JP2889365B2 - Method for producing aldehyde - Google Patents

Description

The present invention relates to a method for producing an aldehyde which is valuable as an intermediate for organic synthesis. More specifically, the present invention relates to an improvement in a method for producing an aldehyde by hydrogenating a carboxylic acid or an alkyl ester thereof.

(Prior Art) Various methods have been reported as methods for producing aldehydes. The most common method using carboxylic acid or a derivative thereof as a raw material is the so-called Rosenmunt via carboxylic acid chloride.
Although a reduction method is mentioned, there is a disadvantage that the production cost is high.

It is most preferable that the aldehydes can be efficiently produced by directly reducing the carboxylic acid with molecular hydrogen, but this method has heretofore been considered extremely difficult. That is, regarding the hydrogenation reaction of a carboxylic acid or a derivative thereof, a method using yttrium oxide as a catalyst (US Pat.
373) or a method using aluminum oxide (US Pat. No. 3,935,265), but these methods have a problem in the selectivity of aldehyde.

The present inventors have previously reported a method for producing a corresponding aldehyde by hydrogenation of a carboxylic acid or an ester thereof using a catalyst containing zirconium oxide as a main component (for example, JP-A-60-152434, Kaisho 60-243037
No., JP-A-61-115043). In this method, when an aliphatic carboxylic acid having two hydrogen atoms bonded to the carbon at the α-position to the carboxyl group or an ester thereof is used as a raw material, a ketone body is by-produced by a decarboxylation condensation reaction. Is not always sufficient. Also, when a heterocyclic carboxylic acid containing a hetero atom such as N, S, or O in a heterocyclic ring or an ester thereof is used as a raw material, the selectivity of the aldehyde was insufficient.

On the other hand, when a cycloalkyl ester of a lower fatty acid such as acetic acid or n-butyric acid is hydrogenated using zinc oxide-chromium oxide as a catalyst, the corresponding acetaldehyde, n-
It is reported that butyraldehyde is produced with a low yield (Japanese Patent Publication No. 47-38410), and when hydrogenation of methyl benzoate, pivalic acid, etc. is performed using iron oxide containing a small amount of chromium oxide as a catalyst, It has been reported that the corresponding aldehydes are produced in a certain yield (European Patent No. 304853), but with these catalysts, the hydrogenation reaction proceeds for a while, but a practically satisfactory yield is obtained. It is difficult, and the appearance of a higher performance catalyst is desired.

As mentioned above, according to previous reports, aliphatic,
A method for efficiently producing the corresponding aldehyde by directly hydrogenating various carboxylic acids such as alicyclic, aromatic and heterocyclic or derivatives thereof has not yet been established, and the catalytic activity and There are many problems to be solved, such as improvement in selectivity of the target substance and extension of the catalyst life.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems caused by the conventional methods, and comprises various carboxylic acids such as aliphatic, alicyclic, aromatic, and heterocyclic or alkyl esters thereof. It is an object of the present invention to provide a method for directly producing each corresponding aldehyde with excellent selectivity.

(Means for Solving the Problems) As a result of repeated studies by the present inventors to solve the above problems, the above object has been achieved by using a specific catalyst supported on a specific carrier. That is, they have reached the present invention. That is, the gist of the present invention is to provide a method for producing an aldehyde by hydrogenating a carboxylic acid or an alkyl ester thereof with molecular hydrogen in the presence of a catalyst, wherein the specific surface area measured by the BET method as a catalyst is 100 m ² / g or less. An aldehyde production method characterized by using chromium oxide supported on an aluminum carrier.

 Hereinafter, the present invention will be described in detail.

[Raw Materials] Examples of starting materials used in the method of the present invention include various carboxylic acids such as aliphatic carboxylic acids, alicyclic carboxylic acids, aromatic carboxylic acids, and heterocyclic compounds, and alkyl esters thereof. In particular, aliphatic carboxylic acids or their alkyl esters and alicyclic carboxylic acids or their alkyl esters are preferably used.

