Continuous alkali fusion process for naphthol

Abstract

The invention belongs to the technical field of organic chemical industry, and discloses a continuous alkali fusion process for naphthol. The continuous alkali fusion process for naphthol comprises the following steps: (1) putting solid caustic soda flakes into a reactor, and heating to obtain liquid alkali; (2) transferring the liquid alkali obtained in the step (1) into a rotary kiln reactor under the protection of inert gas, adding sodium naphthalene sulfonate, and heating for reaction to obtain reaction liquid; and (3) detecting the content of residual alkali in the reaction liquid, and when the total alkalinity is less than 0.2%, determining that the material is qualified, and carrying out the next working section. The naphthol alkali fusion process provided by the invention is simple in flow, low in production cost, capable of effectively improving the working environment of workers and reducing the workload, high in conversion rate and suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of organic chemical industry, and in particular relates to a continuous alkali melting process of naphthol. Background Art

[0002] Naphthol is a chemical substance with the chemical formula C 10 H8O, molecular weight is 144.17. The chemical properties of naphthol are similar to those of phenol, and it can undergo electrophilic substitution of the aromatic ring and reaction of phenolic hydroxyl groups. There are two isomers of naphthol, namely 1-naphthol (α-naphthol) and 2-naphthol (β-naphthol). The main difference between them is the different positions of the hydroxyl groups on the naphthalene ring. 1-Naphthol is an organic compound, a white crystalline powder with an unpleasant phenolic odor, soluble in ethanol, ether, chloroform and alkaline solution, insoluble in water, and toxic. 2-Naphthol, also known as ethyl naphthol, is also a white crystal with a slight phenolic odor. It is mainly used to make pesticides, fragrances, antioxidants, β-naphthol sulfonic acid, β-naphthylamine dyes, rubber antioxidants, etc. The chemical properties of naphthol include coupling reactions with diazonium salts, which is the basis for making azo dyes. 2-Naphthol is coupled at the α position, and the product can react with sodium hydroxide due to the hydrogen bond within the molecule. In addition, naphthol can also undergo electrophilic substitution reactions of the aromatic ring and reaction of phenolic hydroxyl groups. In general, naphthol has a wide range of applications in organic synthesis, dye manufacturing, medicine, and material science due to its unique chemical structure and properties.

[0003] At present, the main industrial method for synthesizing naphthol at home and abroad is still the sulfonation alkali fusion method, and its technology is relatively mature. However, the sulfonation alkali fusion method has disadvantages such as long process flow, discontinuous synthesis process, poor working conditions, serious equipment corrosion, high emission of three wastes, and high synthesis cost.

[0004] For example, Chinese patent number CN104016835A discloses a method of using refined naphthalene as raw material, and preparing 2-naphthol through 98% sulfuric acid sulfonation, salting out, alkali fusion, acidification, distillation and other processes. The method overcomes the deficiencies of sulfonation, hydrolysis naphthalene blowing, neutralization, cold analysis, drying, alkali fusion, acidification and distillation in the traditional process, optimizes the process, shortens the process flow, reduces the production cost, and does not generate waste water; it has positive significance for environmental protection and is particularly suitable for the production and use of 2-naphthol. However, the method still has the disadvantages of low efficiency and high discharge of three wastes.

[0005] Another example is Chinese patent CN101781172B which discloses a novel process for the high-efficiency continuous synthesis of 2-naphthol, comprising the following steps: A. refined naphthalene is placed from a naphthalene melting tank (1) into a pre-stage reactor of a sulfonation reactor, and sulfuric acid is placed from a sulfuric acid metering tank (2) into each stage of the sulfonation reactor for sulfonation reaction for 2 to 6 hours, while the sulfonation reactor is depressurized to remove water generated by the reaction; B. the sulfonation product in step A is introduced into a neutralization tank (7) and directly neutralized with a dilute alkali, and the impurities produced as by-products in the sulfonation reaction are retained, and after preliminary evaporation and dehydration, it is directly introduced into an alkali melting pot (9) for alkali melting reaction; C. the alkali melting reaction product is acidified in an acidification tank (11), and then the 2-naphthol and 1-naphthol therein are extracted with an extractant in an extraction tower (13); D. the organic phase after the naphthol is extracted is rectified in a rectification tower (14) to recover the extractant, and at the same time, the 2-naphthol, 1-naphthol and naphthalene not involved in the reaction are rectified and separated. The present invention adopts a continuous reaction process design, has stable performance and high yield, but still has the disadvantages of complex reaction process and cumbersome procedures.

[0006] Therefore, it is urgent to study a naphthol alkali melting process with simple process, safety and efficiency, low synthesis cost and less emission of three wastes. Summary of the invention

[0007] Based on the problems existing in the prior art, the present invention provides a naphthol continuous alkali melting process which has the advantages of simple process, safety, high efficiency, low synthesis cost and less discharge of three wastes.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] First, the present invention provides a naphthol continuous alkali melting process, which is characterized by comprising the following steps:

[0010] (1) putting solid caustic soda flakes into a reactor and heating them to obtain liquid caustic soda;

[0011] (2) transferring the liquid alkali obtained in step (1) into a rotary kiln reactor under the protection of an inert gas, adding sodium naphthalenesulfonate, and heating to react to obtain a reaction solution;

[0012] (3) Detect the residual alkali content in the reaction solution. When the total alkalinity is less than 0.2%, the material is qualified and proceed to the next stage.

