KR100256441B1 - Method for nitration of aromatic compoud - Google Patents

Abstract

PURPOSE: A nitration reaction method of aromatic compound is provided for obtaining the aromatic compound in high yield by means of the nitration reaction of aromatic compound with no production of waste acid and/or other by-product and under the relatively moderate condition. CONSTITUTION: The method for nitration-reacting aromatic compound comprises introducing aromatic compound such as benzene, toluene or chlorobenzene into a reactor; adding nitrogen dioxide under the presence of less than 1 equivalent % of a catalyst such as inorganic or organic metal compounds containing Fe element based on the amount of the aromatic compound; supplying air and pressurizing the internal reactor in the range of 10-200psi to react for 30 minutes to 5 hours; filtering the reactant mixture to remove the metallic catalyst, adding water to the mixture to separate layers and discarding the aqueous layer containing the metal catalyst to obtain purified oil layer of the resultant material or crystallizing the reactant product from the oil layer.

Description

Method for nitration of aromatic compounds {Method for nitration of aromatic compoud}

The present invention relates to a method for nitrating aromatic compounds, and more particularly, to a method for nitrating aromatic compounds in high yield under mild reaction conditions without generation of waste acid.

Aromatic nitro compounds produced by the nitration process are widely used as products or intermediates in almost all fields of the chemical industry such as petrochemicals, pesticides, medicines, dyes, gunpowder, rubber and pharmaceuticals. One of the most important processes among the organic unit processes, and important petrochemical products that require a large nitration process include aniline, toluidine, MDI and TDI. Recently, the production of rapid nitrification-related products in the fine chemicals industry has been increasing by an annual average of more than 10% since 1990.

The nitration of most aromatic compounds to date has been carried out in a mixed acid process (Euler, H. Ann. Chem. 330, 280 (1903) consisting of concentrated nitric acid and dark sulfur phases. The generation of waste sulfuric acid is inevitable, and the amount of wastewater containing washing water introduced in the washing process is enormously estimated to be at least 300,000 tons per year based on the production of domestic nitration compounds. From the environmental point of view, there are problems such as corrosion of the facility due to the corrosion of the reactor due to the use of strong acid and deterioration of the working environment due to the handling of the strong acid. In developed countries, the new nitrification process has During the progress it has not yet developed a new process that can replace the nitration process by Horn algorithm.

Suzuki, a member of Kyoto University in Japan, has announced that the use of ozone as a gaseous nitrogen dioxide and an oxidizing agent allows the nitration reaction to proceed relatively easily in organic solvents (Suzuki H., et al. , Chem.Letters, 1421 (1993); Suzuki H., et al., JCS Chem.Commun., 1049 (1991); EP 0 497 989 A1, 1991). In addition, it has been found that the nitration reaction by ozone is more efficient (Korean Patent Application No. 95-32526; Bon-Su Lee et al., J. Korean Ind. & Eng. Chem 1.7 (3), 530 (1996) Bon-Su Lee et al., J. Korean Chem. Soc. 40 (6), 457 (1996)). These new nitration reactions have shown that they can significantly solve the problems that have arisen in conventional blending processes. However, ozone, which is used as an oxidizing agent in the nitration reaction, can only be obtained by silent discharge using high voltage on oxygen, and therefore, when the mass production is required, an expensive ozone generator and enormous amount of power are required. There were many difficult problems to do.

Accordingly, Suzuki Group has announced that nitration can be carried out using dichloroethane as a solvent and oxygen in the presence of Fe (acac) ₃ catalyst instead of ozone (Suzuki H., et al., JCS Perkin Trans. 1, 2358 (1996)), a new process that can replace the existing nitration process by requiring a long reaction time (12 to 36 hours) even with an excess of nitrogen dioxide (31 equiv) and a catalyst (10 mole%). There were still many problems to be solved. Moreover, this reaction reports that the reaction is rather slow when no separate solvent is used, and the use of the solvent not only causes the by-products but also increases the cost of nitration. There is a problem such as to be purified.

Therefore, there is still a need for development of a new nitration process of aromatic compounds.

It is an object of the present invention to provide a novel method for nitrating a non-acidic aromatic compound that does not use concentrated nitric acid, concentrated sulfuric acid, or a mixture thereof.

Another object of the present invention is to provide a method for nitrating a new non-acidic aromatic compound having excellent reactivity, simple separation and purification of products, and very stable reaction conditions.

In the nitration method of the aromatic compound according to the present invention for achieving the above object, the aromatic compound to be nitrated is introduced into the reactor, and nitrogen dioxide and oxygen are supplied in the presence of a metal catalyst containing an inorganic metal or an organometallic compound. And pressurizing.

