乙酰水杨酸在微乳液中水解动力学研究

Hydrolysis Kinetic Study of Aspirin in Microemulsions

用紫外分光光度法研究了乙酰水杨酸在十六烷基三甲基溴化铵(CTAB)/正丁醇/25%正辛烷/H_2O微乳液体系中水解动力学,探讨了反应机理.结果表明,微乳液结构和结构转变点对乙酰水杨酸水解有影响.水解速率在油包水(W/O)微乳液结构介质中较大,且随水含量增加而减小,双连续(B.C.)微乳液结构中随水含量增加而变大;水包油(O/W)微乳液结构中随水含量增加而减小.而水解反应速率转变点发生在微乳液结构由W/O到B.C.再到O/W转变点处,认为是水解反应机理不同和界面膜极性改变造成的.

The hydrolysis kinetics of aspirin in micro emulsion system for cetyltrimethyl -ammonium bromide (CTAB) /n - butanol/2 % n - octane/water was studied by using UV method, and the mechanism of the hydrolysis was discussed. The results show that the hydrolysis was affected by the structure and the structural transition of microemulsions. The hydrolysis rates are higher in W/O microemulsion media and decrease with the addition of water, they increase with that in B. C. , and they decrease with that in O/W. The transition points of the hydrolysis rates occur at the points of the structural transition from W/O to B. C. , and B. C. to O/W, and this was considered to be caused by the different hydrolysis mechanism and the change of polarity in interfacial films.