ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of substituents and their position in the benzene nucleus on the insecticide activity of the phenyl-substituted O,O-dimethyl O-phenyl thiophosphates, O,O-diethyl O-phenyl thiophosphates, and N-methyl phenyl carbamates

M. Furdík, J. Drábek, I. Locigová, and J. Ondrejka

Komenský University, Bratislava

Abstract: Nine phenyl-substituted O,O-dialkyl O-phenyl thiophosphates and 3 N-methyl phenyl carbamates were prepd., their insecticidal activity measured, and compared with that of Fosfotion and Tedion. Nine thiophosphates of the general formula (RO)₂PSOR' were prepd. from the resp. substituted phenol and the dialkyl chlorothiophosphate by the methods of Schrader, and Razumov (CA 52, 4018e) which were modified by raising the reaction time from 1 to 6 hrs. in order to increase the yield. Yields ranged from 63 to 80%. Three carbamates of the general formula MeNHCOOR were prepd. from the resp. substituted phenol and methyl isocyanate. The insecticidal activities yields of these 12 compds. were measured and compared with Fosfotion and Tedion against Musca domestica, Tetranychus urticae (eggs and females), and Calandra granaria. The results are tabulated and an explanation of the relation between the structure and insecticidal activity of the examd. compds. is offered: aryl esters with the aromatic nucleus substituted by groups with higher Hammett's σ const. hydrolyze more readily; such substitution increases the insecticidal activity of the dialkyl aryl thiophosphates which act through the products of their hydrolysis; in contrast the activity of the N-alkyl aryl carbamates which are effective as the unhydrolyzed mol., decreases with such substitution.

Full paper in Portable Document Format: 209a650.pdf (in Slovak)

Chemical Papers 20 (9) 650–660 (1966)