The metal catalyst is preferably selected from transition metals such as iron (II, III), copper (I, II), or cobalt (II, III).

The metal catalyst may be used in a trace amount of 1 equivalent or less with respect to the aromatic compound to be nitrated.

The interior of the reactor is pressurized to 10 to 200 psi.

In particular, the inside of the reactor is pressurized by the supply of oxygen.

In addition, the inside of the reactor may be made in a solvent-free condition.

Preferably, in the nitration method of the aromatic compound according to the present invention, the aromatic compound to be nitrated is introduced into a reactor, pressurized while supplying oxygen after adding nitrogen dioxide in the presence of a metal catalyst containing an inorganic metal or an organometallic compound. The reaction was carried out for 30 minutes to 5 hours, and the reaction mixture was filtered to remove the metal catalyst, or by adding water to the reaction mixture, sufficient to separate the metal catalyst, thereby obtaining a reaction product of the pure oil layer, or from the oil layer. It consists of separating the reaction product by crystallization.

Hereinafter, the present invention will be described in detail with reference to specific examples.

The nitration method of an aromatic compound according to the present invention comprises adding an aromatic compound to be nitrated to a reactor, adding nitrogen dioxide in the presence of a metal catalyst containing an inorganic metal or an organometallic compound, and then pressurizing while supplying oxygen. do.

The reactor into which the aromatic compound to be nitrated is introduced may be a conventional high pressure reactor capable of maintaining a pressurized reaction condition pressurized above atmospheric pressure.

The metal catalyst is a catalyst containing an inorganic metal or an organometallic compound, and functions to activate oxygen in the reactor, particularly preferably iron (II, III,), copper (I, II), or cobalt (II, III) and the like selected from transition metals can be used.

The metal catalyst may be used in an amount of 1 equivalent or less based on the aromatic compound to be nitrated.

The inside of the reactor may be pressurized to 10 to 200 psi, it can be understood that it is obvious to those skilled in the art that the reaction time can be adjusted appropriately according to the pressure.

In particular, the inside of the reactor can be pressurized by the supply of oxygen, by the activation of the pressurized oxygen to change the non-reactive nitrogen dioxide into a reactive active species to directly participate in the nitration of the aromatic compound It is believed to be.

In addition, the inside of the reactor may be made in a solvent-free condition, in the solvent-free condition, the aromatic compound to be nitrated may function as a reactant and a solvent. Solvent-free conditions can be considered to prevent the generation of by-products and purification of the reaction product, in the present invention it is possible to obtain the desired nitrated aromatic compound in a sufficiently high yield even in the solvent-free conditions.

Preferably, in the nitration method of the aromatic compound according to the present invention, the aromatic compound to be nitrated is introduced into a reactor, pressurized while supplying oxygen after adding nitrogen dioxide in the presence of a metal catalyst containing an inorganic metal or an organometallic compound. The reaction mixture was filtered for 30 minutes to 5 hours, and then the reaction mixture was filtered to remove the metal catalyst, and water was added to the sufficient amount to separate and remove the water layer together with the metal catalyst to obtain a pure oil reaction product or the oil layer. It consists of separating the reaction product by crystallization.

Separating the reaction mixture into the water layer and the oil layer by adding water to the reaction mixture from which the metal catalyst has been removed is to remove nitric acid as a by-product included in the reaction mixture. The solution is added to water to separate the aqueous layer and dissolved in the water layer. It can effectively remove the nitric acid.

In the separation of the aqueous layer, water is added to the reaction mixture and left to separate the aqueous layer from the oil layer.In the case of separation funnel or other mass production, the water layer located in the lower part of the aqueous layer and oil layer through a separate separation facility equipped with a valve. It can be separated and removed, it is apparent that such a separation process is also very easily understood by those skilled in the art.

In addition, the separation of the reaction product can be carried out through conventional crystallization, it will be understood that such crystallization can be carried out by a variety of conventional known crystallization methods such as salting method and the like.

The nitration method of the aromatic compound according to the present invention having the above-described configuration activates the pressurized oxygen with a metal catalyst so that the activated oxygen species oxidizes nitrogen dioxide to make reactive nitronium ions. It is believed that the reaction proceeds with this direct aromatic compound to nitrate the mechanism. In particular, it is believed that oxygen pressurized at 10 to 200 psi may promote the activation of oxygen by increasing the solubility in the reaction mixture to allow sufficient contact with the metal catalyst introduced to activate the oxygen. Oxygen can be considered to be able to oxidize more nitrogen dioxide to form large amounts of nitronium ions, thus promoting the nitration reaction.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 3 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 100%.

