CN108863875B - Method for purifying thiourea and thiourea - Google Patents
Method for purifying thiourea and thiourea Download PDFInfo
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- CN108863875B CN108863875B CN201810815034.4A CN201810815034A CN108863875B CN 108863875 B CN108863875 B CN 108863875B CN 201810815034 A CN201810815034 A CN 201810815034A CN 108863875 B CN108863875 B CN 108863875B
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- C07—ORGANIC CHEMISTRY
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- C07C335/00—Thioureas, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
- C07C335/02—Thiourea
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Abstract
The invention provides a method for purifying thiourea, which comprises the following steps: dissolving industrial thiourea in a solvent to obtain a thiourea solution; adding a precipitator into the thiourea solution, reacting to generate precipitate, and filtering and collecting filtrate; and cooling and crystallizing the filtrate, performing centrifugal separation to obtain a solid, and drying the solid to obtain the thiourea product. The invention also provides thiourea obtained by the purification method, and the purity of the thiourea is more than or equal to 99.3 percent. The purification method has the advantages of simple operation steps, short reaction period, low energy consumption, simple required equipment and cheap and easily-obtained used added materials; the purification method is suitable for preparing high-purity thiourea from industrial thiourea, has good purification effect, obviously improves various indexes, and can meet the technical requirements of the market on the high-purity thiourea.
Description
Technical Field
The invention belongs to the field of chemical industry, and particularly relates to a thiourea purification method and thiourea obtained by purification through the method.
Background
Thiourea is a compound formed by substituting the oxygen of urea with sulfur, and belongs to the group of thioamides (RC (S) NR2And R is a hydrocarbon group). Thiourea is a colorless to pale yellow orthorhombic crystal or needle-like lustrous crystal, bitter in taste, with an ammoniacal taste. Thiourea is slightly soluble in cold water and easily soluble in hot water, is soluble in ethanol when heated and is separated from ethanol when cooled, is almost insoluble in diethyl ether, is flammable, and has a relative density of 1405kg/m3The melting point is 170-173 ℃. Thiourea can form stable compounds with metals, and a small amount of thiourea is added into the acid liquor during metal cleaning to inhibit the corrosion of the acid liquor to the metals; thiourea is also used as a catalyst for the production of phthalic anhydride and fumaric acid. Thiourea is industrially used as a raw material for producing agricultural chemicals, medicines, fuels, resins, pressed powders, etc., and also as photographic developing materials, rubber vulcanization accelerators, flotation agents for metal minerals, and plating industry and chemical agents, etc. In agriculture, thiourea can be used as a bactericide, a rust remover, a potato germination promoter, a livestock fattening agent, a nitrification-inhibiting fertilizer, and the like. Can be used for producing sulfonamides which are raw materials of ascariasis expelling medicine and contraceptive, and a preparation methodCan be made into anti-hyperthyroidism drugs, anti-tuberculosis drugs, intravenous injection anesthetic drugs, etc. The purity of thiourea is high in the application fields, particularly the medical field, and the common industrial thiourea is difficult to meet the use requirement.
Disclosure of Invention
The invention aims to provide a method for purifying thiourea and thiourea obtained by the method aiming at the defects in the prior art.
In one aspect, the present invention provides a method for purifying thiourea, comprising:
(1) dissolving: dissolving industrial thiourea in a solvent to obtain a thiourea solution;
(2) removing impurities: adding a precipitator into the thiourea solution, reacting to generate precipitate, and filtering and collecting filtrate;
(3) and (3) crystallization: and cooling and crystallizing the filtrate, performing centrifugal separation to obtain a solid, and drying the solid to obtain the thiourea product.
In the purification method, in step (1), the solvent is deionized water or the mother liquor obtained by centrifugal separation in step (3).
In the purification method, in the step (1), the weight ratio of the industrial thiourea to the solvent is 1 to (3-7) (preferably 1 to (4-5)), and the dissolving temperature is 40-95 ℃.
In the purification method, in the step (2), the precipitant is sodium carbonate and activated carbon.
In the purification method, in the step (2), sodium carbonate and activated carbon are added into the thiourea solution according to the weight ratio of 1: (800-.
In the purification method, in the step (2), a precipitant is added to the thiourea solution, and the reaction is carried out at 60 ℃ to 95 ℃ for 1 to 3 hours.
