JP2936698B2 - Method for producing aldehydes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an aldehyde useful as an organic synthetic intermediate. More specifically, the present invention relates to a method for producing aldehydes by hydrogenating a carboxylic acid or an ester thereof.

[Conventional technology]

Conventionally, various methods have been proposed as methods for producing aldehydes, and the most commonly performed method using a carboxylic acid or a derivative thereof as a raw material is the so-called Rosenmund reduction method. However, this method has a drawback that the cost increases because the method involves carboxylic acid chloride.

If carboxylic acid can be directly reduced by molecular hydrogen, it is most preferable as a method for producing aldehydes. As such a method for producing aldehyde, a zirconium oxide catalyst (US Pat.
P4328373), a method using an yttrium oxide catalyst (USP4328373) or an aluminum oxide catalyst (USP3935265) has been reported. However, the method using these catalysts has low selectivity for aldehydes and is satisfactory as an industrial method. Did not.

Further, 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 and other elements such as chromium and manganese is also disclosed in, for example, JP-A-60-152434, JP-A-60-
243037 and JP-A-61-115043.

However, in the method using a catalyst containing zirconium oxide as a main component, in particular, when an aliphatic carboxylic acid having two hydrogen atoms bonded to an α-carbon to a carboxyl group or a derivative thereof is used as a raw material, the removal is difficult. Ketone bodies are by-produced by the carbonic acid condensation reaction, and the selectivity of the target aldehyde was not always sufficient.

Furthermore, when hydrogenating a heterocyclic carboxylic acid or a derivative thereof containing a hetero atom such as N, S, or O in the ring, 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 with a zinc oxide-chromium oxide catalyst, a corresponding aldehyde such as acetaldehyde or n-butyraldehyde may be produced at a low yield. Known (JP-B 47-38410)
issue).

It is also known that when a carboxylic acid such as methyl benzoate or pivalic acid is hydrogenated using an iron oxide catalyst containing a small amount of chromium oxide, the corresponding aldehyde is produced in a certain yield (EP304853).

However, these methods have not been practically satisfactory.

[Problems to be solved by the invention]

The present invention seeks to provide a process for hydrogenating aliphatic, cycloaliphatic, aromatic and heterocyclic carboxylic acids and their alkyl esters to directly obtain the corresponding aldehydes with high selectivity.

[Means for solving the problem]

The gist of the present invention is that when a carboxylic acid or an alkyl ester thereof is contacted with molecular hydrogen in the presence of a chromium oxide catalyst to produce an aldehyde, the concentration of the carboxylic acid or the alkyl ester thereof in the feed gas is reduced to 10%. (Volume)% or less in the method for producing aldehyde by reacting in the gas phase.

 Hereinafter, the present invention will be described in detail.

The starting materials of the present invention are aliphatic, alicyclic, aromatic and heterocyclic carboxylic acids or their alkyl esters.

As the aliphatic carboxylic acid, specifically, 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, undecane Acid, lauric acid,
Tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, stearic acid, isostearic acid, nonadecanoic acid, trichosanoic acid, tetracosanoic acid, 10-undecenoic acid, oleic acid, 11-eicosenoic acid, etc., having 4 to 24 carbon atoms.
And polycarboxylic acids such as oxalic acid, malonic acid, diethylmalonic acid, succinic acid, glutaric acid, adipic acid and decanediacid octadecanedioic acid.

Examples of the alicyclic carboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

Examples of the alicyclic carboxylic acid include cyclopentanecarboxylic acid and cyclohexanecarboxylic acid.
Further, the aliphatic carboxylic acid or alicyclic carboxylic acid,
As a substituent, it may have a group inert to the reaction,
Such substituents include, for example, aryl groups, O, S, N
And the like, a heterocyclic group containing an atom, an alkoxy group and the like.

As the alkyl ester of the aliphatic and alicyclic carboxylic acid used in the present invention, specifically, methyl ester, ethyl ester, n-butyl ester of the aliphatic carboxylic acid and alicyclic carboxylic acid exemplified above, C1-C4 alkyl esters, such as isobutyl ester, are mentioned.

The aromatic carboxylic acid or its alkyl ester used in the present invention can be represented by the general formula ArCOOR) _n .

