JPH1135561A - Production of hetero-aromatic aldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound that is useful as a raw material for medicines and agrochemicals in high selectivity by vapor-phase catalytic oxidation of an alkyl-substituted heteroaromatic compound with molecular oxygen in presence of a specific oxide catalyst. SOLUTION: (A) An alkyl-substituted heteroaromatic compound as an alkyl- substituted pyridine or an alkyl-substituted pyrazine is subjected to he vapor- phase catalytic reaction with (B) molecular oxygen over (C) a catalyst of oxides containing vanadium, phosphorus and aluminum thereby producing (D) a heteroaroamtic aldehyde. The catalyst (C) is preferably composed of oxides of the formula: Va Pb Alc Od (a, b, c and d mean the atomic ratios of vanadium, phosphorus, aluminum and oxygen and b is 0.5-3, c is 0.3-0.7, when a is regarded as 1, and d is determined by the atomic value of oxygen, and the atomic values of other elements and atomic ratio). The catalyst may be used together with a catalyst carrier as silica or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing heteroaromatic aldehydes by subjecting an alkyl-substituted heteroaromatic compound to molecular oxygen in gas phase contact reaction. Heteroaromatic aldehydes are useful as raw materials for medicines and agricultural chemicals.

[0002]

2. Description of the Related Art As a method for producing a heteroaromatic aldehyde by reacting an alkyl-substituted heteroaromatic compound with molecular oxygen in a gas phase, for example, 4-methylpyridine is reacted in a gas phase with molecular oxygen. In the production of 4-aldehyde pyridine by using divanadyl pyrophosphate [(VO) ₂ P ₂ O ₇ ] as a catalyst (German Application DD 298234) has been proposed.

[0003]

The inventors of the present invention conducted gas-phase contact reaction of methylpyridine with molecular oxygen in the presence of divanadyl pyrophosphate as a catalyst in the presence of the catalyst. As shown, the selectivity for 2-aldehydepyridine and 4-aldehydepyridine was as low as 26.3% and 60.9%, respectively. Therefore, the above-mentioned conventional method is hardly satisfactory as a method for producing a heteroaromatic aldehyde, and it is desired to further improve the selectivity of the heteroaromatic aldehyde. The present invention provides a method capable of solving the above-mentioned problems of the conventional method, that is, a method capable of producing a heteroaromatic aldehyde with a high selectivity by reacting an alkyl-substituted heteroaromatic compound with a molecular oxygen in a gas phase. Things.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have conducted a gas-phase catalytic reaction of an alkyl-substituted heteroaromatic compound with molecular oxygen to produce a heteroaromatic aldehyde. The present inventors have found that when an oxide containing vanadium, phosphorus and aluminum is used as a catalyst in the production, heteroaromatic aldehydes can be produced with a high selectivity, and the present invention has been completed.

That is, the present invention relates to a method for producing a heteroaromatic aldehyde by reacting an alkyl-substituted heteroaromatic compound with molecular oxygen in a gas phase to produce an oxide containing vanadium, phosphorus and aluminum as a catalyst. The present invention relates to a method for producing a heteroaromatic aldehyde, which is used. The catalyst in the present invention contains aluminum as a catalyst constituent element, thereby improving the selectivity of heteroaromatic aldehydes.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Catalyst used in the present invention is an oxide containing vanadium, phosphorus and aluminum, preferably has the formula _{(1): V a P b} Al c O d (1) ( wherein, a, b, c, and d represents an atomic ratio of vanadium, phosphorus, aluminum and oxygen, and when a is 1, b is 0.5 to 3, c is 0.3 to 0.7,
d is a value determined by the valence of oxygen and the valence and atomic ratio of another element. ).

[0007] The compound of each of the constituent elements of the catalyst used for the preparation of the catalyst is not particularly limited, and any commonly used compound can be used. For example, as the vanadium compound, ammonium metavanadate, vanadium pentoxide,
Vanadyl oxalate, vanadyl phosphate and the like; phosphorus compounds such as phosphoric acid, metaphosphoric acid, phosphorous acid, and phosphates (eg, ammonium phosphate); aluminum compounds such as aluminum oxide and aluminum hydroxide;
Aluminum sulfate, aluminum phosphate and the like can be used.

The catalyst of the present invention can use an oxide containing vanadium, phosphorus and aluminum as it is,
It may be used together with a carrier. As the carrier, silica, alumina, silica-alumina, silicon carbide, titanium oxide, diatomaceous earth and zeolite are particularly preferred. In preparing the catalyst, powders and colloids thereof can be used.

The catalyst of the present invention can be prepared by a generally known method for preparing a catalyst. The catalyst of the present invention can be easily prepared by any method such as a coprecipitation method, a kneading method and an impregnation method. Is prepared. For example, the compound of the catalyst constituent element is heated in water, reacted by stirring, concentrated, dried, and then calcined in the presence of air.
An oxide containing phosphorus and aluminum is obtained. When a carrier is used, for example, a method of heating the compound of the catalyst constituent element of the present invention in water with the support, stirring, concentrating, drying, and calcining, a solution containing the compound of the catalyst constituent element of the present invention in the support And drying and firing, or a method in which the oxide containing vanadium, phosphorus and aluminum obtained as described above is kneaded with a carrier.