In the purification method, in the step (2), the filtration includes primary filtration and secondary filtration, wherein the primary filtration employs a PA sintered filter element, and the secondary filtration employs a polypropylene folded filter element.
In the purification method, in the step (3), the filtrate is cooled to 10 ℃ to 20 ℃ for crystallization.
On the other hand, the invention provides the thiourea obtained by the purification method, wherein the purity of the thiourea is more than or equal to 99.3%.
The melting point of the thiourea is 171-173 ℃, the content of calcium ions is less than or equal to 10ppm, and the content of iron ions is less than or equal to 10 ppm.
By adopting the technical scheme of the invention, the method at least has the following beneficial effects:
firstly, the purification method of the invention has the advantages of simple operation steps, short reaction period, low energy consumption, simple required equipment and cheap and easily-obtained used added materials.
Secondly, the purification method is suitable for preparing high-purity thiourea from industrial thiourea, has good purification effect, obviously improves various indexes, and can meet the technical requirements of the market on the high-purity thiourea.
Detailed Description
The present invention will be described in detail with reference to the following embodiments in order to fully understand the objects, features and effects of the invention. The process of the present invention employs conventional methods or apparatus in the art, except as described below. Unless otherwise defined, technical terms referred to herein have the meanings that are commonly understood by those skilled in the art.
In order to solve the problems that the purity of common industrial thiourea is not high and the use requirement of the downstream industry is difficult to meet, the invention provides a method for preparing high-purity thiourea.
In a first aspect, the present invention provides a method for purifying thiourea, comprising: (1) dissolving: dissolving industrial thiourea in a solvent to obtain a thiourea solution; (2) removing impurities: adding a precipitator into the thiourea solution, reacting to generate precipitate, and filtering and collecting filtrate; (3) and (3) crystallization: and cooling and crystallizing the filtrate, performing centrifugal separation to obtain a solid, and drying the solid to obtain the thiourea product.
Specifically, the method for purifying thiourea of the invention comprises the following steps:
step one, dissolving: dissolving industrial thiourea in a solvent to obtain a thiourea solution.
Preferably, the industrial thiourea is dissolved in deionized water at 40 ℃ to 95 ℃ in a weight ratio of 1: 3-7 (more preferably 1: 4-5) to the deionized water to obtain an aqueous thiourea solution. In a specific embodiment, deionized water is added into a reaction kettle, steam is used for heating, when the deionized water in the reaction kettle reaches the temperature, industrial thiourea is added into the deionized water according to the proportion, and stirring is carried out to completely dissolve the industrial thiourea, so as to obtain the thiourea solution.
Step two, impurity removal: a precipitant is added to the thiourea solution to react and form a precipitate, and then the filtrate is collected by filtration.
Preferably, the precipitating agent is sodium carbonate and activated carbon. More preferably, sodium carbonate and activated carbon are added to the thiourea solution in a weight ratio of sodium carbonate to industrial thiourea of 1: (800-.
Preferably, after adding sodium carbonate and activated carbon to the thiourea solution, the mixture is reacted at 60 ℃ to 95 ℃ for 1 to 3 hours to sufficiently precipitate impurity ions in the thiourea solution.
Preferably, after the formation of the precipitate, the filtration of the material is carried out in two steps, i.e. the filtration comprises a primary filtration using a PA sintered filter element and a secondary filtration using a polypropylene folded filter element. The pore size of the filter element is chosen by the person skilled in the art as desired, and a preferred case is: the filter element of the first-stage filter is a PA sintered filter element with the pore diameter of 3 microns, and the filter element of the second-stage filter is a polypropylene folded filter element with the pore diameter of 0.1 micron.
In one embodiment, the removing step comprises: adding sodium carbonate and active carbon into thiourea solution in a reaction kettle according to the weight ratio of the sodium carbonate to the industrial thiourea of 1 to (800-.
Step three, crystallization: and cooling and crystallizing the filtrate, performing centrifugal separation to obtain a solid, and then washing and drying the solid to obtain a thiourea product.
Preferably, the mother liquor obtained by centrifugal separation can be returned to the first-step dissolving step to replace deionized water for dissolving the industrial thiourea, and the mother liquor can be recycled for 1-12 times, so that the recycling of resources is realized.
