Preparation method of 1, 2-bis (2-chlorphenyl) hydrazine

Abstract

The invention relates to a preparation method of 1, 2-bis (2-chlorphenyl) hydrazine. The preparation method comprises the following steps: weighing raw materials including o-nitrochlorobenzene, dioxane and a copper-zinc catalyst; the method comprises the following steps: adding a cylindrical granulation copper-zinc catalyst into a fixed bed reactor, and feeding o-nitrochlorobenzene and dioxane into a fixed bed through a material pump; hydrogen is introduced into the fixed bed reactor, the hydrogen pressure is 1 MPa, and the temperature is increased to 70-100 DEG C for a reaction; and cooling after the reaction to obtain the product 1, 2-bis (2-chlorphenyl) hydrazine. The method has the advantages that the o-nitrochlorobenzene is used as the raw material, under the catalytic action of the copper-zinc catalyst, the fixed bed hydrogenation reaction is performed to obtain the 1, 2-bis (2-chlorphenyl) hydrazine, and the catalyst which is relatively cheap and simple in preparation process is adopted for performing the catalytic reaction, so that the production cost is reduced, and the method is more suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing 1,2-di(2-chlorophenyl)hydrazine. Background Art

[0002] 1,2-Di(2-chlorophenyl)hydrazine is an intermediate for the synthesis of 3,3'-dichlorobenzidine hydrochloride (DCB). Organic dyes based on DCB account for about 25% of the total organic dyes. Because of its strong coloring ability, solvent resistance, good stability, strong antioxidant ability, bright luster and high temperature resistance, it is widely used in printing, ink, paint, and also in the coloring of fibers, rubber, coatings and plastics. In addition, it has a low price, high added value and easy access to raw materials, so it has broad development prospects.

[0003] The main idea for the early synthesis of 1,2-bis(2-chlorophenyl)hydrazine was chemical reduction, that is, the preparation was carried out by reduction reaction by adding various catalysts under certain conditions. Commonly used reduction methods include zinc powder, sodium hydrosulfide method, formaldehyde method, formic acid method and hydrazine hydrate method. These industrial synthesis methods are relatively mature, simple to operate and low in cost. However, the problems are large amount of three wastes, high labor intensity, serious environmental pollution, difficult to handle by-product zinc oxide, and low yield.

[0004] In recent years, 1,2-di(2-chlorophenyl)hydrazine is mainly obtained by catalytic hydrogenation reduction of o-nitrochlorobenzene. The main advantages of the hydrogenation method are easy control of reaction conditions, high yield and less pollution. However, the prior art usually uses precious metal catalysts and catalysts with high activity and complex preparation process, which have high production costs. Therefore, the catalytic reaction using cheap and easily recyclable catalysts is the development direction. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing 1,2-di(2-chlorophenyl)hydrazine, which can solve the problem that the catalyst used in the catalytic hydrogenation reduction reaction to prepare 1,2-di(2-chlorophenyl)hydrazine in the prior art is a noble metal catalyst and a catalyst with high activity and complex preparation process and high production cost.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: comprising the following steps: S1. Weigh the raw materials o-nitrochlorobenzene, dioxane and copper-zinc catalyst; S2, adding a cylindrical granulated copper-zinc catalyst into a fixed bed reactor, and sending o-nitrochlorobenzene and dioxane into the fixed bed through a material pump; S3, hydrogen is introduced into the fixed bed reactor, the hydrogen pressure is 1MPa, the temperature is raised to 70-100°C for reaction, and the reaction process is: ; S4, cooling after the reaction, recovering the solvent to obtain the product 1,2-di(2-chlorophenyl)hydrazine, the melting point of 1,2-di(2-chlorophenyl)hydrazine is 85-86°C.

[0007] Furthermore, in step S2, 10 grams of cylindrical granulated copper-zinc catalyst is added into the fixed bed reactor.

[0008] Furthermore, the volume ratio of the reaction raw materials o-nitrochlorobenzene and dioxane is 1:1.

[0009] Furthermore, in step S2, when the material pump transports o-nitrochlorobenzene and dioxane, the flow rate is 1 ml / min.

[0010] Furthermore, in step S4, the reaction is cooled to 25°C after the reaction.

[0011] The invention has the advantages that: ortho-nitrochlorobenzene is used as a raw material, and 1,2-di(2-chlorophenyl)hydrazine is obtained by a fixed-bed hydrogenation reaction under the catalytic action of a copper-zinc catalyst. By using a relatively cheap catalyst with a simple preparation process for the catalytic reaction, the production cost is reduced, and the invention is more suitable for industrial large-scale production. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. The following examples can enable technicians in this field to understand the present invention more comprehensively, but the present invention is not limited to the scope of the embodiments.

[0013] This specific implementation adopts the following technical solution: comprising the following steps: S1. Weigh the raw materials o-nitrochlorobenzene, dioxane and copper-zinc catalyst, and the volume ratio of the reaction raw materials o-nitrochlorobenzene and dioxane is 1:1.