The catalyst thus prepared and obtained is
It can be formed into a desired shape such as a columnar shape, a cylindrical shape, a spherical shape, a granular shape, a powdery shape, and used as a fixed bed catalyst or a fluidized bed catalyst. In addition, a catalyst obtained by impregnating or coating an oxide containing vanadium, phosphorus and aluminum on the above-mentioned carrier formed in a desired shape in advance and then drying it can be used as the catalyst of the present invention.

In using the catalyst of the present invention in a gas phase catalytic reaction for producing a heteroaromatic aldehyde,
The catalyst can be used alone or diluted with a solid inert to the gas phase catalytic reaction of the present invention, preferably the above-mentioned carrier. When performing the gas phase catalytic reaction of the present invention by diluting the catalyst, a solid inert to the reaction is mixed with the catalyst of the present invention and charged into a reactor, and the alkyl-substituted heteroaromatic compound and molecular The reaction may be performed by supplying a mixed gas containing oxygen. Further, the catalyst prepared by using a carrier during the preparation of the catalyst or the catalyst obtained by impregnating or coating the carrier with an oxide containing vanadium, phosphorus and aluminum is a catalyst diluted with the carrier. ,
The method of using these catalysts is also mentioned as a method of diluting the catalyst, and the catalyst diluted with the carrier can be further diluted with a solid inert to the gas phase contact reaction of the present invention. .

The alkyl-substituted heteroaromatic compound in the present invention is a heteroaromatic compound having at least one alkyl group as a substituent, and is preferably a nitrogen atom such as alkyl-substituted pyridine, alkyl-substituted pyrazine and alkyl-substituted pyrimidines. Is a compound in which is a constituent atom of an aromatic ring. Examples of the alkyl group include a methyl, ethyl, and propyl group. Specific examples of the alkyl-substituted heteroaromatic compound include, for example, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,3-dimethylpyridine 2,4-dimethylpyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine, 2-methyl-5-ethylpyridine, 2,4
6-trimethylpyridine, 2,3,4-trimethylpyridine, 2,3,5-trimethylpyridine, 2,3,6-
Alkyl-substituted pyridines such as trimethylpyridine, methylpyrazine, ethylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-methyl-5-ethylpyrazine, 2-methyl-
Alkyl-substituted pyrazines such as 6-ethylpyrazine;
Alkyl-substituted pyrimidines such as methylpyrimidine, 4-methylpyrimidine, 5-methylpyrimidine, 2-ethylpyrimidine, 2,4-dimethylpyrimidine, 2,5-dimethylpyrimidine, 4,5-dimethylpyrimidine, 4,6-dimethylpyrimidine and the like And the like.

The gas phase catalytic reaction of the present invention can be carried out in a fixed bed reactor or a fluidized bed reactor. The proportion of the alkyl-substituted heteroaromatic compound and molecular oxygen used in the gas phase catalytic reaction of the present invention is usually 0.4 to 5.0 mol of molecular oxygen per mol of alkyl-substituted heteroaromatic compound, preferably. Is 1.1 to 2.1 mol. As the molecular oxygen, air is usually used, but pure oxygen or a mixture thereof with air can be used. In the gas phase contact reaction of the present invention, the mixed gas of the alkyl-substituted heteroaromatic compound and molecular oxygen may be diluted with a diluent. Particularly, when the reaction is carried out in a fixed bed reactor, the diluent may be used. It is preferred to use. Examples of the diluent include an inert gas such as nitrogen and water vapor, and a preferable diluent is water vapor. When a diluent is used, it is used in an amount of usually 15 moles per mole of the alkyl-substituted heteroaromatic compound.
５０50 mol, preferably 20-30 mol.

When the gas-phase catalytic reaction of the present invention is carried out using a fixed-bed reactor, the catalyst of the present invention is filled in a reaction tube, and the catalyst-filled portion is usually at 250 to 500 ° C., preferably 280 to 500 ° C. Raise the temperature to 450 ° C. Then, a mixed gas comprising the alkyl-substituted heteroaromatic compound, the molecular oxygen and the diluent in the above ratio is charged to the catalyst-filled portion at a space velocity (hereinafter, S
It is called V. ) A heteroaromatic aldehyde is formed at a high selectivity when supplied at 700 to 11000 Hr ^-1 , preferably 1500 to 5000 Hr ^-1 to effect a gas phase contact reaction. The reaction can be carried out under normal pressure, reduced pressure or increased pressure.

After the reaction gas obtained by the gas phase catalytic reaction of the present invention is cooled and condensed as it is, or the reaction gas is collected by passing through a suitable solvent, the condensate obtained is distilled or collected. If the collected liquid is concentrated and then distilled, heteroaromatic aldehydes can be isolated.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to only the Examples. The conversion, yield and selectivity were calculated according to the following definitions.

