Process for producing 1-naphthol by mixed phenol crystallization method

Abstract

The invention provides a process for producing 1-naphthol by a mixed phenol crystallization method, and relates to the technical field of organic chemistry. The process comprises the following steps: cooling 1-naphthol to 3-9 DEG C below the melting point at the speed of 0.6-1.5 DEG C per hour; discharging uncrystallized residual liquid; and heating the obtained 1-naphthol at a speed of 0-0.9 DEG C per hour to gradually discharge sweat, thereby obtaining the target product. According to the method disclosed by the invention, the preparation of the ultra-high-purity alpha naphthol product is realized by melting and crystallizing the superior-grade 1-naphthol with the purity of 99.5-99.7%, and the purity of the prepared 1-naphthol is greater than or equal to 99.9%.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemistry, and in particular to a process for producing 1-naphthol by a mixed phenol crystallization method. Background Art

[0002] 1-naphthol is commonly known as methyl naphthol, also known as α-naphthol, and is currently mainly used as the intermediate of the pesticide carbaryl, and can also be used as the intermediate of some medicines and fine chemical products. Its production mainly adopts naphthalene nitration, reduction, hydrolysis method, because nitration produces about 4% 2-nitronaphthalene, and the general product content is about 96%, thereby to obtain the high-quality 1-naphthol that meets the content of national standard GB / T3410-2002 and reaches 99.5%, it is necessary to adopt nitronaphthalene crystallization separation and purification or product crystallization separation, and the steps are long, the cost is high, and the three wastes are many. 1-naphthol can also be produced by low-temperature sulfonation alkali fusion method, but because the isomer produced needs to be separated and removed, the product yield is low, about 40%, and the three wastes are discharged in large quantities.

[0003] The traditional distillation process is usually used to separate and purify 1-naphthol and 2-naphthol. However, since 2-naphthol and 1-naphthol are isomers and the boiling point difference between the two is only 6°C, separating the mixture by distillation requires a large number of plates and a large reflux ratio. Although 1-naphthol products can be obtained, it is still difficult to obtain high-purity products. The existing distillation process for 1-naphthol only achieves 99.5%-99.7%, and there are still 0.3%-0.5% of other impurities, which restricts the use of high-end customers. In order to obtain high-purity 1-naphthol, the melt crystallization method can achieve a 1-naphthol content of 99.9%.

[0004] Chinese patent CN1268596C discloses a method for purifying naphthol by distillation, which includes vacuumizing and adding a distillation device, and then firstly letting the crude naphthol enter the distillation tower through a reboiler and reflux for a period of time, and then transporting it to the distillation tower from different feed ports according to the different naphthol contents in the crude naphthol, controlling a certain reflux ratio, and adjusting the measured contents of naphthol and ethyl to meet the requirements between 99.1% and 99.3%, which cannot meet the needs of high-end customers.

[0005] Melt crystallization separation is to melt the solid melt or the eutectic mixture with the lowest eutectic point, and then cool and crystallize, and use the melt of the crystal itself to wash the crystal, so as to improve the purity of the required components. However, for most mixtures, the product often cannot meet the purity requirements by only a simple melt crystallization process. At this time, after the crystallization process, the temperature of the coarse crystals can be slowly increased to partially dissolve the impurities and further improve the purity of the product. This operation is called the "sweating" process. Compared with the distillation method, the advantages of this technology are: high separation efficiency, low energy consumption and low temperature operation.

[0006] Chinese patent CN1054971A discloses a process for low-temperature refining of naphthol, which controls the cooling rate of naphthol in a low-temperature refining tank, cools the temperature by 0.5-5°C per hour to 10-25°C below the melting point, so that the material is precipitated in the tank as relatively pure naphthol crystals, and then heats up at a rate of 1-5°C per hour to increase the content gradient of naphthol in the distillate, thereby obtaining refined naphthol. However, the purity of the obtained naphthol is between 90% and 99%, which cannot meet the needs of high-end customers.

[0007] Based on this, developing a new process for refining naphthol with low cost, simple operation and purity greater than 99.5%-99.7% is the research focus of researchers in this field. Summary of the invention

[0008] In view of the above problems, the present invention provides a process for producing 1-naphthol by a mixed phenol crystallization method, wherein 99.5%-99.7% of the superior grade 1-naphthol obtained by a refining method is crystallized and refined again, and finally an ultra-high purity naphthol product of more than 99.9% is obtained, thereby meeting the purity requirements of the high-end market.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] In one aspect, the present invention provides a process for producing 1-naphthol by a mixed phenol crystallization method, comprising the following steps:

[0011] S1: Cooling: 1-naphthol is cooled to 3-9°C below the melting point at a rate of 0.6-1.5°C per hour; the uncrystallized residual liquid is discharged;

[0012] S2: Sweating: The 1-naphthol obtained in S1 is heated at a rate of 0°C-0.9°C per hour to discharge sweat liquid to obtain the target product.

[0013] Preferably, the process is carried out in a crystallizer.

[0014] Preferably, the crystallizer is a new type plate crystallizer.

[0015] Preferably, in S1, the purity of the 1-naphthol is 99.5%-99.7%.

[0016] Preferably, in S1, the cooling rate is 0.6°C-1°C per hour. Further preferably, in S1, the cooling rate is 1°C per hour.

[0017] Preferably, in S1, the temperature lowered to a temperature below the melting point is 5° C. to 8° C. Further preferably, in S1, the temperature lowered to a temperature below the melting point is 6° C.

[0018] Preferably, in S2, the heating rate is 0.3° C. to 0.9° C. per hour. More preferably, in S2, the heating rate is 0.5° C. per hour.

