A DIDNTB alkali metal salt, its preparation method and application

Abstract

The present invention provides a DIDNTB alkali metal salt, a preparation method and an application thereof, belonging to the technical field of DIDNTB salt formation. The DIDNTB alkali metal salt described in the present invention is a DIDNTB lithium salt, a DIDNTB sodium salt and a DIDNTB potassium salt. The preparation method of the present invention is as follows: Mix DIDNTB and an alkali metal salt in a solvent for a salt formation reaction to obtain a crude DIDNTB alkali metal salt; Mix the crude DIDNTB alkali metal salt with a solvent for recrystallization to obtain the DIDNTB alkali metal salt. The DIDNTB alkali metal salt obtained in the present invention overcomes the deficiency of poor water solubility of the existing DIDNTB, and the preparation process method is simple, the conditions are mild, the product purity is high, the yield is high, the cost is low, and it can be mass-produced, which is beneficial to further application in detection reagents.

Description

Technical Field

[0001] The present invention relates to the technical field of DIDNTB salt formation, and particularly to an alkali metal salt of DIDNTB, a preparation method thereof, and an application thereof. Background Art

[0002] 5',5”-Dinitro-3',3”-diiodo-3,4,5,6-tetrabromophenolsulfonephthalein, with the English name 5',5”-dinotro-3',3”-diiodo-3,4,5,6-tetrobromophenolsulfonephthalein (abbreviated as DIDNTB), has the following structural formula:

[0003]

[0004] DIDNTB is a protein error indicator. Due to its high sensitivity, it is used to detect trace amounts of albumin in urine or blood in the early diagnosis of kidney diseases. However, since DIDNTB is poorly soluble in water, in clinical diagnostic reagents, a large amount of organic solvents are often used for dissolution, wasting reagents, increasing costs, and being inconvenient to use, which affects the further application of DIDNTB.

[0005] Therefore, how to overcome the deficiencies of the prior art and increase the water solubility of DIDNTB to achieve the purpose of convenient use is a technical problem that needs to be solved at present. Summary of the Invention

[0006] The purpose of the present invention is to provide an alkali metal salt of DIDNTB, a preparation method thereof, and an application thereof to solve the technical problem of poor water solubility and inconvenient use of DIDNTB.

[0007] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides an alkali metal salt of DIDNTB, and the structural formula of the alkali metal salt of DIDNTB is as follows:

[0009]

[0010] Wherein, M is Li, Na or K.

[0011] The present invention provides a preparation method of an alkali metal salt of DIDNTB, including the following steps:

[0012] 1) Salt formation: Mix DIDNTB and an alkali metal salt in a solvent for a salt formation reaction to obtain a crude product of the alkali metal salt of DIDNTB;

[0013] 2) Recrystallization: Mix the crude product of the alkali metal salt of DIDNTB with a solvent for recrystallization to obtain the alkali metal salt of DIDNTB.

[0014] Further, in the step 1), the alkali metal salt is one or more of alkali metal carbonates, alkali metal acetates, and alkali metal bicarbonates; the molar ratio of DIDNTB to the alkali metal salt is 1:0.9 to 1.8.

[0015] Further, in the step 1), the solvent is an aprotic solvent, and the aprotic solvent includes one or more of tetrahydrofuran, acetone, acetonitrile, dioxane, dimethyl sulfoxide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, isobutyl ether, ethylene glycol dimethyl ether, benzene, toluene, and xylene.

[0016] Further, in the step 1), the mass-volume ratio of DIDNTB to the solvent is 1 g: 1 to 18 mL.

[0017] Further, in the step 1), the temperature of the salt formation reaction is 25 to 80 °C, and the time of the salt formation reaction is 0.5 to 13 h.

[0018] Further, in the step 2), the recrystallization includes a first recrystallization and a second recrystallization. The solvent for the first recrystallization includes one or more of ethyl acetate, dichloromethane, chloroform, and carbon tetrachloride; the solvent for the second recrystallization includes one or more of ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, and isobutyl ether.

[0019] Further, the mass-volume ratio of the crude DIDNTB alkali metal salt to the solvent for the first recrystallization is 1 g: 1 to 18 mL; the mass-volume ratio of the crude DIDNTB alkali metal salt to the solvent for the second recrystallization is 1 g: 1 to 18 mL.

[0020] Further, in the step 2), the temperature of the recrystallization is 30 to 80 °C, and the time of the recrystallization is 0.5 to 13 h.

