Abstract: This paper focuses on the synthesis and application of 3-mercaptopropionic acid.
Key words: 3-mercaptopropionic acid, synthesis, application
3-mercaptopropionic acid is an intermediate of pharmaceutical fennel. It can also be used to prepare cross-linking agents, hardeners, resin additives, antioxidants, catalysts and biochemical reagents. It can also be used as a raw material for PVC heat stabilizers. Due to the unique performance of β-mercaptopropionic acid, the market prospect is very broad. However, it is produced only by the third pharmaceutical factory in Northeast China. It adopts the thiourea method, which has low product content, long reaction time, complicated process, high cost and large amount of waste. Therefore, it is of great significance to study the synthesis of 3-mercaptopropionic acid.
Synthesis of 1 3-mercaptopropionic acid
1.1 Synthesis mechanism of 3-mercaptopropionic acid
The synthesis of 3-mercaptopropionic acid is carried out as follows:
The competitive reaction between the two products obtained in the reaction (1) and the continued addition of the AN (2) (3) is the key factor affecting the yield of the target product. The occurrence of (2) can be reduced by adding an appropriate amount of sulfur powder, and (3) the resulting dithiodipropionic acid can be reduced by zinc powder to form 3-mercaptopropionic acid.
1.2 Reaction steps
In a 1000 ml three-necked flask, 261.3 g, a 30% aqueous sodium hydrosulfide solution, and 2.7 g of sulfur powder were placed. After heating and dissolving, 53 g of acrylonitrile was added dropwise at 45 ° C for 1.5 h, fully reacted for 2 h, acidified with 254 ml of concentrated hydrochloric acid, refluxed with water 81 g at 110-112 ° C for 3 h, cooled to 80-90 ° C, and 44 g of zinc powder was added, with hydrochloric acid. The pH was adjusted to 1 to 2 to obtain an aqueous solution of 3-mercaptopropionic acid.
1.3 Purification of 3-mercaptopropionic acid
The β-mercaptopropionic acid aqueous solution was extracted with ethyl acetate and repeated three times to obtain an organic phase. The organic phase was distilled off at 0.095 MPa to obtain a crude product. The crude product was subjected to vacuum distillation, and a fraction of 100 ° C to 102 ° C was collected at 665 Pa to obtain a colorless transparent liquid. The purity of 3-mercaptopropionic acid was determined by iodometric method.
2. 3-mercaptopropionic acid application
Preparation of 3-mercaptopropionic acid stabilized CdSe quantum dots
CdSe quantum dots are important II-VI semiconductor nanomaterials, which have been widely used in solar cells, fluorescent labeling and chemical analysis. The Na2SeO3 was reduced by NaBH4, and CdSe quantum dots with 3-mercaptopropionic acid as stabilizer were prepared by heating and refluxing, which provided a simple and effective method for the synthesis of high quality water-soluble CdSe quantum dots.
3. Preparation of 3-mercaptopropionic acid self-assembled gold electrode
3-mercaptoacetic propionic acid (MPA) self-assembled membrane modified gold electrode, and then characterized by cyclic voltammetry, alternating current impedance and other electrochemical methods. The effective surface area of the electrode was 1.97×10- 2cm2. The electrochemical behavior of uric acid (UA) on the modified electrode was studied. The results show that the MPA/SAM/Au electrode has good stability and electrochemical activity, and the disodium hydrogen phosphate-lime at pH=6.0 In the acid (Na2HPO4-C6H8O7) buffer solution, the peak current of the UA response of the MPA/SAM/Au electrode is larger than that of the bare gold electrode. The oxidation peak current and uric acid concentration have a good linear relationship in the concentration range of 1.6×10-4～1×10-6mol/L. The linear regression equation is ip/(μA)=0.7389+0.04046c0/( Μmol/L), correlation coefficient R=0.9986, detection limit is 5×10-7mol/L.