Process for the preparation of insecticidal phenylhydrazine derivatives

Abstract

Disclosed herein is a method for making compounds having the structural formulae (I) or (II): ##STR1## wherein: X is a) phenyl; lower phenylalkoxy; phenoxy; or benzyl; or b) one substituent from group a) and one or more substituents selected from C.sub.1 -C.sub.4 alkoxy; hydroxyl; halogen; lower alkyl; and lower alkylthio; or c) along with the phenyl to which it is attached, forms a multiple fused ring heterocycle such as dibenzofuranyl; Y is H, C.sub.1 -C.sub.4 alkanoyl, C.sub.1 -C.sub.4 haloalkanoyl dialkoxyphosphoryl, alkylaminocarbonyl, haloalkylsulfonyl, or C.sub.1 -C.sub.4 alkoxy carbonyl; and R is H, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.3 -C.sub.6 cycloalkoxy, haloalkyl, alkoxyalkyl, arylalkoxy, alkenyl, alkylthio, alkoxycarbonyl, alkylamino, heteroaryl, arylalkyl, haloalkoxy, aryloxy, or C.sub.3 -C.sub.6 cycloalkyl; and Z is O or S, wherein the process comprises the steps of: A) selecting as a starting material a compound of the structural formula ##STR2## B) reacting compound III with sodium nitrite in the presence of HCl to form the diazonium salt IV ##STR3## C) adding compound IV to freshly prepared alkali metal sulfite prepared by purging sulfur dioxide into an alkali metal hydroxide until the pH is between 7.3 and 7.5, thereby forming compound V ##STR4## D) reducing compound V with an alkali metal dithionite to form compound VI ##STR5## E) hydrolyzing compound VI under aid conditions to form compound VII ##STR6## and F) acylating compound VII to form compound I.