[0021] The present invention provides an application of a DIDNTB alkali metal salt in the preparation of a microalbumin detection reagent.

[0022] Advantages of the present invention:

[0023] By salifying and recrystallizing DIDNTB to obtain a DIDNTB alkali metal salt, the present invention overcomes the problem of poor water solubility of existing DIDNTB. The purity of the finally obtained DIDNTB alkali metal salt product reaches 99.0%, and the total yield reaches 80%; moreover, the preparation method is simple, the conditions are mild, the product purity is high, the yield is high, the cost is low, and it can be mass-produced, which is beneficial for further application in microalbumin detection reagents. Specific embodiments

[0024] The present invention provides a DIDNTB alkali metal salt, and the structural formula of the DIDNTB alkali metal salt is as follows:

[0025]

[0026] Wherein, M is Li, Na or K.

[0027] In the present invention, the DIDNTB alkali metal salt is preferably a lithium salt of DIDNTB, a sodium salt of DIDNTB and a potassium salt of DIDNTB.

[0028] The present invention provides a method for preparing a DIDNTB alkali metal salt, comprising the following steps:

[0029] 1) Salt formation: Mix DIDNTB and an alkali metal salt in a solvent for a salt formation reaction to obtain a crude product of the DIDNTB alkali metal salt;

[0030] 2) Recrystallization: Mix the crude product of the DIDNTB alkali metal salt with a solvent for recrystallization to obtain the DIDNTB alkali metal salt.

[0031] In the present invention, the preparation process of the DIDNTB alkali metal salt is shown as follows:

[0032]

[0033] In the present invention, in step 1), the alkali metal salt is one or more of an alkali metal carbonate, an alkali metal acetate and an alkali metal bicarbonate, preferably an alkali metal bicarbonate, more preferably lithium bicarbonate, sodium bicarbonate or potassium bicarbonate; the molar ratio of DIDNTB to the alkali metal salt is 1:0.9 to 1.8, preferably 1:1 to 1.6, more preferably 1:1.2 to 1.4.

[0034] In the present invention, when the base selected for the salt formation reaction is a strong base, due to the too strong alkalinity, the product turns black; when the selected alkali metal salt is a carbonate, due to the relatively strong alkalinity, the product turns dark green; when the selected alkali metal salt is an acetate, due to the too weak alkalinity, the reaction time will be too long and the reaction will not be complete enough.

[0035] In the present invention, if the amount of the alkali metal salt selected for the salt formation reaction is too small, less than 1.0 equivalent, the reaction will not be complete, affecting the yield and purity; if the amount of the selected alkali metal salt is greater than 1.6 equivalents, there will be alkali residue, which is not easy to remove and affects the purity.

[0036] In the present invention, in step 1), the solvent is an aprotic solvent, and the aprotic solvent includes one or more of tetrahydrofuran, acetone, acetonitrile, dioxane, dimethyl sulfoxide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, isobutyl ether, ethylene glycol dimethyl ether, benzene, toluene, and xylene, preferably tetrahydrofuran, acetone, acetonitrile, and dioxane.

[0037] In the present invention, when the reaction solvent selected for the salt formation reaction is a protic solvent, it will cause the color of the DIDNTB alkali metal salt to deepen and is not suitable for use; when the selected solvent is an aprotic solvent, the color of the DIDNTB alkali metal salt does not change and can be used.

[0038] In the present invention, in step 1), the mass-volume ratio of DIDNTB to the solvent is 1 g: 1 - 18 mL, preferably 1 g: 2 - 16 mL, and more preferably 1 g: 5 - 12 mL.

[0039] In the present invention, when the volume of the reaction solvent selected for the salt formation reaction is too small compared to DIDNTB, the reaction is not sufficient and the reaction effect is poor; when the volume of the reaction solvent is too large compared to DIDNTB, the reagent is wasted and the yield is low.

[0040] In the present invention, in step 1), the temperature of the salt formation reaction is 25 - 80 °C, preferably 30 - 75 °C, and more preferably 35 - 70 °C; the time of the salt formation reaction is 0.5 - 13 h, preferably 1 - 12 h, and more preferably 3 - 10 h.

[0041] In the present invention, when the reaction temperature selected for the salt formation reaction is lower than 30 °C, the reaction rate is too slow, the time is too long, and the reaction efficiency is low; when the reaction temperature is higher than 75 °C, the color of the product is too deep and side reactions are likely to occur. When the reaction time of the salt formation reaction is less than 1 hour, the reaction is not complete, the yield is low, the purity is low, and the free DIDNTB is high; when the reaction time is greater than 12 hours, the reaction time is too long, there are many side reactions, the impurities are high, and the purity is low.

