JPH0796533B2 - Method for producing aromatic nitro compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a process for producing an aromatic nitro compound,
More specifically, an aromatic nitro compound characterized by nitrating benzene or a benzene derivative in the liquid phase using an aqueous solution of nitric acid in the presence of a crystalline aluminosilicate-containing catalyst having a silica / alumina molar ratio of at least 20. It relates to the manufacturing method of.

(Prior Art) Aromatic nitro compounds are intermediates of useful organic chemicals used as raw materials for aromatic amino compounds. The industrial production method of aromatic nitro compounds is carried out using a mixed acid which is a mixture of nitric acid and concentrated sulfuric acid, but since a large amount of sulfuric acid is used, there are problems such as waste sulfuric acid and wastewater treatment. On the other hand, a gas phase nitration method has been proposed as a method that does not generate waste sulfuric acid. For example, in JP-A-50-121234, there is disclosed a method of vapor-phase nitration of halobenzene using silica-alumina or aluminosilicate as a catalyst, and in JP-A-54-95521, a method of about 5-10 liters is disclosed. In the presence of a molecular sieve catalyst having a pore size, a method of gas phase nitration of chlorobenzene, JP-A-58-157748, JP-A-59-216851,
A method for vapor-phase nitration of aromatic compounds using aluminosilicate zeolite as a catalyst is disclosed.

(Problems to be Solved by the Invention) Although the known gas-phase nitration method leads to solving the problem of the treatment of waste sulfuric acid, etc. The yield of the nitro compound is relatively low and not at a satisfactory level. In addition, there is a problem that thermal decomposition of the nitrating agent occurs due to a relatively high temperature condition in the gas phase, the efficiency of the nitrating agent becomes low, and the generated nitric oxide gas is harmful and requires waste gas treatment. Have

The gas-phase nitration reaction is presumed to be according to the following equation as the reaction equation described in Industry and Engineering Chemistry, June, 1936 , p.662, etc.

Moreover, even if nitric acid is used as a nitrating agent, nitric acid decomposes to nitric oxide in the gas phase according to the following formula, and hydrated nitric acid is more stable. And Theoretical Chemistry "8
Vol., Page 572.

4HNO ₃ → 4NO ₂ + 2H ₂ O + O ₂ (2) Therefore, in the gas phase nitration reaction, the production of nitric oxide gas is essentially unavoidable.

The generation of oxygen and nitric oxide may cause side reactions other than the nitration reaction.

(Means for Solving Problems) As a result of intensive studies on the nitration method of an aromatic compound capable of obtaining a high yield at a relatively low temperature, the present inventors have found that benzene or a benzene derivative is treated with silica. It has been found that the object can be achieved by nitrating in the liquid phase with an aqueous nitric acid solution using a crystalline aluminosilicate having a / alumina molar ratio of at least 20 as a catalyst. That is, by using an aqueous solution of nitric acid as a nitrating agent and reacting in a liquid phase, it is possible to suppress the generation of harmful gases such as nitric oxide, and the above-mentioned catalyst has a high activity in a liquid phase reaction at a relatively low temperature. It has been found to have.

The method of the present invention also has a feature that byproducts such as dinitro compounds are scarcely produced as compared with conventionally known nitration methods. Further, it also has a feature such that a useful para-substituted product can be obtained with a high selectivity in the distribution of isomers of the ortho-form, meta-form, and para-form produced in nitration such as monohalobenzene.

In the present invention, benzene and a benzene derivative are used as the aromatic compound. As the benzene derivative, alkylbenzene such as toluene and ethylenebenzene, monochlorobenzene, dichlorobenzene, monobromobenzene, dibromobenzene, monoiodinated benzene,
Halogenated benzenes such as diiodinated benzene can be exemplified. These aromatic compounds are used for the reaction in a liquid phase state.

The nitrating agent used in the present invention is an aqueous nitric acid solution, and the nitric acid concentration is 10 to 98%, preferably 30 to 90%.
If the nitric acid concentration is too low, the reaction rate will be low, and if it exceeds 98%,
NO generation of _X occurs, decreases the efficiency of nitrating agent.

