采用电位滴定法在 DMSO/ H2 O(质量比 80∶ 2 0 )混合体系中测定了磺酰脲和三唑并嘧啶磺酰胺类除草剂的酸离解常数 ,进而采用回归分析方法探讨了测得的 p Ka 值与化合物的前沿轨道能级以及取代基效应之间的相关性 ,结果较为满意 ,从而证明从该体系测得的 p Ka 值用于构效关系分析是完全可行的 The acid dissociation constants of sulfonylurea and triazolopyrimidine sulfonamide herbicides were determined by potentiometric titration in DMSO / H 2 O (mass ratio 80:20). The regression analysis was used to investigate the measured The correlation between p Ka value and the frontier orbital energy level of the compound and the substituent effect is satisfactory and the results prove that the p Ka value measured from the system is completely feasible for the structure-activity relationship analysis