[0042] In the present invention, the DIDNTB alkali metal salt after the salt formation reaction mainly contains three types of substances: the first type is small polar salt-forming or non-salt-forming small molecules brought in from the raw materials, the second type is free DIDNTB, and the third type is small polar small molecules; the salt formation reaction described in the present invention not only enables DIDNTB to form a salt with an alkali metal, but also crystallizes in the salt formation solvent to effectively remove the large polar salt-forming or non-salt-forming small molecules in DIDNTB.

[0043] In the present invention, the DIDNTB with a purity of 90% is used to prepare a crude product of the DIDNTB alkali metal salt with a purity of 94% and a reaction yield of 90% through a salt formation reaction and crystallization.

[0044] In the present invention, in step 2), the recrystallization includes a first recrystallization and a second recrystallization. The solvent for the first recrystallization includes one or more of ethyl acetate, dichloromethane, chloroform, and carbon tetrachloride, preferably ethyl acetate and / or dichloromethane; the solvent for the second recrystallization includes one or more of diethyl ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, and isobutyl ether, preferably diethyl ether and / or petroleum ether.

[0045] In the present invention, the recrystallization reaction in step 2) is to perform recrystallization once with each of two different aprotic solvents; in the first recrystallization, the DIDNTB alkali metal salt is insoluble in the solvent, while DIDNTB is soluble, so that the remaining free DIDNTB in the reaction can be removed; in the second solvent recrystallization, small polar small molecule impurities contained in the DIDNTB alkali metal salt are soluble in the solvent, while the DIDNTB alkali metal salt is insoluble, thereby achieving the removal of impurities; therefore, the recrystallization using two different aprotic solvents for recrystallization once each has a better effect.

[0046] In the present invention, the mass-to-volume ratio of the crude DIDNTB alkali metal salt to the solvent for the first recrystallization is 1 g: 1 - 18 mL, preferably 1 g: 2 - 16 mL, and more preferably 1 g: 5 - 10 mL; the mass-to-volume ratio of the crude DIDNTB alkali metal salt to the solvent for the second recrystallization is 1 g: 1 - 18 mL, preferably 1 g: 2 - 16 mL, and more preferably 1 g: 5 - 10 mL.

[0047] In the present invention, when the mass-to-volume ratio of the crude DIDNTB alkali metal salt to the solvent in the recrystallization reaction is too large, the recrystallization is not sufficient and the purification effect is not good; when the mass-to-volume ratio of the crude DIDNTB alkali metal salt to the solvent is too small, the reagent is wasted and the yield is reduced.

[0048] In the present invention, in step 2), the temperature of the recrystallization is 30 - 80 °C, preferably 35 - 75 °C, and more preferably 40 - 70 °C; the time of the recrystallization is 0.5 - 13 h, preferably 1 - 12 h, and more preferably 5 - 10 h.

[0049] In the present invention, when the recrystallization reaction temperature is lower than 35 °C or the time is less than 1 hour, the dissolution and dispersion are not sufficient; when the recrystallization temperature is higher than 75 °C and the time is greater than 12 hours, the color of the product is too deep.

[0050] In the present invention, for the DIDNTB alkali metal salt (purity 94%), after recrystallization with two different aprotic solvents, the purity of the DIDNTB alkali metal salt product reaches 99.0%, and the total yield of the two recrystallizations reaches 88%.

[0051] The purity of the finally obtained DIDNTB alkali metal salt product of the present invention reaches 99.0%, and the total yield reaches 80%.

[0052] The present invention provides an application of a DIDNTB alkali metal salt in the preparation of a microalbumin detection reagent.

[0053] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0054] The DIDNTB used in the following experimental examples and embodiments is a commercially available raw material with a purity of 90.02%.

[0055] Experimental Example 1

[0056] Comparison of the salt formation reaction effect

[0057] (1) Alkali metal salts

[0058] Weigh 4 portions of DIDNTB, each portion being 104.6 g (0.1 mol), and add them to the reactor respectively. Weigh 0.11 mol of alkali metal salts of sodium ions according to 1.1 eq, namely sodium hydroxide, sodium carbonate, sodium bicarbonate, and sodium acetate, and add them to the reactor respectively. Then add 300 mL of acetonitrile and stir the reaction at 50 °C for 6 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake to obtain the crude product, collect and weigh it. The relevant experimental data are shown in Table 1.

