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CN-117630266-B - Method for judging vanillin oxidation end point based on thin-layer chromatography

CN117630266BCN 117630266 BCN117630266 BCN 117630266BCN-117630266-B

Abstract

The invention relates to the technical field of chemical analysis, in particular to a method for judging a vanillin oxidation end point based on thin layer chromatography, which comprises the following steps that S1, a reference substance is taken to prepare a reference liquid; S2, preparing a liquid to be detected for standby, S3, developing the control liquid obtained in S1 and the liquid to be detected obtained in S2 in a developing agent according to a thin-layer chromatography condition, confirming corresponding spots of vanilla mandelic acid, the control liquid and 3-methoxy-4-hydroxy-5-glycollic acid benzaldehyde in the liquid to be detected on a silica gel plate after the developing is completed, and S4, judging the oxidation reaction progress and the reaction time according to the diameter and the color of the vanilla mandelic acid spot in the liquid to be detected. The invention solves the technical problem that the analysis time is too long in the existing method for judging the vanillin reaction end point.

Inventors

  • WU QINWEN
  • CHEN ROU
  • YANG LINLIN
  • GAN JIANQIANG
  • HUANG ZHONGGUI
  • TANG LING
  • HONG WEI

Assignees

  • 重庆欣欣向荣精细化工股份有限公司

Dates

Publication Date
20260508
Application Date
20231129

Claims (8)

  1. 1. A method for judging the oxidation end point of vanillin based on thin-layer chromatography is characterized by comprising the following steps: S1, preparing a reference substance into a reference solution; s2, taking vanillin oxidation liquid of which the reaction progress is to be judged, adding an acidification liquid into the vanillin oxidation liquid to acidify the vanillin oxidation liquid, and shaking the vanillin oxidation liquid uniformly to prepare a liquid to be detected for standby; S3, developing the control solution obtained in the step S1 and the solution to be tested obtained in the step S2 in a developing agent according to a thin-layer chromatography condition, and confirming corresponding spots of vanilla mandelic acid, the control solution and 3-methoxy-4-hydroxy-5-glycollic acid benzaldehyde in the solution to be tested on a silica gel plate after the developing is completed, wherein the developing agent is a mixture of dichloromethane, isopropanol and glacial acetic acid, and the volume ratio of the dichloromethane, the isopropanol and the glacial acetic acid in the mixture is 8-20:2-7:1; S4, measuring the diameter (d) of the vanilla mandelic acid corresponding spot in the liquid to be detected to obtain the oxidation reaction time T 1 , simultaneously taking out a color chart and comparing the color of the vanilla mandelic acid corresponding spot in the liquid to be detected to obtain the oxidation reaction time T 2 , and if the T 1 and the T 2 are in the same interval, carrying the diameter of the vanilla mandelic acid spot in the liquid to be detected into a formula to calculate the specific reaction time, wherein the formula is T=9.55d-3.725, d is the diameter of the vanilla mandelic acid spot in the liquid to be detected, the unit is millimeter, and T is the reaction time required for minutes.
  2. 2. The method for determining an oxidation end point of vanillin according to claim 1, wherein the control solution in S1 is a solution of vanillin in an amount of 0.01-0.2% (wt).
  3. 3. The method for judging the oxidation end point of vanillin based on thin-layer chromatography of claim 1, wherein 2-10 ml of vanillin oxidation liquid is taken in the step S2, the acidizing fluid is sulfuric acid solution with the concentration of 20% -60%, and the adding amount of the acidizing fluid is 0.25-1.5 ml.
  4. 4. The method for determining the oxidation end point of vanillin based on thin-layer chromatography of claim 3, wherein the vanillin oxidation solution in S2 is oxidized for 110-120 minutes.
  5. 5. The method for determining an oxidation end point of vanillin based on thin-layer chromatography of claim 1, wherein the specific relationship between the diameter d of the vanilla mandelic acid spot in the solution to be measured and the oxidation reaction time T 1 in step S4 is: When d is less than or equal to 0mm and less than 1mm, T 1 is less than or equal to 0mm and less than 3min; When d is less than or equal to 1mm and less than 2mm, T 1 is less than or equal to 3min and less than 15min; When d is less than or equal to 2mm and less than 3mm, 15min is less than or equal to T 1 min; When d is less than or equal to 3mm and less than 4mm, 25min is less than or equal to T 1 min; When 4mm is less than or equal to d, 35min is less than or equal to T 1 .
  6. 6. The method for determining the oxidation end point of vanillin based on thin-layer chromatography of claim 1, wherein the colorimetric card in the step S4 comprises a blank background and a plurality of colored bands, and the number of the colored bands is 4-8.
  7. 7. The method for determining the oxidation end point of vanillin according to claim 1, wherein said color chart in said step S4 comprises a blank background and 5 colored bands, said colored bands include a first colored band, a second colored band, a third colored band, a fourth colored band and a fifth colored band, said first colored band RGB is (230,230,255), said second colored band RGB is (203,195,227), said third colored band RGB is (170,152,169), said fourth colored band RGB is (159,43,104), and said fifth colored band RGB is (128,0,128).
  8. 8. The method for determining an oxidation end point of vanillin according to claim 7, wherein the specific relationship between the color of the vanilla mandelic acid spot in the solution to be measured in the step S4 and the oxidation reaction time T 2 is: When the color of the vanilla mandelic acid spot in the liquid to be detected is closest to that of the colored band, the T 2 is more than or equal to 0 and less than 3 min; when the color of the vanilla mandelic acid spot in the liquid to be detected is closest to that of the colored band II, the temperature is 3min less than or equal to T 2 and less than 15min; when the color of the vanilla mandelic acid spot in the liquid to be detected is closest to that of the colored band III, 15min is less than or equal to T 2 and less than 25min; When the color of the vanilla mandelic acid spot in the liquid to be detected is closest to the color band IV, the color is 25min less than or equal to T 2 <35min; When the color of the vanilla mandelic acid spot in the liquid to be detected is closest to the color band five, 35min is less than or equal to T 2 .

