KR20020095771A - Process for the preparation of benzidine compound - Google Patents

Abstract

PURPOSE: A method for preparing a benzidine compound is provided to obtain a benzidine compound from a nitrobenzene compound in a single solvent continuously through processes, for improving the production yield. CONSTITUTION: The method comprises the steps of mixing sodium hydroxide, 2,3-dichloro-1,4-naphthoquinone, a surfactant, a nitrobenzene compound (a), toluene and a platinum catalyst; reacting the mixture with injecting nitrogen gas; making vacuous; supplying hydrogen gas to proceed the hydrogen reductive reaction to prepare a hydrazobenzene compound (b); filtering the solution to recover the catalyst; and adding a HCl solution the remaining solution to proceed the displacement reaction to obtain the benzidine compound (c). In the reaction formula 1, R is H, methyl group, methoxy group or Cl. The surfactant is sodium dodecyl benzene sulfonate. Preferably the reduction is carried out at 80-90 deg.C.

Description

The manufacturing method of the benzidine compound {PROCESS FOR THE PREPARATION OF BENZIDINE COMPOUND}

The present invention relates to a method for preparing a benzidine compound from a nitro benzene compound, and in particular, a hydrogenation reduction reaction is performed on the nitro benzene compound under a platinum catalyst (Pt / C) to produce a hydrazo benzene compound, and subsequently the hydra It relates to a process for producing a benzidine compound by carrying out a potential reaction with respect to the crude bansene compound.

Benzidine compounds have excellent mechanical properties and thermal stability, and have been applied to various fields such as materials for forming protective films of semiconductor devices. Among them, 3, 3'-dichlorobenzidine dihydrochloride (3, 3'-dichlorobenzidine dihydrochloride) is the most important economic material of all diphenyl base, both the free base and salt of the material for the synthesis of the dye Widely used as starting material.

Due to the economic importance of these materials, a number of methods for preparing benzidine compounds have been proposed. However, conventionally, the method for preparing the benzidine compound comprises synthesizing a hydrazo benzene compound through a reduction reaction of nitro benzene and preparing a benzidine compound by continuously conducting a potential reaction with respect to the hydrazo benzene compound. In particular, a key part of the manufacturing method is a step of proceeding with a reduction reaction with nitrobenzene to the hydrazo benzene compound, and the yield and economic efficiency of the entire manufacturing process according to the yield and economic efficiency of the reduction step. This will depend.

For this reason, many methods for improving the yield and economics of the reduction reaction and preventing generation of contaminants have been proposed. Among these, the zinc powder method is a method in which a sodium hydroxide aqueous solution of a nitro benzene compound is added and stirred while warming, and a small amount of zinc powder is added thereto over a long period of time, followed by reaction while introducing water. After the reduction reaction is carried out in this manner, dilute hydrochloric acid is added to the reaction product hydrazo benzene compound and replaced with benzidine over a period of about 2 days at a temperature of room temperature or less. In the dislocation termination step, sodium sulfate is added to remove heavy metals, and rock salt is added to precipitate benzidine hydrochloride compound to obtain a final product.

However, since the process proceeds separately with the reduction reaction of azo benzene and the translocation process of hydrazo benzene, the process is complicated and requires a long reaction time, and in particular, the use of pollution by heavy metal wastewater and expensive zinc powder is large. It is a problem.

Since the diatom iron method, which is a different method from the zinc powder, is expensive, another method developed to replace the zinc powder method, in which the benzene, diatom iron powder, calcium hydroxide, and sodium hydroxide aqueous solution are mixed, The crystals of hydrazo benzene are separated by reacting with extremely vigorous agitation. This also requires an extremely fast stirring speed, requiring an expensive mechanical device and a difficult operation and color problem.

In addition, one of the conventional methods, the metanol method (also known as the Allied Chemical method) is a method of reducing and preparing a hydrazo compound from a nitro compound by heating and refluxing with methanol and sodium hydroxide using 1,4-nitroquinone as a reducing accelerator. The yield is low and by using methanol, there is a risk of explosion and fire.

Due to the problems of the conventional manufacturing method, a method for producing a benzidine compound has been continuously studied, and Korean Patent No. 1850 has proposed a benzidine production method using a noble metal catalyst.

Specifically, in the nitrogen gas stream, 2, 3-dichloro-1, 4-naphthoquinone (2, 3-dichloro-1, 4-naphtoquinone) and a surfactant were mixed and stirred for 1 hour. Then, nitrobenzene was added at a temperature elevated state and stirred for about 2 hours, an organic solvent was injected therein to completely dissolve the nitrobenzene, and then a noble metal catalyst was added to the resultant and stirred for 3 hours again, followed by nitrogen gas. After the reaction was stirred for 1 hour, the nitrogen gas was completely exhausted, and then the hydrogen gas was continuously injected until the reduction reaction was completed. After the reduction reaction is completed, water is injected to cool the temperature below room temperature, and then the hydrazo benzene produced through the reduction reaction is filtered off.