As the aliphatic carboxylic acid, for example, acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid,
Nonanoic acid, decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, stearic acid, isostearic acid, nonadecanoic acid, tricosanoic acid, tetracosanoic acid, 10-undecenoic acid, oleic acid, 11-eicosene A saturated or unsaturated aliphatic monocarboxylic acid having 2 to 24 carbon atoms such as an acid; an aliphatic polyacid such as oxalic acid, malonic acid, diethylmalonic acid, succinic acid, glutaric acid, adipic acid, decandioic acid, and octadecandioic acid; Carboxylic acids.

Examples of the alicyclic carboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. These aliphatic carboxylic acids and alicyclic carboxylic acids have a substituent inert to the reaction, for example, an aryl group, an alkoxy group, N, S,
It may have a heterocyclic group containing a hetero atom such as O.
Further, as the alkyl ester of the aliphatic carboxylic acid and the alicyclic carboxylic acid, lower alkyl esters having 1 to 4 carbon atoms such as methyl ester, ethyl ester, propyl ester, n-butyl ester and isobutyl ester are preferable.

As the aromatic carboxylic acid and its alkyl ester used in the raw material of the present invention, the following formula (1) Ar- (COOR) n (1) (wherein R represents a hydrogen atom or an alkyl group, and Represents a number of 1 or 2, and Ar represents an aryl group which may have a substituent other than a COOR group).

In the compound of the formula (1), Ar is a phenyl group,
And aryl groups such as a naphthyl group and an anthryl group. Examples of the substituent other than the COOR group that Ar may have include an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, a halogen atom, a hydroxyl group, a formyl group, and an acyl group. Examples of R further include a hydrogen atom and an alkyl group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, and an isobutyl group. Specific examples of the compound of the formula (1) include, for example, benzoic acid, toluic acid, dimethylbenzoic acid, cyclohexylbenzoic acid, cumic acid, t-butylbenzoic acid, phenylbenzoic acid, anisic acid, phenoxybenzoic acid, and chlorobenzoic acid Acid, hydroxybenzoic acid, acetylbenzoic acid,
Examples include naphthoic acid, phthalic acid, and anthracene carboxylic acid. Examples of the ester include methyl ester, ethyl ester, propyl ester, and n-
C 1-4 carbon atoms such as butyl ester and isobutyl ester
Lower alkyl esters are preferred.

Further, the heterocyclic carboxylic acid and its ester used in the raw material of the present invention may have at least one N,
A carboxylic acid containing a hetero atom such as S or O or an ester thereof, and specific examples of the heterocyclic ring include a pyrrole ring,
Furan ring, thiophene ring, oxazole ring, thiazole ring, oxazoline ring, imidazole ring, imidazoline ring, pyrazole ring, pyran ring, thiopyran ring, pyridine ring, quinoline ring, oxazine ring, thiazine ring, pyrimidine ring, pyrazine ring, triazine ring Azepine ring, oxepin ring and the like. The carboxylic acid ester group is preferably a lower alkyl ester having 1 to 4 carbon atoms such as methyl ester, ethyl ester, propyl ester, n-butyl ester, isobutyl ester and the like. Specific examples of the heterocyclic carboxylic acid and its ester include, for example, nicotinic acid, furan carboxylic acid, thiazole carboxylic acid and alkyl esters thereof.

[Catalyst] In the present invention, it is essential to use a chromium oxide supported on an aluminum oxide carrier having a specific surface area of 100 m ² / g or less as measured by the BET method as a catalyst for hydrogenating the above raw material. This is an important feature of the present invention. The specific surface area of the preferred aluminum oxide support is 1 to 80 m ² / g, and the particularly preferred specific surface area is ² to 50 m ² / g. In addition, the values of the specific surface areas described below all indicate values measured by the BET method.

