O-PYRAZOLOPYRIMIDINE-(THIONO)-PHOSPHORIC (PHOSPHONIC) ACID ESTERS, PROCESS FOR THEIR PRODUCTION AND R USE AS INSECTICIDES AND ACARICIDES

1397997 Organophosphorus esters containing a pyrazolopyrimidine ring BAYER AG 23 Aug 1973 [23 Aug 1972] 39938/73 Headings C2P and C2C Novel compounds of the general formula in which R 1 is C 1 -C 6 alkyl, R 2 is C 1 -C 4 alkyl, C 1 -C 6 alkoxy, or phenyl, R 3 is H, Cl or Br and X is O or S are obtained by reacting an ester halide with a hydroxy derivative of the formula in the presence of an acid acceptor, or in the form of an alkali metal-, alkaline earth metal- or ammonium salt. The reaction is preferably carried out in a diluent or solvent and preferred reaction temperatures are 25‹ to 65‹ C. The products have insecticidal and acaricidal properties and may be used as active ingredients in conventional pesticidal formulations. 2 - Hydroxy - 5 - methyl - pyrazolo - (1,5 - α - )- pyrimidine is obtained by adding ethylformate and acetone to a suspension of sodium methylate in dry ether, stirring the mixture overnight, cooling the mixture, dissolving it in water and then adding thereto a mixture of aminopyrazolone, water and glacial acetic acid to precipitate the product. Treatment of the product with chlorine and bromine respectively in glacial acetic at 70‹ C. yields the corresponding 2- hydroxy - 3 - chloro (or 3 - bromo) - 5 - methylpyrazolopyrimidine derivative.