[0013] The inert gas in step (1) is one of nitrogen, argon and helium;

[0014] Preferably, the inert gas in step (1) is nitrogen.

[0015] The heating temperature in the above step (1) is 300-350°C, preferably 320°C.

[0016] The temperature of the liquid alkali in the above step (2) is 300-350°C, preferably 320°C.

[0017] The flow rate of the liquid alkali in the above step (2) into the rotary kiln reactor is 3.0-5.0 L / min, preferably 4.0 L / min.

[0018] The sodium naphthalenesulfonate addition rate in the above step (2) is 10-15 Kg / min; preferably 12 Kg / min.

[0019] The heating temperature in the above step (2) is 300-400°C;

[0020] The heating time in the above step (2) is 20-30 min, preferably 25 min.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The naphthol alkali melting process provided by the present invention has a simple process and low production cost, and can effectively improve the working environment of workers and reduce workload.

[0023] (2) The naphthol alkali fusion process provided by the present invention has stable product quality and high conversion rate, and is suitable for industrial production.

[0024] (3) The naphthol alkali fusion process provided by the present invention has low energy consumption and saves natural gas. DETAILED DESCRIPTION

[0025] The technical scheme of the present invention is clearly and completely described below with specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The materials, reagents, etc. used, if not otherwise specified, are reagents and materials available from commercial sources.

[0026] Embodiment 1 A kind of naphthol continuous alkali melting process

[0027] The steps include:

[0028] (1) putting solid caustic soda flakes into a reactor and heating it to 320° C. to obtain liquid caustic soda;

[0029] (2) the liquid alkali obtained in step (1) is transferred into a rotary kiln reactor at a flow rate of 5.0 L / min under nitrogen protection, and sodium naphthalenesulfonate is added at a rate of 15 Kg / min, and heated to 400° C. for reaction to obtain a reaction solution;

[0030] (3) Detect the residual alkali content in the reaction solution. When the total alkalinity is less than 0.2%, the material is qualified and proceed to the next stage.

[0031] Embodiment 2 A kind of naphthol continuous alkali melting process

[0032] The only difference from Example 1 is that in step (2), the liquid alkali is added at a flow rate of 3.0 L / min, and the sodium naphthalenesulfonate is added at a flow rate of 10 Kg / min; in step (2), the two materials are mixed and heated to 300° C. in the reactor. The remaining steps are the same as in Example 1.

[0033] Comparative Example 1 A naphthol continuous alkali melting process

[0034] The only difference from Example 1 is that in step (2), the liquid alkali is added at a flow rate of 25.0 L / min, and the sodium naphthalenesulfonate is added at a flow rate of 25 Kg / min. The remaining steps are the same as in Example 1.

[0035] Comparative Example 2 A naphthol continuous alkali melting process

[0036] The only difference from Example 1 is that in step (2), the liquid alkali is added at a flow rate of 2.0 L / min and the sodium naphthalenesulfonate is added at a flow rate of 25 Kg / min. The remaining steps are the same as in Example 1.

[0037] Technical Effects

[0038] The content of naphthalene salt in the reaction solution obtained by the above process was detected, and the results obtained are shown in Table 1.

[0039] Table 1 Naphthalene salt content

[0040] Example 1 Example 2 Comparative Example 1 Comparative Example 2 content(%) 96 94 87 85

[0041] It can be seen from the data in Table 1 that the content of naphthalene salt in Examples 1-2 is higher than that in Comparative Examples 1-2. It can be seen that the naphthalene salt obtained by the naphthol continuous alkali fusion process provided by the present invention has a high content and has broad application prospects in industry.

Claims

1. A naphthol continuous alkali melting process, characterized in that: The steps include: (1) putting solid caustic soda flakes into a reactor and heating them to obtain liquid caustic soda; (2) transferring the liquid alkali obtained in step (1) into a rotary kiln reactor under the protection of an inert gas, adding sodium naphthalenesulfonate, and heating to react to obtain a reaction solution; (3) Detect the residual alkali content in the reaction solution. When the total alkalinity is less than 0.2%, the material is qualified and proceed to the next stage.

2. The process according to claim 1, characterized in that: The heating temperature in step (1) is 300-350°C.

3. The process according to claim 1, characterized in that: The heating temperature in step (1) is 320°C.

4. The process according to claim 1, characterized in that: The protective gas in step (1) is one of nitrogen, argon and helium.

5. The process according to claim 1, characterized in that: The protective gas described in step (1) is nitrogen.

6. The process according to claim 1, characterized in that: The temperature of the liquid alkali in step (2) is 300-350°C.

7. The process according to claim 1, characterized in that: The flow rate of the liquid alkali in step (2) into the rotary kiln reactor is 3.0-5.0 L / min.

8. The process according to claim 1, characterized in that: The addition rate of the sodium naphthalenesulfonate described in step (2) is 10-15Kg / min.

9. The process according to claim 1, characterized in that: The heating temperature in step (2) is 300-400°C.

10. The process according to claim 1, characterized in that: The heating time in step (2) is 20-30 minutes.