Examples of chromium oxide include commercially available hydroxides, sulfates, nitrates, and halides of chromium; chromic anhydride; inorganic salts such as ammonium salts or alkali metal salts of dichromic acid, and formate, acetate, and oxalate of chromium. Such as an organic salt as a raw material, and those prepared by thermally decomposing, but from the point of containing no impurities exhibiting poisoning, hydroxide or nitrate of chromium, chromic anhydride,
It is desirable to use a material obtained by thermally decomposing a raw material which decomposes at a relatively low temperature and does not contain other poisoning elements, such as ammonium salt of dichromic acid or chromium formate, acetate, oxalate and the like.

On the other hand, aluminum oxide carriers (hereinafter referred to as alumina carriers) include commercially available gibbsite, vialite, boehmite, norstrandite, sheasbore, amorphous alumina gel, χ-, ρ-, η-, θ-, γ-, σ −, Δ
-, Α-alumina or inorganic salts such as aluminum sulfates, nitrates and halides, and organic salts such as acetates, oxalates, and aluminum alkoxides as raw materials, and these are precipitated by a precipitation method, a thermal decomposition method, or the like. It is prepared by processing, but it is desirable to use raw materials that do not contain poisoning elements. Alumina carrier can be used in powder form,
It is practically convenient to mold and use it in an appropriate shape.
The specific surface area of the alumina support is affected by its preparation method, but can generally be controlled by changing the firing temperature. For example, γ- with a surface area of 270 m ² / g
When alumina is used, the alumina carrier having a specific surface area of 100 m ² / g or less can be obtained by firing at a temperature of 900 ° C. or more.

To support chromium oxide on the alumina carrier, using the above-described chromium raw material, a known method such as an impregnation method, an adsorption method, a kneading method, a deposition method or an evaporation to dryness method is employed, and then 400 ° C to 1 ° C.
Firing at a temperature of 200 ° C, preferably 500 ° C to 1000 ° C. The catalyst can be formed by a known method. For example,
Tablet compression method, spray drying and firing method, or adding water to chromium compound and alumina carrier, adding binder if necessary, kneading, extrusion molding, drying and firing at a predetermined temperature, etc. Molded.

[Hydrogenation reaction] The hydrogenation reaction of carboxylic acid or its alkyl ester with molecular hydrogen is carried out in the presence of the above-mentioned catalyst in the gas phase at a temperature of 200 ° C to 500 ° C, preferably 250 ° C to 450 ° C. It is advantageous. The reaction pressure may be normal pressure, but the reaction may be carried out in a slightly pressurized state.

When the catalyst is used, for example, as a solid bed catalyst, the space velocity of the starting carboxylic acid or its alkyl ester is about 0.01 to ¹ hr ^-1 as LHSV, preferably about 0.03 to 0.5 hr ^-1 . On the other hand, the space velocity of hydrogen is 100 ~ 2 as GHSV.
It is appropriate to set it to about 0,000 hr ^-1 , preferably about 500 to 5,000 hr ^-1 . The hydrogen used may contain some inert gas such as nitrogen and water vapor. In addition, the hydrogenation reaction of the present invention is not limited to the fixed bed system, and other reaction systems such as a fluidized bed system may be employed.

(Examples) Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 An aqueous solution obtained by dissolving 25.8 g of chromium nitrate / 9 hydrate in 100 ml of water was added to 44.0 g of a commercially available spherical α-alumina carrier having a diameter of 5 mm and a specific surface area of 2.3 m ² / g. In
By baking at 700 ° C. for 3 hours, a chromium oxide / α-alumina supported catalyst (10% by weight as Cr ₂ O ₃ ) was prepared.

Using the above catalyst, the hydrogenation reaction of n-caprylic acid was carried out under normal pressure under the conditions of acid space velocity: LHSV = 0.11 kg / l · Cat · hr and hydrogen space velocity: GHSV = 1250 hr ⁻¹ . Reaction temperature 380
The conversion of n-caprylic acid at 9 ° C. is 96.4%
The selectivity for caprylaldehyde was 95.7%.

Example 2 A commercially available spherical γ-alumina carrier having a diameter of 4 mm and a specific surface area of 273 m ² / g was calcined in the air at 1080 ° C. for 3 hours to prepare an alumina carrier having a specific surface area of 27.3 m ² / g. The crystal form of the fired alumina was confirmed to be α-alumina by X-ray diffraction.