[0059] Table 1 Selection of alkali metal salts

[0060]

[0061]

[0062] The data in Table 1 show that when sodium hydroxide is used as the reaction base, the alkalinity is too strong, and the appearance of the product is black, which does not meet the requirements; when sodium carbonate is used as the reaction base, the alkalinity is relatively strong, the appearance of the crude product is blackish green, and the excessive alkali is not easy to remove, which does not meet the requirements; when sodium acetate is used as the reaction base, the alkalinity is too weak, the reaction is slow and incomplete, and the appearance of the crude product is orange, which does not meet the requirements; when sodium bicarbonate is used as the reactant, the product is light green, with a relatively high yield and high purity.

[0063] (2) Alkali metal salt feeding equivalent

[0064] Weigh 5 portions of DIDNTB, each portion being 104.6 g (0.1 mol), add them to the reactor, then measure 0.9 eq, 1.0 eq, 1.2 eq, 1.6 eq and 1.8 eq of sodium bicarbonate respectively, add them to the reactor in sequence, add 300 mL of dioxane respectively, stir and react at 55 °C for 2 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake to obtain the crude product, collect and weigh. The relevant experimental data are shown in Table 2.

[0065] Table 2 Selection of feed equivalents of alkali metal salts

[0066]

[0067] The data in Table 2 show that when the feed ratio of sodium bicarbonate to DIDNTB is 0.9 eq, the reaction is incomplete; when the feed ratio is 1.8 eq, the alkali is excessive in the system, which affects the darkening of the color of the crude product, and the excessive alkali is not easy to remove; when the feed ratio is 1.0 eq - 1.6 eq, the yield is relatively high, the purity is relatively high, and the effect is good.

[0068] (3) Salt-forming solvent

[0069] Weigh 5 portions of DIDNTB, each portion being 104.6 g (0.1 mol), add them to the reactor in sequence, weigh 5 portions of 1.1 eq of sodium bicarbonate, add them to the reactor in sequence, add 450 mL of tetrahydrofuran, acetone, acetonitrile, dioxane and methanol respectively, react at 40 °C for 10 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake to obtain the crude product, collect and weigh. The relevant experimental data are shown in Table 3.

[0070] Table 3 Selection of salt-forming solvents

[0071]

[0072] The data in Table 3 show that when the salt-forming reaction solvents are tetrahydrofuran, acetone, acetonitrile and dioxane, the yields can all reach more than 90%, and the purities are more than 94%; when the reaction solvent is methanol (protic solvent), the relative yield is lower and the purity is lower.

[0073] (4) Salt-forming solvent usage amount

[0074] Weigh 5 portions of DIDNTB, each portion being 104.6 g (0.1 mol), add them to the reactor, weigh 5 portions of 1.2 eq of sodium bicarbonate respectively, add them to the reactor respectively, add acetonitrile according to the mass-volume ratio of DIDNTB to the solvent of 1:1, 1:2, 1:6, 1:16, 1:18 respectively, stir and react at 50 °C for 6 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake to obtain the crude product, collect and weigh. The relevant experimental data are shown in Table 4.

[0075] Selection of the amount of salt-forming solvent used in Table 4

[0076]

[0077] The data in Table 4 show that when the mass-volume ratio of DIDNTB to acetonitrile is 1 g:1 mL, the reaction is incomplete and the product purity is low; when the mass-volume ratio is 1 g:18 mL, the yield is too low; when the mass-volume ratio is 1 g:2 - 16 mL, the product yield is high, the purity is high, and the effect is good.

[0078] (5) Salt-forming temperature

[0079] Weigh 5 portions of DIDNTB, each portion being 104.6 g (0.1 mol), add them to the reactor. Weigh 1.1 eq of sodium bicarbonate respectively, add them to the reactor, and add 500 mL of acetonitrile respectively. Stir and react at 25 °C, 30 °C, 50 °C, 75 °C, and 80 °C for 6 hours. After the reaction is completed, filter, dry the filter cake, weigh it, and obtain the crude product. The relevant experimental data are shown in Table 5.

[0080] Selection of salt-forming temperature in Table 5

[0081]

[0082] The data in Table 5 show that when the reaction temperature is 25 °C, the obtained crude product is orange, the reaction is not complete enough, the yield is low, and the purity is low; when the reaction temperature is 80 °C, the obtained crude product is dark green, side reactions increase, impurities are high, the yield is low, and the purity is low; when the reaction temperature is 30 °C - 75 °C, the product is light green, the yield is high, the purity is high, and the effect is good.

