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Process for preparing lemon chrome

A technology of tartrazine and p-aminobenzenesulfonic acid, applied in chemical instruments and methods, azo dyes, organic dyes, etc., can solve the problems of lack of reaction conversion rate, high product purity, and low content of organic impurities

Inactive Publication Date: 2007-04-25
上海染料研究所有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] In summary, this area lacks a method for preparing tartrazine with high reaction conversion rate, high product purity and low organic impurity content

Method used

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  • Process for preparing lemon chrome
  • Process for preparing lemon chrome
  • Process for preparing lemon chrome

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preparation example Construction

[0040] Figure 1 is a process flow diagram of the preparation method of tartrazine of the present invention. DMAS is dimethyl 2-acetylsuccinate, sodium sulfite is sodium nitrite, and para-acid is p-aminobenzenesulfonic acid.

[0041] As shown in Figure 1, the preparation method of tartrazine according to the present invention includes a diazotization reaction, a condensation reaction, a coupling reaction, a hydrolysis reaction, and post-treatment steps, wherein each post-treatment step includes a crystallization step, a membrane separation step, and a drying step. .

[0042] Phase transfer catalyst

[0043] The phase transfer catalyst is selected from ethanol, Span-Tween series, polyethylene glycol series, Ping Ping O (such as Ping Ping O produced by Shanghai Auxiliary Factory) and other additives or emulsifiers and dispersing agents, preferably polyethylene two The alcohol phase transfer catalyst is more preferably polyethylene glycol 400. The dosage is 0.1-2.0% of the weight of t...

Embodiment 1

[0063] In a 500mL four-necked flask, add 180mL of hot water at 60°C, add 20g of polyethylene glycol 400 (PEG-400), add 34.6g (0.20mol) of p-aminobenzenesulfonic acid with rapid stirring, stir for ten minutes, and cool to room temperature. Add 32 mL of industrial hydrochloric acid (31%). Continue to cool to 0-5°C, add dropwise 30% sodium nitrite solution 47g (0.20mol) under the liquid, maintain the temperature at 5-10°C, about 20min after adding, the Congo red test paper is blue and the potassium iodide starch test paper is light blue. After the addition, continue to stir for 20 minutes, add a small amount of sulfamic acid to eliminate excess nitrous acid.

[0064] In the above diazonium solution, after stirring for 5 minutes, add 37.64g (0.20mol) of DMAS (dimethyl 2-acetylsuccinate) in a trickle, control the temperature at 10-15℃, and slowly add 15wt% disodium hydrogen phosphate solution dropwise Adjust the pH to 5.0, and the system turns into a transparent wine red. After the dia...

Embodiment 2

[0069] Use 15 g polyethylene glycol 1000 (PEG-1000) instead of 20 g polyethylene glycol 400 (PEG-400), and the rest are the same as in Example 1. The finished product is 105.6 g, the content is 90.5%, the liquid phase purity is 99.25% (238 nm), and the yield is 91.1%.

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Abstract

The invention discloses a preparing method of lemon yellow through condensing, coupling and hydrolyzing, which improves switching rate and production purity with lower organic impurity content.

Description

Technical field [0001] The invention relates to a method for preparing food coloring, in particular to a method for preparing lemon yellow. Background technique [0002] Food additives, food colorings, can be divided into two categories: synthetic colorings and natural colorings. Compared with natural pigments, synthetic pigments have the advantages of bright color, multiple shades, stable performance, strong coloring power, high fastness, easy toning, convenient use, low cost, and wide application. In addition, after hundreds of years of practice in various countries, the number has gone from a hundred species at most to thirty species. Food additives, food colorings, are widely used in food, medicine, cosmetics, paper, daily necessities, toys, new packaging materials and other fields. It can be said that the safety of synthetic colorings allowed by various countries is quite reliable. In food coloring, synthetic colorings It is much more used than natural pigments. With the rap...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09B29/036
Inventor 丁秋龙王丽斌
Owner 上海染料研究所有限公司
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