Methods for the preparation of Benzotriazole herbicidal agents

A process for the preparation of a compound having the structure:

• ##STR40## wherein M is C--X, N or N.sup.+ --O;
• W, X, Y and Z each independently represent hydrogen, halogen, nitro, cyano, C.sub.1 -C.sub.4 haloalkyl or C.sub.1 -C.sub.4 haloalkoxy;
• R and R.sub.1 are each independently hydrogen or C.sub.1 -C.sub.4 alkyl or when taken together R and R.sub.1 may form a ring in which RR.sub.1 are represented by the structure --(CH.sub.2).sub.n -- where n is an integer of 2, 3, 4 or 5;
• R.sub.9 is C.sub.1 -C.sub.4 alkyl;
• and when R.sub.1 is C.sub.1 -C.sub.4 alkyl, the optical isomer thereof, which comprises reacting a compound having the structure:
• ##STR41## wherein B is halogen with 1.0 to 2.0 molar equivalents of a compound having the structure:
• ##STR42## wherein R, R.sub.1 and R.sub.9 are as described hereinabove in the presence of dimethyl sulfoxide at a temperature of about 80.degree. C. to 150.degree. C. to form 6-benzyloxy-2-(substituted)-amino-nitrobenzene, removing the dimethyl sulfoxide from and hydrogenating said nitrobenzene intermediate in the presence of Raney nickel and a solvent selected from the group consisting of tetrahydrofuran and a lower alkanol to form 6-benzyloxy-2-(substituted)-aminoaniline, isolating and reacting said aniline with about 1.0 to 1.1 molar equivalents of aqueous nitrous acid at a temperature of about 5.degree. C. to 10.degree. C. to form a reaction mixture, heating the reaction mixture to form 6-benzyloxy-1H-benzotriazole-.alpha.,.alpha.(disubstituted)-1-acetaldehyde dialkyl acetal, catalytically hydrogenating said 6-benzyloxy-1H-benzotriazole in the presence of palladium on carbon and a suitable solvent, isolating and reacting the resultant 6-hydroxy-1H-benzotriazole with about 1.0 to 2.0 molar equivalents of a compound having the structure:
• ##STR43## wherein B is halogen and M, W, Y and Z are as described hereinabove in the presence of dimethyl sulfoxide at a temperature of about 20.degree. C. to 100.degree. C. to form the compound having the structure IA.