which was purged with nitrogen (charged with 200 mmol of acrolein and cooled to OC).

Zen suspension (I Mol/13) 1 ml (1
mmol) was added, and the reaction was continued for 5.5 hours under stirring under OC. After the reaction was completed, the contents were analyzed by gas chromatography, and 182 mmol of unreacted acrolein and 5.2 mmol of allyl acrylate were detected.

These results correspond to a conversion of aldehyde of 9.0% and a selectivity of converted aldehyde to ester of 58%, respectively.

The catalyst was prepared under the same conditions as in Example 1 except that 10 mmol of methylhydroquinone was used instead of 10 mmol of hydroquinone.

Example 13 Acetaldehyde IOθ mmol and acrolein 100 mmol were charged into a nitrogen-substituted Erlenmeyer flask with an internal volume of 5 Qml, and the flask was cooled to Oc. Add 1 mz (1 mmol) of benzene suspension (IMO) to it, and heat at 25C.
The reaction was continued for 6 hours under stirring at a temperature of about 100 ml. After the reaction was completed, the contents were analyzed by gas chromatography, and it was found that 0.4 mm of unreacted acetaldehyde and 63 mm of unreacted acrolein were found. '8 mmol, ethyl acetate 29.5 mmol, allyl acetate 27.3 mmol,
1.8 mmol of ethyl acrylate and 2.7 mmol of allyl acrylate were detected.

These results show that the conversion rate of total aldehydes was 67.9% and the escape rate of all converted aldehydes to total esters was 90.9%.
Each corresponds to 3%.

Example 14 In an Erlenmeyer flask with an internal volume of 50 ml and which was purged with nitrogen, 200 ml of tylin aldehyde was poured and the reaction was continued at 25 C for 5 hours with stirring. After the reaction was completed, the contents were analyzed by gas chromatography, and 16.8 mmol of unreacted pelargonaldehyde and 89.1 mmol of -n-nonyl pelargonate were detected.

These results indicate that the conversion rate of pelargonaldehyde is 91,6
% and selectivity of converted aldehyr to ester9
This corresponds to 7.3%, respectively.

The catalyst was prepared in Example 1 using 10 mmol of hydroquinone and 10 mmol of iso7'o)<
? 10 mmol of 1-methyl-
Similar conditions were used except that 3,7-dihydroxynaphthalene and 10 mmol of 5ec-butanol were used.

Benzene suspension (I Mol/13) of 0. 5
rtrl (0.5mIMO00-5C4H Novenzene Suspension (IMO'-6) 0.5mA!
When the reaction was carried out under the same conditions except that (0.5 mmol) was used, 20.0 mmol of unreacted pelargonaldehyde and 87 nonyl pelargonate were obtained.
．． 5 mmol were detected in each case.

These results indicate that the conversion rate of gonaldehyde is 90.0.
% and selectivity of converted aldehydes to esters 97
．． Each corresponds to 2%.

The catalyst was prepared under the same conditions as in Example 14 except that 10 mmol of 1-methyl-6,8-dihydroxynaphthalene was used instead of 10 mmol of 1-methyl-3,7-dihydroxynaphthalene. I did it.

Example 16 10 ml of 0-i C3H7 benzene suspension was thoroughly stirred with 1.2 g of alumina fine powder, and the catalyst was sufficiently adhered to the alumina, and the mixture was filled into a jacketed glass tube with an inner diameter of 8tMR/16. . The filling has a height of 3011I11 and a volume of 1.
It was 51 ml.

Next, water was passed through the jacket and cooled to about 25C, while probionaldehyde V was continuously allowed to flow down from the upper part, and the product accumulated in the lower receiver was taken out at regular intervals.
Each fraction was analyzed by gas chromatography, and the results shown in Table 1 were obtained.

The catalyst was prepared as follows.

20 ml of penzene and 2 Q ml of a 1.4-dioxane solution containing 10 mm of aluminum triynepropoxide were added to a nitrogen-substituted flask with an internal volume of 100 mA', and heated with stirring. and alcohol produced by exchange reaction-1. Using 0.5 mmol of the Tishchenko reaction of propionaldehyde (continuous method) and reacting for 4 hours, 0.5 mmol of aluminum triinzolopoxide (1yo
l/. When the reaction was carried out under the same conditions except that the reaction was carried out for 4.5 hours, 15.1 mmol of unreacted aldehy and 66.1 mmol of n-propyl proionate were detected. .

These results indicate that the conversion rate of zolopionaldehyde is 92,5
% and converted selectivity of aldehyde to ester 7
Each corresponds to 1.5%.

Aluminum triethoxide (DRP 766027 (19
When the reaction was carried out under the same conditions except that 0.5 mmol of 43)) was used and the reaction was carried out for 5.5 hours, 13.5 mmol of unreacted aldehyde and 69.2 mmol of -propyl zolopionate were detected. It was done.

These results indicate that the conversion rate of blown aldehyde is 9-3.
3% and selectivity of converted aherdehyde to ester 74. 2% each.