Description

Method for judging vanillin oxidation end point based on thin-layer chromatography Technical Field The invention relates to the technical field of chemical analysis, in particular to a method for judging a vanillin oxidation end point based on thin-layer chromatography. Background Vanillin is also called vanillin, the academic name is 3-methoxy-4-hydroxybenzaldehyde, has special aroma of vanilla, is an indispensable important raw material in the food additive industry, and is also an important intermediate of synthetic perfume and a plurality of medicines with the largest worldwide yield. At present, a glyoxylate method is mainly adopted in China to synthesize vanillin, and the specific steps are that guaiacol and glyoxylate are taken as raw materials to synthesize 3-methoxy-4-hydroxy-phenylglycolic acid, the 3-methoxy-4-hydroxy-phenylglycolic acid is oxidized to generate 3-methoxy-4-hydroxy-vanillone, and finally the vanillin is obtained through decarboxylation. Most of domestic vanillin production companies choose to introduce air in the oxidation section to oxidize 3-methoxy-4-hydroxy-phenylglyoxylic acid. However, if the aeration time is too long in the oxidation process, more impurities and tar are generated in the reaction, which reduces the quality of vanillin production and increases the environmental protection treatment cost. Insufficient aeration time may result in incomplete conversion of 3-methoxy-4-hydroxy-benzilic acid, reducing yield and productivity. Therefore, the effective judgment of the oxidation end point in the production of vanillin has important significance for improving the oxidation yield and the production efficiency and controlling the quality index of vanillin products. In the prior art, traditional analysis and detection methods are mostly adopted for judgment, such as spectrophotometry, high performance liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry and the like, and the method judges the progress degree of oxidation reaction by detecting the content of each substance in reaction liquid. However, the above method requires too long detection time to be suitable for rapid and accurate judgment in such industrial production process. Therefore, the thin-layer chromatography identification method for accurately and rapidly judging the oxidation end point of vanillin is developed, the production efficiency of an oxidation reaction section can be improved, the oxidation yield can be improved, the problems of poor product quality, large tar treatment amount in wastewater at an environment-friendly place and the like caused by overlong oxidation time can be avoided, and the method has important significance for subsequent production. Disclosure of Invention The invention aims to provide a method for judging a vanillin oxidation end point based on thin-layer chromatography, which aims to solve the technical problem that the analysis time is too long in the existing method for judging the vanillin reaction end point. In order to achieve the aim, the invention adopts the following technical scheme that the method for judging the oxidation end point of vanillin based on thin layer chromatography is characterized by comprising the following steps: S1, preparing a reference substance into a reference solution; s2, taking vanillin oxidation liquid of which the reaction progress is to be judged, adding an acidification liquid into the vanillin oxidation liquid to acidify the vanillin oxidation liquid, and shaking the vanillin oxidation liquid uniformly to prepare a liquid to be detected for standby; S3, taking the control solution obtained in the step S1 and the solution to be detected obtained in the step S2, developing in a developing agent according to a thin-layer chromatography condition, and confirming corresponding spots of vanilla mandelic acid, the control solution and 3-methoxy-4-hydroxy-5-glycollic acid benzaldehyde in the solution to be detected on a silica gel plate after developing is completed; S4, measuring the diameter (d) of the corresponding spot of the vanilla mandelic acid in the liquid to be detected to obtain the further oxidation reaction time T 1, simultaneously taking out the color chart and comparing the color chart with the corresponding spot of the vanilla mandelic acid in the liquid to be detected to obtain the further oxidation reaction time T 2, and if the T 1 and the T 2 are in the same interval, carrying the diameter of the vanilla mandelic acid spot in the liquid to be detected into a formula to calculate the specific reaction time. The principle and the advantages of the scheme are as follows: According to the method, a thin-layer chromatography method is used for judging the oxidation end point of vanillin, spots corresponding to vanillin in the liquid to be detected can be identified on a thin-layer chromatography silica gel plate through a color reaction, the diameter and the color of the spots corre