Since the organic solvent remains in the filtrate remaining after the filtration, the filtrate is separated from the aqueous layer and then used again. The separated hydrazo benzene was added to the mixed solution of dilute hydrochloric acid, surfactant, and ice at 10 ° C. or lower, stepwise at 20 ° C. or below for 20 hours, 5 ° C. or below for 5 hours, 5 hour or less for 30 ° C., or 40 ° C. or less. After stirring for 3 hours, the benzidine compound is obtained by dissolving it, followed by infusing water to complete dissolution, followed by filtration to separate the catalyst, adding activated carbon to the filtrate, discoloring and salting to precipitate the benzidine compound.

However, this method also requires several steps in the preparation step and the reduction reaction for the reduction reaction, and the raw material mixing and preparation process for the reduction reaction takes about 7 hours, thereby reducing the economic efficiency of the entire process. In addition, in the above method, after the completion of the reduction reaction, the hydrazo benzene compound is separated and then the potential reaction process is carried out again. Thus, the reduction reaction process and the potential reaction process of the hydrazo benzene compound are completely performed. It is a fact that there has been a problem in that the entire reaction process is complicated and takes a long time to proceed separately.

For this reason, there is an urgent need for a method capable of producing the benzidine compound in a process which solves the problems of the conventional manufacturing method and is simpler and requires less time.

Accordingly, an object of the present invention is to solve the problems of the conventional manufacturing method as described above, through a simple process that can be performed in a short time, can proceed with the reduction reaction of nitro benzene, single reduction reaction process and potential reaction process Process for producing benzidine compounds which can proceed continuously under solvent, which can improve the yield and economics of the entire manufacturing process, minimize the waste of the reactants and the generation of contaminants, and at the same time obtain the product in high yield To provide.

In order to achieve the above object, the present invention is caustic soda, 2, 3-dichloro-1, 4-naphthoquinone (2, 3-dichloro-1, 4-naphtoquinone), surfactant, nitrobenzene compound (a ), Toluene and platinum catalyst (Pt / C) are mixed, and then reacted by injecting nitrogen gas, followed by a hydrogen reduction reaction by producing a vacuum state and supplying hydrogen gas to produce a hydrazobenzene compound (b). step;

Recovering the catalyst by filtering the reducing solution that has undergone the reduction reaction;

Provided is a method for preparing the benzidine compound (c) represented by the following formula (1), characterized in that the step of recovering the catalyst and adding a hydrochloric acid solution to the remaining product, the reaction proceeds.

(Formula 1)

In the formula, R represents hydrogen, methyl group, methoxy group or chlorine.

The method for producing the benzidine compound according to the present invention can proceed with the reduction reaction through a simple process requiring less time than the conventional manufacturing method, it is possible to improve the economics and yield of the manufacturing process, the hydra after the reduction reaction It is possible to continue the dislocation reaction while the crude benzene compound is dissolved in the solvent, thereby shortening the process to bring about productivity improvement, and minimizing the catalyst poison that may occur in the dislocation process by recovering the catalyst after the reduction process is completed. As a result, the reuse of the catalyst can be greatly increased.

Hereinafter, a method for preparing the benzidine compound according to the present invention will be described in detail.

First, caustic soda, 2, 3-dichloro-1, 4-naphthoquinone, surfactant, nitro benzene compound, toluene and platinum catalyst (Pt / C) were mixed, nitrogen gas was injected and stirred for about 30 minutes. After that, it is vacuumed and hydrogen gas is injected until the reduction reaction is completed. The resultant is then heated to 50-60 ° C. and the catalyst is filtered off. Next, MNX was added to the resultant after the completion of the above steps, and after cooling to 15 ° C. or lower, hydrochloric acid (22%) was added, 9 hours at 15 ° C. or lower, 9 hours at 20 to 30 ° C., 30 to 60 ° C. Stirring at 2 ° C. for 2 hours and 4 hours at 60 ± 1 ° C., followed by a dislocation reaction to produce a benzidine compound, and toluene is separated and purified from the resultant using a dissolution separation apparatus when the dislocation process is completed. As such, the separated and purified toluene solvent can be recycled in the benzidine production process.

Thereafter, hydrochloric acid and saturated brine are added to the filtrate from which toluene is separated, followed by salting to precipitate and purify the benzidine compound produced in the resultant product. By proceeding with this process, it is possible to increase the purity of the benzidine compound and to obtain particles of a desired size, thereby increasing the merchandise value of the final product. Finally, by treating the benzidine compound with the remaining waste liquid using caustic soda, secondary generation of contaminants can be prevented.

In the production method according to the present invention as described above, the temperature in the reactor in which the reduction reaction proceeds is preferably 80 to 90 ℃, the pressure of the hydrogen gas supplied for the reduction reaction in the reactor is It is preferred to be 1 to 3 kg / cm ² . In addition, although the general surfactant can be used as the surfactant, it is preferable to use sodium dodecyl benzene sulfonate.