Example 2

0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 1 hour. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 72%.

Example 3

0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 1.5 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 100%.

Example 4

0.1 mol benzene and 0.001 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 1.5 hours. After the reaction was analyzed by gas chromatography it was confirmed that the mononitrobenzene in a yield of 50%.

Example 5

0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 40 psi and then reacted for 3 hours. After the reaction was analyzed by gas chromatography to confirm that the mononitrobenzene in 75% yield.

Example 6

0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 60 psi and reacted for 1.5 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 100%.

Example 7

0.1 mol benzene and 0.005 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 60 psi and reacted for 1.5 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 91%.

Example 8

0.1 mol benzene and 0.01 mol FeCl ₃ were added as a metal catalyst in a high pressure reactor followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 60 psi and reacted for 1.5 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 100%.

Example 9

0.1 mol benzene and 0.01 mol FeCl ₃ were added as a metal catalyst in a high pressure reactor followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 60 psi and reacted for 1.5 hours. After the reaction, the result of gas chromatography analysis showed that mononitrobenzene was obtained in a yield of 100%.

Example 10

In a high pressure reactor, 0.1 mol chlorobenzene as a solvent and 0.01 mol Fe (acac) ₃ as a metal catalyst were added, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 3 hours. After the reaction, the result of gas chromatography analysis showed that mononitrochlorobenzene was obtained in a yield of 70%.

Example 11

0.1 mol toluene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst in a high pressure reactor, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 3 hours. After the reaction, the result of gas chromatography analysis showed that mononitrotoluene was obtained in a yield of 92%.

Comparative Example 1

In a high pressure reactor, 70 ml of dichloroethane was added as a solvent, 0.1 mol benzene and 0.01 mol Fe (acac) ₃ were added as a metal catalyst, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 3 hours. After the reaction, gas chromatography analysis showed that 5-10% of mononitrobenzene was detected.

Comparative Example 2

70 ml of dichloroethane was added as a solvent in a high pressure reactor, 0.1 mol benzene was added, followed by 0.25 mol of liquid nitrogen dioxide. Oxygen was injected at 80 psi and reacted for 3 hours. As a result of gas chromatography analysis, it was confirmed that mononitrobenzene was not detected, and the reaction did not proceed.

As a result of the synthesis of the above embodiments, the use of a metal catalyst activates oxygen to oxidize nitrogen dioxide to form highly reactive nitronium ions, which can be directly reacted with an aromatic compound to nitrate. In particular, it was confirmed that the reaction time can be adjusted according to the degree of pressurization of oxygen, and that pure aromatic nitration compounds can be obtained with very high yield even in solvent-free conditions.

In the above examples, only the nitration method of benzene, toluene and chlorobenzene is illustrated, but it will be apparent to those skilled in the art that the same method can be applied to all aromatic compounds.

Therefore, according to the present invention, the aromatic compound is purely nitrated under very mild conditions without generation of waste acid and very high yield and without generation of by-products, thereby obtaining the desired aromatic nitration compound.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and variations belong to the appended claims. .

Claims (5)

It is composed of adding an aromatic compound to be nitrated into a reactor, adding nitrogen dioxide in the presence of an inorganic metal compound or an organometallic compound including iron (Fe) as a catalyst, and then pressurizing it in the range of 10 to 200 psi while supplying oxygen. A nitration method of an aromatic compound, characterized in that. The method of claim 1, The catalyst is used in the nitration of the aromatic compound, characterized in that less than 1 equivalent% to the aromatic compound to be nitrated. The method of claim 1, The interior of the reactor is pressurized by the supply of oxygen, characterized in that the nitration of the aromatic compound. The method of claim 1, The inside of the reactor is a nitration method of the aromatic compound, characterized in that the solvent-free conditions. The aromatic compound to be nitrated was added to the reactor, nitrogen dioxide was added in the presence of an inorganic metal compound or an organic metal compound containing iron (Fe) as a catalyst, and then pressurized in the range of 10 to 200 psi while supplying oxygen for 30 minutes. After the reaction for 5 hours, the reaction mixture is filtered to remove the metal catalyst, or the reaction mixture containing the metal catalyst is separated by layer separation by adding water to the reaction mixture of the pure oil layer by removing and removing the aqueous layer together with the metal catalyst. A method of nitrating an aromatic compound, characterized in that it is obtained by crystallizing or separating the reaction product from the oil layer.