(In the formula, n is 1 or 2, R represents a hydrogen atom or an alkyl group, and Ar represents an aryl group which may have a substituent.) The aryl group is usually a phenyl group or a naphthyl Group, an anthryl group, and a substituent which the aryl group may have, for example, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, a halogen atom,
Examples include a hydroxyl group, a formyl group, and an acyl group. When n = 2, R may be the same or different. Specific compounds include, for example, benzoic acid,
Toluic acid, dimethyl benzoic acid, cyclohexyl benzoic acid cumic acid, t-butyl benzoic acid, phenyl benzoic acid,
Carboxylic acids such as anisic acid, phenoxybenzoic acid, chlorobenzoic acid, hydroxybenzoic acid, acetylbenzoic acid, naphthoic acid, anthracenecarboxylic acid and the like can be mentioned. Examples of the carboxylic acid alkyl ester include alkyl esters having 1 to 4 carbon atoms such as methyl ester, ethyl ester and n-butyl ester of these carboxylic acids. Also, phthalic acid and its dimethyl ester can be used.

The heterocycle constituting the raw material heterocyclic carboxylic acid or alkyl ester thereof used in the present invention has at least one N, S or O atom in the ring, and specifically, , 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,
Examples include a triazine ring, an azepine ring, and an oxepin ring.

As the heterocyclic carboxylic acid having these rings or an alkyl ester thereof, an alkyl ester having about 1 to 4 carbon atoms is preferable.

Specific examples include nicotinic acid, furan carboxylic acid, thiazole carboxylic acid and the like and alkyl esters thereof such as methyl, ethyl and n-butyl.

Of the carboxylic acids or their alkyl esters as raw materials, in the present invention, it is particularly preferable to use aliphatic carboxylic acids or their alkyl esters and alicyclic carboxylic acids or their alkyl esters.

The chromium oxide catalyst used in the present invention is prepared by a usual method, and the starting material is commercially available chromium oxide, chromium hydroxide, sulfate, nitrate or halide, or chromic anhydride, dichromic acid or Inorganic salts such as ammonium salts and alkali metal salts thereof, and organic salts such as chromium formate, acetate, oxalate and organometallic complex can be used. The chromium oxide can be prepared by the above-described salt pyrolysis method, but since it does not contain impurities exhibiting general poisoning effects, chromium raw materials include chromium hydroxide, nitrate, Salts which decompose at relatively low temperatures and do not contain other poisoning elements, such as chromic anhydride, ammonium bichromate, formate, acetate and oxalate, are preferred.

When a raw material such as chromium sulfate or halide is used, it may be used after being converted to hydroxide with sodium hydroxide or aqueous ammonia. The calcination temperature of the chromium oxide catalyst is 400 to 1200 ° C, preferably 500 to 10 ° C.
A range of 00 ° C is appropriate. The chromium oxide catalyst can be formed by a usual method. For example, a tableting method, a method of baking after spray drying, or a method of adding water to chromium hydroxide or chromium oxide powder, mixing if necessary in the presence of a binder component, extruding and drying, and then drying at a predetermined temperature Baking method.

Further, the chromium oxide catalyst can be used by being supported on a carrier inert to the present reaction.

The hydrogenation with molecular hydrogen in the present invention is performed in a gas phase. The reaction temperature is preferably 200 to 500 ° C, preferably about 250 to 450 ° C. The reaction pressure may be normal pressure, but may be slightly pressurized. As a reaction method,
A fixed bed system in which a fixed catalyst bed is formed with the above-mentioned catalyst, and a raw material gas containing carboxylic acid or its alkyl ester and hydrogen is supplied thereto is preferable. The concentration of the carboxylic acid or its alkyl ester in the raw material gas is not more than 10 (volume)%, preferably about 0.01 to 10 (volume)%, more preferably about 0.1 to 10 (volume)%. If the concentration is too low, the efficiency of the reaction will be poor, while if the concentration is too high, a higher reaction temperature will be required to promote the reaction, not only the selectivity will be poor, but also the catalyst life will be short and practical There are many problems. The space velocity of the feed for such a concentration range is such that the feed carboxylic acid or its alkyl ester is 0.01 to 2 hr ^-1 as LHSV, preferably 0.03 to ¹ hr.
It is about ^-1, hydrogen 100～20,000Hr ^-1 as GHSV, preferably suitable to be about 500～5,000Hr ^-1.
In addition, some inert gas, such as nitrogen, is used as hydrogen.
Water vapor or the like may be contained.

〔Example〕

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 6N ammonia water was added dropwise to an aqueous solution consisting of 159.1 gr of chromium nitrate / 9 hydrate and 500 ml of water with stirring to adjust the pH to 8.0. The obtained chromium hydroxide was filtered, washed with water, dried, and then calcined in air at 700 ° C. for 3 hours to obtain a chromium oxide powder. Using this chromium oxide powder, tablet molding was performed, followed by sizing to 10 to 20 mesh to prepare a chromium oxide catalyst.

