JPS59134737A - Preparation of benzaldehyde and benzyl alcohol - Google Patents

Abstract

PURPOSE:To obtain a ratio of the titled substance to benzoic acid with keeping high catalytic activity, by oxidizing toluene with molecular oxygen in a liquid phase, using an alkali metal compound and a compound of Co, Mn, V, etc. as a catalyst. CONSTITUTION:In preparing a mixture consisting essentially of the titled compound and benzoic acid by oxidizing toluene with molecular oxygen in a liquid phase, the reaction is carried out using (A) an alkali metal compound and (B) a compound of an element selected from Co, Mn, and V as a catalyst. Especially Na benzoate, Na acetate, etc. are preferable as the component A, and an amount of it used is preferably about 100-500ppm calculated as metal based on the reaction system. The component B is used in the form of acetate, naphtenate, acetylacetonato, etc., and its amount used is 0.5-40ppm based on the reaction system in the case of Co. In the reaction, preferably formed water is continuously removed from the reaction system by azeotropic distillation with toluene, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing benzaldehyde and benzyl alcohol by oxidizing toluene with molecular oxygen in a liquid phase. As a method for producing benzaldehyde and benzyl alcohol, a method is conventionally known in which toluene is chlorinated and the resulting chlorinated product is hydrolyzed. However, this method requires a large amount of chlorine, and has the disadvantage that small amounts of organic chlorine compounds remain in the produced benzaldehyde and the like, making purification difficult. A method is also known in which toluene is catalytically oxidized in the gas phase in the presence of a compound catalyst such as tungsten or molybdenum.

Currently recognized as an industrially useful method for producing benzaldehyde, etc., when toluene is oxidized in the liquid phase with molecular oxygen in the presence of a cobalt-based catalyst to produce benzoic acid, benzaldehyde and benzyl are co-produced. This is a method of recovering alcohol. On the other hand, as the demand for benzaldehyde and benzyl alcohol increases recently, it is desired to increase the co-production ratio of benzaldehyde and other benzoic acids. However, with conventional technology using cobalt-based catalysts, it has been difficult to adjust the co-production ratio to increase. Under these circumstances, the present inventors used a new catalyst in place of the conventional simple cobalt-based catalyst during the liquid phase oxidation reaction of toluene, thereby improving the co-production ratio of benzaldehyde and benzyl alcohol to benzoic acid. The present invention was developed as a result of extensive research aimed at improving the performance and meeting market demands.

%9 in the method of the present invention means that when performing liquid phase oxidation with toluene and gold molecular oxygen, an alkali metal compound and a compound of one or more elements selected from cobalt, manganese, and vanadium are used as catalysts. There is a change to use.

Conventionally, it has been known that when a cobalt catalyst is used alone, the catalytic activity is high, but as mentioned above, the co-production of useful products is low. In addition, when compounds of other metals such as alkali metals are used for catalyst washing, the activity is too low and the reaction is on the verge of stopping at a low conversion rate, making it difficult to sustain the reaction stably. It could not be used as a catalyst. The method of the present invention has succeeded in solving these problems and increasing the co-production ratio of co-products while maintaining high catalytic activity.

The alkali metal compounds used in the method of the present invention include:
Preference is given to compounds of lithium, sodium, potassium, rubidium and cesium, especially sodium compounds. The alkali metal compound may be used in any form as long as it is at least partially soluble in the reaction system under the reaction conditions, but it must be in a form that does not cause corrosion to the reactor, usually benzoate. , it may be used as an organic acid salt such as acetate. Alternatively, hydroxide, carbonate, etc. may be added to the reaction product benzoic acid present. The amount of alkali metal compound to be used is 20% as metal in the reaction system.
〜Yu, θθo ppm or so, preferably 10θ~50
Approximately 0 ppm is good.

Next are cobalt, manganese, and vanadium compounds, which are also preferably used in a form that is soluble or solubilized in the reaction system, such as acetate.

Naphthenic acid group, acetylacetonate, etc. are used.

The amount used is about θ, / ~ /, 000 ppm, based on the reaction system.
More preferably 1, for example, 0.5~'l OD for cobalt
It is about pm. The liquid phase oxidation reaction is usually carried out in a vacuum, but it may also be carried out in the presence of an inert solvent such as acetic acid or benzoic acid.

What is the reaction temperature? It is preferably selected between /SθC and /Deo'c rather than OC and U20C1. The reaction pressure is from 3 kq/ant to 20 kq/cr& more preferably from kq/crd/ok,q
,,/crd is selected within the range of FW, but it is not decisive and linear.

