|
|
|
| Regioselective oxidation of curdlan assisted by ultrasonic |
| 1.School of Food Science and Biological Technology, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.School of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong 510640, China) |
|
|
|
|
Abstract The regioselective oxidation of curdlan primary hydroxyls was conducted by 4acetamideTEMPO/NaClO/NaClO2 oxidized system at pH value of 4.7 assisted by ultrasonic. The production of oxoammonium 4acetamideTEMPO+ can be promoted by ultrasonic with increased reaction rate, and carboxylate content of oxidized products is increased about 30% for the same reaction time. The structural characterizations of oxidized products by FTIR and NMR indicate that the primary hydroxyls of curdlan are successfully oxidized to carboxylate groups assisted by ultrasonic, and the carboxylate content of resultant oxidized products is higher than that without ultrasonic. The effects of ultrasonic on molecular weight (MW) and molecular weight distribution (MWD) of oxidized products were further studied by SECMALLS. The results show that the influence of ultrasonic on MW and MWD of oxidized products is less than that of active radical species of reactive system in a given time. Compared with the situation without ultrasonic， the molecule of the oxidized products by ultrasonic is more uniform with smaller size of molecular chain.
|
|
|
|
|
|
|
|
|
2012, Vol. 33 