[0014] S2. Add 10 g of cylindrical granulated copper-zinc catalyst into the fixed bed reactor, and deliver o-nitrochlorobenzene and dioxane into the fixed bed through a material pump at a flow rate of 1 ml / min.

[0015] S3, hydrogen is introduced into the fixed bed reactor, the hydrogen pressure is 1MPa, the temperature is raised to 70-100°C for reaction, and the reaction process is: .

[0016] S4. After the reaction, the mixture is cooled to 25°C, and the solvent is recovered to obtain the product 1,2-di(2-chlorophenyl)hydrazine. The melting point of 1,2-di(2-chlorophenyl)hydrazine is 85-86°C.

[0017] Embodiment 1: 10 g of cylindrical granulated copper-zinc catalyst was added to a fixed bed reactor, and o-nitrochlorobenzene and dioxane in a volume ratio of 1:1 were fed into the fixed bed by a material pump at a flow rate of 1 ml / min. The hydrogen pressure was 1 MPa, and the temperature was raised to 85°C for reaction. After the reaction, the temperature was cooled to 25°C, and the solvent was recovered to obtain 1,2-di(2-chlorophenyl)hydrazine. The conversion rate of o-nitrochlorobenzene was 98%, the selectivity of 1,2-di(2-chlorophenyl)hydrazine was 91%, and the melting point was 85-86°C.

[0018] The structural analysis of the obtained product 1,2-di(2-chlorophenyl)hydrazine is shown in the following table.

[0019] Elemental analysis C(56.90%), H(3.97%), N(11.01%) Mass spectrometry m / z 252 1 HNMR δ=6.2(2H,NH), 6.8(2H), 6.9(2H), 7.1(2H), 7.3(2H); Embodiment 2: 10 g of cylindrical granulated copper-zinc catalyst was added to a fixed bed reactor, and o-nitrochlorobenzene and dioxane in a volume ratio of 1:1 were fed into the fixed bed by a material pump at a flow rate of 1 ml / min. The hydrogen pressure was 1 MPa, and the temperature was raised to 100°C for reaction. After the reaction, the temperature was cooled to 25°C, and the solvent was recovered to obtain 1,2-di(2-chlorophenyl)hydrazine. The conversion rate of o-nitrochlorobenzene was 99%, the selectivity of 1,2-di(2-chlorophenyl)hydrazine was 85%, and the melting point was 85-86°C.

[0020] Embodiment 3: 10 g of cylindrical granulated copper-zinc catalyst was added to a fixed bed reactor, and o-nitrochlorobenzene and dioxane in a volume ratio of 1:1 were fed into the fixed bed by a material pump at a flow rate of 1 ml / min. The hydrogen pressure was 1 MPa, and the temperature was raised to 70°C for reaction. After the reaction, the temperature was cooled to 25°C, and the solvent was recovered to obtain 1,2-di(2-chlorophenyl)hydrazine. The conversion rate of o-nitrochlorobenzene was 90%, the selectivity of 1,2-di(2-chlorophenyl)hydrazine was 92%, and the melting point was 85-86°C.

[0021] It can be seen from the above Examples 1-3 that in Example 1, when the reaction temperature is 85°C, the conversion rate of o-nitrochlorobenzene is 98%, the selectivity of 1,2-di(2-chlorophenyl)hydrazine is 91%, and its yield is the highest, which is the best example.

[0022] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing 1,2-bis(2-chlorophenyl)hydrazine, characterized in that: The following steps are involved: S1. Weigh the raw materials o-nitrochlorobenzene, dioxane and copper-zinc catalyst; S2, adding a cylindrical granulated copper-zinc catalyst into a fixed bed reactor, and sending o-nitrochlorobenzene and dioxane into the fixed bed through a material pump; S3, hydrogen is introduced into the fixed bed reactor, the hydrogen pressure is 1MPa, the temperature is raised to 70-100°C for reaction, and the reaction process is: ; S4, cooling after the reaction, recovering the solvent to obtain the product 1,2-di(2-chlorophenyl)hydrazine, the melting point of 1,2-di(2-chlorophenyl)hydrazine is 85-86°C.

2. The method for preparing 1,2-di(2-chlorophenyl)hydrazine according to claim 1, characterized in that: In the step S2, 10 grams of cylindrical granulated copper-zinc catalyst is added into the fixed bed reactor.

3. The method for preparing 1,2-di(2-chlorophenyl)hydrazine according to claim 1, characterized in that: The volume ratio of the reaction raw materials o-nitrochlorobenzene and dioxane is 1:

1.

4. The method for preparing 1,2-di(2-chlorophenyl)hydrazine according to claim 1, characterized in that: In the step S2, when the material pump transports o-nitrochlorobenzene and dioxane, the flow rate is 1 ml / min.

5. The method for preparing 1,2-di(2-chlorophenyl)hydrazine according to claim 1, characterized in that: In the step S4, the reaction is followed by cooling to 25°C.

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