[0017]

(Equation 1)

[0018]

(Equation 2)

[0019]

(Equation 3)

Example 1 500 g of ion-exchanged water and 98.0 g of 85% phosphoric acid were
After mixing and heating to 90 ° C. with stirring, 181.9 g of vanadium pentoxide and 102.0 wt% alumina sol
g was added and reacted at the same temperature for 20 minutes. The obtained reaction solution was concentrated, and the concentrate was dried at 200 ° C. for 24 hours, and then calcined at 670 ° C. for 4 hours in an air stream. Thus, an oxide excluding oxygen and having a composition of V ₁ P _1.2 Al _0.5 was obtained. Using the obtained oxide as a catalyst, 4-aldehydepyridine was produced. Align the above catalyst to 10-16 mesh,
10 ml of the mixture was filled in a Pyrex reaction tube having an inner diameter of 16 mmφ, and the temperature of the catalyst-filled portion of the reaction tube was raised to 360 ° C.
A mixed gas comprising 4-methylpyridine, water and air (mixing molar ratio is 4-methylpyridine: water:
(Air = 1: 30: 10) from the top of the reaction tube to the SV
= 1940Hr- ¹ and 30 minutes from the start of mixed gas supply
After 10 minutes, the reaction gas was passed through water for 10 minutes to collect the reaction product. When the obtained collected liquid was analyzed by gas chromatography, the conversion of 4-methylpyridine was 77.0.
% And the yield of 4-aldehydepyridine were 54.6% (selectivity 71.0%).

Reference Example 1 Divanadyl pyrophosphate was synthesized according to the method described below, based on the description in JP-B-56-45815. 450.0 g of ion-exchanged water, 34.6 g of 85% phosphoric acid and 20.9 g of hydroxylamine hydrochloride were mixed with stirring and the temperature was raised to 80 ° C., and then 300.0 g of ion-exchanged water was added.
g and then 27.3 g of vanadium pentoxide. Since the reaction involves foaming, vanadium pentoxide was added little by little. After the completion of the addition of vanadium pentoxide, the mixture was concentrated to obtain a dark blue slurry. The obtained slurry was dried at 170 ° C. for 24 hours, then pulverized, washed by stirring in deionized water, and filtered. The obtained solid was dried at 120 ° C. for 24 hours, then filled in a 22 mmφ Pyrex reaction tube, and calcined at 500 ° C. for 6 hours in a nitrogen stream. As a result of analysis by X-ray diffraction, divanazyl pyrophosphate was obtained. Using the obtained divanadyl pyrophosphate as a catalyst, 4-aldehydepyridine was produced. Example 1
A gas phase contact reaction of 4-methylpyridine was carried out in the same manner as in Example 1 except that divanadyl pyrophosphate was used in place of the oxide catalyst obtained in the above, and the reaction temperature was 350 ° C. As a result, the conversion of 4-methylpyridine was 86.7%,
The yield of aldehyde pyridine is 52.9% (selectivity 60.
9%).

Example 2 A reaction tube filled with the catalyst of Example 1 was used, and the temperature of the catalyst-filled portion of the reaction tube was raised to 340 ° C. A mixed gas consisting of 2-methylpyridine, water and air (mixing molar ratio is 2-methylpyridine: water: air = 1: 30:
SV from the reaction tube upper part was 10) = 3400Hr ^-1
And the reaction gas 5.5 hours after the start of the mixed gas supply was passed through water for 6 minutes to collect the reaction product. When the obtained collected liquid was analyzed by gas chromatography,
The conversion of 2-methylpyridine is 47.9% and the yield of 2-aldehydepyridine is 32.5% (selectivity 67.8).
%)Met. Pyridine was produced in a yield of 7.5%.

Reference Example 2 The procedure of Example 3 was repeated, except that the reaction tube filled with the catalyst of Reference Example 1 was used, and the temperature of the catalyst-filled portion of the reaction tube was raised to 390 ° C. As a result, the conversion of 2-methylpyridine was 48.2% and the yield of 2-aldehydepyridine was 12.
7% (selectivity 26.3%). Further, pyridine was produced in a yield of 12.9%.

Claims (3)

[Claims] 1. An oxide containing vanadium, phosphorus and aluminum is used as a catalyst when producing an aromatic aldehyde by reacting an alkyl-substituted heteroaromatic compound with molecular oxygen in a gas phase. For producing heteroaromatic aldehydes. 2. A catalyst having the formula _{(1): V a P b} Al c O d (1) ( wherein, a, indicated b, c and d, respectively vanadium, phosphorus, the atomic ratio of aluminum and oxygen, When a is 1, b is 0.5 to 3, c is 0.3 to 0.7,
d is a value determined by the valence of oxygen and the valence and atomic ratio of another element. 2. The method according to claim 1, which is an oxide having a composition represented by the formula: 3. The method according to claim 1, wherein the alkyl-substituted heteroaromatic compound is an alkyl-substituted pyridine, an alkyl-substituted pyrazine, or an alkyl-substituted pyrimidine.