[0083] (6) Salt-forming reaction time

[0084] Weigh 5 portions of DIDNTB, each portion being 104.6 g (0.1 mol), add them to the reactor respectively. Weigh 1.1 eq of sodium bicarbonate, add it to the reactor, and add 500 mL of dioxane respectively. Stir and react at 50 °C for 0.5 hour, 1 hour, 6 hours, 12 hours, and 13 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake, obtain the crude product, collect it, and weigh it. The relevant experimental data are shown in Table 6.

[0085] Selection of salt-forming reaction time in Table 6

[0086]

[0087] Table 6 data shows that: when the reaction time is 0.5 hours, the obtained crude product is orange-red, the reaction is not complete enough, the yield is low, and the purity is low; when the reaction time is 13 hours, the obtained crude product is dark green, side reactions increase, impurities are high, the yield is low, and the purity is low; when the reaction time is 1 - 12 hours, the obtained crude product is light green, the yield is high, and the purity is high.

[0088] Experimental Example 2

[0089] Comparison of recrystallization effects

[0090] Salt formation reaction: Weigh a total of 4183 g (4.0 mol) of DIDNTB and add it to the reactor. Add 369.6 g (4.4 mol) of sodium bicarbonate at 1.1 eq. Add a total of 12000 mL of acetonitrile according to the mass - volume ratio of DIDNTB to the solvent of 1:3. Stir and react at 50 °C for 6 hours. After the reaction is completed, cool it to room temperature, filter, dry the filter cake, collect it, and obtain 3905 g of crude DIDNTB sodium salt, with a yield of 91.6% and a purity of 94.36%; for the next experiment.

[0091] (1) Selection of the first recrystallization solvent

[0092] Take 500 g of the crude DIDNTB sodium salt prepared in the previous experiment, divide it into 5 equal parts, each part being 100 g, and add them to the reactor respectively. Add 400 mL of ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, and methanol respectively. Among them, stir at 45 °C for 5 hours respectively, stop stirring, cool to room temperature, filter, dry the filter cake, obtain the product, collect it, and weigh it. The relevant experimental data is shown in Table 7.

[0093] Table 7 Selection of the first recrystallization solvent

[0094]

[0095] The data in Table 7 shows that: when the first recrystallization solvent is ethyl acetate, dichloromethane, chloroform, or carbon tetrachloride, the purity is above 97% and the yield is above 95%; when the solvent is the protic solvent methanol, the yield is lower and the purity does not increase.

[0096] Selection of the second recrystallization solvent

[0097] First recrystallization: Take 900 g of the crude DIDNTB sodium salt prepared in the previous experiment, add it to the reactor, add 3600 mL of ethyl acetate, stir at 45 °C for 5 hours, stop stirring, cool to room temperature, filter, dry the filter cake, obtain the product, collect it, and weigh it as 860 g, with a yield of 95.6% and a purity of 97.18%, for the next experiment;

[0098] Second recrystallization: Divide 800 g of the DIDNTB sodium salt obtained in the previous step into 8 equal parts, each part being 100 g. Add them separately to the reactor, and then add diethyl ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, isobutyl ether, ethylene glycol dimethyl ether, and ethanol (protic solvent) respectively, with a volume of 600 mL. Stir at 35 °C for 6 hours. After stopping stirring, cool to room temperature, filter, dry the filter cake to obtain the pure product. Collect and weigh. The relevant experimental data are shown in Table 8.

[0099] Table 8 Selection of solvents for the second recrystallization

[0100]

[0101] The data in Table 8 show that when the solvents for the second recrystallization are diethyl ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether, isobutyl ether, and ethylene glycol dimethyl ether, the yield of the obtained pure product is over 94%, and the purity is over 99.0%; the yield of ethylene glycol dimethyl ether is relatively low, and the purity has not increased significantly; for other protic solvents such as ethanol, the yield of the obtained product is lower than 90.0%, and the purity decreases after recrystallization.

[0102] (3) Amount of recrystallization solvent used

[0103] Take 500 g of the crude DIDNTB sodium salt obtained in the previous experiment and divide it into 5 equal parts, each part being 100 g. Add them separately to the reactor, and then add ethyl acetate according to the mass-volume ratios of the crude DIDNTB sodium salt to the recrystallization solvent of 1:1, 1:2, 1:6, 1:16, and 1:18 respectively. Stir at 50 °C for 5 hours. After stopping stirring, filter, dry the filter cake, weigh, and obtain the product. The relevant experimental data are shown in Table 9.

