Herbicidal Activity and Persistency in Aqueous Solution of Ortho Disubstituted Benzenesulfonyl Urea Derivatives

새로운 Ortho 이치환 Benzenesulfonyl Urea 유도체의 제초활성과 수용액중의 잔류성

The new sixteen herbicidal N-2-(1-hydroxy-2-fluoroethyl)-6-substituted(X)-benzenesulfonyl-N'-4,6-dimethoxypyrimidinyl-2-yl urea derivatives(S) were synthesized and thier herbicidal activities$(pI_{50})$ in vivo against rice(Orysa Sativa L.), Barnyard grass(Echninochloa orizicola) and Bulrush(Scirpus juncoides) were measured by the pot test under paddy conditions. The structure activity relationship(SAR) were studied using the physicochemical parameters of ortho-substituents(X) and hydrolysis rate constant(logk) and herbicidal activities by the multiple regression technique. The SAR suggested that the herbicidal activities were more dependant on the hydrolysis rate constant(logk>0) than the steric constants $(Es, small width($B_4$) and length($L_1$). Among them, halogens(2 & 5), methyl(15) and non(H) substituent(1) showed higher herbicidal activity for weeds which was not tolerent to rise and weeds. The herbicidal activity was increased and the persistency in aqueous solution was decreased by electron donating(${\sigma}0<0$) groups as ortho-substituent(X). From the relationship equation between herbicidal activity and hydrolysis rate constant, it was assumed that the both reactions would be proceeds with similar process. And the conditions on the ortho substituents to show higher herbicidal activity and the persistency in aqueous solution were also discussed.

새로운 16종의 ortho 이치환 benzenesulfonyl urea계 제초성 화합물인 N-2-(1-hydroxy-2-fluoroethyl)-6-치환(X)-benzenesulfonyl-N'-4,6-dimethoxypyrimidinyl-2-yl urea 유도체들을 합성하고 벼(Orysa sativa L.)를 위시하여 논 잡초인 강피(Echninochloa orizola) 및 올챙이고랭이(Scirpus juncoides)를 대상으로 측정된 제초활성값$(pI_{50})$과 ortho-치환기{X)들의 변화에 따른 물리-화학적 파라미터와 가수분해 반응 속도상수로 부터 구조-활성 관계(SAR)를 검토하였다. 잡초들의 제초활성에 미치는 물리-화학적 파라미터의 영향은 입체상수가 음의값$(Es,\;L_1,$ 및 $B_4<0)$이고 반응 속도상수는 양의 값(logk>0)으로 ortho-치환기에 의한 입체효과보다 반응속도 상수에 의존적이었다. 초종간의 선택성은 나타나지 않았으나, 강피>볍씨>올챙이고랭이>벼 3엽기의 순으로 halogen(2 및 5), methyl(15) 및 비(H)치환체(1) 등이 가장 큰 제초활성을 보였다. Ortho-치환기(X)는 전자를 밀수록 제초활성이 증가되었고 수용액 중에서 잔류성은 단축되었으며 pH 6.0의 $45^{\circ}C$에서 반감기(T1/2)는 14시간${sim}$58일 범위였다. 그리고 가수분해와 제초활성 반응이 유사한 경로로 진행될 것임을 예상 할 수 있었다.