A process for preparing fluorescein

A process method and fluorescein technology, applied in the field of fluorescein preparation, can solve the problems of being difficult to meet industrialized large-scale production, do not meet the requirements of green synthesis, and the catalyst is dangerous, and achieve high production and operation safety, high yield and applicable scope. wide effect

Active Publication Date: 2018-07-17
BEIJING J&K SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0014] The methanesulfonic acid used in this route is relatively corrosive and has many sulfonated by-products, which does not meet the requirements of green synthesis and is difficult to meet the needs of industrialized mass production
[0015] The above-mentioned process for preparing fluorescein has the problems of many reaction by-products and high risk of catalysts. Therefore, it is of great significance to find a green industrial production method for synthesizing fluorescein.

Method used

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  • A process for preparing fluorescein
  • A process for preparing fluorescein
  • A process for preparing fluorescein

Examples

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Effect test

example 1

[0037] Under stirring at room temperature, 30 L of toluene, 3 Kg of phthalic anhydride, 4.4 Kg of resorcinol and 200 g of citric acid were successively added to a 50 L reactor equipped with a water separator.

[0038] Heat to reflux and stir the reaction, and divide water while heating. After insulated reaction for 3 hours, use TLC spot plate to confirm that the reaction of the raw materials is complete and all of them are converted into products, and then change the water separation device to a distillation device. Atmospheric pressure distillation toluene, stop distillation after steaming about 15L toluene.

[0039] The reaction kettle was naturally cooled and crystallized overnight, filtered, and the filter cake was collected. The filter cake was beaten with 1L of pure water for 30 minutes, filtered again, and the filter cake was collected. The filter cake was vacuum-dried at 100° C. for 4 hours to obtain 6.3 kg of an orange-yellow solid with an HPLC purity of 99.5% and a...

example 2

[0042] Under stirring at room temperature, 25L of 2-methyltetrahydrofuran, 3Kg of phthalic anhydride, 4.7Kg of resorcinol and 300g of citric acid were successively added into the 50L reactor.

[0043] After heating to reflux and stirring for 3 hours, use thin-layer chromatography (TLC) spot plate to confirm that the raw materials are completely reacted and all of them are converted into products, and then a distillation device is installed. The 2-methyltetrahydrofuran was distilled at atmospheric pressure, and the distillation was stopped after about 14L of 2-methyltetrahydrofuran was distilled off.

[0044] The reaction kettle was naturally cooled and crystallized overnight, filtered, and the filter cake was collected. The filter cake was beaten with 1L of pure water for 30 minutes, filtered again, and the filter cake was collected. The filter cake was vacuum-dried at 90° C. for 5 hours to obtain 5.7 kg of an orange-yellow solid with an HPLC purity of 99.1% and a yield of 85...

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Abstract

The invention discloses a process for preparing fluorescein. The process comprises the following steps: taking critic acid as the catalyst, and reacting phthalic anhydride with resorcinol in the presence of a solvent to prepare fluorescein. The provided process for preparing fluorescein has the advantages of simple and convenient operation, low cost, high yield, safety, and high purity of finished product; the prepared fluorescein can meet the pharmaceutical requirements, and the process can be applied to industrial production.

Description

technical field [0001] The invention relates to a new method for preparing a fluorescent tracer compound, in particular to a process for preparing fluorescein. Background technique [0002] Fluorescein, also known as fluorescent yellow or fluorescent orange red, was first synthesized by Von Bayer in 1871. Its appearance is dark orange or red powder, soluble in hot ethanol, glacial acetic acid, alkali solution, showing green fluorescence, insoluble in water, benzene, chloroform and ether. The maximum absorption wavelength of fluorescein in water is 492nm, the maximum emission wavelength is 571nm, and the fluorescence quantum yield can reach 0.92 (pH>8). It emits strong green fluorescence under blue or ultraviolet light. [0003] The characteristic of green fluorescence after fluorescein dissolves makes it one of the most widely used pigments in the field of antifreeze. Fluorescein produces strong fluorescence after being stimulated, which makes it widely used in the fie...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D493/10C09K11/06
CPCC07D493/10C09K11/06C09K2211/1088
Inventor 龙韬习文兵邹增龙
Owner BEIJING J&K SCI
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