[0104] Table 9 Selection of the amount of recrystallization solvent used

[0105]

[0106]

[0107] The data in Table 9 show that when the mass-volume ratio of the crude DIDNTB sodium salt to ethyl acetate is 1 g:1 mL, the stirring and dispersion are not sufficient, the product purity is low, and the purity has not increased significantly; when the mass-volume ratio is 1 g:18 mL, the product yield is too low; when the mass-volume ratio is 1 g:2 - 16 mL, the yield is high and the purity is high.

[0108] (4) Recrystallization temperature

[0109] Take 500 g of the crude DIDNTB sodium salt obtained from the previous experiment, divide it into 5 equal parts, 100 g each, add them to the reactor respectively, then add 400 mL of ethyl acetate respectively, stir at 30 °C, 35 °C, 50 °C, 75 °C, and 80 °C for 9 hours respectively. After stopping stirring, cool to room temperature, filter, dry the filter cake, obtain the product, collect and weigh. The relevant experimental data are shown in Table 10.

[0110] Table 10 Selection of recrystallization temperature

[0111]

[0112] The data in Table 10 show that: when the recrystallization temperature is 30 °C, the recrystallization is not sufficient and the purity is low; when the reaction temperature is 80 °C, the color of the obtained product deepens, the purity decreases, and the yield decreases; when the reaction temperature is 35 °C - 75 °C, the color of the product meets the requirements, the yield is high, and the purity is high.

[0113] (5) Recrystallization time

[0114] Take 500 g of the crude DIDNTB sodium salt obtained from the previous experiment, divide it into 5 equal parts, 100 g each, add them to the reactor respectively, add 400 mL of ethyl acetate respectively, stir for 0.5 hour, 1 hour, 7 hours, 12 hours, and 13 hours respectively. After stopping stirring, cool to room temperature, filter, dry the filter cake, obtain the product, collect and weigh. The relevant experimental data are shown in Table 11.

[0115] Table 11 Selection of recrystallization time

[0116]

[0117] The data in Table 11 show that: when the recrystallization time is 0.5 hour, the recrystallization is not sufficient and the purity is low; when the recrystallization time is 13 hours, the color of the obtained product deepens, the product purity is low, and the yield decreases; when the recrystallization time is 1 - 12 hours, the color of the product meets the requirements, the yield is high, and the purity is high.

[0118] Example 1

[0119] Preparation of DIDNTB lithium salt

[0120] Salt formation reaction: Weigh 104.6 g (0.1 mol) of DIDNTB and add it to the reactor, add 8.2 g (0.12 mol) of lithium bicarbonate at 1.2 eq, add 300 mL of acetone, stir and react at 40 °C for 8 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake, collect, and obtain 96.8 g of the crude DIDNTB lithium salt, with a yield of 92.3% and a purity of 94.13%.

[0121] Recrystallization:

[0122] First recrystallization: Add 96.8 g of the crude product from the previous step to a reactor, add 200 mL of dichloromethane, stir at 40 °C for 4 hours, stop stirring, cool to room temperature, filter, dry the filter cake, collect, and weigh it as 91.5 g, with a yield of 94.5% and a purity of 97.32%.

[0123] Second recrystallization: Add 91.5 g of the product from the previous step to a reactor, add 400 mL of isopropyl ether, stir at 55 °C for 1 hour, stop stirring, cool to room temperature, filter, dry the filter cake, collect, and obtain the pure product of DIDNTB lithium salt, weigh it as 86.5 g, with a yield of 94.5%, an overall yield of 82.4%, and a purity of 99.13%.

[0124] Example 2

[0125] Preparation of DIDNTB sodium salt

[0126] 1) Salt formation reaction: Weigh 104.6 g (0.1 mol) of DIDNTB and add it to a reactor, add 9.2 g (0.11 mol) of sodium bicarbonate at 1.1 eq, add 300 mL of acetonitrile, stir and react at 40 °C for 8 hours. After the reaction is completed, cool to room temperature, filter, dry the filter cake, collect, and obtain 99.3 g of the crude product of DIDNTB sodium salt, with a yield of 93.2% and a purity of 95.15%.

