A method for synthesizing a standard sample for the detection of tartrazine intermediates
By preparing a standard sample of methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monopotassium salt, the problem of difficult detection of tartrazine intermediates in existing technologies was solved, enabling rapid and accurate quantitative analysis that meets food safety requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI DYESTUFFS RES INST
- Filing Date
- 2025-12-31
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies make it difficult to quickly and accurately detect the content of methyl 5-pyrazolone monosodium salt of 1-(4'-sulfonylphenyl)-3-carboxylic acid. Furthermore, the potassium and sodium salts have the same retention time in high-performance liquid chromatography, which makes detection difficult.
A diazo reaction was performed using p-aminobenzenesulfonic acid, sodium nitrite, and hydrochloric acid, followed by condensation with dimethyl acetyl succinate to close the ring. Then, a potassium salt monopotassium salt of 1-(4'-sulfonylphenyl)-3-carboxylic acid methyl ester-5-pyrazolone was prepared by potassium salt substitution reaction. Finally, a standard sample was obtained by purification and used for high performance liquid chromatography detection.
This method enables rapid and accurate quantitative detection of tartrazine intermediates, improving the accuracy and purity of the detection and meeting food safety standards.
Smart Images
Figure CN122127279A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of synthetic food colorant manufacturing, in particular to a synthesis method of a standard sample for detecting a lemon yellow intermediate. BACKGROUND
[0002] Lemon yellow is the most widely used and applied variety of synthetic food colorants, commonly used in food, medicine, cosmetics, toys, daily chemicals, feed, food packaging and other fields, with an annual demand of more than ten thousand tons worldwide, accounting for one fourth of the synthetic food colorants market.
[0003] 1- (4'-sulfonic acid phenyl) -3-carboxylic acid methyl ester-5-pyrazolone monosodium salt (CAS No: 104236-34-2) is an important dye, pesticide and pharmaceutical intermediate, and also a reaction intermediate in the synthesis of lemon yellow. A small amount of the intermediate is left in the lemon yellow during production. The national standard for food safety, lemon yellow, GB4481.1-2010, stipulates that the mass fraction of the intermediate in lemon yellow should not exceed 0.1%.
[0004] Since the retention time of 1- (4'-sulfonic acid phenyl) -3-carboxylic acid methyl ester-5-pyrazolone monopotassium salt and sodium salt in high performance liquid chromatography is the same, and the crystal structure formed by the combination of potassium ion and sulfonic acid group is more stable, the potassium salt is more likely to crystallize from the reaction system than the sodium salt, the product has high purity and less by-products. Therefore, the patent selects to prepare potassium salt instead of sodium salt. SUMMARY
[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide a synthesis method of a standard sample for detecting a lemon yellow intermediate.
[0006] The present application uses p-aminobenzenesulfonic acid and acetylsuccinic acid dimethyl ester as raw materials, and obtains the finished product through diazotization, condensation ring closure, potassium salt substitution reaction and purification. The finished product can quickly and accurately detect 1- (4'-sulfonic acid phenyl) -3-carboxylic acid methyl ester-5-pyrazolone monosodium salt in lemon yellow.
[0007] In order to achieve the purpose of the present application, the technical scheme adopted is:
[0008] A synthesis method of a standard sample for detecting a lemon yellow intermediate as shown in structural formula 1, as shown in reaction formula 1 below:
[0009]
[0010] Reaction formula 1;
[0011]
[0012] Structural Formula 1;
[0013] The lemon yellow intermediate is the methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monopotassium salt C shown in structural formula 1. 11 H 11 N2KO6S.
[0014] A method for synthesizing a standard sample for the detection of tartrazine intermediates, comprising the following steps:
[0015] 1) Diazo reaction:
[0016] p-Aminobenzenesulfonic acid, sodium nitrite, and hydrochloric acid are mixed in a molar ratio of 1:1-1.05:2-2.5 (preferably 1:1.05:2.5) and allowed to undergo a full diazo reaction to obtain p-aminobenzenesulfonic acid diazonium salt.
[0017] The diazo reaction was carried out at a temperature of 10℃-15℃ and a pH of <1.0.