The nitric acid is used in an amount of 0.1 to 10 mol, preferably 0.2 to 3.0 mol, per 1 mol of benzene or a benzene derivative.

The reaction temperature varies depending on the benzene or benzene derivative used, but is usually 50 to 150 ° C, preferably 6
0-120 ° C is used.

The reaction pressure is usually normal pressure, but it may be increased to maintain the reaction system in the liquid phase.

The crystalline aluminosilicate used in the present invention has a silica / alumina molar ratio of at least 20 and preferably 30 or more, and in particular, those having an intermediate pore diameter of about 5 to 6.5Å are conveniently used. Examples of these crystalline aluminosilicates are ZSM-5, ZSM-11, ZS.
Examples thereof include M-12, ZSM-23, ZSM-34, high silica mordenite, dealuminated and stabilized Y zeolite, and AZ-1 type zeolite (started in JP-A-59-128210). In particular, ZSM-5 type has high activity and high selectivity of para-substituted compounds useful in nitration of monohalobenzenes,
It can be conveniently used. These crystalline aluminosilicates are usually used in a proton exchange type, but those exchanged with a polyvalent cation can also be used.

The catalysts can be used in a suspension state or a fixed bed system such as those used in ordinary liquid phase reactions. In the case of the distribution system, the amount of catalyst used is based on the total standard of benzene or benzene derivative and nitric acid.
A weight hourly space velocity (WHSV) of 0.1-20 hr ^-1 is used. When used in a suspended state, it is 5 to 50%, preferably 10 to 30% based on the total weight of benzene or a benzene derivative and nitric acid.
% Catalyst is used.

(Effects of the Invention) According to the method of the present invention, nitration of benzene or a benzene derivative can be carried out at a relatively low temperature and at a high space-time yield, and the treatment of waste sulfuric acid and harmful effects of NO _{X and the} like can be achieved. No gas treatment is required, and its industrial advantage is extremely large. Further, there is almost no formation of a dinitro compound which is difficult to handle as a by-product, and there is an advantage in separation operation.
In addition, it has an advantage that the selectivity of para isomers useful as a heat-resistant polymer raw material can be increased in nitration of monohalobenzene and the like.

(Examples) Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

It was prepared in Example 1 known methods connexion H-type _{ZSM-5 (SiO 2 / Al} 2 O 3 = 46)
Was prepared and subjected to the reaction.

Chlorobenzene 6.8g, 61% nitric acid 12.5g and H type ZSM-5
4 g of the powder was placed in a glass 50 ml flask equipped with a stirrer, heated to 90 ° C. under stirring and reacted for 2 hours. After cooling, the organic layer was taken out and analyzed using a gas chromatograph. As a result, the yield of nitrochlorobenzene is
At 45 mol%, the isomer ratio of nitrochlorobenzene was ortho isomer: meta isomer: para isomer = 19: 1: 80. No formation of dinitro body was observed.

Example 2 The nitration reaction of chlorobenzene was carried out in the same manner as in Example 1 except that the reaction temperature was 80 ° C. As a result, the yield of nitrochlorobenzene was 30 mol%, and the ortho-form: meta-form: para-form = 19.7: 0.8: 79.5. No formation of dinitro body was observed.

Example 3 Using a 100 ml autoclave made of SUS lined with Teflon, 17 g of chlorobenzene, 30 g of 61% nitric acid and the above H-type ZSM-
Charge 5 10 g, heat with nitrogen pressure 2 kg / cm ³ , stirring, 12
The reaction was carried out at 0 ° C for 2 hours. As a result, the yield of nitrochlorobenzene was 65.9 mol%, and the ortho-form: meta-form: para-form = 17.5: 0.5: 82.0.

Example 4 As in Example 1, except that the nitric acid content was 6.2 g and the H-type ZSM-
The amount was adjusted to 2 g and the reaction was carried out at a reaction temperature of 80 ° C. for 2 hours.
As a result, the yield of nitrochlorobenzene was 14 mol%,
The isomer ratio was ortho isomer: meta isomer: para isomer = 19: 0: 81.