[0127] 2) Recrystallization:

[0128] First recrystallization: Add 99.3 g of the crude product from the previous step to a reactor, add 200 mL of dichloromethane, stir at 40 °C for 4 hours, stop stirring, cool to room temperature, filter, dry the filter cake, collect, and weigh it as 93.8 g, with a yield of 94.5% and a purity of 97.32%.

[0129] Second recrystallization: Add 93.8 g of the product from the previous step to a reactor, add 400 mL of isopropyl ether, stir at 55 °C for 1 hour, stop stirring, cool to room temperature, filter, dry the filter cake, collect, and obtain the pure product of DIDNTB sodium salt, weigh it as 89.2 g, with a yield of 95.1%, an overall yield of 83.7%, and a purity of 99.34%.

[0130] Example 3

[0131] Preparation of DIDNTB potassium salt

[0132] 1) Salt formation reaction: Weigh 104.6 g (0.1 mol) of DIDNTB and add it to the reactor. Then add 10.0 g (0.1 mol) of potassium bicarbonate (1.0 eq), 300 mL of acetone, and stir the reaction at 40 °C for 8 hours. After the reaction is completed, cool it to room temperature, filter, dry the filter cake, collect it, and obtain 99.3 g of the crude potassium salt of DIDNTB, with a yield of 91.8% and a purity of 95.21%.

[0133] 2) Recrystallization:

[0134] First recrystallization: Add 99.3 g of the crude product from the previous step to the reactor, add 200 mL of dichloromethane, stir at 40 °C for 4 hours, stop stirring, cool it to room temperature, filter, dry the filter cake, collect it, weigh it to be 92.5 g, with a yield of 93.2% and a purity of 97.63%.

[0135] Second recrystallization: Add 92.5 g of the product from the previous step to the reactor, add 400 mL of isopropyl ether, stir at 55 °C for 1 hour, stop stirring, cool it to room temperature, filter, dry the filter cake, collect it, and obtain the pure potassium salt of DIDNTB, weigh it to be 88.0 g, with a yield of 95.1%, a total yield of 81.3%, and a purity of 99.13%.

[0136] Test example:

[0137] The solubility data of the lithium salt, sodium salt, and potassium salt of DIDNTB obtained in Test Examples 1, 2, and 3 and DIDNTB are compared as shown in Table 12:

[0138] Table 12 Solubility of the alkali metal salts of DIDNTB obtained in Examples 1 - 3

[0139]

[0140]

[0141] Definition of the name terms represented by solubility:

[0142] Very soluble: It means that 1 g (mL) of the solute can dissolve in less than 1 mL of the solvent;

[0143] Freely soluble: It means that 1 g (mL) of the solute can dissolve in 1 - less than 10 mL of the solvent;

[0144] Soluble: It means that 1 g (mL) of the solute can dissolve in 10 - less than 30 mL of the solvent;

[0145] Sparingly soluble: It means that 1 g (mL) of the solute can dissolve in 30 - less than 100 mL of the solvent;

[0146] Sparingly soluble: It means that 1 g (mL) of solute can dissolve in 100 to less than 1000 mL of solvent;

[0147] Very slightly soluble: It means that 1 g (mL) of solute can dissolve in 1000 to less than 10000 mL of solvent;

[0148] Practically insoluble or insoluble: It means that 1 g (mL) of solute cannot completely dissolve in 10000 mL of solvent;

[0149] As can be seen from Table 12, the solubility of lithium salt of DIDNTB, sodium salt of DIDNTB and potassium salt of DIDNTB in water increases significantly.

[0150] Example 4

[0151] Application of lithium salt of DIDNTB in detection reagent

[0152] 1) Preparation of solutions: Preparation of chromogenic solution: Weigh 30 mg of lithium salt of DIDNTB and 0.3 g of surfactant respectively, add them to 100 mL of distilled water, stir evenly and set aside; Preparation of albumin standard solution: Weigh human serum albumin, dissolve it with distilled water, and prepare concentration gradients of 10, 25, 50, 100, and 200 mg / L respectively and set aside; Preparation of buffer solution: Prepare 100 mL of pH 3.0 citric acid - sodium citrate buffer solution, stir evenly and set aside;

[0153] 2) Determination of albumin content: In 6 colorimetric tubes, add 4.8 mL of buffer solution, 100 μL of chromogenic solution, 100 μL of 5 kinds of concentration gradients of human serum albumin standard solution, and 100 μL of protein standard solution to be measured respectively, establish a standard curve, and measure the content of trace albumin in the sample to be measured.