In this step, the crystallization may be carried out at 10 ℃ to 20 ℃. The specific operation conditions of centrifugation, washing and drying can be selected by the skilled person according to the actual needs. In one embodiment, the crystallizing step comprises: transferring the filtrate to a crystallization tank, reducing the temperature to 10-20 ℃ for crystallization, then centrifuging at the rotating speed of 800-1200rmp, separating to obtain a solid, washing the solid with deionized water at 10-15 ℃ for 2-3 minutes, and then drying at 80-100 ℃ for 20-30 minutes, thereby obtaining the purified thiourea product.
The method of the invention has no special requirements for industrial thiourea, sodium carbonate and active carbon, and the industrial grade products obtained by conventional market can be used for the invention. The industrial thiourea with the main content of 97.70-98.50% and the industrial sodium carbonate with the total alkali content of more than or equal to 98.8% are adopted in the embodiment of the invention, but the method is only exemplary, and other contents of the industrial thiourea and the industrial sodium carbonate are also suitable for the method of the invention.
The thiourea product with high purity can be obtained by adopting the method of the invention, therefore, in the second aspect, the invention provides the thiourea product with the purity of more than or equal to 99.3 percent (weight), the melting point of 171-173 ℃, the content of calcium ions of less than or equal to 10ppm and the content of iron ions of less than or equal to 10 ppm. The high-purity thiourea product can meet the requirements of the fields of medicine and the like.
Examples
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
First, a detection method employed in the following examples is explained:
the thiourea product purity detection method comprises the following steps: HG/T3266-2002 Standard test
The impurity content detection method comprises the following steps: by inductively coupled plasma emission spectroscopy
Example 1
Adding 3000L of deionized water into a 5000L reaction kettle, heating by using steam, starting to add 1000KG of industrial thiourea with the main content of 98.00% when the temperature of the deionized water in the reaction kettle reaches 40 ℃, stirring to completely dissolve the thiourea, adding 1KG of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 1KG of activated carbon. When the temperature of the materials in the reaction kettle reaches 75 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at 75 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, carrying out centrifugal filtration at 10 ℃, washing and drying to obtain a 746KG product with the yield of 75.7 percent.
Example 2
Adding 3000L of deionized water into a 5000L reaction kettle, heating by using steam, starting to add 1000KG of industrial thiourea with the main content of 98.20% when the temperature of the deionized water in the reaction kettle reaches 95 ℃, stirring to completely dissolve the thiourea, adding 1KG of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 1KG of activated carbon. Controlling the steam input amount to keep the temperature of the materials in the kettle at 95 ℃ for 1 hour, pumping the materials in the kettle into a filter by using a centrifugal pump, transferring the filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, centrifugally filtering at 10 ℃, washing and drying to obtain 738KG product with the yield of 74.8 percent.
Example 3
Adding 3000L of deionized water into a 5000L reaction kettle, heating by using steam, starting to add 1000KG of industrial thiourea with the main content of 98.50% when the temperature of the deionized water in the reaction kettle reaches 65 ℃, stirring to completely dissolve the thiourea, adding 833g of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 833g of activated carbon. When the temperature of the materials in the reaction kettle reaches 75 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at 75 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, carrying out centrifugal filtration at 10 ℃, washing and drying to obtain a 733KG product with the yield of 73.9 percent.
Example 4
Adding 3000L of deionized water into a 5000L reaction kettle, heating by using steam, starting to add 600KG of industrial thiourea with the main content of 97.7% when the temperature of the deionized water in the reaction kettle reaches 65 ℃, stirring to completely dissolve the thiourea, adding 600g of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 600g of activated carbon. When the temperature of the materials in the reaction kettle reaches 75 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at 75 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, centrifugally filtering at 10 ℃, washing and drying to obtain a 446KG product with the yield of 75.8 percent.
Example 5
Adding 3000L of mother liquor which circulates for 1 time into a 5000L reaction kettle, heating by using steam, starting to add industrial thiourea with the main content of 750KG of 98.1% when the temperature of the mother liquor in the reaction kettle reaches 65 ℃, stirring to completely dissolve the thiourea, adding 800g of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 800g of activated carbon. When the temperature of the materials in the reaction kettle reaches 80 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at the temperature of 80 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, carrying out centrifugal filtration at the temperature of 10 ℃, washing and drying to obtain a 728KG product, wherein the yield is 98.4%.
