JPS6317821B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing benzophenone azine. Benzophenone azine is a compound useful as an intermediate in producing hydrazine or its salt. That is, benzophenone azine has the following reaction formula (1) As shown in Figure 2, it is quantitatively hydrolyzed with mineral acids to produce hydrazine salts. Related known technology for producing benzophenone azine is U.S. Patent No. 2870206, Tokukai 52-131987
There are numbers etc. These methods use a catalyst containing copper halide to oxidize benzophenone imine with molecular oxygen to obtain benzophenone azine. These known methods have various drawbacks, such as the instability of the copper compound as the catalyst, the strong corrosivity of the equipment due to the use of a halogen compound, and the high consumption of benzophenone imine due to the large number of side reactions. Therefore, as a result of intensive study on methods using other catalysts, the present inventor newly discovered that benzophenone azine can be obtained by oxidizing benzophenone imine and aldehydes with molecular oxygen using a cobalt salt as a catalyst. completed. That is, the present invention relates to benzophenone imine and a compound having the general formula R-(CHO) _o [where n is an integer of 1 or 2, and R represents hydrogen or an aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms]
The present invention relates to a method for producing benzophenone azine, which comprises oxidizing an aldehyde represented by the formula with molecular oxygen in the presence of a cobalt salt as a catalyst. Further improvements include a method of coexisting a manganese salt as a promoter and a method of coexisting an alkylamine or a cyclic amidine as a reaction promoter. The present invention can be expressed by the following reaction formula (2). Although the reaction mechanism of the present invention is not clear, it is believed that molecular oxygen first acts on aldehydes to form intermediates such as peroxides, which further reacts with benzophenone imine to produce benzophenone azine. Conceivable. The cobalt salt of the catalyst is presumed to have a catalytic effect on both the formation of this intermediate, such as peroxide, and the reaction of this intermediate with benzophenone imine to produce benzophenone azine. It is also assumed that the manganese salt acts on the latter benzophenone azine production process, and the alkylamine or cyclic amidine is thought to form a cobalt matrix and increase the catalytic activity of the cobalt salt, but there is no clear reason why. It is unknown. Excessive use of manganese salt is disadvantageous to the reaction and peroxide stability and is not preferred. Similarly, the use of an excessive amount of alkylamine or cyclic amidine is disadvantageous because it has a suppressive effect. The cause of this is still unknown. The present invention is characterized by good reactivity at low temperatures due to the excellent catalytic action of the present invention, and side reactions are significantly suppressed when low-temperature reactions are carried out. The catalyst may be used at a low concentration and can be recycled repeatedly. The catalyst of the present invention is less expensive than conventional copper-based compounds, and the aldehydes used can be obtained as corresponding useful carboxylic acids. The benzophenone imine used as a starting material in the present invention is not limited to benzophenone imine isolated from a benzophenone imine-containing solution prepared by iminating benzophenone by a known method, but also the above-mentioned solution. can be used directly. The commonly used benzophenone imine is prepared by the reaction of benzophenone with ammonia, and is prepared by the reaction of benzophenone with ammonia.
A mixture with benzophenone containing up to 75% by weight is preferably used. General formula used in the present invention R-(CHO) _o [In the formula, n is an integer of 1 or 2, R represents hydrogen or an aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms]
Specific examples of the aldehydes represented by the formula include formaldehyde, acetaldehyde, propanal, butanal, n-pentanal, isobutyraldehyde, benzaldehyde, phthalaldehyde, and the like. Usually, the amount used is not particularly limited, but the raw material benzophenone imine 1
1 to 50 moles per mole is suitable. The cobalt salt used as a catalyst in the present invention is a divalent or trivalent cobalt salt, and specific examples include cobalt chloride, cobalt bromide, cobalt formate, cobalt acetate, cobalt propionate, cobalt oxalate, cobalt malonate, and succinic acid. Examples include cobalt and cobalt benzoate.
The amount of this catalyst used is not particularly limited, but it is usually
0.001 to 10 atoms of cobalt can be used, preferably 0.01 to 2 atoms of cobalt. The manganese salt used as a cocatalyst in the present invention is preferably in the form of an organic carboxylate or an inorganic mineral salt, and specific examples include manganese chloride, manganese bromide, manganese nitrate, manganese sulfate, manganese chloride, and acetic acid. Examples include manganese, manganese propionate, manganese oxalate, manganese malonate, manganese succinate, manganese benzoate, and the like.
The amount of cocatalyst used, when used, is preferably 0.01 to 0.5 manganese atoms per 1 atom of cobalt in the catalyst. Specific examples of the alkylamine or cyclic amidine as the reaction accelerator used in the present invention include:
Di-n-butylamine, tri-n-butylamine, diisobutylamine, 1,8-diaza-bicyclo[5,4,0]-7-undecene, 1,6-
Diaza-bicyclo[4,3,0]-5-nonene and the like can be mentioned. The preferred amount of this reaction accelerator, if used, is 0.5 to 5 mol per cobalt atom of the catalyst. The reaction is advantageously carried out in the presence of a solvent inert to the reaction, specific examples of which include dimethylformamide, methanol, ethanol, propanol, butanol, methyl acetate, ethyl acetate,
Dioxane, acetone, methyl ethyl ketone, acetonitrile, benzonitrile, pyridine and the like can be mentioned. Preferably dimethylformamide, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, dioxane, acetonitrile,
is used. The amount to be used is not particularly limited, but it is sufficient as long as the raw materials, catalyst, etc. to be used can be sufficiently stirred. The reaction temperature can be carried out within a wide range, but is usually -20 to 80℃, preferably -15 to 60℃.
It is ℃. The reaction pressure is not particularly limited, and can be carried out under reduced pressure to increased pressure, preferably from atmospheric pressure to about 10 kg/cm ² G. The molecular oxygen used in the present invention can be air, isolated oxygen, or oxygen diluted with a gas inert to the reaction, such as nitrogen or helium, to avoid explosive composition in the reaction system. The reaction time varies depending on the reaction conditions, but is usually about 5 minutes to 5 hours. In a normal room temperature reaction, the reaction is completed in about 1 hour. As a specific example of the reaction operation, for example, a benzophenone imine-benzophenone mixture and benzaldehyde in a dimethylformamide solvent, cobalt bromide as a catalyst, manganese bromide as a promoter, and 1,8-diaza-bicyclo as a reaction promoter. 5,4,0〕-
7-Undecene is dissolved or suspended and brought into contact with a gas containing molecular oxygen to cause a reaction. After extracting the reaction solution with an acidic aqueous solution to remove the catalyst, promoter, and cyclic amidine, benzophenone azine can be separated by distillation or recrystallization with methanol. The separated benzophenone azine is further hydrolyzed with a mineral acid such as sulfuric acid to form a hydrazine mineral salt, which is used industrially. The recovered benzophenone is recycled and used as a raw material for the synthesis of benzophenone imine. The catalyst, cocatalyst, cyclic amidine, and by-product carboxylic acid corresponding to the aldehyde used can be recovered by distillation, concentration, crystallization, etc., extracted and separated from the reaction solution with an acidic aqueous solution. The present invention can be carried out either batchwise or continuously. Next, the present invention will be explained with reference to examples, but the present invention is not limited to the embodiments shown in the examples. Example 1 A mixture of 1.0 g (5.5 mmol) of benzophenone imine and 1.05 g of benzophenone, cobalt bromide was placed in a 200 ml flask equipped with a thermometer and a stirrer.
0.06g (0.28mmol), benzaldehyde 9.55g
(90 mmol), solvent dimethylformamide 17.5
1 ml and kept at 15℃ in an oxygen stream while stirring.
Allowed time to react. Analysis of the reaction solution by gas chromatography revealed that benzophenone azine was 0.604
g (1.68 mmol) was produced. This corresponded to a yield of 61% based on the raw material benzophenone imine. Furthermore, it was confirmed that the infrared absorption spectrum of the benzophenone azine isolated from this reaction solution completely matched that of a separately synthesized standard benzophenone azine. Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that cobalt bromide was omitted, and as a result, no benzophenone azine was obtained. From the above, it is clear whether the cobalt salt has a catalytic effect or not. Example 2 In addition to Example 1, 0.043 g of 1,8-diaza-bicyclo[5,4,0]-7-undecene
(0.28 mmol) was added and reacted in the same manner.
As a result, 0.684 g (1.90 mmol) of benzophenone azine was obtained, which corresponded to a yield of 69% (based on benzophenone imine). Example 3 In addition to Example 1, 0.043 g of 1,8-diaza-bicyclo[5,4,0]-7-undecene
(0.28 mmol) and 0.005 g (0.028 mmol) of manganese bromide were added and reacted in the same manner. As a result, 0.742 g (2.06 mmol) of benzophenone azine was obtained, which corresponded to a yield of 75% (based on benzophenone imine). Examples 4 to 7 In place of the cobalt bromide in Example 2, the corresponding cobalt salts shown in Table 1 were used as catalysts, and the reactions were carried out in the same manner. The results are shown in Table-1.

