compounds of the formula ## str1 ## wherein r is aliphatic hydrocarbyl , alicyclic hydrocarbyl or aryl suitably substituted , if desired , or a heterocyclic group , r 1 is hydrogen or alkyl , r 2 is alkyl or alkoxy , r 3 is ## str2 ## wherein a is 0 or 1 , r 4 is hydrogen or cw &# 39 ; 3 , the w &# 39 ; being hydrogen or halogen , z is halogen and x is halogen , hydroxy , alkoxy , acetoxy , carbethoxyalkoxy , phenoxy , alkylthio , carbethoxyalkylthio , phenylthio , phosphono , dithiophosphonoxy , phosphoramido , isocyanato , isothiocyanato , alkyl - and dialkylthiocarbamoylthio , alkyl - and dialkylcarbamoyloxy , alkylsulfonyl , etc ., have herbicidal activity .