In the production method according to the present invention, toluene is used as the surfactant and the container solvent to increase the dispersibility in the solvent when the reactant is dissolved so as to cause a uniform reaction and to increase the reaction contact area. will be. In addition, the 2, 3-dichloro-1, 4-naphtho quinone will act as a reduction promoter.

Hereinafter, a preferred embodiment of the present invention will be described in detail. However, the scope of the present invention is not limited thereto, which is presented by reference only.

Example 1 Preparation of 3, 3'-Dichlorobenzidine Dihydrochloride (DCB)

176 kg of caustic soda (50%), 6 kg of 2, 3-dichloro-1, 4-naphthoquinone, 6 kg of sodium dodecyl benzene sulfonate, 1000 kg of o-nitrochlorobenzene, 900 kg of toluene, platinum catalyst (Pt / C ) 1.65kg and 480kg of water are added, and after mixing them, nitrogen gas is injected into the reduction tank and stirred for about 30 minutes. Thereafter, the inside of the reducing tank is vacuumed, and hydrogen gas is injected at a pressure of 1 to 3 kg / cm ² until the reduction reaction is completed at a temperature of 85 ° C., and then a hydrogen reduction reaction is performed to carry out 2, 2′- in the solution. Produces dichloro hydrazobenzene (2, 2'-dichloro-hydrazobenznen). The resultant is then heated to 50-60 ° C. and the catalyst is filtered off.

Next, 2 kg of MNX was added to the resultant after the completion of the above steps, and after cooling it to 15 ° C. or less, 5800 kg of hydrochloric acid (22%) was added, 9 hours or less at 15 ° C. or less, 9 hours or 20 to 30 ° C. or 30 ° C. To 2 hours at 60 ° C, 4 hours at 60 ± 1 ° C, followed by a dislocation reaction to produce 3, 3'-dichlorobenzidine dihydrochloride of the following Chemical Formula 2, and dissolution separation apparatus when the dislocation process is completed Toluene is separated and purified from the resultant. As such, the isolated, purified toluene solvent can be recycled in the subsequent process for the preparation of 3, 3'-dichlorobenzidine dihydrochloride.

Thereafter, hydrochloric acid and saturated brine are added to the filtrate from which the toluene is separated, followed by salting, to thereby precipitate and purify the 3,3'-dichlorobenzidine dihydrochloride produced in the resultant. By proceeding with this process it is possible to increase the purity of the product, to obtain particles of a desired size, thereby increasing the product value of the final product. Finally, by purifying the 3, 3'-dichlorobenzidine dihydrochloride and the remaining waste liquid by using a caustic soda, it is possible to prevent the generation of contaminants. The yield here was 92%.

(Formula 2)

However, only 3, 3'-dichlorobenzidine dihydrochloride can be prepared by the method according to the present invention, and other nitrobenzene compounds such as nitro benzene, o-nitrotoluene and o-nitro anisole are used as reactants. Various benzidine compounds can be prepared.

As described above, the production method according to the present invention requires little time, and can proceed with the reduction process of the nitro benzene compound through a simple process to improve the yield and economics of the benzidine compound production process, and through the reduction process Since the process of dislocation can be carried out continuously in the same solvent without separating the produced hydrazo benzene compound, the entire process can be shortened, and the catalyst can be separated and reused after the reduction process is completed, which can occur during the dislocation process. It is possible to prevent catalyst poisoning and maximize the reuse efficiency of the catalyst.

Claims (6)

Caustic soda, 2, 3-dichloro-1, 4-naphthoquinone (2, 3-dichloro-1, 4-naphtoquinone), surfactant, nitrobenzene compound (a), toluene and platinum catalyst (Pt / C) After mixing, reacting by injecting nitrogen gas, and then proceeding with a hydrogen reduction reaction by making a vacuum and supplying hydrogen gas to produce a hydrazo benzene compound (b); Recovering the catalyst by filtering the reducing solution that has undergone the reduction reaction; Recovering the catalyst and adding a hydrochloric acid solution to the remaining product, the method for producing a benzidine compound (c) represented by the following formula (1), characterized in that the potential reaction. (Formula 1) In the formula, R represents hydrogen, methyl group, methoxy group or chlorine. The method according to claim 1, wherein the surfactant is sodium dodecyl benzene sulfonate. The method of claim 1, wherein the reduction reaction is a method for producing a benzidine compound, characterized in that at a temperature of 80 to 90 ℃. The method for producing a benzidine compound according to claim 1, wherein the hydrogen reduction reaction proceeds by supplying hydrogen gas at a pressure of 1 to 3 kg / m ² . The method for preparing a benzidine compound according to claim 1, further comprising the step of separating and purifying toluene after the translocation reaction. The method for preparing a benzidine compound according to claim 5, further comprising, after the separation and purification step of toluene, adding hydrochloric acid and saturated brine to the resultant of the step, and performing salting out. .