QUANTITATIVE STRUCTURE ACTIVITY INVESTIGATIONS ON NOVEL HOMOLOGOUS SERIES OF ORGANIC PHOSPHATE

Abstract

Di ethyl aryl phosphate pesticides used in this work have been synthesized by the reaction of different ortho substituted phenols with excess of 0,0-diethylchloro­ phosphate in the presence of triethylamine as a base to precipitate the resulted hydrochloric acid. The reaction g oes smoothly in toluene at room temperature or below Jin good yields. The phenolic compounds with on ortho ester or i amide group were prepared by esterification with excess of

1 f methanol or ethanol to insure reaction completion. The ll resulted methyl salicylate reacted faster than ethyl salicy­ l ate with d iphenylamine to yield crystals of diphenylamide. The synthesized organophosphorus compounds were subjected to G.C anal ysis in order to check purity and assure identifi ca­ tion. G.C-MS analysis had been used to determine the degree , of purity and conform the molecular structure. The resolu­

tion of G.C was fairly good to allow accurate determination. Electron Impact (EI) technique has been used in MS analysis. The major peaks in the spectrum of each compound have been identifi ed for structural conformation. FT-IR analysis of the synthesi zed organophosphorus compounds were performed and the characteristi c peaks were tentatively identified.

Absorbance of the synthesized organophosphorus compounds in relation to wavelength were studied by using U.V.spectro­ photometery. The biological acti vity of the synthesized organophosphorus compounds were studied against mosquito, nematode and fungi under laboratory conditions. 0,0-d i ethyl- 0-(2-N,N- diphenylcarbamoylphenyl) phosphate proved superior biol ogical activity against all the tested organisms, 0,0- diethyl-0-(2-methylphenyl) phosphate proved distinguished fungicidal activity, but was slightly effective against mosquito. As for organism species, the compounds 0,0- diethyl-0-(2-N,N-diphenylcarbamoylphenyl) nJO,O-diethy l-0-(2ethoxycarbamoylphenyl) phosphate and phosphate showed t·superi or insecti cidal activity against Culex pipien s.

For nematode the compounds 0,0-diethyl-0-(2-N,N-diphenyl- carbamoylphenyl) phosphate and 0,0-diethyl-0-(2-methylphenyl) phosphate proved excell ent nematicidal activity, but in values vari ed accordi ng to the tested concentrations. As for fungus diseases. products could be arranged according to their fungitoxic effects in the following descending order: 0,0-diethyl-0-(2-methylphenyl)phosphate,O,O-diethyl-0-(2-N,N­ diphenylcarbamoylphenyl) phosphate, 0,0-diethyl-0-(phenyl) pl1osphate, 0.0-diethyl-0-(2-ethoxycarbamoylphenyl) phosphate and 0,0-diethyl-0-(2-methoxycarbonylphenyl) phosphate.