Purification method of 1-hydroxy-2-naphthoic acid

Abstract

The invention discloses a purification method of 1-hydroxy-2-naphthoic acid, which belongs to the field of production and manufacturing of storage batteries, and specifically comprises the following steps: (1) dissolving 1-hydroxy-2-naphthoic acid by using industrial alcohol or absolute ethyl alcohol, filtering and collecting filtrate; and (2) adding pure water into the filtrate, standing for layering to obtain a lower-layer solution, and drying the lower-layer solution to obtain the high-purity 1-hydroxy-2-naphthoic acid. According to the method, the 1-hydroxy-2-naphthoic acid is completely dissolved by adopting the industrial alcohol solution, then the 1-hydroxy-2-naphthoic acid is washed by using the purified water and separated out, so that the filtrate containing no 1-hydroxy-2-naphthoic acid is completely separated from the precipitate, and finally the precipitate is dried by using the drying oven, so that the impurity-free high-purity 1-hydroxy-2-naphthoic acid is obtained, and the method is rapid, simple and convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of battery production and manufacturing, and in particular relates to a method for purifying 1-hydroxy-2-naphthoic acid. Background Art

[0002] Lead-acid batteries are the main starting and power supply for automobiles, electric vehicles and special vehicles. The advantage of dry-charged batteries is that they can be put into use 20 minutes after injecting H2SO4, and do not need to be initially charged. The key to manufacturing dry-charged batteries is to prevent the negative plate from being oxidized by air after formation, or to oxidize it to a limited extent.

[0003] At present, in order to prevent the oxidation of spongy lead, the negative plate is usually treated by adding 1-hydroxy-2-naphthoic acid antioxidant to the lead paste. The antioxidant isolates the lead from the oxygen in the air by adsorbing on the lead surface, which becomes a higher barrier for the reaction between lead and oxygen, greatly reducing the reaction rate and achieving the purpose of inhibiting lead oxidation. However, when 1-hydroxy-2-naphthoic acid is used as a negative electrode additive for batteries, the content is required to be ≥97%. However, in actual use, the actual content of 1-hydroxy-2-naphthoic acid is lower than this requirement due to impurities and other reasons, and cannot meet the use.

[0004] Therefore, being able to provide a method for purifying 1-hydroxy-2-naphthoic acid is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0005] In view of this, the present invention provides a method for purifying 1-hydroxy-2-naphthoic acid.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for purifying 1-hydroxy-2-naphthoic acid, specifically comprising the following steps:

[0008] (1) dissolving 1-hydroxy-2-naphthoic acid with industrial alcohol (above industrial grade) or anhydrous ethanol, and collecting the filtrate by filtering;

[0009] (2) adding pure water to the filtrate, standing and separating the layers to obtain a lower layer solution, and drying the lower layer solution to obtain high-purity 1-hydroxy-2-naphthoic acid.

[0010] The method comprises the following steps: completely dissolving 1-hydroxy-2-naphthoic acid with industrial alcohol or anhydrous ethanol solution, washing with pure water and then precipitating the 1-hydroxy-2-naphthoic acid, so that a filtrate free of 1-hydroxy-2-naphthoic acid is completely separated from the precipitate, and finally drying the precipitate in an oven to obtain high-purity 1-hydroxy-2-naphthoic acid free of impurities, thereby forming a purification method capable of effectively increasing the content of 1-2-naphthoic acid.

[0011] Preferably, in step (1), the mass ratio of the industrial alcohol or anhydrous ethanol to the 1-hydroxy-2-naphthoic acid is 5-10:1.

[0012] Preferably, the dissolving in step (1) is performed by stirring for 1-4 hours.

[0013] Preferably, the filtration in step (1) is performed by vacuum filtration with filter paper.

[0014] Preferably, the temperature of the pure water in step (2) is 80-100°C.

[0015] Preferably, the mass ratio of the pure water to the filtrate in step (2) is 5:1-10:1.

[0016] Preferably, the standing time in step (2) is more than 0.5 h.

[0017] Preferably, the drying temperature in step (2) is 65-80°C.

[0018] Preferably, the static stratification in step (2) is performed using a separatory funnel.