[0154] Example 5

[0155] Application of sodium salt of DIDNTB in detection reagent

[0156] 1) Preparation of solutions: Preparation of chromogenic solution: Weigh 40 mg of sodium salt of DIDNTB and 0.3 g of surfactant respectively, dissolve them in 100 mL of distilled water, stir evenly and set aside; Preparation of albumin standard solution: Weigh human serum albumin, dissolve it with distilled water, and prepare concentration gradients of 10, 25, 50, 100, and 200 mg / L respectively and set aside; Preparation of buffer solution: Prepare 100 mL of pH 3.0 citric acid - sodium citrate buffer solution, stir evenly and set aside;

[0157] 2) Determination of albumin content: In 6 colorimetric tubes, add 4.8 mL of buffer solution respectively, add 100 μL of chromogenic solution respectively, add 100 μL of human serum albumin standard solutions of 5 concentrations respectively, and add 100 μL of the protein sample to be tested, establish a standard curve, and measure the content of trace albumin in the sample to be tested.

[0158] Example 6

[0159] Application of DIDNTB potassium salt in detection reagent

[0160] 1) Preparation of solutions: Preparation of chromogenic solution: Weigh 50 mg of DIDNTB potassium salt and 0.3 g of surfactant respectively, dissolve them in 100 mL of distilled water, stir evenly, and set aside; Preparation of albumin standard solution: Weigh human serum albumin, dissolve it with distilled water, and prepare concentration gradients of 10, 25, 50, 100, and 200 mg / L respectively, and set aside; Preparation of buffer solution: Prepare 100 mL of citric acid-sodium citrate buffer solution with pH 3.0, stir evenly, and set aside.

[0161] 2) Determination of albumin content: In 6 colorimetric tubes, add 4.8 mL of buffer solution respectively, add 100 μL of chromogenic solution respectively, then add 100 μL of human serum albumin standard solutions of 5 concentrations respectively, and add 100 μL of the protein sample to be tested, establish a standard curve, and measure the content of trace albumin in the sample to be tested.

[0162] As can be seen from the above examples, the present invention provides a DIDNTB alkali metal salt, its preparation method and application. The present invention obtains the DIDNTB alkali metal salt by salifying and recrystallizing DIDNTB, overcomes the problem of poor water solubility of existing DIDNTB, and finally the obtained DIDNTB alkali metal salt product has a purity of 99.0% and a total yield of 80%; moreover, the preparation process method is simple, the conditions are mild, the product purity is high, the yield is high, the cost is low, it can be mass-produced, and it is beneficial to further application in trace albumin detection reagents.

[0163] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a DIDNTB alkali metal salt, characterized in that, It includes the following steps: 1) Salt formation: Mix DIDNTB and an alkali metal salt in a solvent for a salt formation reaction to obtain a crude product of the DIDNTB alkali metal salt; 2) Recrystallization: Mix the crude product of the DIDNTB alkali metal salt with a solvent for recrystallization to obtain the DIDNTB alkali metal salt; The structural formula of the DIDNTB alkali metal salt is as follows: ； wherein M is Li, Na or K; in the DIDNTB alkali metal salt, DIDNTB is 5',5''-dinitro-3',3''-diiodo-3,4,5,6-tetrabromophenolsulfonphthalein; the alkali metal salt is lithium bicarbonate, sodium bicarbonate or potassium bicarbonate; the molar ratio of DIDNTB to the alkali metal salt is 1:1.0 - 1.6; in step 1), the solvent is tetrahydrofuran, acetone, acetonitrile or dioxane; in step 1), the mass-volume ratio of DIDNTB to the solvent is 1 g: 2 - 16 mL; in step 1), the temperature of the salt formation reaction is 30 - 75 °C, and the time of the salt formation reaction is 1 - 12 h; in step 2), the recrystallization includes a first recrystallization and a second recrystallization. The solvent for the first recrystallization is ethyl acetate, dichloromethane, chloroform or carbon tetrachloride; the solvent for the second recrystallization is diethyl ether, petroleum ether, n-propyl ether, isopropyl ether, n-butyl ether or isobutyl ether; the mass-volume ratio of the crude product of the DIDNTB alkali metal salt to the solvent for the first recrystallization is 1 g: 2 - 16 mL; the mass-volume ratio of the crude product of the DIDNTB alkali metal salt to the solvent for the second recrystallization is 1 g: 2 - 16 mL; in step 2), the temperature of the recrystallization is 35 - 75 °C, and the time of the recrystallization is 1 - 12 h.

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