In place of the α-alumina support having a specific surface area of 2.3 m ² / g used in Example 1, α having a specific surface area of 27.3 m ² / g obtained by the above method was used.
A chromium oxide / α-alumina carrier catalyst (Cr ₂ O) was mixed with an aqueous solution of chromium nitrate, evaporated to dryness, and calcined in the same manner as in Example 1 except for using an alumina carrier.
₃ as 10% by weight).

Using the above catalyst, n was obtained under the same conditions as in Example 1.
-When the hydrogenation reaction of caprylic acid was performed, the reaction temperature
The conversion of n-caprylic acid at 380 ° C. was 97.4%, and the selectivity for n-caprylic aldehyde was 94.9%.

Example 3 The commercially available spherical γ-alumina carrier used in Example 2 was calcined in air at 1200 ° C. for 3 hours to prepare an alumina carrier having a specific surface area of 9.2 m ² / g.

Instead of the alumina support having a specific surface area of 2.3 m ² / g used in Example 1, the alumina support having a specific surface area of 9.2 m ² / g obtained by the above method was used, and the other method was the same as in Example 1. It is mixed with an aqueous solution of chromium nitrate, evaporated to dryness, and calcined to obtain a chromium oxide / α-alumina carrier catalyst (1% as Cr ₂ O _3).
0% by weight).

Using the above catalyst, n was obtained under the same conditions as in Example 1.
-When the hydrogenation reaction of caprylic acid was performed, the reaction temperature
The conversion of n-caprylic acid at 380 ° C. was 57.0% and the selectivity for n-caprylic aldehyde was 95.5%. The amount of by-products such as ketone bodies was extremely small.

Examples 4 to 7 Using the chromium oxide / α-alumina carrier catalyst (10% by weight as Cr ₂ O ₃ ) prepared by the method of Example 1, pivalic acid, cyclohexanecarboxylic acid, benzoic acid and A hydrogenation reaction was carried out using methyl 3-nicotinate under the conditions shown in Table 1. Table 1 shows the results.

Comparative Example 1 The commercially available spherical γ-alumina carrier used in Example 2 was calcined in air at 900 ° C. for 3 hours to prepare an alumina carrier having a specific surface area of 131 m ² / g.

Instead of the alumina support having a specific surface area of 2.3 m ² / g used in Example 1, the alumina support having a specific surface area of 131 m ² / g obtained by the above method was used, and the other method was the same as that in Example 1. It is mixed with an aqueous solution of chromium nitrate, evaporated to dryness, and calcined to obtain a chromium oxide / α-alumina carrier catalyst (10% as Cr ₂ O _3).
% By weight).

Using the above catalyst, n was obtained under the same conditions as in Example 1.
-When the hydrogenation reaction of caprylic acid was performed, the reaction temperature
The conversion of n-caprylic acid at 390 ° C. was 60.0% and the selectivity for n-caprylic aldehyde was 44.7%.

(Effects of the Invention) According to the method of the present invention, various carboxylic acids can be obtained by using a chromium oxide catalyst supported on an alumina carrier having a specific specific surface area, as specifically shown in the above Examples. And their esters, the corresponding aldehydes can be efficiently obtained with excellent selectivity,
Significant contribution to the industrial production of these aldehydes.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 47/54 C07C 47/54 // C07B 61/00 300 C07B 61/00 300 (58) Investigation field (Int.Cl. ⁶ C07C 47/02-47/54 C07C 45/41 B01J 35/10 B01J 23/26 C07B 61/00 WPI / L (QUESTEL) CA (STN)

Claims (1)

(57) [Claims] 1. A method for producing an aldehyde by hydrogenating a carboxylic acid or an alkyl ester thereof with molecular hydrogen in the presence of a catalyst, the method comprising the steps of: using an aluminum oxide support having a specific surface area of 100 m ² / g or less as measured by a BET method as a catalyst. A method for producing an aldehyde, comprising using a supported chromium oxide.