This indicates that the catalyst, aluminum trialkoxide, has low selectivity. - The reaction was carried out under similar conditions except that 1 mmol of unreacted acetaldehyde, 7 mmol of unreacted propionaldehyde, 8 mmol of ethyl acetate, 14.7 mmol of ethyl acetate, 11.7 mmol of ethyl propionate, 22.2 mmol of n-z-acetate, and 19.1 mmol of n-propyl proionate were detected, respectively. .

These results indicate a conversion of total aldehydes of 91.0% and a selectivity of total converted aldehydes to total esters of 74.0%.
Each corresponds to 4%. That is, it can be seen that the catalytic performance of NaI phthoxyaluminum dialkoxy P is inferior to that of the catalyst of the present invention.゛The above catalyst was prepared in Example 1 using 10 mmol of hydroquinone and 10 mmol of hydroquinone.
Similar conditions were used except that instead of using mmol of inpropatol, 10 mmol of α-naphthol and 20 mmol of inzolopanol were used, respectively.

Instead of using 1 mmol and reacting for 5.5 hours, a benzene solution of aluminum triisozolopoxide' (I
MoL/43) 0. When the reaction was carried out under the same conditions except that 5 ml (0.5 mmol) was used and the reaction was carried out for 5 hours, 10.5 ml of unreacted acetaldehyde was obtained.
6 mmol, unreacted noropionaldehyde 5.8 mmol, ethyl acetate 15.5 mmol, ethyl zolopionate 10.8 mmol, 〇-propyl acetate 22.7 mmol, and 〇-propyl propionate 17.8 mmol. millimoles of each were detected.

These results show that the conversion rate of all aldehydes is 91.8% and the selectivity of all converted aldehydes to all esters is 72,
Each corresponds to 8%.

This Comparative Example, like Comparative Examples 1 and 2, shows that the performance of the aluminum trialkoxide catalyst is inferior to that of the catalyst of the present invention.

Comparative Example 5 Q-iC3H7 Nohe/Zen suspension (I MoL/J3) was added to Q, 5 mJ
(0.5 mmol) and 8
When the reaction was carried out under similar conditions except that 6 mmol of each was used, unreacted propio/aldehy P5
．． 9 mmol, 3 g of unreacted isobutyraldehyde, 9 mmol of isobutyraldehyde, 20.4 mmol of n-furogyl soropionic acid, 10.0 mmol of n-sobutyl isobutyrate, 23.9 mmol of isobutyl soropionic acid, and 12.8 mmol of inbutyl isobutyrate was detected in each case.

These results indicate a total conversion of all aldehydes of 94.7% and a total ester (total ester) selectivity of all converted aldehydes of 76.2%.
% respectively.

In the above, 0 indicates a saturated cycloaliphatic group, and this comparative example is a case where a saturated cycloaliphatic group is used instead of an aromatic group. It shows that it is noticeably inferior to .

The catalyst was prepared using 10 mmol of 1.4-hydroquinone instead of 10 mmol in Example 1.
The same conditions were used except that cyclohexanediol was used.

When Comparative Example 6 was carried out, unreacted acetaldehyde was 73.0
mmol, 71.6 mmol of unreacted propionaldehyde, 4.8 mmol of ethyl acetate, 3.4 mmol of broonic acid ethyde, 7.2 mmol of n-zorobyl acetate, and 5.3 mmol of -propyl broonic acid, respectively. was detected.

These results indicate a conversion rate of total aldehydes of 27.7% and a selectivity of total converted aldehydes to total esters of 74.7%.
% respectively. In other words, a catalyst derived from a compound in which two phenolic hydroxyl groups are present adjacent to each other has low activity and low selectivity.

The above catalyst was prepared under the same conditions as in Example 1 except that lθ mmol of catechol was used instead of 10 mmol of hydroquino.

[Brief explanation of the drawing]

Figure 1 shows the IR spectrum of the product obtained in Example 1, Figure 2 shows the IR spectrum of the product obtained in Example 2, and Figure 3 shows the IR spectrum of the product obtained in Example 3. FIG. 4 is the IR spectrum of the product obtained in Example 4, and FIG. 5 is its NMR spectrum.

Claims (1)

[Scope of Claims] [In the formula, R1 is an alkyl group or a cycloalkyl group having 2 to 5 carbon atoms, n is 1 to about 40, and X is nml or n≧
2, (where n and 2-a+3 represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a cycloalkyl group)]. 2) (2) The aluminum alkoxide phenoxytes according to claim 1, wherein 2 to B13 are hydrogen or methyl groups. [In the formula, R1 is an alkyl group or a cycloalkyl group having 2 to 5 carbon atoms, n is 1 to about 40, and X is n=1 or (1
42 (where R2 to R'' represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a cycloalkyl group)] is used as a catalyst to trimerize aldehydes. 4) The method according to claim 3, characterized in that the catalyst is suspended in a reaction system. 5) The catalyst is suspended in a reaction column. 6) In the reaction, the reaction temperature - 7) R 7. The method according to any one of claims 3 to 6, wherein -R is hydrogen or a methyl group.