JPS5821608B2 - Benzaldehyde Oyobi/Mataha Benzyl Alcohol Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing benzaldehyde and/or benzyl alcohol by reduction of benzoic acid.

Benzaldehyde and benzyl alcohol are useful as solvents in their own right, as well as in pesticides, pharmaceuticals, plasticizers,
It is extremely useful as a raw material for the synthesis of other general organic reagents.

However, an industrial method for obtaining these at low cost and with high quality has not yet been established.

Conventionally used methods include, for example, chlorinating toluene to produce benzyl chloride, then hydrolyzing this to obtain benzyl alcohol, and pressurizing and heating the benzyl chloride with milk of lime etc. to obtain benzaldehyde. ,
There are methods to obtain benzaldehyde by oxidizing toluene with manganese dioxide, and methods to obtain benzyl alcohol by liquid phase pressure hydrogenation of methyl benzoate, but these methods require steps such as chlorination, hydrolysis, or esterification. None of these methods can be said to be industrially advantageous, as they are complicated due to the presence of carbon dioxide, or are not suitable for large-scale production, such as in the case of oxidation with manganese dioxide.

In view of the above-mentioned circumstances, the present inventors have determined that benzaldehyde and/or
Or, as a result of intensive studies to find a method for industrially advantageous production of benzyl alcohol, we found that benzoic acid, which can be industrially obtained at an extremely low cost by oxidizing toluene, was used as a raw material without pretreatment such as esterification, and a specific The present invention was achieved based on the discovery that benzaldehyde and/or benzyl alcohol can be efficiently produced in an i-stage by reacting with hydrogen in the gas phase in the presence of a suitable catalyst.

When aromatic carboxylic acids such as benzoic acid are hydrogenated to produce the corresponding alcohol or aldehyde, alicyclic carboxylic acids are obtained by nuclear hydrogenation, hydrocarbons that are more hydrogenated than alcohols, or hydrocarbons obtained by decarboxylation. In other words, in the case of benzoic acid, it is expected that by-products such as cyclohexanecarboxylic acid, toluene, and benzene will be produced, and in fact, the inventors have also found that the above-mentioned side reactions are likely to occur. It has been found that suppression of this side reaction is an issue in the production of benzaldehyde or benzyl alcohol by hydrogenation of benzoic acid.

However, as a result of further studies based on this knowledge, the present inventors succeeded in avoiding the above side reactions by reacting benzoic acid with hydrogen in the gas phase in the presence of a catalyst mainly composed of copper and chromium. It was discovered that aldehydes and/or alcohols can be advantageously produced, and the present invention was achieved.

That is, the gist of the present invention is to provide benzaldehyde and/or benzyl alcohol, which is characterized in that, in the catalytic hydrogen reduction of benzoic acid, the reaction is carried out in a gas phase and a catalyst mainly composed of copper and chromium is used. It consists in the manufacturing method.

Next, the present invention will be explained in more detail.

In the present invention, benzoic acid vapor is brought into contact with hydrogen at high temperature, and at this time, the benzoic acid and hydrogen supplied to the reaction system have a molar ratio of hydrogen:benzoic acid -0.25:1 to 20:1, particularly 6.
The range from 25:1 to 10:1 is advantageous.

Outside this range, practically unfavorable results are given in terms of reaction rate and/or selectivity.

The reaction temperature is suitably 230 to 400°C, especially 2.5°C.
0 to 350°C is preferred.

The pressure is preferably 0.5 atm to IO atm.

The catalyst used in the present invention is solid under the reaction conditions and is based on copper and chromium.

As for the form of use in the reaction of copper and chromium, the metals themselves or their oxides are suitable.

Furthermore, a solid catalyst containing these two types and one of metals or oxides such as manganese, barium, calcium, and magnesium as a third metal component is particularly preferred.

The catalyst may contain diatomaceous earth, alumina, or the like as a carrier.

The common method for producing catalysts is the so-called Adkins type copper-chromite preparation method, but catalysts obtained by other immersion methods or coprecipitation methods can also be used. can be obtained by air oxidation of toluene in the liquid phase in the presence of a transition metal catalyst such as cobalt, or by oxidation with manganese dioxide persulfate, etc., but the present invention is applicable to products obtained by any method. is applicable.

From the reaction mixture obtained as described above, the target product is separated by a well-known appropriate method.

Also, those that can be reused in the reaction can be recycled to the reaction system.

When benzoic acid is reduced according to the present invention, benzaldehyde and benzyl alcohol can be obtained economically, and the industrial value of the method of the present invention is extremely large.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 1 mol of copper nitrate, 0.4 mol of chromium nitrate, and 0.05 mol of manganese nitrate were dissolved in 31 water, and a 20% aqueous solution of caustic soda was added dropwise thereto with stirring to neutralize the solution.

The resulting precipitate was washed with water, dried, and then roasted at 350°C.

Next, take this copper-chromium-manganese oxide in a mortar,
After adding 26 g of diatomaceous earth and mixing well, 40% chromic acid aqueous solution 50S' was gradually added, and after drying, it was molded.

5ml of the above catalyst was packed into a 15mmφ Pyrex glass reactor, and heated at 160'C for about 5 hours while passing H2 through it.
rs reduction was performed.

After the reduction, the temperature was raised to 270°C and benzoic acid (BA
) while evaporating H23,6 at 3.84P/hr.
The mixture was mixed with 5Nl/hr and flowed into the catalyst bed.

The H2/BA ratio at this time was 5/1.

The gas coming out of the reactor is first trapped with high boiling points using air conditioning, then cooled with dry ice-methanol,
Traps low boiling point components.

These collection liquids were each analyzed by gas chromatography, and the results shown in the table below were obtained.

Example 2 Reduction was carried out in the same manner as in Example 1, except that the H2 flow rate in Example 1 was changed to 7.30 Nl/hr.

The H2/BA ratio at this time was 10/1.

The results were as shown in Table-1.

Example 3 In Example 1, the reaction temperature was 300°C and the benzoic acid supply amount was 2.
．． 56? /hr Hydrogen flow rate 0.49Nl/hr, H2
Reduction was carried out in the same manner as in Example 1 with a /BA ratio of -1/1.

The results were as shown in Table-1. Example 4 The same procedure as in Example 3 was carried out except that the hydrogen flow rate was changed to 0.98 Nl/hr.

The H2/BA ratio at this time was 2/1.

The results were as shown in Table-1.

Example 5 The same procedure as in Example 1 was conducted except that manganese nitrate was replaced with barium nitrate during catalyst production.

The H2/BA ratio at this time was 5/1. The results are in Table-1
It was as follows.

Example 6 The same procedure as in Example 5 was carried out except that the H2 flow rate was changed to 0.73 Nl/hr.

The H2/BA ratio at this time is 1/1.

The results were as shown in Table-1.

Claims (1)

[Claims] 1. A method for producing benzaldehyde and/or benzyl alcohol, which comprises carrying out the catalytic hydrogen reduction of benzoic acid in a gas phase and using a catalyst mainly composed of copper and chromium.