[0018] 2) Condensation and ring-closing reaction:
[0019] Add acetyl succinate dimethyl to the diazonium salt obtained in step 1) and allow it to undergo a condensation and ring-closure reaction at a temperature of 15℃-25℃. Adjust the pH to <5.0 with sodium carbonate solution. The reaction ends when the solution is clear, transparent and wine-red, and the condensation and ring-closure product is obtained.
[0020] 3) Potassium salt substitution reaction:
[0021] Add edible salt to the solution in step 2), and salt out to obtain intermediate sodium salt filter cake. Dissolve the filter cake in water, add potassium carbonate solution to adjust the pH to 7.5-8.0, filter out the insoluble matter, and obtain intermediate potassium salt solution.
[0022] 4) Purification:
[0023] Add potassium acetate and hydrochloric acid to the solution in step 3) to adjust the pH to 2.5-5.0. After precipitation, filter to obtain intermediate potassium salt filter cake. Wash with organic solvent and dry in a vacuum oven to obtain the final product.
[0024] The molar fractions of p-aminobenzenesulfonic acid, dimethyl acetylsuccinate, and potassium acetate are 1:0.9-1:0.7-0.8.
[0025] In a preferred embodiment of the present invention, the reaction time of the diazo reaction is 1 hour.
[0026] In a preferred embodiment of the present invention, in the potassium salt substitution reaction, the proportion of added edible salt is 20%-25% of the volume of the condensation-closed ring product solution in step 2).
[0027] In a preferred embodiment of the present invention, the molar fractions of p-aminobenzenesulfonic acid, dimethyl acetylsuccinate, and potassium acetate are 1:0.95:0.76.
[0028] In a preferred embodiment of the present invention, potassium acetate and hydrochloric acid are added to the solution in step 3) to adjust the pH to 3.5-4.0.
[0029] In a preferred embodiment of the present invention, the organic solvent is any one of ethanol, propanol, propylene glycol, or glycerol. Preferably, it is an aqueous solution of ethanol with a volume fraction of 95%.
[0030] In a preferred embodiment of the present invention, the purification step is replaced by membrane separation or ion exchange resin reaction.
[0031] The beneficial effects of this invention are as follows:
[0032] This patent provides a method for preparing a standard sample for detecting the content of tartrazine intermediates, the structure of which is shown in structural formula 1. This method can quickly and accurately quantify the methyl 5-pyrazolone monosodium salt of 1-(4'-sulfonylphenyl)-3-carboxylic acid ester. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of the results of Embodiment 1 of the present invention. Figure One .
[0034] Figure 2 This is a schematic diagram of the results of Embodiment 1 of the present invention. Figure Two .
[0035] Figure 3 This is a schematic diagram of the results of Embodiment 2 of the present invention. Figure One .
[0036] Figure 4 This is a schematic diagram of the results of Embodiment 2 of the present invention. Figure Two . Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, in the following descriptions, well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.
[0038] Example 1:
[0039] 1) Diazo reaction
[0040] Add 90 mL of water and 17.32 g of 100% p-aminobenzenesulfonic acid to a 250 mL beaker, start stirring, and add 14.21 g of 36% hydrochloric acid. Cool to 0-5°C in an ice-water bath. Slowly add approximately 23.1 g of 30% sodium nitrite solution dropwise, maintaining the temperature at 5-10°C. The reaction endpoint is reached when the solution turns blue on starch-potassium iodide test paper. After the reaction is complete, continue stirring for 30 minutes.
[0041] 2) Condensation and ring-closing reaction
[0042] Slowly add 18.82g of dimethyl thioacetyl succinate to the diazo solution, and slowly add saturated sodium carbonate solution to adjust the pH to about 5.0. During this process, control the temperature to not exceed 15℃. When the precipitate disappears and the solution turns a transparent wine red color, continue stirring for 30 minutes.
[0043] 3) Potassium salt substitution reaction
[0044] Add 20-25% edible salt to the solution, stir to precipitate, filter, and obtain a filter cake of methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monosodium salt. Transfer the filter cake to a beaker, add 100 mL of water, slowly add 15% potassium carbonate solution to adjust the pH to 7.5-8.0, stir continuously for 30 minutes, and then filter off the insoluble matter.
[0045] 4) Purification
[0046] Add 7.5g of potassium acetate to the solution, adjust the pH to 3.5-4 with hydrochloric acid, filter after precipitation, wash the filter cake with 95% ethanol, dry it in a vacuum oven, grind it, and obtain the finished product.