The conversion rate of toluene is usually about IO to 15%. When the conversion rate is high, the co-production ratio of benzaldehyde and benzyl alcohol decreases, and in some cases, a reaction termination phenomenon is observed. On the other hand, when the conversion rate is low, co-production increases, but a large amount of energy is required to recover and reuse unreacted toluene, resulting in low F.

The reaction time is determined by the required conversion rate, but in the case of the method of the present invention, the reaction rate is generally high and the desired conversion rate can be reached in a short time.

During the reaction, an initiator such as azobisisobutyronitrile or benzaldehyde may be used in combination. Of course, such additives are not required when the reaction is carried out continuously.

Air can be used as the gas for oxidation, but the oxygen concentration may also be appropriately adjusted. Care must be taken to prevent the formation of explosive mixtures in the gas phase of the reaction system. In the liquid phase oxidation reaction of toluene, peroxide accumulates, which can cause problems in the safety of the reaction itself or in the recovery and purification process, but in the method of the present invention, the accumulation of peroxide is small, and this point is But this method is superior.

During the reaction, it is preferable to carry out the reaction so that the produced water is continuously removed from the reaction system.

This can be easily carried out, for example, by an azeotropic method with toluene.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples unless the gist of the invention is exceeded.

Example 1 Toluenta in a 100ye autoclave.

Azobisisobutyronitrile θ, o tr, and sodium benzoate as sodium to the whole system as sodium tj [, 2θo ppm, cobalt naphthenate as cobalt s ppm to the whole system, /gO”
The temperature was raised to Q, and air was blown into the reactor while stirring at a reaction pressure of 10 kg/at. Oxygen absorption started quickly and remained stable. After one hour, the reaction was stopped and the product was analyzed, giving the following results.

Toluene conversion rate /, left Aq6 benzaldehyde yield β, /cutibenzyl alcohol yield /, 110% benzoic acid yield
g, 33 benzaldehyde benzyl alcohol molar ratio = θ, lI/41 Benzoic acid Examples 2 to 6 * The compounds used were the same as in Example 1 for Na and CO, and for K, Mn, and V. These are potassium benzoate, manganese naphthenate, and vanadyl naphthinate, respectively.

Reference Example: In the known liquid phase oxidation method of toluene, a cobalt compound is used as a catalyst and the whole system is oxidized as cobalt. / (zq,t
x)) The reaction was carried out under the same conditions as in Example 1, except that λθo ppm of cobalt naphthenate was added to the entire system as a catalyst. After 1 hour and 10 minutes, the reaction was stopped and the product was analyzed, and the following results were obtained.

Toluene conversion rate / 2. / /% benzaldehyde yield /, 4 /% benzyl alcohol yield, 0.3g% benzoic acid yield
A reaction was carried out under the same conditions as in Comparative Example/Example/9.4'7, except that the catalyst was changed to only cobalt naphthenate, and the amount of cobalt was t ppm based on the entire system.

No oxygen absorption was observed and the reaction was about to proceed.

Comparative Example I/Ii+- was treated under the same conditions as Example/with only sodium benzoate at a concentration of 10 θppm based on the total system.
I changed it to use and performed the reaction.

Oxygen absorption started after a long induction period, but the absorption situation was unstable. After several hours, the reaction stopped, so the product was analyzed and the following results were obtained.

Toluene conversion rate g, 'st% benzaldehyde yield, 2.70% benzyl alcohol yield Hi, gtaty benzoic acid yield g,
3. Because the reaction conditions are unstable and the reaction stops when the conversion rate of small toluene is low, it is judged that it is difficult to use it as a practical catalyst.

Comparative Example 3 The reaction was carried out under the same conditions as in Example S except that the catalyst component (glass) was removed. Since the reaction stopped after /hour sO minutes, the anastomosis produced was analyzed and the following results were obtained.

Toluene conversion rate g, oq benzaldehyde yield c, tAq6 pendyl alcohol yield 4 0.33% benzoic acid yield
Haku 4 (%) A large amount of insoluble components were observed to precipitate in the reaction solution.

Sender: Mitsubishi Kakai Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (1)

[Claims] (1) When toluene is oxidized with molecular oxygen in the liquid phase to produce a mixture mainly consisting of benzaldehyde, benzyl alcohol and benzoic acid, the catalyst used is an alkali metal compound selected from cobalt, manganese and vanadium. A method for producing benzaldehyde and benzyl alcohol, characterized by using a compound of one or more elements.