Example 5 H-type ZSM-5 having SiO ₂ / Al ₂ O ₃ = 90 was prepared by a known method and used in the reaction. Chlorobenzene 6.4g, 50% nitric acid 10g
And 2 g of H-type ZSM-5 at 90 ° C. in the same manner as in Example 1.
I made a time reaction. As a result, the yield of nitrochlorobenzene was 21.6 mol%, and the ortho form: meta form: para form = 8:
It was at 0:82. No formation of dinitro body was observed.

Example 6 By the same method as in Example 1, benzene 5 g, 61% nitric acid 12.5 g
The same H type ZSM-5 (4 g) used in Example 5 was used and the reaction was carried out at 75 ° C. for 2 hours. As a result, the yield of nitrobenzene was 34 mol%, and byproducts such as dinitro compounds were not found.

Example 7 The nitration reaction was performed in the same manner as in Example 1 except that 9 g of bromobenzene was used instead of chlorobenzene. As a result, the yield of nitrobromobenzene was 24.8 mol%, and the ortho isomer: meta isomer: para isomer = 14.3: 0.3: 85.4. The formation of 0.3 mol% of dibromobenzene was observed, but the formation of dinitro body was not observed.

Example 8 The same H type as used in Example 1 for a quartz reaction tube (10 mmφ)
ZSM-5 was compression molded and crushed into 10 to 20 meshes,
Fill g and heat to 90 ℃, chlorobenzene 4.2cc / Hr, 61
% Nitric acid 1.8 cc / Hr was simultaneously supplied to carry out the reaction. The analysis result of the reaction effluent (organic phase) at 6 hours after the passing was that the yield of nitrochlorobenzene was 17 mol% and the ortho body: meta body: para body = 16: 0: 84, and the formation of dinitro body Was never seen. Moreover, generation of NO _X gas was not observed during the reaction.

Example 9 The procedure of Example 2 was repeated, except that a commercially available high-silica mordenite (SiO ₂ / Al ₂ O ₃ = 22) was used as the H type in the catalyst by a known method. As a result, the ortho form: meta form: para form = 39.2: 0.2: 60 with a yield of nitrochlorobenzene of 25 mol%.
It was 6.

Example 10 Using a commercially available dealuminated Y-type zeolite (SiO ₂ / Al ₂ O ₃ ≈100) as a catalyst, nitration reaction of chlorobenzene was carried out at 85 ° C. for 2 hours in the same manner as in Example 1. As a result, the yield of nitrochlorobenzene was 24 mol%, and the ortho isomer: meta isomer: para isomer = 30: 0: 70.

Example 11 Similar to Example 8, except that the same catalyst as used in Example 5 was molded and used as a catalyst, and chlorobenzene 4.2 cc / H was used.
The reaction was carried out by supplying r and nitric acid 0.9 cc / Hr. The analysis result of the reaction effluent (organic phase) at the 6th hour after passing the solution was that the yield of nitrochlorobenzene was 9 mol%, and the ortho body: meta body: para body = 13.8: 0: 86.2, and the dinitro body was not produced. I couldn't see it. Moreover, generation of NO _X gas was not observed during the reaction.

Comparative Example 1 Same as Example 1, except that the reaction was performed without using a catalyst, and as a result, the conversion rate of chlorobenzene was 7%, and the isomer ratio of nitrochlorobenzene was the ortho body: meta body: para body = 41.5. It was: 0.1: 58.4.

Comparative Example 2 As in Example 1, except that commercially available silica.
The nitration reaction of chlorobenzene was carried out using 4 g of powdered alumina (Al ₂ O ₃ content 13% by weight) in a mortar. As a result, the yield of nitrochlorobenzene was 8%,
Ortho body: meta body: para body = 40: 0: 60.

Claims (2)

[Claims] 1. Benzene or benzene derivative is silica /
A process for producing an aromatic nitro compound, which comprises nitrating in a liquid phase with an aqueous nitric acid solution in the presence of a crystalline aluminosilicate-containing catalyst having an alumina molar ratio of at least 20. 2. The method according to claim 1, wherein the crystalline aluminosilicate has an effective pore size of 5 to 6.5Å.