[0047] Example 2:
[0048] Instead of purification step 4) in Example 1, 500g of solution was processed by membrane separation, and the solution was divided into 350g of pure water and 150g of concentrate. Hydrochloric acid was added to the concentrate to adjust the pH to 4.0, and a solid was precipitated. The filter cake was washed with 95% ethanol, dried and crushed in a vacuum oven to obtain the finished product.
[0049] The monopotassium salt of 1-(4'-sulfonylphenyl)-3-carboxylic acid methyl ester-5-pyrazolone synthesized in this invention has the structural formula shown in structural formula 1:
[0050]
[0051] Structural Formula 1
[0052] Molecular formula: C 11 H 11 N2KO6S, molecular weight: 338.38.
[0053] Purity testing:
[0054] The high performance liquid chromatography operating conditions were as follows: mobile phase: A, ammonium acetate solution; B, methanol; concentration gradient: linear concentration gradient from A(95):B(5) to A(50):B(50) for 40 min; column temperature: 40℃; flow rate: 1 mL / min; detection wavelength: 254 nm.
[0055] Example 1 sample, calculated using the high-performance liquid chromatography area normalization method, had a purity of 93.97%, and the retention time of methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monopotassium salt was 2.965 min. Figure 1 , Figure 2 As shown.
[0056] Example 2: The purity of the sample, calculated by high-performance liquid chromatography (HPLC) area normalization method, was 93.03%. The retention time of methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monopotassium salt was 2.953 min. Figure 3 , Figure 4 As shown.
[0057] The foregoing has shown and described the basic principles and main features of the invention and the advantages of the invention.
[0058] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.
Claims
1. A method for synthesizing a standard sample for detecting tartrazine intermediates as shown in structural formula 1, characterized in that, As shown in the following reaction formula 1: Reaction 1; Structural Formula 1; The lemon yellow intermediate is the methyl 1-(4'-sulfonylphenyl)-3-carboxylate-5-pyrazolone monopotassium salt C shown in structural formula 1. 11 H 11 N2KO6S.
2. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 1, characterized in that, Includes the following steps: 1) Diazo reaction: p-Aminobenzenesulfonic acid, sodium nitrite, and hydrochloric acid were mixed in a molar ratio of 1:1-1.05:2-2.5 and allowed to undergo a diazo reaction to obtain p-aminobenzenesulfonic acid diazonium salt. The diazo reaction was carried out at a temperature of 10℃-15℃ and a pH of <1.
0. 2) Condensation and ring-closing reaction: Add acetyl succinate dimethyl to the diazonium salt obtained in step 1) and allow it to undergo a condensation and ring-closure reaction at a temperature of 15℃-25℃. Adjust the pH to <5.0 with sodium carbonate solution. The reaction ends when the solution is clear, transparent and wine-red, and the condensation and ring-closure product is obtained. 3) Potassium salt substitution reaction: Add edible salt to the solution in step 2), and salt out to obtain intermediate sodium salt filter cake. Dissolve the filter cake in water, add potassium carbonate solution to adjust the pH to 7.5-8.0, filter out the insoluble matter, and obtain intermediate potassium salt solution. 4) Purification: Add potassium acetate and hydrochloric acid to the solution in step 3) to adjust the pH to 2.5-5.
0. After precipitation, filter to obtain intermediate potassium salt filter cake. Wash with organic solvent and dry in a vacuum oven to obtain the final product. The molar fractions of p-aminobenzenesulfonic acid, dimethyl acetylsuccinate, and potassium acetate are 1:0.9-1:0.7-0.
8.
3. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, The reaction time for the diazo reaction is 1 hour.
4. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, In the potassium salt substitution reaction, the proportion of added edible salt is 20%-25% of the volume of the condensation ring-closed product solution in step 2).
5. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, The molar fractions of p-aminobenzenesulfonic acid, dimethyl acetylsuccinate, and potassium acetate are 1:0.95:0.
76.
6. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, Potassium acetate and hydrochloric acid are added to the solution in step 3) to adjust the pH to 3.5-4.
0.
7. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, The organic solvent is any one of ethanol, propanol, propylene glycol, or glycerol.
8. The method for synthesizing a standard sample for detecting tartrazine intermediates as described in claim 2, characterized in that, The purification step is replaced by membrane separation or ion exchange resin exchange reaction.