[0019] Preferably, in S1, the control of the cooling rate is achieved by regulating the temperature of the heat exchange medium by an automatic temperature control system.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention provides a process for producing 1-naphthol by a mixed phenol crystallization method. The process comprises the following steps: re-crystallizing and refining 99.5%-99.7% of high-quality 1-naphthol, accurately controlling the cooling rate and the heating rate in a sweating process, and timely discharging residual liquid after cooling and crystallizing, and timely discharging sweating liquid in a sweating process during heating, thereby realizing the preparation of an ultra-high-purity naphthol product. The purity of the 1-naphthol prepared by the invention is ≥99.9%. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, purpose and effect of the present invention easy to understand, the present invention is further explained below in conjunction with specific embodiments, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without making creative work all belong to the protection scope of the present invention. It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited. The technology and scientific terms used in the embodiments have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0023] Example 1

[0024] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0025] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, and the temperature is reduced to 6°C below the melting point at a rate of 1°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0026] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.5°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0027] The purity of the product was 99.92% and the yield was 71.2%.

[0028] Example 2

[0029] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0030] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is placed in a new plate crystallizer. The temperature of the heat exchange medium is regulated by an automatic temperature control system, and the temperature is lowered to 8°C below the melting point at a rate of 0.6°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0031] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.9°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0032] The purity of the product was 99.93% and the yield was 71.0%.

[0033] Example 3

[0034] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0035] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, and the temperature is reduced to 3°C below the melting point at a rate of 1.5°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0036] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.1°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0037] The purity of the product was 99.92% and the yield was 71.1%.

[0038] Comparative Example 1

[0039] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0040] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, at a rate of 3°C per hour to 6°C below the melting point; and the residual liquid that has not been crystallized is discharged in time;

[0041] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.5°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0042] The purity of the product was 99.83% and the yield was 68.2%.

[0043] Comparative Example 2

[0044] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0045] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, and the temperature is reduced to 6°C below the melting point at a rate of 1°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0046] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 3°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0047] The purity of the product was 99.84% and the yield was 69.2%.

[0048] Comparative Example 3

[0049] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0050] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, and the temperature is reduced to 15°C below the melting point at a rate of 1°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0051] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.5°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0052] The purity of the product is 99.88% and the yield is 70.1%. The economic benefit is low due to the long cooling time.

[0053] Comparative Example 4

[0054] Compared with Example 1, the only difference is that the uncrystallized residual liquid is not discharged in S1; the details are as follows:

[0055] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0056] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled to 6°C below the melting point at a rate of 1°C per hour by regulating the temperature of the heat exchange medium through an automatic temperature control system in a new plate crystallizer;

[0057] S2: Sweating: The 1-naphthol obtained in S1 after the uncrystallized residual liquid is discharged is heated at a rate of 0.5°C per hour, so that the sweating liquid is gradually discharged and the content of naphthol gradually increases to obtain the target product.

[0058] The purity of the product was 99.76% and the yield was 57.3%.

[0059] Comparative Example 5

[0060] Compared with Example 1, the only difference is that no sweating liquid is discharged in S2; the details are as follows:

[0061] A process for producing 1-naphthol by a mixed phenol crystallization method comprises the following steps:

[0062] S1: Cooling: 1-naphthol with a purity of 99.5%-99.7% is cooled in a new plate crystallizer by an automatic temperature control system to control the temperature of the heat exchange medium, and the temperature is reduced to 6°C below the melting point at a rate of 1°C per hour; and the residual liquid that has not been crystallized is discharged in time;

[0063] S2: Sweating: The 1-naphthol obtained in S1 after the residual liquid without crystallization is discharged is heated at a rate of 0.5°C per hour, and the content of naphthol gradually increases to obtain the target product.

[0064] The purity of the product was 99.79% and the yield was 56.8%.

[0065] It can be seen from the above embodiments and comparative examples that the purity of naphthol obtained in the embodiments of the present invention is greater than or equal to 99.92%, and the yield is greater than 71%. However, the purity of naphthol prepared in the comparative examples is less than 99.9%, which is related to the cooling and sweating rates. Fast cooling and sweating will cause the finished product to be mixed with impurities, thereby reducing the purity of the product. Moreover, in the cooling and sweating process, the embodiments of the present invention timely discharge the residual liquid and sweating liquid, so that the purity of naphthol exceeds 99.9%, and compared with comparative examples 4-5, the yield is significantly improved.

[0066] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A process for producing 1-naphthol by a mixed phenol crystallization method, characterized in that: The following steps are involved: S1: Cooling: 1-naphthol is cooled to 3-9°C below the melting point at a rate of 0.6-1.5°C per hour; the uncrystallized residual liquid is discharged; S2: Sweating: The 1-naphthol obtained in S1 is heated at a rate of 0°C-0.9°C per hour to discharge sweat liquid to obtain the target product.

2. The process according to claim 1, characterized in that The process is carried out in a crystallizer.

3. The process according to claim 1, characterized in that The crystallizer is a new type of plate crystallizer.

4. The process according to claim 1, characterized in that In S1, the purity of the 1-naphthol is 99.5%-99.7%.

5. The process according to claim 1, characterized in that In S1, the cooling rate is 0.6°C-1°C per hour.

6. The process according to claim 5, characterized in that In S1, the cooling rate is 1°C per hour.

7. The process according to claim 1, characterized in that In S1, the temperature is lowered to a temperature below the melting point of 5°C-8°C.

8. The process according to claim 7, characterized in that In S1, the temperature is lowered to 6°C below the melting point.

9. The process according to claim 1, characterized in that In S2, the heating rate is 0.5°C-0.90°C per hour.

10. The process according to claim 1, characterized in that In S1, the control of the cooling rate is achieved by regulating the temperature of the heat exchange medium through an automatic temperature control system.