[0019] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The method of the invention is rapid and simple, and can improve the purity of 1-hydroxy-2-naphthoic acid to more than 97%, or even more than 99%. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] The present invention provides a method for purifying 1-hydroxy-2-naphthoic acid, which comprises the following steps:

[0024] (1) Weigh 100 g of the 1-hydroxy-2-naphthoic acid sample (purity 96%) to be purified using a balance, dissolve it in industrial alcohol at a ratio of 1:5, and stir for 1 hour until it is completely dissolved. Prepare filter paper, filter bottle, sand core funnel, funnel holder, suction bottle, circulating vacuum pump, etc., place the filter paper on the sand core funnel to ensure that it fits well without gaps, connect the suction bottle and the circulating vacuum pump, wet the periphery of the filter paper appropriately, pour the completely dissolved mixed solution into the sand core funnel, turn on the vacuum pump, generate negative pressure through the vacuum pump, accelerate the filtration process, use the filter bottle to collect the filtrate, and ensure that the container is clean to avoid secondary contamination.

[0025] (2) After the filtration is completed, 3000 g of pure water at 80° C. is added to the filtrate. At this time, 1-hydroxy-2-naphthoic acid will precipitate out in the filtrate. The filtrate is allowed to stand and settle for 0.5 h to completely precipitate out 1-hydroxy-2-naphthoic acid in the filtrate. The filtrate added with pure water is separated with a separatory funnel. After the liquid is layered, the glass stopper on the separatory funnel is opened, and the lower layer solution (containing the precipitate) is discharged from the lower port. The upper clear liquid is poured out from the upper port. The lower layer solution (containing the precipitate) is taken and placed in an oven at 65° C. for drying. The solid sediment obtained after drying is then crushed with a stirrer to obtain high-purity 1-hydroxy-2-naphthoic acid. The detection purity is 99.3%. The mass of the sample after drying is 95.3 g, and the yield is 95.3%.

[0026] Example 2

[0027] The present invention provides a method for purifying 1-hydroxy-2-naphthoic acid, which comprises the following steps:

[0028] (1) Weigh 50 g of the 1-hydroxy-2-naphthoic acid sample (purity 97.1%) to be purified using a balance, dissolve it in industrial alcohol at a ratio of 1:10 according to the mass of 1-hydroxy-2-naphthoic acid and the mass of industrial alcohol, stir for 4 hours until completely dissolved, prepare filter paper, filter bottle, sand core funnel, funnel holder, suction filtration bottle, circulating vacuum pump, etc., place the filter paper on the sand core funnel to ensure that there is no gap, connect the suction filtration bottle and the circulating vacuum pump, properly wet the periphery of the filter paper, pour the completely dissolved mixed solution into the sand core funnel, turn on the vacuum pump, generate negative pressure through the vacuum pump, accelerate the filtration process, use the filter bottle to collect the filtrate, ensure that the container is clean, and avoid secondary contamination;

[0029] (2) After the filtration is completed, 5000 g of pure water at 100° C. is added to the filtrate. At this time, 1-hydroxy-2-naphthoic acid will precipitate out in the filtrate. The filtrate is allowed to stand for sedimentation for 2 h to completely precipitate out 1-hydroxy-2-naphthoic acid in the filtrate. The filtrate added with pure water is separated with a separatory funnel. After the liquid is layered, the glass stopper on the separatory funnel is opened, and the lower layer solution (containing the precipitate) is discharged from the lower port. The upper clear liquid is poured out from the upper port. The lower layer solution (containing the precipitate) is taken and placed in an oven at 80° C. for drying. The solid sediment obtained after drying is then crushed with a stirrer to obtain high-purity 1-hydroxy-2-naphthoic acid. The detection purity is 99.3%. The mass of the sample after drying is 48.6 g, and the yield is 97.2%.