Example 6
Adding 3000L of mother liquor which circulates for 12 times into a 5000L reaction kettle, heating by using steam, starting to add industrial thiourea with the main content of 750KG being 97.9% when the temperature of the mother liquor in the reaction kettle reaches 65 ℃, stirring to completely dissolve the thiourea, adding 1200g of industrial sodium carbonate with the total alkali content being more than or equal to 98.8%, and adding 1200g of activated carbon. When the temperature of the materials in the reaction kettle reaches 80 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at the temperature of 80 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, carrying out centrifugal filtration at the temperature of 10 ℃, washing and drying to obtain a 725KG product, wherein the yield is 98.0%.
Example 7
Adding 3000L of mother liquor which circulates for 5 times into a 5000L reaction kettle, heating by using steam, starting to add industrial thiourea with the main content of 750KG of 98.1% when the temperature of the mother liquor in the reaction kettle reaches 65 ℃, stirring to completely dissolve the thiourea, adding 1000g of industrial sodium carbonate with the total alkali content of more than or equal to 98.8%, and adding 1000g of activated carbon. When the temperature of the materials in the reaction kettle reaches 80 ℃, controlling the steam introduction amount to ensure that the materials in the reaction kettle are kept at the temperature of 80 ℃ for 1 hour, then pumping the materials in the reaction kettle into a filter by using a centrifugal pump, transferring filtrate into a crystallizing tank after primary filtration and secondary filtration, cooling and crystallizing, carrying out centrifugal filtration at the temperature of 20 ℃, washing and drying to obtain a 656KG product with the yield of 88.6 percent.
The products obtained in examples 1 to 7 were analyzed, and the results are shown in Table 1.
TABLE 1
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | |
| Purity (wt%) | 99.4 | 99.5 | 99.3 | 99.6 | 99.5 | 99.3 | 99.4 |
The present invention has been disclosed in the foregoing in terms of preferred embodiments, but it will be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to those of the embodiments are intended to be included within the scope of the claims of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined in the claims.
Claims (6)
1. A method for purifying thiourea, which is characterized by comprising the following steps:
(1) dissolving: dissolving industrial thiourea in a solvent to obtain a thiourea solution;
(2) removing impurities: adding a precipitator into the thiourea solution, reacting to generate precipitate, and filtering and collecting filtrate;
(3) and (3) crystallization: cooling and crystallizing the filtrate, performing centrifugal separation to obtain a solid, and drying the solid to obtain a thiourea product;
wherein, in the step (2), the precipitating agents are sodium carbonate and activated carbon, and the sodium carbonate and the activated carbon are added into the thiourea solution according to the weight ratio of the sodium carbonate to the industrial thiourea of 1 (800-1200) and the weight ratio of the activated carbon to the industrial thiourea of 1 (800-1200);
in the step (2), the filtration comprises primary filtration and secondary filtration, wherein the primary filtration adopts a PA sintered filter element with the aperture of 3 microns, and the secondary filtration adopts a polypropylene folded filter element with the aperture of 0.1 micron;
wherein, in the step (2), equal amounts of sodium carbonate and activated carbon are added to the thiourea solution.
2. The purification method according to claim 1, wherein in step (1), the solvent is deionized water or the mother liquor obtained by centrifugation in step (3).
3. The purification method according to claim 1, wherein in the step (1), the weight ratio of the industrial thiourea to the solvent is 1 (3-7), and the dissolution temperature is 40-95 ℃.
4. The purification method as claimed in claim 1, wherein in the step (2), sodium carbonate and activated carbon are added to the thiourea solution in such a manner that the weight ratio of sodium carbonate to industrial thiourea is 1 (900-.
5. The purification method according to claim 1, wherein in the step (2), a precipitant is added to the thiourea solution, and the reaction is carried out at 60 ℃ to 95 ℃ for 1 to 3 hours.
6. The purification method according to claim 1, wherein in the step (3), the filtrate is cooled to 10 ℃ to 20 ℃ for crystallization.
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| CN102584660A (en) * | 2011-12-27 | 2012-07-18 | 山东益丰生化环保股份有限公司 | Method for purifying thiocarbamide |
| JP2013202606A (en) * | 2012-03-29 | 2013-10-07 | Kurita Water Ind Ltd | Treatment method and device of thiourea-containing water |
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