[Table] Examples 8 to 12 The corresponding aldehydes shown in Table 2 were used in place of the benzaldehyde in Example 2, and the reaction temperature was 9°C.
The reaction was otherwise carried out in the same manner as in Example 2. The results are shown in Table-2.

[Table] Examples 13-15 1,8-diaza-bicyclo[5,
A similar reaction was carried out using the corresponding alkylamine or cyclic amidine shown in Table 3 instead of 4,0]-7-undecene. The results are shown in Table-3.

[Table] Example 16 In Example 2, only the reaction temperature was lowered to -10℃,
Others were reacted in the same manner. As a result, 0.544 g (1.51 mmol) of benzophenone azine was obtained.
This corresponded to a yield of 55% (based on benzophenone imine). Example 17 The reaction was carried out in the same manner as in Example 2 under an air stream instead of under an oxygen stream. As a result, 0.567 g (1.57 mmol) of benzophenone azine was obtained. This corresponded to a yield of 57% (based on benzophenone imine).

Claims (1)

[Claims] 1. Benzophenone imine and the general formula R-(CHO) _o [In the formula, n is an integer of 1 or 2, R is hydrogen, or an aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms] show. ]
A method for producing benzophenone azine, which comprises oxidizing an aldehyde represented by the following with molecular oxygen in the presence of a cobalt salt as a catalyst. 2. The method according to claim 1, wherein the aldehyde is formaldehyde, acetaldehyde, propanal, butanal, isobutyraldehyde, n-pentanal, benzaldehyde or phthalaldehyde. 3. The method according to claim 1, wherein the cobalt salt is a divalent or trivalent cobalt salt. 4 Cobalt salts include cobalt chloride, cobalt bromide,
4. The method according to claim 3, wherein cobalt formate, cobalt acetate, cobalt propionate, cobalt oxalate, cobalt malonate, cobalt succinate or cobalt benzoate.