[0030] Example 3

[0031] (1) Weigh 100 g of the 1-hydroxy-2-naphthoic acid sample (purity 96%) to be purified using a balance, dissolve it in anhydrous ethanol at a ratio of 1:5 according to the mass of 1-hydroxy-2-naphthoic acid and the mass of anhydrous ethanol, stir for 1 hour until it is completely dissolved, prepare filter paper, filter bottle, sand core funnel, funnel holder, suction filtration bottle, circulating vacuum pump, etc., place the filter paper on the sand core funnel to ensure that it fits without gaps, connect the suction filtration bottle and the circulating vacuum pump, properly wet the periphery of the filter paper, pour the completely dissolved mixed solution into the sand core funnel, turn on the vacuum pump, generate negative pressure through the vacuum pump, accelerate the filtration process, use the filter bottle to collect the filtrate, ensure that the container is clean, and avoid secondary contamination;

[0032] (2) After the filtration is completed, 3000 g of pure water at 80° C. is added to the filtrate. At this time, 1-hydroxy-2-naphthoic acid will precipitate out in the filtrate. The filtrate is allowed to stand and settle for 0.5 h to completely precipitate out 1-hydroxy-2-naphthoic acid in the filtrate. The filtrate added with pure water is separated with a separatory funnel. After the liquid is layered, the glass stopper on the separatory funnel is opened, and the lower layer solution (containing the precipitate) is discharged from the lower port. The upper clear liquid is poured out from the upper port. The lower layer solution (containing the precipitate) is taken and placed in an oven at 65° C. for drying. The solid sediment obtained after drying is then crushed with a stirrer to obtain high-purity 1-hydroxy-2-naphthoic acid. The detection purity is 99.3%. The mass of the sample after drying is 95.5 g, and the yield is 95.5%.

[0033] Comparative Example 1

[0034] (1) Weigh 100 g of a 1-hydroxy-2-naphthoic acid sample (purity 96%) to be purified using a balance, dissolve it in ether at a ratio of 1:5 according to the mass of 1-hydroxy-2-naphthoic acid to the mass of ether, stir for 1 hour until completely dissolved, prepare filter paper, filter bottle, sand core funnel, funnel holder, suction filtration bottle, circulating vacuum pump, etc., place the filter paper on the sand core funnel to ensure that it fits without gaps, connect the suction filtration bottle and the circulating vacuum pump, properly wet the periphery of the filter paper, pour the completely dissolved mixed solution into the sand core funnel, turn on the vacuum pump, generate negative pressure through the vacuum pump, accelerate the filtration process, use the filter bottle to collect the filtrate, ensure that the container is clean, and avoid secondary contamination;

[0035] (2) After the filtration is completed, 3000 g of pure water at 80° C. is added to the filtrate. At this time, 1-hydroxy-2-naphthoic acid will precipitate out in the filtrate. The filtrate is allowed to stand and settle for 0.5 h to completely precipitate out 1-hydroxy-2-naphthoic acid in the filtrate. The filtrate added with pure water is separated with a separatory funnel. After the liquid is layered, the glass stopper on the separatory funnel is opened, and the lower layer solution (containing the precipitate) is discharged from the lower port. The upper clear liquid is poured out from the upper port. The lower layer solution (containing the precipitate) is taken and placed in an oven at 65° C. for drying. The solid sediment obtained after drying is then crushed with a stirrer to obtain high-purity 1-hydroxy-2-naphthoic acid. The detection purity is 99.3%. The mass of the sample after drying is 95.1 g, and the yield is 95.1%.

[0036] Compared with ether, industrial alcohol is easy to obtain and much less dangerous, so it is recommended to use alcohol for operations.

[0037] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying 1-hydroxy-2-naphthoic acid, characterized in that: The specific steps include: (1) dissolving 1-hydroxy-2-naphthoic acid with industrial alcohol or anhydrous ethanol, and collecting the filtrate by filtering; (2) adding pure water to the filtrate, standing and separating the layers to obtain a lower layer solution, and drying the lower layer solution to obtain high-purity 1-hydroxy-2-naphthoic acid.

2. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, In step (1), the mass ratio of the industrial alcohol or anhydrous ethanol to the 1-hydroxy-2-naphthoic acid is 5-10:

1.

3. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The dissolution in step (1) can be carried out by stirring for 1-4 hours.

4. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The filtration in step (1) is performed by vacuum filtration with filter paper.

5. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The temperature of the pure water in step (2) is 80-100°C.

6. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The mass ratio of the pure water to the filtrate in step (2) is 5:1-10:

1.

7. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The standing time in step (2) is more than 0.5 h.

8. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The drying temperature in step (2) is 65-80°C.

9. A method for purifying 1-hydroxy-2-naphthoic acid according to claim 1, characterized in that, The static separation in step (2) is performed using a separatory funnel.