Next, using this chromium oxide catalyst, the hydrogenation reaction of lauric acid was carried out at normal pressure, at a reaction temperature of 360 ° C, and the space velocity of lauric acid: LH
SV = 0.11kg / -Cat · hr, hydrogen space velocity: GHSV = 1250h
A gas-phase hydrogenation reaction of n-lauric acid was performed under the condition of r ^-1 (raw material concentration: 1.4 (volume)%). At a reaction temperature of 360 ° C,
92.0% lauric acid conversion, lauryl aldehyde selectivity
93.1% were obtained.

Comparative Example 1 Commercially available zirconium oxyhydroxide (ZrO ₂ content: 85.4
(Weight%) 23.4gr, chromium nitrate / 9 hydrate 3.25gr and water 50ml
Solution, and evaporated to dryness.
C. for 3 hours to prepare an oxide powder composed of chromium and zirconium. (Chromium: zirconium = 5:10
(0 atomic ratio) The obtained powder was tablet-formed and then sized for 10-20 mesh.

Using the above catalyst, the gas phase hydrogenation reaction of lauric acid was performed at normal pressure, at a reaction temperature of 320 ° C., and the space velocity of lauric acid: LHSV = 0.11
kg / Cat · hr, hydrogen space velocity: GHSV = 1250 hr ⁻¹ . At a reaction temperature of 320 ° C, the conversion of lauric acid was 91.9%.
% And lauryl aldehyde selectivity was 78.6%.

[Example 2] Using the chromium oxide catalyst obtained by the method shown in Example 1, the gas phase hydrogenation reaction of stearic acid was carried out at normal pressure and reaction temperature.
330 ° C, space velocity of stearic acid: LHSV = 0.11kg / Cat h
r, Space velocity of hydrogen: GHSV: 1250 hr ^-1 (material concentration: 1.4 vol%). At a reaction temperature of 330 ° C, stearic acid conversion rate 84.7%, stearyl aldehyde selectivity 95.1%
was gotten.

Example 3 Using the chromium oxide catalyst obtained by the method shown in Example 1, the gas-phase hydrogenation reaction of n-caprylic acid was carried out at a reaction temperature of 350.
° C, normal pressure, space velocity of n-caprylic acid: LHSV = 0.11 kg /
Cat hr, space velocity of hydrogen: GHSV = 1250 hr ^-1 (material concentration: 1.4 (volume)%).

At a reaction temperature of 350 ° C., the conversion of n-caprylic acid was 95.2.
%, N-capryaldehyde selectivity of 95.9%.

[Comparative Example 2] A zinc oxide-chromium oxide (30:70) catalyst was coprecipitated with ammonia from a zinc nitrate-chromium nitrate aqueous solution.
It was prepared by baking at 0 ° C. Using this catalyst, a gas phase hydrogenation reaction of n-caprylic acid was carried out under the same conditions as in Example 3.

At a reaction temperature of 350 ° C., the conversion of n-caprylic acid was 96.8.
%, N-capryaldehyde selectivity was 74.3%.

Example 4 A gas phase hydrogenation reaction of n-caprylic acid was performed using the chromium oxide catalyst obtained by the method shown in Example 1. The hydrogenation reaction is carried out at a temperature of 400 ° C., at normal pressure, and LHSV of n-caprylic acid =
GHSV of 0.73 kg / Cat · hr hydrogen was performed at 1250 hr ⁻¹ . At this time, the concentration of n-caprylic acid in the raw material was 8.3% by volume.

At a reaction temperature of 400 ° C., n-caprylic acid conversion was 46.2.
%, N-capryaldehyde selectivity was 97.4%.

[Comparative Example-3] A gas phase hydrogenation reaction was carried out in the same manner as in Example 4, except that the GHSV of hydrogen was reduced to 530 hr- ¹ . At this time, the concentration of n-caprylic acid in the raw material is 17.6 (volume)%.

At a reaction temperature of 440 ° C., the conversion of n-caprylic acid was 69.0.
% And n-capryaldehyde selectivity was 88.9%. Note that a time-dependent decrease in the catalyst activity was observed.

(Effect of the Invention) According to the method of the present invention, the corresponding aldehyde can be produced with a high selectivity by direct hydrogenation of a carboxylic acid or an ester thereof using a specific catalyst. It is.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 47/00-47/02 C07C 45/41 C07B 61/00 B01J 23/26 WPI / L (QUSETEL) CA (STN)

Claims (1)

(57) [Claims] In producing a aldehyde by contacting a carboxylic acid or its alkyl ester with molecular hydrogen in the presence of a chromium oxide catalyst, the concentration of the carboxylic acid or its alkyl ester in the feed gas is reduced to 10 ( volume)%
A method for producing an aldehyde, characterized by reacting in the gas phase as follows.